SPECIFICATIONS

TIGHTENING SPECIFICATIONS

DIAGRAMS AND SCHEMATICS

ECM WIRING DIAGRAM (1 of 10)

ECM WIRING DIAGRAM (2 of 10)

ECM WIRING DIAGRAM (3 of 10)

ECM WIRING DIAGRAM (4 of 10)

ECM WIRING DIAGRAM (5 of 10)

ECM WIRING DIAGRAM (6 of 10)

ECM WIRING DIAGRAM (7 of 10)

ECM WIRING DIAGRAM (8 of 10)

ECM WIRING DIAGRAM (9 of 10)

ECM WIRING DIAGRAM (10 of 10)

ECM PINOUTS

ECM Pinout Table, 32–Pin Red Connector

– Row ”A”

ECM Pinout Table, 32–Pin Red Connector

– Row ”B”

ECM Pinout Table, 32–Pin White Connector

– Row ”C”

ECM Pinout Table, 32–Pin White Connector

– Row ”D”

ECM Pinout Table, 32–Pin White Connector

– Row ”E”

ECM Pinout Table, 32–Pin White Connector

– Row ”F”

COMPONENT LOCATOR

Undercarriage Component Locator Table

Fuse And Relay Panel (Underhood

Electrical Center)

DIAGNOSIS Strategy–Based Diagnostics

Strategy–Based Diagnostics

DTC Stored

No DTC

No Matching Symptom

Intermittents

No Trouble Found

Verifying Vehicle Repair

GENERAL SERVICE INFORMATION

Non–OEM Parts

Environment

Emissions Control Information Label

Maintenance Schedule

Visual/Physical Engine Compartment

Inspection

Basic Knowledge Of Tools Required

SERIAL DATA COMMUNICATIONS

Class II Serial Data Communications

ON–BOARD DIAGNOSTIC (OBD)

On–Board Diagnostic Tests

Comprehensive Component Monitor

Diagnostic Operation

Common OBD Terms

The Diagnostic Executive

DTC Types

Verifying Vehicle Repair

Reading Diagnostic Trouble Codes Using

A Tech 2 Scan Tool

Tech 2 Features

Getting Started

Operating Procedure (Example)

DTC Modes

DTC Information Mode

Miscellaneous Test

Lamps Test

Relays Test

EVAP Test

Idle Air Control System Test

Fuel System Test

EGR Control Test

Injector Balance Test

Plotting Snapshot Graph

Plotting Graph Flow Chart (Plotting graph

after obtaining vehicle information)

Flow Chart for Snapshot Replay (Plotting

Graph)

PRIMARY SYSTEM–BASED DIAGNOSTICS

Primary System–Based Diagnostics

Fuel Control Heated Oxygen Sensors

HO2S Heater

ON–BOARD DIAGNOSTIC (OBD) SYSTEM

CHECK

Circuit Description

Diagnostic Aids

Test Description

A/C CLUTCH CONTROL CIRCUIT

DIAGNOSIS

Circuit Description

Diagnostic Aids

A/C Clutch Diagnosis

ELECTRONIC IGNITION SYSTEM

DIAGNOSIS

VISUAL CHECK OF THE EVAPORATIVE

EMISSION CANISTER

SECTION 6E1 - ENGINE DRIVEABILITY AND EMISSIONS

Techline

IDLE AIR CONTROL (IAC) VALVE

ENGINE CONTROL MODULE (ECM)

DIAGNOSIS

MULTIPLE ECM INFORMATION SENSOR

DTCs SET

Circuit Description

Diagnostic Aids

EXHAUST GAS RECIRCULATION (EGR)

DIAGNOSIS

ENGINE Tech 2 DATA DEFINITIONS AND

RANGES

TYPICAL SCAN DATA VALUES

Test Conditions

2.2L L–4 Engine

NO MALFUNCTION INDICATOR LAMP

(MIL)

Circuit Description

Diagnostic Aids

Test Description

MALFUNCTION INDICATOR LAMP (MIL) ON

STEADY

Circuit Description

Diagnostic Aids

Test Description

ENGINE CRANKS BUT WILL NOT RUN

Circuit Description

Diagnostic Aids

FUEL SYSTEM ELECTRICAL TEST

Circuit Description

Diagnostic Aids

Test Description

Fuel Pressure Relief Procedure

Fuel Gauge Installation

FUEL SYSTEM DIAGNOSIS

Circuit Description

Test Description

Fuel Pressure Relief Procedure

Fuel Gauge Installation

IDLE AIR CONTROL (IAC) SYSTEM CHECK

Circuit Description

Diagnostic Aids

EXHAUST GAS RECIRCULATION (EGR)

SYSTEM CHECK

Circuit Description

Diagnostic Aids

MANIFOLD ABSOLUTE PRESSURE (MAP)

OUTPUT CHECK

Circuit Description

Test Description

ECM DIAGNOSTIC TROUBLE CODES

ECM Diagnostic Trouble Codes

DIAGNOSTIC TROUBLE CODE (DTC) P0106

MANIFOLD ABSOLUTE PRESSURE (MAP)

CIRCUIT/RANGE PERFORMANCE

PROBLEM

DIAGNOSTIC TROUBLE CODE (DTC) P0107

MANIFOLD ABSOLUTE PRESSURE (MAP)

SENSOR CIRCUIT LOW INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P0108

MANIFOLD ABSOLUTE PRESSURE (MAP)

CIRCUIT HIGH INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P0112

INTAKE AIR TEMPERATURE (IAT) SENSOR

CIRCUIT LOW INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P0113

INTAKE AIR TEMPERATURE (IAT) SENSOR

CIRCUIT HIGH INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P0117

ENGINE COOLANT TEMPERATURE (ECT)

SENSOR CIRCUIT LOW INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P0118

ENGINE COOLANT TEMPERATURE (ECT)

SENSOR CIRCUIT HIGH INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P0121

THROTTLE POSITION (TP) SENSOR

CIRCUIT RANGE/PERFORMANCE

PROBLEM

DIAGNOSTIC TROUBLE CODE (DTC) P0122

THROTTLE POSITION (TP) SENSOR

CIRCUITLOW INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P0123

THROTTLE POSITION (TP) SENSOR

CIRCUIT HIGH INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P0131

O2 SENSOR CIRCUIT LOW VOLTAGE

(BANK 1 SENSOR 1)

DIAGNOSTIC TROUBLE CODE (DTC) P0132

O2 SENSOR CIRCUIT HIGH VOLTAGE

(BANK 1 SENSOR 1)

DIAGNOSTIC TROUBLE CODE (DTC) P0134

O2 SENSOR CIRCUIT NO ACTIVITY

DETECTED (BANK 1 SENSOR 1)

DIAGNOSTIC TROUBLE CODE (DTC) P0135

O2 SENSOR HEATER CIRCUIT

MALFUNCTION

DIAGNOSTIC TROUBLE CODE (DTC) P0171

SYSTEM TOO LEAN (BANK 1)

DIAGNOSTIC TROUBLE CODE (DTC) P0172

SYSTEM TOO RICH (BANK 1)

DIAGNOSTIC TROUBLE CODE (DTC) P0201

INJECTOR CIRCUIT MALFUNCTION –

CYLINDER 1

DIAGNOSTIC TROUBLE CODE (DTC) P0202

INJECTOR CIRCUIT MALFUNCTION –

CYLINDER 2

DIAGNOSTIC TROUBLE CODE (DTC) P0203

INJECTOR CIRCUIT MALFUNCTION –

CYLINDER 3

DIAGNOSTIC TROUBLE CODE (DTC) P0204

INJECTOR CIRCUIT MALFUNCTION –

CYLINDER 4

DIAGNOSTIC TROUBLE CODE (DTC) P0325

KNOCK SENSOR (KS) CIRCUIT

MALFUNCTION

DIAGNOSTIC TROUBLE CODE (DTC) P0327

KNOCK SENSOR (KS) CIRCUIT LOW

INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P0336

CRANKSHAFT POSITION (CKP) SENSOR

CIRCUIT RANGE/PERFORMANCE

DIAGNOSTIC TROUBLE CODE (DTC) P0337

CRANKSHAFT POSITION (CKP) SENSOR

CIRCUIT LOW INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P0341

CAMSHAFT POSITION (CMP) SENSOR

CIRCUIT RANGE/PERFORMANCE

DIAGNOSTIC TROUBLE CODE (DTC) P0342

CAMSHAFT POSITION (CMP) SENSOR

CIRCUIT LOW INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P0351

IGNITION COIL ”A” PRIMARY/SECONDARY

CIRCUIT MALFUNCTION

DIAGNOSTIC TROUBLE CODE (DTC) P0352

IGNITION COIL ”B” PRIMARY/SECONDARY

CIRCUIT MALFUNCTION

DIAGNOSTIC TROUBLE CODE (DTC) P0401

EXHAUST GAS RECIRCULATION (EGR)

FLOW INSUFFICIENT DETECTED

DIAGNOSTIC TROUBLE CODE (DTC) P0402

EXHAUST GAS RECIRCULATION (EGR)

EXCESSIVE FLOW DETECTED

DIAGNOSTIC TROUBLE CODE (DTC) P0404

EXHAUST GAS RECIRCULATION (EGR)

CIRCUIT RANGE/PERFORMANCE

DIAGNOSTIC TROUBLE CODE (DTC) P0405

EXHAUST GAS RECIRCULATION (EGR)

SENSOR CIRCUIT LOW

DIAGNOSTIC TROUBLE CODE (DTC) P0406

EXHAUST GAS RECIRCULATION (EGR)

SENSOR CIRCUIT HIGH

DIAGNOSTIC TROUBLE CODE (DTC) P0443

EVAPORATIVE EMISSION (EVAP)

CONTROL SYSTEM PURGE CONTROL

VALVE CIRCUIT MALFUNCTION

DIAGNOSTIC TROUBLE CODE (DTC) P0480

COOLING FAN 1 CONTROL CIRCUIT

MALFUNCTION

DIAGNOSTIC TROUBLE CODE (DTC) P0481

COOLING FAN 2 CONTROL CIRCUIT

MALFUNCTION

DIAGNOSTIC TROUBLE CODE (DTC) P0502

VEHICLE SPEED SENSOR (VSS) CIRCUIT

LOW INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P0506

IDLE CONTROL SYSTEM RPM LOWER

THAN EXPECTED

DIAGNOSTIC TROUBLE CODE (DTC) P0507

IDLE CONTROL SYSTEM RPM HIGHER

THAN EXPECTED

DIAGNOSTIC TROUBLE CODE (DTC) P0563

SYSTEM VOLTAGE HIGH

DIAGNOSTIC TROUBLE CODE (DTC) P0601

INTERNAL CONTROL MODULE MEMORY

CHECK SUM ERROR

DIAGNOSTIC TROUBLE CODE (DTC) P1106

MANIFOLD ABSOLUTE PRESSURE (MAP)

SENSOR CIRCUIT INTERMITTENT HIGH

VOLTAGE

DIAGNOSTIC TROUBLE CODE (DTC) P1107

MANIFOLD ABSOLUTE PRESSURE (MAP)

SENSOR CIRCUIT INTERMITTENT LOW

VOLTAGE

DIAGNOSTIC TROUBLE CODE (DTC) P1111

INTAKE AIR TEMPERATURE (IAT) SENSOR

CIRCUIT INTERMITTENT HIGH VOLTAGE

DIAGNOSTIC TROUBLE CODE (DTC) P1112

INTAKE AIR TEMPERATURE (IAT) SENSOR

CIRCUIT INTERMITTENT LOW VOLTAGE

DIAGNOSTIC TROUBLE CODE (DTC) P1114

ENGINE COOLANT TEMPERATURE (ECT)

SENSOR CIRCUIT INTERMITTENT LOW

VOLTAGE

DIAGNOSTIC TROUBLE CODE (DTC) P1115

ENGINE COOLANT TEMPERATURE (ECT)

SENSOR CIRCUIT INTERMITTENT HIGH

VOLTAGE

DIAGNOSTIC TROUBLE CODE (DTC) P1121

THROTTLE POSITION (TP) SENSOR

CIRCUIT INTERMITTENT HIGH

VOLTAGE

DIAGNOSTIC TROUBLE CODE (DTC) P1122

THROTTLE POSITION (TP) SENSOR

CIRCUIT INTERMITTENT LOW

VOLTAGE

DIAGNOSTIC TROUBLE CODE (DTC) P1171

FUEL SYSTEM LEAN DURING

ACCELERATION

DIAGNOSTIC TROUBLE CODE (DTC) 1404

EXHAUST GAS RECIRCULATION (EGR)

CLOSED VALVE

DIAGNOSTIC TROUBLE CODE (DTC) P1625

ECM UNEXPECTED RESET

DIAGNOSTIC TROUBLE CODE (DTC) P1627

PCM A/D CONVERSION MALFUNCTION

DIAGNOSTIC TROUBLE CODE (DTC) P1635

5 VOLT REFERENCE VOLTAGE CIRCUIT

MALFUNCTION

DIAGNOSTIC TROUBLE CODE (DTC) P1640

ODM OUTPUT CIRCUIT FAULT

SYMPTOM DIAGNOSIS

DEFAULT MATRIX TABLE

Camshaft Position (CMP) Sensor

Crankshaft Position (CKP) Sensor

EEPROM

Engine Coolant Temperature (ECT) Sensor

Heated Oxygen Sensor (HO2S)

Intake Air Temperature (IAT) Sensor

Manifold Absolute Pressure (MAP) Sensor

Malfunction Indicator Lamp (MIL)

Engine Control Module (ECM)

Throttle Position (TP) Sensor

Vehicle Speed Sensor (VSS)

Air Filter

Idle Air Control (IAC) Valve

Intake Air Duct

Knock Sensor

Oil Pressure Switch

FUEL METERING SYSTEM

Accelerator Cable Assembly

Accelerator Pedal Replacement

Fuel Filler Cap

Fuel Filter

Fuel Injectors

Fuel Pressure Regulator

Fuel Pump Assembly

Fuel Pump Relay

Fuel Rail Assembly

Fuel Tank

Throttle body (TB)

ELECTRONIC IGNITION SYSTEM

Ignition Control Module (ICM)

Ignition Coil

Spark Plugs

Spark Plug Cables

EMISSIONS Catalytic Converter

Air Conditioning Relay

Ignition Timing Adjustment

EVAP Canister Hoses

EVAP Canister

Linear Exhaust Gas

Recirculation (EGR) Valve

Wiring and Connectors

ECM Connectors And Terminals

Connectors And Terminals

Wire Harness Repair: Twisted Shielded

Cable

Twisted Leads

Weather–Pack Connector

Com–Pack III

Metri–Pack

GENERAL DESCRIPTION — ECM AND

SENSORS

58X Reference ECM Input

A/C Request Signal

Crankshaft Position (CKP) Sensor

Camshaft Position (CMP) Sensor And

Signal

Engine Coolant Temperature (ECT) Sensor

Electrically Erasable Programmable Read

Only Memory (EEPROM)

Fuel Control Heated Oxygen Sensor

(Pre Catalyst)

Intake Air Temperature (IAT) Sensor

Linear Exhaust Gas Recirculation (EGR)

Control

Manifold Absolute Pressure (MAP) Sensor

Engine Control Module (ECM)

ECM Function

ECM Components

ECM Voltage Description

ECM Inputs/Outputs

ECM Service Precautions

Throttle Position (TP) Sensor

Transmission Range Switch

Vehicle Speed Sensor (VSS)

Use of Circuit Testing Tools

Aftermarket Electrical And Vacuum

Equipment

Electrostatic Discharge Damage

GENERAL DESCRIPTION — AIR

INDUCTION

Air Induction System

GENERAL DESCRIPTION — FUEL

METERING

Acceleration Mode

Accelerator Controls

Battery Voltage Correction Mode

CMP Signal

Clear Flood Mode

Deceleration Fuel Cutoff (DFCO) Mode

Engine Speed/Vehicle Speed/ Fuel

Disable Mode

Fuel Cutoff Mode

Fuel Injector

Fuel Metering System Components

Fuel Metering System Purpose

Fuel Pressure Regulator

Fuel Pump Electrical Circuit

Fuel Rail

Idle Air Control (IAC) Valve

Run Mode

Starting Mode

Throttle Body Unit

GENERAL DESCRIPTION — ELECTRONIC

IGNITION SYSTEM

Camshaft Position (CMP) Sensor

Crankshaft Position (CKP) Sensor

Electronic Ignition

Ignition Coils

Ignition Control

Ignition Control Module (ICM)

Ignition Control ECM Output

Engine Control Module (ECM)

Spark Plug

A/C CLUTCH DIAGNOSIS

A/C Clutch Circuit Operation

A/C Clutch Circuit Purpose

A/C Request Signal

GENERAL DESCRIPTION — EVAPORATIVE

EMISSION (EVAP) SYSTEM

EVAP Emission Control System Purpose

EVAP Emission Control System Operation

GENERAL DESCRIPTION — EXHAUST

GAS RECIRCULATION (EGR) SYSTEM

EGR Purpose

Linear EGR Valve

Linear EGR Control

Linear EGR Valve Operation And Results

Of Incorrect Operation

EGR Pintle Position Sensor

GENERAL DESCRIPTION — POSITIVE

CRANKCASE VENTILATION (PCV)

SYSTEM

Crankcase Ventilation System Purpose

SPECIAL TOOLS

SPECIFICATIONS

TIGHTENING SPECIFICATIONS

Application N–m Lb Ft kg·m Lb In

Crankshaft Position Sensor Mounting Bolt 9 0.9 — 78

EGR Nut 14 1.4 — 130

Engine Coolant Temperature Sensor 30 3.1 22 —

Fuel Drain Plug 20 2.0 14 —

Fuel Pressure Regulator Attaching Screw 6.5 0.6 — 60

Fuel Rail Bolts 7 0.7 — 75

Fuel Tank Undercover Retaining Bolts 36 3.7 27 —

Heated Oxygen Sensor 42 4.3 32 —

Spark Plugs 25 2.5 18 —

Throttle Body Mounting Bolts 13 1.3 — 120

VSS Retaining Bolt 13 1.3 — 120

DIAGRAMS AND SCHEMATICS

ECM WIRING DIAGRAM (1 of 10)

D06RX097

ECM WIRING DIAGRAM (2 of 10)

060RX091

ECM WIRING DIAGRAM (3 of 10)

D06RX099

ECM WIRING DIAGRAM (4 of 10)

060RX095

ECM WIRING DIAGRAM (5 of 10)

D06RX119

ECM WIRING DIAGRAM (6 of 10)

D06RX102

ECM WIRING DIAGRAM (7 of 10)

D06RX103

ECM WIRING DIAGRAM (8 of 10)

D06RX104

ECM WIRING DIAGRAM (9 of 10)

D06RX105

ECM WIRING DIAGRAM (10 of 10)

D06RX106

ECM PINOUTS

ECM Pinout Table, 32–Pin Red Connector – Row ”A”

TS23344

PIN PIN Function Wire Color IGN ON ENG RUN Refer To

A1 5 Volt Reference Signal RED 5.0 V 5.0 V Appropriate Sensor

A2 Knock Sensor Input YEL —3.0 V (MAX) General Description and

Operation, Knock Sensor

A3 Not Used —

A4 Battery Feed RED/WHT B+ B+ Chassis Electrical

A5 Idle Air Control (IAC) ”A”

High BLU B+/0.8 V B+/0.8 V General Description and

Operation, IAC

A6 IAC ”A” Low BLU/WHT B+/0.8 V B+/0.8 V General Description and

Operation, IAC

A7 IAC ”B” Low BLU/BLK B+/0.8 V B+/0.8 V General Description and

Operation, IAC

A8 IAC ”B” High BLU/RED B+/0.8 V B+/0.8 V General Description and

Operation, IAC

A9 Not Used — — — —

A10 Not Used — — — —

A11 Not Used — — — —

A12 Not Used — — — —

A13 Malfunction Indicator

Lamp (MIL) Control WHT/GRN 0.4–0.9 V B+ Chassis Electrical

A14 Rear Defogger Relay RED/WHT B+ B+ Classis Electrical

A15 EVAP Canister Vent

Solenoid Control RED/BLU B+ 0–5 V

(varies) General Description and

Operation, EVAP Emission

Control System

A16 Not Used — — — —

ECM Pinout Table, 32–Pin Red Connector – Row ”B”

TS23344

PIN Function Wire Color IGN ON ENG RUN Refer To

B1 5 Volt Reference Signal BLU/ORG 5.0 V 5.0 V Appropriate Sensor

B2 Not Used — — — —

B3 Not Used — — — —

B4 Not Used — — — —

B5 Not Used — — — —

B6 Not Used — — — —

B7 Exhaust Gas Recirculation

(EGR) Position Feedback YEL/RED 0.6 V 0.6 V General Description and

Operation, Linear EGR

Control

B8 Intake Air Temperature

(IAT) Sensor YEL/GRN ~3V

(0V = 151°C) ~3 V

(5V = –40°C) General Description and

Operation, IAT

B9 A/C Pressure Sensor

Signal GRN ~1 V ~1 V A/C System

B10 Not Used — — — —

B11 Power Steering Pressure

(PSP) Switch Input GRN/YEL B+ B+ General Description and

Operation, PSP

B12 Illumination Switch GRN/YEL B+ B+ Chassis Electrical

B13 Class 2 Data ORN/BLK 0.0 V 0.0 V Diagnosis, Class 2 Serial

Data

B14 A/C Compressor Clutch

Relay Control Compressor GRN/RED 0

(A/C OFF) B+

(A/C ON) General Description and

Operation, A/C Clutch Circuit

Operation

B15 Not Used — — — —

B16 Not Used — — — —

ECM Pinout Table, 32–Pin White Connector – Row ”C”

TS23345

PIN PIN Function Wire Color IGN ON ENG RUN Refer To

C1 Injector Cylinder #2 GRN/RED B+ Varies B+ Varies General Description and

Operation, Fuel Injector

C2 Not Used — — — —

C3 Not Used — — — —

C4 Ignition Control Module

(ICM) Input RED 0.0 V 0.1 V General Description and

Operation, Fuel Injector

C5 Crankshaft Position (CKP)

Sensor Low BLUE 4.98 V 0.76 V

(at idle) General Description and

Operation, Crankshaft

Position Sensor

C6 Crankshaft Position

Sensor (CKP) High GRN 5V 5V General Description and

Operation, Crankshaft

Position Sensor

C7 ECM Ground BLK/BLU 0.0 V 0.0 V Chassis Electrical

C8 ECM Ground BLK/BLU 0.0 V 0.0 V Chassis Electrical

C9 ECM Ground BLK/BLU 0.0 V 0.0 V Chassis Electrical

C10 Tachometer Signal BLK/RED — — General Description and

Operation

C11 Fuel Gauge PWM Output YEL/RED Varies with

Fuel Level Varies with

Fuel Level General Description and

Operation

C12 High Fan Relay Control RED/YEL 10.5 V B+ Chassis Electrical

C13 Low Fan Relay Control RED/BLU — — Chassis Electrical

C14 Bank 1 HO2S 1 High WHT 0.3 V –0.1 to 1.1 V General Description and

Operation, Fuel HO2S 1

C15 Bank 1 HO2S 1 Low RED 0.0 V 0.1 V General Description and

Operation, Fuel HO2S 1

C16 Not Used — — — —

ECM Pinout Table, 32–Pin White Connector – Row ”D”

TS23345

PIN PIN Function Wire Color IGN ON ENG RUN Refer To

D1 Injector Cylinder #3 GRN/ORN B+ B+ General Description and

Operation, Fuel Injector

D2 Not Used — — — —

D3 Injector Cylinder #1 GRN/WHT B+ B+ General Description and

Operation, Fuel Injector

D4 Not Used — — — —

D5 Ignition Control Module

(ICM) Input RED/BLK — — General Description and

Operation

D6 Not Used — — — —

D7 VSS Input BLU/BLK — — Chassis Electrical

D8 Sensor Ground 5 V

Reference A Return GRN 0.0 V 0.0 V Appropriate Sensor

D9 Sensor Ground 5 V

Reference B Return BLU/YEL 0.0 V 0.0 V Appropriate Sensor

D10 Not Used — — — —

D11 Camshaft Position Sensor

Input BLU 5.0 V 4.6 V General Description and

Operation, Camshaft

Position Sensor

D12 Not Used — — — —

D13 Not Used — — — —

D14 Not Used — — — —

D15 Not Used — — — —

D16 Not Used — — — —

ECM Pinout Table, 32–Pin White Connector – Row ”E”

TS23346

PIN PIN Function Wire Color IGN ON ENG RUN Refer To

E1 Not Used — — — —

E2 Fan Control RED/GRN 0.0V B+ Chassis Electrical

E3 Not Used — — — —

E4 Not Used — — — —

E5 Ignition Feed BLK/YEL B+ B+ General Description and

Operation

E6 Exhaust Gas Recirculation

(EGR) Valve Low YEL B+ Varies B+ Varies General Description and

Operation, EGR Control

E7 Not Used — — — —

E8 Throttle Position (TP)

Sensor Input BLU 0.25 V

(0% = 0.25 V) 0.25 V

(at idle)

(100% =

4.75 V)

General Description and

Operation, Throttle Position

Sensor

E9 Engine Coolant

Temperature (ECT)

Sensor Input

BLU/RED 2.3 V

(O V =

151°C)

2.1 V

(5 V = –40°C) General Description and

Operation, Engine Coolant

Temperature (ECT) Sensor

E10 Not Used — — — —

E11 Not Used — — — —

E12 Rear Defogger Switch YEL/GRN B+ B+ Chassis Electrical

E13 Fuel Pump (FP) Relay

Control PNK/WHT 0.0 V B+ On–Vehicle Service, Fuel

Pump Relay

E14 Not Used — — — —

E15 A/C Request (Thermo

Relay) GRN/BLK 0.0 V 0.0 V Electric Cooling Fans

E16 Ignition Feed RED/BLU B+ B+ General Description and

Operation

ECM Pinout Table, 32–Pin White Connector – Row ”F”

TS23346

PIN PIN Function Wire Color IGN ON ENG RUN Refer To

F1 Not Used — — — —

F2 Not Used — — — —

F3 Not Used — — — —

F4 Not Used — — — —

F5 Not Used — — — —

F6 Not Used — — — —

F7 Not Used — — — —

F8 Manifold Absolute

Pressure (MAP) Sensor

Input

GRY ~4.7 V

(0 V = 10kPa) ~1.1 V

(5 V =

104kPa)

General Description and

Operation, Manifold Absolute

Pressure

F9 Not Used — — — —

F10 Not Used — — — —

F11 Not Used — — — —

F12 DLC (Digital Input) — — — Class 2 Serial Data

F13 Injector ”C” Cylinder #4 GRN B+ B+ General Description and

Operation, Fuel Injector

F14 Not Used — — — —

F15 Not Used — — — —

F16 Ignition Feed RED/BLU B+ B+ General Description and

Operation

COMPONENT LOCATOR

755RX030

Engine Component Locator Table

Number Name Location

1Engine Coolant Temperature (ECT) Sensor Rear of engine, near ignition coils

2Linear Exhaust Gas Recirculation (EGR) Valve On the left rear of the engine at the bulkhead

3Heated Oxygen Sensor (HO2S), Bank 1,

Sensor 1 On the exhaust pipe, left side of engine,

immediately behind the exhaust manifold

4Air Cleaner Left front of the engine bay

5Intake Air Temperature (IAT) Sensor On the intake air duct near the air cleaner

6Camshaft Position (CMP) Sensor Inside the front cover assembly

7Positive Crankcase Ventilation (PCV) Port On the right front corner of the valve cover

8Fuel Pressure Regulator On the forward end of the fuel rail, to the right of

the PVC port

9Throttle Body Between the intake air duct and the intake

manifold

10 Fuse/Relay Box Along the inside of the right fender

11 Throttle Position (TP) Sensor On the front of the throttle body

12 Idle Air Control (IAC) Valve On the rear of the throttle body

13 Ignition Control Module (ICM) Mounted on a heat sink on the lower right side of

the engine block, above the starter motor

14 Manifold Absolute Pressure (MAP) Sensor Bolted to the front edge of the intake manifold,

under the fuel rail

15 High Fan Relay In the relay box

16 Low Fan Relay In the relay box

010RX001

028RX001

Undercarriage Component Locator Table

Name Location

Fuel Pump Assembly Installed in the top of the fuel tank

EVAP Canister Behind rear axle, near fuel tank filler nozzle

EVAP Canister Purge Valve Solenoid Behind rear axle, near fuel tank filler nozzle

Vehicle Speed Sensor (VSS) Protrudes from the right side of the transmission housing, near the

output shaft

Crankshaft Position (CKP) Sensor Lower left hand front of engine, behind power steering pump bracket

Fuse And Relay Panel (Underhood Electrical Center)

Underhood (U/H) Fuse and Relay Panel

060RX096

DIAGNOSIS Strategy–Based

Diagnostics

Strategy–Based Diagnostics

The strategy–based diagnostic is a uniform approach to

repair all Electrical/Electronic (E/E) systems. The

diagnostic flow can always be used to resolve an E/E

system problem and is a starting point when repairs are

necessary. The following steps will instruct the technician

how to proceed with a diagnosis:

1.Verify the customer complaint.

DTo verify the customer complaint, the technician

should know the normal operation of the system.

2.Perform preliminary checks.

DConduct a thorough visual inspection.

DReview the service history.

DDetect unusual sounds or odors.

DGather diagnostic trouble code information to

achieve an effective repair.

3.Check bulletins and other service information.

DThis includes videos, newsletters, etc.

4.Refer to service information (manual) system

check(s).

D”System checks” contain information on a system

that may not be supported by one or more DTCs.

System checks verify proper operation of the

system. This will lead the technician in an organized

approach to diagnostics.

5.Refer to service diagnostics.

DTC Stored

Follow the designated DTC chart exactly to make an

effective repair.

No DTC

Select the symptom from the symptom tables. Follow the

diagnostic paths or suggestions to complete the repair.

You may refer to the applicable component/system check

in the system checks.

No Matching Symptom

1.Analyze the complaint.

2.Develop a plan for diagnostics.

3.Utilize the wiring diagrams and the theory of

operation.

Combine technician knowledge with efficient use of the

available service information.

Intermittents

Conditions that are not always present are called

intermittents. To resolve intermittents, perform the

following steps:

1.Observe history DTCs, DTC modes, and

freeze–frame data.

2.Evaluate the symptoms and the conditions described

by the customer.

3.Use a check sheet or other method to identify the

circuit or electrical system component.

4.Follow the suggestions for intermittent diagnosis

found in the service documentation.

Most Scan Tools, such as the Tech 2, have

data–capturing capabilities that can assist in detecting

intermittents.

No Trouble Found

This condition exists when the vehicle is found to operate

normally. The condition described by the customer may

be normal. Verify the customer complaint against another

vehicle that is operating normally. The condition may be

intermittent. Verify the complaint under the conditions

described by the customer before releasing the vehicle.

1.Re–examine the complaint.

When the complaint cannot be successfully found or

isolated, a re–evaluation is necessary. The complaint

should be re–verified and could be intermittent as

defined in

Intermittents,

or could be normal.

2.Repair and verify.

After isolating the cause, the repairs should be made.

Validate for proper operation and verify that the

symptom has been corrected. This may involve road

testing or other methods to verify that the complaint

has been resolved under the following conditions:

DConditions noted by the customer.

DIf a DTC was diagnosed, verify a repair by

duplicating conditions present when the DTC was

set as noted in the Failure Records or Freeze

Frame data.

Verifying Vehicle Repair

Verification of the vehicle repair will be more

comprehensive for vehicles with OBD II system

diagnostics. Following a repair, the technician should

perform the following steps:

IMPORTANT:Follow the steps below when you verify

repairs on OBD II systems. Failure to follow these steps

could result in unnecessary repairs.

1.Review and record the Failure Records and the

Freeze Frame data for the DTC which has been

diagnosed (Freeze Fame data will only be stored for

an A or B type diagnostic and only if the MIL (”Check

Engine” lamp) has been requested).

2.Clear the DTC(s).

3.Operate the vehicle within conditions noted in the

Failure Records and Freeze Frame data.

4.Monitor the DTC status information for the DTC which

has been diagnosed until the diagnostic test

associated with that DTC runs.

GENERAL SERVICE INFORMATION

Non–OEM Parts

All of the OBD diagnostics have been calibrated to run

with OEM parts. Something as simple as a

high–performance exhaust system that affects exhaust

system back pressure could potentially interfere with the

operation of the EGR valve and thereby turn on the MIL

(”Check Engine” lamp). Small leaks in the exhaust

system near the post catalyst oxygen sensor can also

cause the MIL (”Check Engine” lamp) to turn on.

Aftermarket electronics, such as transceiver, stereos,

and anti–theft devices, may radiate EMI into the control

system if they are improperly installed. This may cause a

false sensor reading and turn on the MIL (”Check Engine”

lamp).

Environment

Temporary environmental conditions, such as localized

flooding, will have an effect on the vehicle ignition system.

If the ignition system is rain–soaked, it can temporarily

cause engine misfire and turn on the MIL (”Check Engine”

lamp).

Emissions Control Information Label

The engine compartment ”Vehicle Emissions Control

Information Label” contains important emission

specifications and setting procedures. In the upper left

corner is exhaust emission information. There is also an

illustrated emission components and vacuum hose

schematic.

This label is located in the engine compartment of every

vehicle. If the label has been removed it should be

replaced, it can be ordered from Isuzu Dealer ship.

Maintenance Schedule

Refer to the Maintenance Schedule.

Visual/Physical Engine Compartment

Inspection

Perform a careful visual and physical engine

compartment inspection when performing any diagnostic

procedure or diagnosing the cause of an emission test

failure. This can often lead to repairing a problem without

further steps. Use the following guidelines when

performing a visual/physical inspection:

DInspect all vacuum hoses for pinches, cuts,

disconnection, and Droper routing.

DInspect hoses that are difficult to see behind other

components.

DInspect all wires in the engine compartment for proper

connections, burned or chafed spots, pinched wires,

contact with sharp edges or contact with hot exhaust

manifolds or pipes.

Basic Knowledge Of Tools Required

NOTE:Lack of basic knowledge of this powertrain when

performing diagnostic procedures could result in an

incorrect diagnosis or damage to powertrain

components. Do not attempt to diagnose a powertrain

problem without this basic knowledge.

A basic understanding of hand tools is necessary to

effectively use this section of the Service Manual.

SERIAL DATA COMMUNICATIONS

Class II Serial Data Communications

Government regulations require that all vehicle

manufacturers establish a common communication

system. This vehicle utilizes the ”Class II” communication

system. Each bit of information can have one of two

lengths: long or short. This allows vehicle wiring to be

reduced by transmitting and receiving multiple signals

over a single wire. The messages carried on Class II data

streams are also prioritized. If two messages attempt to

establish communications on the data line at the same

time, only the message with higher priority will continue.

The device with the lower priority message must wait. The

most significant result of this regulation is that it provides

Tech 2 manufacturers with the capability to access data

from any make or model vehicle that is sold.

The data displayed on the other Tech 2 will appear the

same, with some exceptions. Some Scan Tools will only

be able to display certain vehicle parameters as values

that are a coded representation of the true or actual value.

For more information on this system of coding, refer to

Decimal/Binary/Hexadecimal Conversions. On this

vehicle the Tech 2 displays the actual values for vehicle

parameters. It will not be necessary to perform any

conversions from coded values to actual values.

ON–BOARD DIAGNOSTIC (OBD)

On–Board Diagnostic Tests

A diagnostic test is a series of steps, the result of which is

a pass or fail reported to the diagnostic executive. When a

diagnostic test reports a pass result, the diagnostic

executive records the following data:

DThe diagnostic test has been completed since the last

ignition cycle.

DThe diagnostic test has passed during the current

ignition cycle.

DThe fault identified by the diagnostic test is not

currently active.

When a diagnostic test reports a fail result, the diagnostic

executive records the following data:

DThe diagnostic test has been completed since the last

ignition cycle.

DThe fault identified by the diagnostic test is currently

active.

DThe fault has been active during this ignition cycle.

DThe operating conditions at the time of the failure.

Remember, a fuel trim DTC may be triggered by a list of

vehicle faults. Make use of all information available (other

DTCs stored, rich or lean condition, etc.) when

diagnosing a fuel trim fault.

Comprehensive Component Monitor

Diagnostic Operation

Input Components:

Input components are monitored for circuit continuity and

out–of–range values. This includes rationality checking.

Rationality checking refers to indicating a fault when the

signal from a sensor does not seem reasonable, i.e.

Throttle Position (TP) sensor that indicates high throttle

position at low engine loads or MAP voltage). Input

components may include, but are not limited to the

following sensors:

DVehicle Speed Sensor (VSS)

DCrankshaft Position (CKP) sensor

DThrottle Position (TP) sensor

DEngine Coolant Temperature (ECT) sensor

DCamshaft Position (CMP) sensor

DManifold Absolute Pressure (MAP) sensor

In addition to the circuit continuity and rationality check

the ECT sensor is monitored for its ability to achieve a

steady state temperature to enable ”Closed Loop” fuel

control.

Output Components:

Output components are diagnosed for proper response to

control module commands. Components where

functional monitoring is not feasible will be monitored for

circuit continuity and out–of–range values if applicable.

Output components to be monitored include, but are not

limited to the following circuit:

DIdle Air Control (IAC) Motor

DEVAP Canister Purge Valve Solenoid

DA/C relays

DCooling fan relay(s)

DVSS output

DMIL control

Refer to ECM and Sensors in General Descriptions.

Passive and Active Diagnostic Tests

A passive test is a diagnostic test which simply monitors a

vehicle system or component. Conversely, an active test,

actually takes some sort of action when performing

diagnostic functions, often in response to a failed passive

test. For example, the EGR diagnostic active test will

force the EGR valve open during closed throttle decel

and/or force the EGR valve closed during a steady state.

Either action should result in a change in manifold

pressure.

Intrusive Diagnostic Tests

This is any on–board test run by the Diagnostic

Management System which may have an effect on

vehicle performance or emission levels.

Warm–Up Cycle

A warm–up cycle means that engine at temperature must

reach a minimum of 70°C (160°F) and rise at least 22°C

(40°F) over the course of a trip.

Freeze Frame

Freeze Frame is an element of the Diagnostic

Management System which stores various vehicle

information at the moment an emissions–related fault is

stored in memory and when the MIL is commanded on.

These data can help to identify the cause of a fault. Refer

to Storing And Erasing Freeze Fame Data for more

detailed information.

Failure Records

Failure Records data is an enhancement of the OBD

Freeze Frame feature. Failure Records store the same

vehicle information as does Freeze Frame, but it will store

that information for any fault which is stored in on–board

memory, while Freeze Frame stores information only for

emission–related faults that command the MIL ON.

Common OBD Terms

Diagnostic

When used as a noun, the word diagnostic refers to any

on–board test run by the vehicle’s Diagnostic

Management System. A diagnostic is simply a test run on

a system or component to determine if the system or

component is operating according to specification. There

are many diagnostics, shown in the following list:

DOxygen sensors

DOxygen sensor heaters

DEGR

Enable Criteria

The term ”enable criteria” is engineering language for the

conditions necessary for a given diagnostic test to run.

Each diagnostic has a specific list of conditions which

must be met before the diagnostic will run. ”Enable

criteria” is another way of saying ”conditions required”.

The enable criteria for each diagnostic is listed on the first

page of the DTC description in Section 6E under the

heading ”Conditions for Setting the DTC”. Enable criteria

varies with each diagnostic, and typically includes, but is

not limited to the following items:

Dengine speed

Dvehicle speed

DECT

DMAP

Dbarometric pressure

DIAT

DTP

DA/C ON

Trip

T echnically , a trip is a key on–run–key off cycle in which all

the enable criteria for a given diagnostic are met, allowing

the diagnostic to run. Unfortunately, this concept is not

quite that simple. A trip is official when all the enable

criteria for a given diagnostic are met. But because the

enable criteria vary from one diagnostic to another, the

definition of trip varies as well. Some diagnostics are run

when the vehicle is at operating temperature, some when

the vehicle first starts up; some require that the vehicle be

cruising at a steady highway speed, some run only when

the vehicle is at idle; some diagnostics function with the

TCC disabled. Some run only immediately following a

cold engine start–up.

A trip then, is defined as a key on–run–key off cycle in

which the vehicle was operated in such a way as to satisfy

the enabling criteria for a given diagnostic, and this

diagnostic will consider this cycle to be one trip. However ,

another diagnostic with a different set of enable criteria

(which were not met) during this driving event, would not

consider it a trip. No trip will occur for that particular

diagnostic until the vehicle is driven in such a way as to

meet all the enable criteria.

The Diagnostic Executive

The Diagnostic Executive is a unique segment of

software which is designed to coordinate and prioritize

the diagnostic procedures as well as define the protocol

for recording and displaying their results. The main

responsibilities of the Diagnostic Executive are listed as

follows:

DCommanding the MIL (”Check Engine” lamp) ON and

OFF

DDTC logging and clearing

DFreeze Frame data for the first emission related DTC

recorded

DNon–emission related Service Lamp (future)

DOperating conditions Failure Records buffer, (the

number of records will vary)

DCurrent status information on each diagnostic

DSystem Status (I/M ready)

The Diagnostic Executive records DTCs and turns ON

the MIL when emission–related faults occur. It can also

turn OFF the MIL if the conditions cease which caused the

DTC to set.

Diagnostic Information

The diagnostic charts and functional checks are designed

to locate a faulty circuit or component through a process

of logical decisions. The charts are prepared with the

requirement that the vehicle functioned correctly at the

time of assembly and that there are no multiple faults

present.

There is a continuous self–diagnosis on certain control

functions. This diagnostic capability is complimented by

the diagnostic procedures contained in this manual. The

language of communicating the source of the malfunction

is a system of diagnostic trouble codes. When a

malfunction is detected by the control module, a

diagnostic trouble code is set and the Malfunction

Indicator Lamp (MIL) (”Check Engine” lamp) is

illuminated.

Malfunction Indicator Lamp (MIL)

The Malfunction Indicator Lamp (MIL) looks the same as

the MIL you are already familiar with (”Check Engine”

lamp). However, OBD requires that it illuminate under a

strict set of guide lines.

Basically, the MIL is turned ON when the ECM detects a

DTC that will impact the vehicle emissions.

The MIL is under the control of the Diagnostic Executive.

The MIL will be turned ON if an emissions–related

diagnostic test indicates a malfunction has occurred. It

will stay ON until the system or component passes the

same test, for three consecutive trips, with no

emissions–related faults.

Extinguishing the MIL

When the MIL is ON, the Diagnostic Executive will turn

OFF the MIL after

three (3) consecutive

trips that a ”test

passed” has been reported for the diagnostic test that

originally caused the MIL to illuminate.

Although the MIL has been turned OFF, the DTC will

remain in the ECM memory (both Freeze Frame and

Failure Records) until

forty(40) warm–up cycles after no

faults

have been completed.

If the MIL was set by either a fuel trim or misfire–related

DTC, additional requirements must be met. In addition to

the requirements stated in the previous paragraph, these

requirements are as follows:

DThe diagnostic tests that are passed must occur with

375 RPM of the RPM data stored at the time the last

test failed.

DPlus or minus ten (10) percent of the engine load that

was stored at the time the last test failed.

DSimilar engine temperature conditions (warmed up or

warming up) as those stored at the time the last test

failed.

Meeting these requirements ensures that the fault which

turned on the MIL has been corrected.

The MIL (”Check Engine” lamp) is on the instrument panel

and has the following functions:

DIt informs the driver that a fault that affects vehicle

emission levels has occurred and that the vehicle

should be taken for service as soon as possible.

DAs a bulb and system check, the MIL will come ON

with the key ON and the engine not running. When the

engine is started, the MIL will turn OFF.

DWhen the MIL remains ON while the engine is

running, or when a malfunction is suspected due to a

driveability or emissions problem, a Powertrain

On–Board Diagnostic (OBD) System Check must be

performed. The procedures for these checks are

given in On–Board Diagnostic (OBD) System Check.

These checks will expose faults which may not be

detected if other diagnostics are performed first.

DTC Types

Each DTC is directly related to a diagnostic test. The

Diagnostic Management System sets DTC based on the

failure of the tests during a trip or trips. Certain tests must

fail two (2) consecutive trips before the DTC is set. The

following are the four (4) types of DTCs and the

characteristics of those codes:

DType A

DEmissions related

DRequests illumination of the MIL of the first trip with a

fail

DStores a History DTC on the first trip with a fail

DStores a Freeze Frame (if empty)

DStores a Fail Record

DUpdates the Fail Record each time the diagnostic

test fails

DType B

DEmissions related

D”Armed” after one (1) trip with a fail

D”Disarmed” after one (1) trip with a pass

DRequests illumination of the MIL on the

second

consecutive trip

with a fail

DStores a History DTC on the second consecutive trip

with a fail (The DTC will be armed after the first fail)

DStores a Freeze Frame on the second consecutive

trip with a fail (if empty)

DStores a Fail Record when the first test fails (not

dependent on

consecutive trip

fails)

DUpdates the Fail Record each time the diagnostic

test fails

(Some special conditions apply to misfire and fuel trim

DTCs)

DType C (if the vehicle is so equipped)

DNon–Emissions related

DRequests illumination of the Service Lamp or the

service message on the Drive Information Center

(DIC) on the

first trip

with a fail

DStores a History DTC on the

first trip

with a fail

Does not

store a Freeze Frame

DStores Fail Record when test fails

DUpdates the Fail Record each time the diagnostic

test fails

DType D. (

Type D

non–emissions related are not

utilized on certain vehicle applications).

DNon–Emissions related

DDoes not request illumination of any lamp

DStores a History DTC on the

first trip

with a fail

Does not

store a Freeze Frame

DStores Fail Record when test fails

DUpdates the Fail Record each time the diagnostic

test fails

IMPORTANT:Only four Fail Records can be stored.

Each Fail Record is for a different DTC. It is possible that

there will not be Fail Records for every DTC if multiple

DTCs are set.

Storing and Erasing Freeze Frame Data and Failure

Records

Government regulations require that engine operating

conditions be captured whenever the MIL is illuminated.

The data captured is called Freeze Frame data. The

Freeze Frame data is very similar to a single record of

operating conditions. Whenever the MIL is illuminated,

the corresponding record of operating conditions is

recorded to the Freeze Frame buffer.

Freeze Frame data can only be overwritten with data

associated with a misfire or fuel trim malfunction. Data

from these faults take precedence over data associated

with any other fault. The Freeze Frame data will not be

erased unless the associated history DTC is cleared.

Each time a diagnostic test reports a failure, the current

engine operating conditions are recorded in the

Failure

Records

buffer. A subsequent failure will update the

recorded operating conditions. The following operating

conditions for the diagnostic test which failed

typically

include the following parameters:

DEngine Speed

DEngine Load

DEngine Coolant Temperature

DVehicle Speed

DTP

DMAP/BARO

DInjector Base Pulse Width

DLoop Status

Intermittent Malfunction Indicator Lamp

In the case of an ”intermittent” fault, the MIL (”Check

Engine” lamp) may illuminate and then (after three trips)

go OFF. However, the corresponding diagnostic trouble

code will be stored in the memory. When unexpected

diagnostic trouble codes appear, check for an intermittent

malfunction.

A diagnostic trouble code may reset. Consult the

”Diagnostic Aids” associated with the diagnostic trouble

code. A physical inspection of the applicable sub–system

most often will resolve the problem.

Data Link Connector (DLC)

The provision for communicating with the control module

is the Data Link Connector (DLC). It is located at the lower

left of the instrument panel. The DLC is used to connect to

the Tech 2 Scan tool. Some common uses of the Tech 2

are listed below:

DIdentifying stored Diagnostic Trouble Codes (DTCs)

DClearing DTCs

DPerforming output control tests

DReading serial data

TS24064

Verifying Vehicle Repair

Verification of vehicle repair will be more comprehensive

for vehicles with OBD II system diagnostics. Following a

repair, the technician should perform the following steps:

1.Review and record the Fail Records and/or Freeze

Frame data for the DTC which has been diagnosed

(Freeze Frame data will only be stored for an A or B

type diagnostic and only if the MIL has been

requested).

2.Clear DTC(s).

3.Operate the vehicle within conditions noted in the Fail

Records and/or Freeze Frame data.

4.Monitor the DTC status information for the DTC which

has been diagnosed until the diagnostic test

associated with that DTC runs.

Following these steps are very important in verifying

repairs on OBD systems. Failure to follow these steps

could result in unnecessary repairs.

Reading Diagnostic Trouble Codes Using

A Tech 2 Scan Tool

The procedure for reading diagnostic trouble code(s) is to

use a diagnostic Scan tool. When reading DTC(s), follow

instructions supplied by tool manufacturer.

Clearing Diagnostic Trouble Codes

IMPORTANT:Do not clear DTCs unless directed to do

so by the service information provided for each diagnostic

procedure. When DTCs are cleared, the Freeze Frame

and Failure Record data which may help diagnose an

intermittent fault will also be erased from memory.

If the fault that caused the DTC to be stored into memory

has been corrected, the Diagnostic Executive will begin to

count the ”warm–up” cycles with no further faults

detected, the DTC will automatically be cleared from the

ECM memory.

To clear Diagnostic Trouble Codes (DTCs), use the

diagnostic Scan tool ”clear DTCs” or ”clear information”

function. When clearing DTCs follow instructions

supplied by the tool manufacturer.

When a Tech 2 is not available, DTCs can also be cleared

by disconnecting one of the following sources for at least

thirty (30) seconds.

NOTE: To prevent system damage, the ignition key must

be OFF when disconnecting or reconnecting battery

power.

DThe power source to the control module. Examples:

fuse, pigtail at battery ECM connectors etc.

DThe negative battery cable. (Disconnecting the

negative battery cable will result in the loss of other

on–board memory data, such as preset radio tuning).

Tech 2

From 98 MY, Isuzu dealer service departments are

recommended to use the T ech 2 scan tool. Please refer to

the Tech 2 user guide.

901RW180

Legend

(1) PCMCIA Card

(2) R232 Loop Back Connector

(3) SAE 16/19 Adaptor

(4) DLC Cable

(5) Tech 2

Tech 2 Features

1.Tech 2 is a 12 volt system. Do not apply 24 volt.

2.After connecting and/or installing, the Vehicle

Communications Interface (VCI) module, PCMCIA

card and DLC connector to the Tech 2, connect the

tool to the vehicle DLC.

3.Make sure the Tech 2 is powered OFF when

removing or installing the PCMCIA card.

4.The PCMCIA card has a capacity of 10 Megabytes

which is 10 times greater than the memory of the T ech

1 Mass Storage Cartridge.

5.The Tech 2 has the capability of two snapshots.

6.The PCMCIA card is sensitive to magnetism and

static electricity, so care should be taken in the

handling of the card.

7.The Tech 2 can plot a graph when replaying a

snapshot.

8.Always return to the Main Menu by pressing the EXIT

key several times before shutting down.

9.To clear Diagnostic Trouble Codes (DTCs), open

Application Menu and press “F1: Clear DTC Info”.

Getting Started

DBefore operating the Isuzu PCMCIA card with the

Tech 2, the following steps must be performed:

1.The Isuzu 99 System PCMCIA card (1) inserts into

the Tech 2 (5).

2.Connect the SAE 16/19 adapter (3) to the DLC cable

(4).

3.Connect the DLC cable to the Tech 2 (5)

4.Make sure the vehicle ignition is off.

5.Connect the Tech 2 SAE 16/19 adapter to the vehicle

DLC.

810RW317

6.Turn on the vehicle ignition.

7.Power the Tech 2 ON and V erify the Tech 2 power up

display.

060RW009

NOTE: The RS232 Loop back connector is only to use for

diagnosis of Tech 2 and refer to user guide of the Tech 2.

Operating Procedure (Example)

The power up screen is displayed when you power up the

tester with the Isuzu system PCMCIA card. Follow the

operating procedure below.

060RX060

060RX058

DThe following table shows which functions are used

for the available equipment versions.

060RW224

DTC Modes

060RW229

On OBD II vehicles there are five options available in T ech

2 DTC mode to display the enhanced information

available. After selecting DTC, the following menu

appears:

DDTC Info

DFreeze Frame

DFail Records (not all applications)

DClear Info

060RW223

The following is a brief description of each of the sub

menus in DTC Info and DTC. The order in which they

appear here is alphabetical and not necessarily the way

they will appear on the Tech 2.

DTC Information Mode

Use the DTC info mode to search for a specific type of

stored DTC information. There are six choices. The

service manual may instruct the technician to test for

DTCs in a certain manner. Always follow published

service procedures.

060RW221

DTC Status

This selection will display any DTCs that have not run

during the current ignition cycle or have reported a test

failure during this ignition up to a maximum of 33 DTCs.

DTC tests which run and pass will cause that DTC

number to be removed from Tech 2 screen.

Fail This Ignition

This selection will display all DTCs that have failed during

the present ignition cycle.

History

This selection will display only DTCs that are stored in the

ECM’s history memory. It will display all type A and B

DTCs that have requested the MIL and have failed within

the last 40 warm-up cycles. In addition, it will display all

type C and type D DTCs that have failed within the last 40

warm-up cycles.

Last Test Failed

This selection will display only DTCs that have failed the

last time the test run. The last test may have run during a

previous ignition cycle if a type A or type B DTC is

displayed. For type C and type D DTCs, the last failure

must have occurred during the current ignition cycle to

appear as Last Test Fail.

MILSVC or Message Request

This selection will display only DTCs that are requesting

the MIL. Type C and type D DTCs cannot be displayed

using this option. This selection will report type B DTCs

only after the MIL has been requested.

Not Run Since Code Cleared

This option will display up to 33 DTCs that have not run

since the DTCs were last cleared. Since any displayed

DTCs have not run, their condition (passing or failing) is

unknown.

Test Failed Since Code Cleared

This selection will display all active and history DTCs that

have reported a test failure since the last time DTCs were

cleared. DTCs that last failed more than 40 warm-up

cycles before this option is selected will not be displayed.

Miscellaneous Test

This test consists of eight menus-Lights, Relays, EVAP,

IAC System, Fuel System, EGR Control, Variable Intake

Manifold Solenoid, and Injector Balance Tests.

In these tests, Tech 2 sends operating signals to the

systems to confirm their operations thereby to judge the

normality of electric circuits.

To judge intermittent trouble,

1.Confirm DTC freeze frame data, and match the

freeze frame data as test conditions with the data list

displayed by Miscellaneous Test.

2.Confirm DTC setting conditions, and match the

setting conditions as test conditions with the data list

displayed by Miscellaneous Test.

Lamps Test

This test is conducted check MIL and Low Fuel Lamp for

its working.

Tech2 must be used for this test.

Test Procedure:

1.Connect Tech 2 to the vehicle DLC.

2.Run the Engine at idle.

3.Select F3: Miscellaneous Test in the Application

Menu.

060RW228

4.Select F0:Lamps Test in the Miscellaneous Test.

060RX043

060RX044

5.Select F0:Malfunction Indicator Lamp.

060RX019

6.Push “On” soft key.

7.Make sure Lamp illuminates.

8.If lamp illuminates, the Lamp is operating correctly.

DF1; Up Shift Lamp = Not Used

DF2; Low Fuel Lamp = Not Used

Relays Test

This test is conducted to check Fuel Pump Relay, A/C

Clutch Low Fan and High Fan for prepor operation.

Tech 2 must be used for this test.

Test Procedure:

1.Connect Tech 2 to the vehicle DLC.

2.Ignition SW is “On”.

3.Select F3: Miscellaneous Test in the Application

Menu.

060RW228

4.Select F1:Relay Test in the Miscellaneous Test.

060RX046

5.Select F0:Fuel Pump Relay.

060RX047

6.Push “On” soft key.

060RX022

7.Control Fuel Pump Relay and check a data list.

8.If the data list chenges, the Fuel Pump Relay is

normal.

9.Select F1:A/C Clutch Relay.

10.*Run the Engine at idle.

11.Turn on Air Condtioning.

060RX023

12.Push “On” and “Off” of soft key.

13.Control A/C Clutch Relay and check a data list.

14.If the data list changes, the A/C Clutch Relay is

normal.

15.Select F2: Low Fan Relay.

060RX048

16.Push “On” and “Off” of soft key.

17.Control Low Fan Relay and check a data list.

18.If the data list changes, the Low Fan Relay is normal.

19.Run the Fan Motor.

20.Select F3: High Fan Relay.

060RX049

21.Push “On” and “Off” of soft key.

22.Control High Fan Relay and check a data list.

If the data list changes, the High Fan Relay is normal.

23.Run the Fan Motor.

EVAP Test

This test is conducted check EV AP system for its working.

Tech 2 must be used for this test.

Test Procedure:

1.Connect Tech 2 to the vehicle DLC.

2.Run the Engine at idle.

3.Select F3: Miscellaneous Test in the Application

Menu.

060RW228

4.Select F2:EVAP Test in the Miscellaneous Test.

060RX050

5.Select F0: Purge Solenoid.

060RX025

6.Push “Decrease” or “Increase” soft key.

060RX026

7.Control EVAP Purge Solenoid and check a data list.

8.If the data list changes, the purge Solenoid is normal.

Ignition SW is “On”.

DF1; Vent Solenoid = Not Used

Idle Air Control System Test

This test is conducted check to IAC system for proper

operation.

Tech 2 must be used for this test.

Test Procedure:

1.Connect Tech 2 to the vehicle DLC.

2.Run the Engine at idle.

3.Select F3: Miscellaneous Test in the Application

Menu.

060RW228

4.Select F3: IAC System Test in the Miscellaneous

Test.

060RX051

5.Select F1: IAC Control Test.

060RX052

6.Push “Increase” or “Decrease” soft key.

7.Control IAC system and check a data list.

DF0: IAC Control

060RX015

8.Select F1: IAC Reset.

9.Push “Reset IAC” soft key.

10.Control IAC Reset and check data list.

11.If data list changes, the IAC has been Reset.

060RW231–1

Fuel System Test

This test is conducted check Fuel Level Gauge for proper

operation.

Tech 2 must be used for this test.

Test Procedure:

1.Connect Tech 2 to the vehicle DLC.

2.Ignition SW is “On”.

3.Select F3: Miscellaneous Test in the Application

Menu.

060RW228

4.Select F4: Fuel System in the Miscellaneous Menu.

060RX053

5.Select F0: Fuel Trim Reset.

060RX028

6.Push “Reset” of soft key.

060RX029

DF1; Fuel Gauge Level = Not Used

EGR Control Test

This test is conducted check EGR valve for proper

operation.

Tech 2 must be used for this test.

Test Procedure:

1.Connect Tech 2 to the vehicle DLC.

2.Run the Engine at idle.

3.Select F3: Miscellaneous Test in the Application

Menu.

060RW228

4. Select F5: EGR Control Test in the Miscellaneous

Test.

060RX054

5.Control EGR Valve and check data list.

060RX017

6.If the change, the EGR Control is normal.

Injector Balance Test

This test is conducted to make sure the appropriate

electric signals are being sent to injectors Nos. 1–6.

Tech 2 must be used for this test.

Test Procedure:

1.Connect Tech 2 to the vehicle DLC.

2.Run the Engine at idle.

3.Select F3: Miscellaneous Test in the Application

Menu.

060RW228

4.Select F6: Injector Balance Test in the Miscellaneous

Test.

060RX055

5.Select injector number and push “injector off” of soft

key.

060RW230–1

6.Make sure of engine speed change.

7.If engine speed changes, the injector electric circuit is

normal.

If engine speed does not change, the injector electric

circuit or the injector itself is not normal.

Plotting Snapshot Graph

This test selects several necessary items from the data

list to plot graphs and makes data comparison on a long

term basis. It is an effective test particularly in emission

related evaluations.

060RX037

For trouble diagnosis, you can collect graphic data (snap

shot) directly from the vehicle. You can replay the

snapshot data as needed. There fore, accurate diagnosis

is possible, even though the vehicle is not available.

Plotting Graph Flow Chart (Plotting graph after obtaining vehicle information)

060RX085

Flow Chart for Snapshot Replay (Plotting Graph)

060RX040

PRIMARY SYSTEM–BASED

DIAGNOSTICS

Primary System–Based Diagnostics

There are primary system–based diagnostics which

evaluate system operation and its effect on vehicle

emissions. The primary system–based diagnostics are

listed below with a brief description of the diagnostic

function:

Oxygen Sensor Diagnosis

The fuel control heated oxygen sensor (HO2S 1) is

diagnosed for the following conditions:

DHeater performance (time to activity on cold start)

DSlow response

DResponse time (time to switch R/L or L/R)

DInactive signal (output steady at bias voltage –

approx. 450 mV)

DSignal fixed high

DSignal fixed low

The catalyst monitor heated oxygen sensor (HO2S 2) is

diagnosed for the following conditions:

DHeater performance (time to activity on cold start).

DSignal fixed low during steady state conditions or

power enrichment (hard acceleration when a rich

mixture should be indicated).

DSignal fixed high during steady state conditions or

deceleration mode (deceleration when a lean mixture

should be indicated).

DInactive sensor (output steady at approx. 438 mV).

If the oxygen sensor pigtail wiring, connector or terminal

are damaged, the entire oxygen sensor assembly must

be replaced. DO NOT attempt to repair the wiring,

connector or terminals. In order for the sensor to function

properly, it must have clean reference air provided to it.

This clean air reference is obtained by way of the oxygen

sensor wire(s). Any attempt to repair the wires, connector

or terminals could result in the obstruction of the

reference air and degrade oxygen sensor performance.

Refer to On–Vehicle Service, Heated Oxygen Sensors.

Fuel Control Heated Oxygen Sensors

The main function of the fuel control heated oxygen

sensors is to provide the control module with exhaust

stream oxygen content information to allow proper fueling

and maintain emissions within mandated levels. After it

reaches operating temperature, the sensor will generate

a voltage, inversely proportional to the amount of oxygen

present in the exhaust gases. The control module uses

the signal voltage from the fuel control heated oxygen

sensors while in ”Closed Loop” to adjust fuel injector

pulse width. While in ”Closed Loop”, the ECM can adjust

fuel delivery to maintain an air/fuel ratio which allows the

best combination of emission control and driveability . The

fuel control heated oxygen sensors are also used to

determine catalyst efficiency.

HO2S Heater

Heated oxygen sensors are used to minimize the amount

of time required for ”Closed Loop” fuel control to begin

operation and to allow accurate catalyst monitoring. The

oxygen sensor heater greatly decreases the amount of

time required for fuel control sensor (HO2S 1) to become

active. Oxygen sensor heaters are required by the

catalyst monitor sensor (HO2S 2) to maintain a

sufficiently high temperature which allows accurate

exhaust oxygen content readings further away from the

engine.

ON–BOARD DIAGNOSTIC (OBD) SYSTEM CHECK

D06RX108

Circuit Description

The on–board diagnostic system check is the starting

point for any driveability complaint diagnosis. Before

using this procedure, perform a careful visual/physical

check of the ECM and engine grounds for cleanliness and

tightness.

The on–board diagnostic system check is an organized

approach to identifying a problem created by an

electronic engine control system malfunction.

Diagnostic Aids

An intermittent may be caused by a poor connection,

rubbed–through wire insulation or a wire broken inside the

insulation. Check for poor connections or a damaged

harness. Inspect the ECM harness and connectors for

improper mating, broken locks, improperly formed or

damaged terminals, poor terminal–to–wire connection,

and damaged harness.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

1. The MIL (”Check Engine” lamp) should be ON

steady with the ignition ON/engine OFF. If not,

isolate the malfunction in the MIL circuit.

2. Checks the Class 2 data circuit and ensures that the

ECM is able to transmit serial data.

3. This test ensures that the ECM is capable of

controlling the MIL and the MIL driver circuit is not

shorted to ground.

4. If the engine will not start, the Cranks But Will Not

Run chart should be used to diagnose the condition.

7. A Tech 2 parameter which is not within the typical

range may help to isolate the area which is causing

the problem.

On–Board Diagnostic (OBD) System Check

Step Action Value(s) Yes No

11. Ignition ON, engine OFF.

2. Observe the malfunction indicator lamp (MIL or

”Check Engine lamp”).

Is the MIL (”Check Engine lamp”) ON? —Go to Step 2 Go to No MIL

21. Ignition OFF.

2. Install a Tech 2.

3. Ignition ON.

4. Attempt to display ECM engine data with the T ech 2.

Does the Tech 2 display ECM data? —Go to Step 3 Go to Step 8

31. Using the Tech 2 output tests function, select MIL

dash lamp control and command the MIL OFF.

2. Observe the MIL.

Did the MIL turn OFF? —Go to Step 4

Go to MIL

(”Check

Engine

Lamp”) On

Steady

4Attempt to start the engine.

Did the engine start and continue to run? —Go to Step 5

Go to Cranks

But Will Not

Run

5Select ”Display DTCs” with the Tech 2.

Are any DTCs stored? —Go to Step 6 Go to Step 7

6Are two or more of the following DTCs stored? P0107,

P0113, P0118, P0122, P0123.

—

Go to

“Multiple

ECM

Information

Sensor DTCs

Set”

Go to

applicable

DTC table

7Compare ECM data values displayed on the Tech 2 to

the typical engine scan data values.

Are the displayed values normal or close to the typical

values? —

Go to “Typial

Scan” Data

Value

Go to

indicated

Component

System

Checks

81. Ignition OFF, disconnect the ECM.

2. Ignition ON, engine OFF.

3. Check the Class 2 data circuit for an open, short to

ground, or short to voltage. Also, check the DLC

ignition feed circuit for an open or short to ground

and the DLC ground circuits for an open.

4. If a problem found, repair as necessary.

Was a problem found? —Go to Step 2 Go to Step 9

91. Attempt to reprogram the ECM. Refer to Engine

Control Module (ECM) in On–Vehicle Service.

2. Attempt to display ECM data with the Tech 2.

Does the Tech 2 display ECM engine data? —Go to Step 2 Go to Step 10

10 Replace the ECM.

Is the action complete? — Verify repair —

A/C CLUTCH CONTROL CIRCUIT DIAGNOSIS

D06RX107

Circuit Description

When air conditioning and blower fan are selected, and if

the system has a sufficient refrigerent charge, a 12–volt

signal is supplied to the A/C request input of the engine

control module (ECM). The A/C request signal may be

temporarily cancelled during system operation by the

electronic thermostat in the evaporator case. The

electronic thermostat may intermittently remove the

control circuit ground for the A/C thermostat relay to

prevent the evaporator from forming ice. When the A/C

request signal is received by the ECM, the ECM supplies

a ground from the compressor clutch relay if the engine

operating conditions are within acceptable ranges. With

the A/C compressor relay energized, battery voltage is

supplied to the compressor clutch coil.

The ECM will enable the compressor clutch to engage

whenever A/C has been selected with the engine running,

unless any of the following conditions are present:

DThe throttle is greater than 90%.

DThe ignition voltage is below 10.5 volts.

DThe engine speed is greater than 4500 RPM for 5

seconds or 5400 RPM.

DThe engine coolant temperature (ECT) is greater

than 125°C (257°F)

DThe intake air temperature (IAT) is less than 5°C

(41°F).

DThe power steering pressure switch signals a high

pressure condition position.

Diagnostic Aids

To diagnose an intermittent fault, check for the following

conditions:

DPoor connection at the ECM – Inspect harness

connections for backed–out terminals, improper

mating, broken locks, improperly formed or damaged

terminals, and poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery voltage,

and open circuits. If the harness appears to be OK,

observe the A/C clutch while moving connnectors and

wiring harnesses related to the A/C. A sudden clutch

malfunction will indicate the source of the intermittent.

A/C Clutch Diagnosis

This chart should be used for diagnosing the electrical

portion of the A/C compressor clutch circuit. A Tech 2 will

be used in diagnosing the system. The Tech 2 has the

ability to read the A/C request input to the ECM. The Tech

2 can display when the ECM has commended the A/C

clutch ON. The Tech 2 should have the ability to override

the A/C request signal and energize the A/C compressor

relay.

A/C Clutch Control Circuit Diagnosis

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON, engine OFF.

2. Review and record Tech 2 Failure Records data,

then clear the DTCs.

3. Operate the vehicle within the Failure Records

conditions as noted.

4. Using the Tech 2, monitor ”DTC” info for DTC

P1546.

Does the Tech 2 indicate DTC P1546 ”Ran and

Passed”? —

Refer to

Diagnostic

Aids Go to Step 3

31. Ignition OFF.

2. Remove the A/C Compressor Relay from the

Underhood Electrical Center.

3. Ignition ON, engine OFF.

4. Using a Digital Voltmeter (DVM), check for voltage

on the Fused pins of the A/C Compressor Clutch

Relat connector.

Does the DVM read the following value? 12 Volts Go to Step 5 Go to Step 4

4Check the suspect circuit(s) between the A/C

Compressor Clutch Relay connector and the Fuse for

the following conditions:

DA short to ground

DAn open circuit

DA short to voltage

Was the problem found? — Verify repair —

51. Ignition OFF.

2. Disconnect the Engine Controlm Module (ECM)

connectors from the ECM.

3. Check the A/C Compressor Clutch Relay control

circuit between the ECM and Underhood Electrical

Center for the following conditions:

DA short to ground

DAn open circuit

DA short to voltage

Was the problem found? — Verify repair Go to Step 6

Step NoYesValue(s)Action

61. Reinstall the A/C Compressor Clutch Relay.

2. Using a fused jumper, ground the A/C Compressor

Clutch Relay control circuit at the ECM connector.

3. Ignition ON, engine OFF.

Does the A/C Compressor turn ON? —Go to Step 9 Go to Step 7

71. Ignition OFF.

2. Check the A/C Compressor Clutch circuit between

the A/C Compressor Clutch Relay and A/C

Compressor Clutch for the following conditions:

DA short to ground

DAn open circuit

DA short to voltage

Was the problem found? — Verify repair Go to Step 8

8Replace the A/C Compressor Clutch Relay.

Is the action complete? — Verify repair —

9Replace the ECM.

Verify repair. ———

ELECTRONIC IGNITION SYSTEM

DIAGNOSIS

If the engine cranks but will not run or immediately stalls,

the Engine Cranks But Will Not Start chart must be used

to determine if the failure is in the ignition system or the

fuel system.

VISUAL CHECK OF THE

EVAPORATIVE EMISSION CANISTER

014RX001

DIf the canister is cracked or damaged, replace the

canister.

DIf fuel is leaking from the canister, replace the canister

and check hoses and hose routing.

IDLE AIR CONTROL (IAC) VALVE

0006

The Tech 2 displays the IAC pintle position in counts. A

count of ”0” indicates the ECM is commanding the IAC

pintle to be driven all the way into a fully–seated position.

This is usually caused by a vacuum leak.

The higher the number of counts, the more air is being

commanded to bypass the throttle blade. In order to

diagnose the IAC system, refer to IAC System Check.

For other possible causes of idle problems, refer to

Rough, Unstable, or Incorrect Idle, Stalling in Symptoms.

ENGINE CONTROL MODULE (ECM)

DIAGNOSIS

014RX002

To read and clear diagnostic trouble codes, use a Tech 2.

901RX031

IMPORTANT:Use of a Tech 2 is recommended to clear

diagnostic trouble codes from the ECM memory.Diagnostic trouble codes can also be cleared by turning

the ignition OFF and disconnecting the battery powerfrom the ECM for 30 seconds. Turning off the ignition and

disconnecting the battery power from the ECM will cause

all diagnostic information in the ECM memory to becleared. Therefore, all the diagnostic tests will have to bere–run.

Since the ECM can have a failure which may affect only

one circuit, following the diagnostic procedures in this

section will determine which circuit has a problem andwhere it is.If a diagnostic chart indicates that the ECM connectionsor the ECM is the cause of a problem, and the ECM isreplaced, but this does not correct the problem, one of the

following may be the reason:

DThere is a problem with the ECM terminalconnections. The terminals may have to be removedfrom the connector in order to check them properly.

DThe problem is intermittent. This means that the

problem is not present at the time the system is being

checked. In this case, make a careful physicalinspection of all components and wiring associated

with the affected system and refer to the Symptoms

portion of the manual.

DThere is a shorted solenoid, relay coil, or harness.

Solenoids and relays are turned ON and OFF by the

ECM using internal electronic switches called drivers.

A shorted solenoid, relay coil, or harness will not

damage the ECM but will cause the solenoid or relay

to be inoperative.

MULTIPLE ECM INFORMATION

SENSOR DTCs SET

Circuit Description

The engine control module (ECM) monitors various

sensors to determine the engine operating conditions.

The ECM controls fuel delivery, spark advance, and

emission control device operation based on the sensor

inputs.

The ECM provides a sensor ground to all of the sensors.

The ECM applies 5 volts through a pull–up resistor, and

determines the status of the following sensors by

monitoring the voltage present between the 5–volt supply

and the resistor:

DThe Fuel Tank Vapor Pressure Sensor

DThe throttle position (TP) sensor

DThe manifold absolute pressure (MAP) sensor

The ECM provides the following sensors with a 5–volt

reference and a sensor ground signal:

DThe Linear exhaust gas recirculation (EGR) valve

DThe A/C Pressure Sensor

The ECM monitors the separate feedback signals from

these sensors in order to determine their operating

status.

Diagnostic Aids

Be sure to inspect ECM and engine grounds for being se-

cure and clean.

A short to voltage in one of the sensor input circuits may

cause one or more of the following DTCs to be set:

DP0108

DP0113

DP0118

DP0123

If a sensor input circuit has been shorted to voltage, en-

sure that the sensor is not damaged. A damaged sensor

will continue to indicate a high or low voltage after the af-

fected circuit has been repaired. If the sensor has been

damaged, replace it.

An open in the sensor ground circuit between the ECM

and the splice will cause one or more of the following

DTCs to be set:

DP0108

DP0113

DP0118

DP0123

A short to ground in the 5–volt reference A circuit will

cause one or more of the following DTCs to be set:

DP0107

DP0122

DP0112

DP0117

DP0454

DP0405

DP0532

Check for the following conditions:

DPoor connection at ECM. Inspect the harness

connectors for backed–out terminals, improper

mating, broken locks, improperly formed or damaged

terminals, and a poor terminal–to–wire connection.

DDamaged harness. Inspect the wiring harness for

damage. If the harness is not damaged, observe an

affected sensor’s displayed value on the Tech 2 with

the ignition ON and the engine OFF while you move

the connectors and the wiring harnesses related to

the following sensors:

DIAT

DECT

DTP

DMAP

DEGR

DA/C Pressure Sensor

Multiple ECM Information Sensor DTCs Set

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Turn the ignition OFF, disconnect the ECM.

2. Turn the ignition ON, check the 5 volt reference

circuits for the following conditions:

DA poor connection at the ECM.

DAn open between the ECM connector and the

splice.

DA short to ground.

DA short to voltage.

Is there an open or short? —Go to Step 3 Go to Step 4

3Repair the open or short.

Is the action complete? — Verify repair —

4Check the sensor ground circuit for the following

conditions:

DA poor connection at the ECM or the affected

sensors.

DAn open between the ECM connector and the

affected sensors.

Is there an open or a poor connection? —Go to Step 5 Go to Step 6

5Repair the open or the poor connection.

Is the action complete? — Verify repair —

6Measure the voltage between the EGR pintle position

sensor signal circuit at the ECM harness connector and

ground.

Does the voltage measure near the specified value? 0 V Go to Step 7 Go to Step 13

7Measure the voltage between the MAP sensor signal

circuit at the ECM harness connector and ground.

Does the voltage measure near the specified value? 0 V Go to Step 8 Go to Step 14

8Measure the voltage between the TP sensor signal

circuit at the ECM harness connector and ground.

Does the voltage measure near the specified value? 0 V Go to Step 9 Go to Step 15

9Measure the voltage between the IAT sensor signal

circuit at the ECM harness connector and ground.

Does the voltage measure near the specified value? 0 V Go to Step 10 Go to Step 16

10 Measure the voltage between the ECT sensor signal

circuit at the ECM harness connector and ground.

Does the voltage measure near the specified value? 0 V Go to Step 20 Go to Step 17

11 Measure the voltage between the A/C Pressure

Sensor circut at the ECM harness connector and

ground.

Does the voltage measure near the specified value? 0 V Go to Step 13 Go to Step 19

Step NoYesValue(s)Action

12 1. Disconnect the EGR valve.

2. Measure the voltage between the EGR pintle

position sensor signal circuit at the ECM harness

connector and ground.

Does the voltage measure near the specified value? 0 V Go to Step 12 Go to Step 17

13 Replace the EGR valve.

Is the action complete? — Verify repair —

14 Locate and repair the short to voltage in the MAP

sensor signal circuit.

Is the action complete? — Verify repair —

15 Locate and repair the short to voltage in the TP sensor

signal circuit.

Is the action complete? — Verify repair —

16 Locate and repair the short to voltage in the IA T sensor

signal circuit.

Is the action complete? — Verify repair —

17 Locate and repair the short to voltage in the ECT

sensor signal circuit.

Is the action complete? — Verify repair —

18 Locate and repair the short to voltage in the A/C

Pressure Sensor circuit.

Is the action complete? — Verify repair —

19 Locate and repair the short to voltage in the EGR pintle

position sensor signal circuit.

Is the action complete? — Verify repair —

20 Replace the ECM.

Is the action complete? —

Go to OBD

System

Check —

EXHAUST GAS RECIRCULATION

(EGR) DIAGNOSIS

057RX001

An EGR flow check diagnosis of the linear EGR system is

covered by DTC P0401, P0404, and P0405. If EGR

diagnostic trouble code P0401 is encountered, refer to

the DTC charts.

ENGINE Tech 2 DATA DEFINITIONS

AND RANGES

A/C CLUTCH – Tech 2 Displays ON or OFF

Indicates whether the ECM has commanded the A/C

clutch ON. Used in A/C system diagnostics.

A/C REQUEST – Tech 2 Displays YES or NO

Indicates the state of the A/C request input circuit from the

HVAC controls. The ECM uses the A/C request signal to

determine whether A/C compressor operation is being

requested.

AIR/FUEL RATIO – Tech 2 Range 0.0–25.5

Air/fuel ratio indicates the ECM commanded value. In

”Closed Loop”, the air/fuel ratio should normally be

displayed around ”14.2–14.7.” A lower air/fuel ratio

indicates a richer commanded mixture, which may be

seen during power enrichment or TWC protection modes.

A higher air/fuel ratio indicates a leaner commanded

mixture. This can be seen during deceleration fuel mode.

BARO kPa – Tech 2 Range 10–105 kPa/0.00–5.00

Volts

The barometric pressure reading is determined from the

MAP sensor signal monitored during key up and wide

open throttle (WOT) conditions. The barometric pressure

is used to compensate for altitude differences and is

normally displayed around ”61–104” depending on

altitude and barometric pressure.

CMP ACT. COUNTER – Cam Position Activity

DECEL FUEL MODE – Tech 2 Displays ACTIVE or

INACTIVE

”ACTIVE” displayed indicates that the ECM has detected

conditions appropriate to operate in deceleration fuel

mode. The ECM will command the deceleration fuel

mode when it detects a closed throttle position while the

vehicle is traveling over 20 mph. While in the deceleration

fuel mode, the ECM will decrease the amount of fuel

delivered by entering ”Open Loop” and decreasing the

injector pulse width.

DESIRED EGR POS. – Tech 2 Range 0%–100%

Represents the EGR pintle position that the ECM is

commanding.

DESIRED IDLE – Tech 2 Range 0–3187 RPM

The idle speed that the ECM is commanding. The ECM

will compensate for various engine loads based on engine

coolant temperature, to keep the engine at the desired

speed.

ECT – (Engine Coolant Temperature) Tech 2 Range

–40°C to 151°C (–40°F to 304°F)

The engine coolant temperature (ECT) is mounted in the

coolant stream and sends engine temperature

information to the ECM. The ECM applies 5 volts to the

ECT sensor circuit. The sensor is a thermistor which

changes internal resistance as the temperature changes.

When the sensor is cold (high resistance), the ECM

monitors a high signal voltage and interprets that as a cold

engine. As the sensor warms (decreasing resistance),

the voltage signal will decrease and the ECM will interpret

the lower voltage as a warm engine.

EGR DUTY CYCLE – Tech 2 Range 0%–100%

Represents the EGR valve driver PWM signal from the

ECM. A duty cycle of 0% indicates that no EGR flow is

being commanded; a 100% duty cycle indicates

maximum EGR flow commanded.

EGR FEEDBACK – Tech 2 Range 0.00–5.00 Volts

Indicates the EGR pintle position sensor signal voltage

being monitored by the ECM. A low voltage indicates a

fully extended pintle (closed valve); a voltage near 5 volts

indicates a retracted pintle (open valve).

EGR TEST COUNT – Tech 2 Range 0–255

Indicates the number of EGR flow test samples collected

during the current ignition cycle. Under normal operation,

only one sample is allowed during an ignition cycle. If the

ECM battery feed has been disconnected or a DTC

P0401 has been cleared, 10 EGR flow test samples will

be allowed during the ignition cycle. This is to allow repair

verification during a single ignition cycle.

ENGINE LOAD – Tech 2 Range 0%–100%

Engine load is calculated by the ECM from engine speed

and MAP sensor readings. Engine load should increase

with an increase in RPM or air flow.

ENGINE RUN TIME – Tech 2 Range 00:00:00–

99:99:99 Hrs:Min:Sec

Indicates the time elapsed since the engine was started.

If the engine is stopped, engine run time will be reset to

00:00:00.

ENGINE SPEED – Range 0–9999 RPM

Engine speed is computed by the ECM from the 58X

reference input. It should remain close to desired idle

under various engine loads with engine idling.

FUEL PUMP – Tech 2 Displays ON or OFF

Indicates the ECM commanded state of the fuel pump

relay driver circuit.

FUEL TRIM CELL – Tech 2 Range 0–21

The fuel trim cell is dependent upon engine speed and

MAF sensor readings. A plot of RPM vs. MAF is divided

into 22 cells. Fuel trim cell indicates which cell is currently

active.

FUEL TRIM LEARN – Tech 2 Displays NO or YES

When conditions are appropriate for enabling long term

fuel trim corrections, fuel trim learn will display YES. This

indicates that the long term fuel trim is responding to the

short term fuel trim. If the fuel trim learn displays NO, then

long term fuel trim will not respond to changes in short

term fuel trim.

HO2S BANK 1, SEN. 1 – Tech 2 Range 0–1000 mV

Represents the fuel control exhaust oxygen sensor

output voltage. Should fluctuate constantly within a range

between 10 mV (lean exhaust) and 1000 mV (rich

exhaust) while operating in ”Closed Loop”.

HO2S BANK 1, SEN. 1 – Tech 2 Displays NOT

READY or READY

Indicates the status of the exhaust oxygen sensor. The

Tech 2 will indicate that the exhaust oxygen sensor is

ready when the ECM detects a fluctuating HO2S voltage

sufficient to allow ”Closed Loop” operation. This will not

occur unless the exhaust sensor is warmed up.

HO2S WARM UP TIME BANK 1, SEN. 1 – Tech 2

Range 00:00:00–99:99:99 HRS:MIN:SEC

Indicates warm–up time for each HO2S. The HO2S

warm–up time is used for the HO2S heater test. The ECM

will run the heater test only after a cold start (determined

by engine coolant and intake air temperature at the time

of start–up) and only once during an ignition cycle. When

the engine is started the ECM will monitor the HO2S

voltage. When the HO2S voltage indicates a sufficiently

active sensor, the ECM looks at how much time has

elapsed since start–up. If the ECM determines that too

much time was required for the HO2S to become active,

a DTC will set. If the engine was warm when started,

HO2S warm–up will display ”00:00:00.”

IAC POSITION – Tech 2 Range 0–255 Counts

Displays the commanded position of the idle air control

pintle in counts. A larger number of counts means that

more air is being commanded through the idle air

passage. Idle air control should respond fairly quickly to

changes in engine load to maintain desired idle RPM.

IAT (INTAKE AIR TEMPERATURE) – Tech 2 Range

–40°C to 151°C (–40°F to 304°F)

The ECM converts the resistance of the intake air

temperature sensor to degrees. Intake air temperature

(IA T) is used by the ECM to adjust fuel delivery and spark

timing according to incoming air density.

IGNITION 1 – Tech 2 Range 0–25.5 Volts

This represents the system voltage measured by the

ECM at its ignition feed.

INJ. PULSE BANK 1 – Tech 2 Range 0–1000 msec.

Indicates the amount of time the ECM is commanding

each injector ON during each engine cycle. A longer

injector pulse width will cause more fuel to be delivered.

Injector pulse width should increase with increased

engine load.

MAP – Tech 2 Range 10–105 kPa (0.00–4.97 Volts)

The manifold absolute pressure (MAP) sensor measures

the change in the intake manifold pressure from engine

load, EGR flow, and speed changes. As intake manifold

pressure increases, intake vacuum decreases, resulting

in a higher MAP sensor voltage and kPa reading. The

MAP sensor signal is used to monitor intake manifold

pressure changes during the EGR flow test, to update the

BARO reading, and as an enabling factor for several of

the diagnostics.

MIL – Tech 2 Displays ON or OFF

Indicates the ECM commanded state of the malfunction

indicator lamp (”Check Engine Lamp”).

POWER ENRICHMENT – Tech 2 Displays ACTIVE

or INACTIVE

”ACTIVE” displayed indicates that the ECM has detected

conditions appropriate to operate in power enrichment

mode. The ECM will command power enrichment mode

when a large increase in throttle position and load is

detected. While in the power enrichment mode, the ECM

will increase the amount of fuel delivered by entering

”Open Loop” and increasing the injector pulse width. This

is done to prevent a possible sag or hesitation from

occurring during acceleration.

SPARK – Tech 2 Range –64° to 64°

Displays the amount of spark advance being commanded

by the ECM on the IC circuit.

START–UP ECT – Tech 2 Range –40°C to 151°C

(–40°F to 304°F)

Indicates the engine coolant temperature at the time that

the vehicle was started. Used by the HO2S diagnostic to

determine if the last start–up was a cold start.

START–UP ECT – Tech 2 Range –40°C to 151°C

(–40°F to 304°F)

Indicates the intake air temperature at the time that the

vehicle was started. Used by the HO2S diagnostic to

determine if the last start–up was a cold start.

TP ANGLE – Tech 2 Range 0%–100%

TP (throttle position) angle is computed by the ECM from

the TP sensor voltage. TP angle should display ”0%” at

idle and ”100%” at wide open throttle.

TP SENSOR – Tech 2 Range 0.00–5.00 Volts

The voltage being monitored by the ECM on the TP

sensor signal circuit.

VEHICLE SPEED – Tech 2 Range 0–255 km/h

(0–155 mph)

The vehicle speed sensor signal is converted into km/h

and mph for display.

WEAK CYLINDER – Tech 2 Displays Cylinder

Number

This indicates that the ECM has detected crankshaft

speed variations that indicate 2% or more cylinder firing

events are misfires.

TYPICAL SCAN DATA VALUES

Use the Typical Scan Data Values Table only after the

On–Board Diagnostic System Check has been

completed, no DTC(s) were noted, and you have

determined that the on–board diagnostics are functioning

properly. Tech 2 values from a properly–running engine

may be used for comparison with the engine you are

diagnosing. The typical scan data values represent

values that would be seen on a normally–running engine.

NOTE:A Tech 2 that displays faulty data should not be

used, and the problem should be reported to the Tech 2

manufacturer. Use of a faulty Tech 2 can result in

misdiagnosis and unnecessary replacement of parts.

Only the parameters listed below are referred to in this

service manual for use in diagnosis. For further

information on using the Tech 2 to diagnose the ECM and

related sensors, refer to the applicable reference section

listed below. If all values are within the typical range

described below, for diagnosis, refer to the Symptoms

section.

Test Conditions

Engine running, lower radiator hose hot, transmission in

park or neutral, ”Closed Loop”, accessories OFF, brake

not applied and air conditioning OFF.

2.2L L–4 Engine

Tech 2

Parameter Data List Units

Displayed Typical Data

Values (IDLE) Typical Data

Values

(2500 RPM)

Refer To

Engine Speed Engine RPM Within -50 to

+100 of

“Desired Idle”

Actul engine

speed General Discription and

Operation

Desired Idle

Speed Engine RPM 750 800 General Discription and and

Operation, Idle Air Control

Engine Coolant

Tenpereture Engine °C80 – 100 (176 –

212 °F) 80 – 100 (176 –

212 °F) General Discription and and

Operation, Engin coolant

tempereture sensor

Start Up ECT Engine °C––General Discription and and

Operation, Engin coolant

tempereture sensor

Intake Air

Tenpereture Engine °C0 – 100,

depends on

underhood

0 – 80, depends

on underhood General Discription and and

Operation, Intake Air

tempereture sensor

Start Up IAT Engine °C––General Discription and and

Operation, Intake Air

tempereture sensor

Manifold

Absolute

Pressure

Engine kPa 23 – 40 19 – 32 General Discription and

Operation, Manifold

Absolute Pressure Sensor.

DTC P0106,P0107,P0108

Manifold

Absolute

Pressure

Engine V0.65 – 1.32 0.46 – 1.10 General Discription and

Operation, Manifold

Absolute Pressure Sensor.

DTC P0106,P0107,P0108

Barometric

Pressure Engine kPa 61 – 104

(depends pn

altitude and

barometric)

61 – 104

(depends pn

altitude and

barometric)

General Discription and

Opreration

Throttle Position Engine % 0 3 – 5 General Discription and

Opreration, Throttle Position

Sensor. DTC

P0121,P0122,P0123

Throttle Position

Sensor Engine V0.35 – 0.39 0.55 – 0.59 General Discription and

Opreration, Throttle Position

Sensor. DTC

P0121,P0122,P0123

Air Fuel Ratio Engine Ratio:_to1 14.6:1 14.6:1 General Discription and

Operation, Fuel System

Metering Purpose, Fuel Trim

Tech 2

Parameter Refer ToTypical Data

Values

(2500 RPM)

Typical Data

Values (IDLE)

Units

Displayed

Data List

Spark Advance Engine °CA 10 – 12 27 – 29 General Discription and and

Operation, Electronic

Ignition System

Engine Load Engine % – – –

Fuel system

Status Engine Closed

Loop ––EVAP System

EGR Duty Cycle Engine %00General Discription and and

Operation, Liner EGR

Operation and Results of

Incorrect Operation

Desired EGR

Position Engine %00General Discription and and

Operation, EGR Pintle

Position Sensor

EGR

Normalized Engine % 0 0 –

EGR Feed Back Engine V0.6 – 0.8 0.6 – 0.8 –

EGR Closed

Pintle Position Engine Steps 20 – 40 20 – 40 General Discription and and

Operation, EGR Pintle

Position Sensor

Knock Counter Engine Yes/No Yes Yes DTC P0325,P0327

Knock Retard Engine °CA – – DTC P0325,P0327

A/C Pressure

Sensor Engine mV 0–DTC P0532,P0533

A/C Clutch

Relay Engine On/Off Off –General Discription and and

Operation, A/C Culutch

Circuit Operation

A/C Request Engine Yes/No No –General Discription and and

Operation, A/C Request

Signal

Low Fan

Comanded Engine Yes/No ––General Discription and and

Operation, Cooling Fan

Control. DTC P0480,P0481

High Fan

Comanded Engine Yes/No ––General Discription and and

Operation, Cooling Fan

Control. DTC P0480,P0481

Camshaft

Activity Engine Counts 0 – 255 0 – 255 DTC P0341,P0342

Fuel Pump Engine On/Off On On Engine Fuel System

Deceleration

Fuel Cutoff Engine Inactive/Ac

tive Inactive Inactive General Discription and and

Operation

Idle Air Control Engine Steps ––General Discription and and

Operation, Intake Air

tempereture sensor

Vehicle Speed Engine MPH or

km/h 00Manual Transmission

Ignition Voltage Engine V12.8 – 14.1 12.8 – 14.1 General Discription and and

Operation, Electronic

Ignition System

Malfunction

Indicator Lamp Engine On/Off Off Off On–Board Diagnostic

System Check

Tech 2

Parameter Refer ToTypical Data

Values

(2500 RPM)

Typical Data

Values (IDLE)

Units

Displayed

Data List

ABS Rough

Road Engine

Misfire Value Okey Okey DTC P1380,P1381

B1S1 Status

(Bank1,Sensor1) Engine

HO2S Rich/Lean ––General Discription and and

Operation, Fuel Control

HO2S

B1S1 O2 Sensor

(Bank1,Sensor1) Engine

HO2S mV 50 – 950

changing quickly 50 – 950

changing quickly General Discription and and

Operation, Fuel Control

HO2S

Fuel Trim

Learned Engine

HO2S Yes/No Yes Yes Diagnosis, Fuel Trim Monitor

Fuel Trim Cell Engine

HO2S Cell No. 18 2 or 6 Diagnosis, Fuel Trim Cell

Diagnostic Weights

B1 Long Fuel

Trim Engine

HO2S %––DTC P0171,P0172

B2 Short Fuel

Trim Engine

HO2S %––DTC P0171,P0172

Power

Enrichment Engine

HO2S Yes/No No No General Discription and and

Operation, Acceleration

Mode

NO MALFUNCTION INDICATOR LAMP (MIL)

D06RX109

Circuit Description

The ”Check Engine” lamp (MIL) should always be

illuminated and steady with the ignition ON and the

engine stopped. Ignition feed voltage is supplied to the

MIL bulb through the meter fuse. The engine control

module (ECM) turns the MIL ON by grounding the MIL

driver circuit.

Diagnostic Aids

An intermittent MIL may be caused by a poor connection,

rubbed–through wire insulation, or a wire broken inside

the insulation. Check for the following items:

DInspect the ECM harness and connections for

improper mating, broken locks, improperly formed or

damaged terminals, poor terminal–to–wire

connection, and damaged harness.

DIf the engine runs OK, check for a faulty light bulb, an

open in the MIL driver circuit, or an open in the

instrument cluster ignition feed.

DIf the engine cranks but will not run, check for an open

ECM ignition or battery feed, or a poor ECM to engine

ground.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2. A ”No MIL” condition accompanied by a no–start

condition suggests a faulty ECM ignition feed or

battery feed circuit.

9. Using a test light connected to B+, probe each of

the ECM ground terminals to ensure that a good

ground is present. Refer to ECM Terminal End View

for terminal locations of the ECM ground circuits.

12. In this step, temporarily substitute a known good

relay for the ECM relay. The horn relay is nearby,

and it can be verified as ”good” simply by honking

the horn. Replace the horn relay after completing

this step.

No Malfunction Indicator Lamp (MIL)

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Attempt to start the engine.

Does the engine start? —Go to Step 3 Go to Step 6

3Check the meter fuse for the instrument cluster ignition

feed circuit.

Is the fuse OK? —Go to Step 4 Go to Step 16

41. Ignition ON.

2. Engine OFF.

3. Probe the ignition feed circuit at the cluster

connector with a test light to ground.

Is the test light ON? —Go to Step 5 Go to Step 13

51. Ignition OFF.

2. Disconnect the ECM.

3. Jumper the MIL driver circuit at the ECM connector

to ground.

4. Ignition ON.

Is the MIL ON? —Go to Step 10 Go to Step 11

6Check the ECM ignition feed and battery feed fuses

(15A Engine fuse and 15A ECM fuse).

Are both fuses OK? —Go to Step 7 Go to Step 15

71. Ignition OFF.

2. Disconnect the ECM.

3. Ignition ON.

4. Probe the ignition feed circuit at the ECM harness

connector with a test light to ground.

Is the test light ON? —Go to Step 8 Go to Step 12

8Probe the battery feed circuit at the ECM harness

connector with a test light to ground.

Is the test light ON? —Go to Step 9 Go to Step 14

9Check for a faulty ECM ground connection.

Was a problem found? — Verify repair Go to Step 10

10 Check for damaged terminals at the ECM.

Was a problem found? — Verify repair Go to Step 17

11 Check for an open MIL driver circuit between the ECM

and the MIL.

Was a problem found? — Verify repair Go to Step 18

12 Substitute a known ”good” relay for the ECM main

relay.

Was the malfunction fixed? — Verify repair Go to Step 13

13 Repair the open in the ignition feed circuit.

Is the action complete? — Verify repair —

14 Locate and repair the open ECM battery feed circuit.

Is the action complete? — Verify repair —

Step NoYesValue(s)Action

15 Locate and repair the short to ground in the ECM

ignition feed circuit or ECM battery feed circuit.

Is the action complete? — Verify repair —

16 Locate and repair the short to ground in the ignition

feed circuit to the instrument cluster, and replace the

fuse.

Is the action complete? — Verify repair —

17 Replace the ECM.

Is the action complete? — Verify repair —

18 Check the MIL driver circuit for a poor connection at the

instrument panel connector.

Was a problem found? — Verify repair

Go to

Instrument

Panel in

Electrical

Diagnosis

MALFUNCTION INDICATOR LAMP (MIL) ON STEADY

D06RX110

Circuit Description

The malfunction indicator lamp (MIL) should always be

illuminated and steady with the ignition ON and the

engine stopped. Ignition feed voltage is supplied directly

to the MIL indicator. The engine control module (ECM)

turns the MIL ON by grounding the MIL driver circuit.

The MIL should not remain ON with the engine running

and no DTC(s) set. A steady MIL with the engine running

and no DTC(s) suggests a short to ground in the MIL

driver circuit.

Diagnostic Aids

An intermittent may be caused by a poor connection,

rubbed–through wire insulation, or a wire broken inside

the insulation. Check for the following items:

DPoor connection or damaged harness – Inspect the

ECM harness and connectors for improper mating,

broken locks, improperly formed or damaged

terminals, poor terminal–to–wire connection, and

damaged harness.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2. If the MIL does not remain ON when the ECM is

disconnected, the MIL driver wiring is not faulty.

3. If the MIL driver circuit is OK, the instrument panel

cluster is faulty.

Malfunction Indicator Lamp (MIL) ON Steady

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition OFF, disconnect the ECM.

2. Ignition ON, observe the MIL (Service Engine Soon

lamp).

Is the MIL ON? —Go to Step 3 Go to Step 5

31. Ignition OFF, disconnect the instrument panel

cluster.

2. Check the MIL driver circuit between the ECM and

the instrument panel cluster for a short to ground.

3. If a problem is found, repair as necessary.

Was the MIL driver circuit shorted to ground? —

Go to OBD

System

Check Go to Step 4

4Replace the instrument panel cluster.

Is the action complete? —

Go to OBD

System

Check —

51. Ignition OFF, reconnect the ECM.

2. Ignition ON, reprogram the ECM. Refer to

On–Vehicle Service in Engine Control Module and

Sensors for procedures.

3. Using the Tech 2 output controls function, select

MIL dash lamp control and command the MIL OFF.

Did the MIL turn OFF? —

Go to OBD

System

Check Go to Step 6

6Replace the ECM.

Is the action complete? —

Go to OBD

System

Check —

ENGINE CRANKS BUT WILL NOT RUN

D06RX099

D06RX091

Circuit Description

The electronic ignition system uses a dual coil method of

spark distribution. In this type of ignition system, the

engine control module (ECM) triggers the correct driver

inside the ignition control module (ICM), which then

triggers the correct ignition coil based on the 58X signal

received from the crankshaft position sensor (CKP). The

spark plug connected to the coil fires when the ICM opens

the ground circuit for the coil’s primary circuit.

During crank, the ECM monitors the CKP 58X signal. The

CKP signal is used to determine which cylinder will fire

first. After the CKP 58X signal has been processed by the

ECM, it will command all four injectors to allow a priming

shot of fuel for all the cylinders. After the priming, the

injectors are left OFF during the next four 58X reference

pulses from the CKP. This allows each cylinder a chance

to use the fuel from the priming shot. During this waiting

period, a camshaft position (CMP) signal pulse will have

been received by the ECM. The CMP signal allows the

ECM to operate the injectors sequentially based on

camshaft position. If the camshaft position signal is not

present at start–up, the ECM will begin sequential fuel

delivery with a 1–in–4 chance that fuel delivery is correct.

The engine will run without a CMP signal, but will set a

DTC code.

Diagnostic Aids

An intermittent problem may be caused by a poor

connection, rubbed–through wire insulation or a wire

broken inside the insulation. Check for the following

items:

DPoor connection or damaged harness – Inspect the

ECM harness and connectors for improper mating,

broken locks, improperly formed or damaged

terminals, poor terminal–to–wire connection, and

damaged harness.

DFaulty engine coolant temperature sensor – Using a

Tech 2, compare engine coolant temperature with

intake air temperature on a completely cool engine.

Engine coolant temperature should be within 10°C of

intake air temperature. If not, replace the ECT sensor.

Engine Cranks But Will Not Run

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Use the Tech 2 and check for any DTC’s.

Are any DTC’s stored? —

Go to

Applicable

DTC Table Go to Step 3

3Check the 15A ignition coil fuse, the 15A engine device

fuse, and the 15A ECM fuse.

Was a fuse blown? —Go to Step 4 Go to Step 5

4Check for a short to ground and replace the fuse.

Is the action complete? — Verify repair —

51. Ignition ON.

2. Use a grounded test lamp to verify that B+ is

available at the ignition coil fuse, the engine device

fuse, and the ECM fuse.

Was B+ available at the fuses? —Go to Step 7 Go to Step 6

6Repair the open ignition feed circuit.

—

Go to Fuel

System

Electrical Test Go to Fuel

System

Diagnosis

71. Disconnect the ignition secondary wire at the No.1.

2. Install a spark tester 5–8840–0279–0 at the end of

the disconnected ignition coil.

3. Clip the spark tester 5–8840–0279–0 to a good

ground (not near the battery).

4. Observe the spark tester while the engine is

cranking.

Was a crisp blue spark observed? (Only one or two

sparks followed by no result is considered the same as

”No Spark.”) —Go to Step 16 Go to Step 8

81. Disconnect the ignition module harness connector.

2. Check for an open or short circuit between the

ignition control module and the ECM?

Was a problem found? —Go to Step 9 Go to Step 10

9Repair the faulty circuit. — Verify repair —

10 1. Ignition ON.

2. Using a Digital Voltmeter (DVM) check the ignition

wire coil at the ignition module harness connector?

Was the voltage equal to the specified value? B+ Go to Step 12 Go to Step 11

11 Repair the open circuit. — Verify repair —

12 1. Ignition OFF.

2. With DVM, check for an open in the ground wire at

the ignition module harness connector.

Was the ground wire OK? —Go to Step 14 Go to Step 13

13 Repair the faulty wire. — Verify repair —

Step NoYesValue(s)Action

14 Replace the ignition module, verify the repair.

Attempt to start the engine.

Is there still a problem? —Go to Step 15 Verify repair

15 Replace the ECM.

Is the action complete? — Verify repair —

16 Use an ohmmeter to check the ignition coil primary

winding resistance.

Was the primary winding resistance approximately

equal to the specified value? 0.8–18 WGo to Step 17 Go to Step 18

17 Use an ohmmeter to check the ignition coil secondary

winding resistance.

Was the secondary winding resistance equal to the

specified value? 9,000–12,000

WGo to Step 19 Go to Step 18

18 Replace the ignition coil. — Verify repair —

19 T est the resistance of the coil–to–spark plug secondary

ignition wire.

Was the resistance greater than the specified value? 10,000 W per

foot Go to Step 20 Go to Step 21

20 Replace the coil–to–spark plug secondary ignition wire

and any other secondary wires which exceed the

specified value.

Is there still a problem? 10,000 W per

foot Go to Step 21 Verify repair

21 1. Remove the spark plugs from all cylinders.

2. Visually inspect the spark plug electrodes.

3. Replace any spark plugs with loose or missing

electrodes or cracked insulators.

Did your inspection reveal any spark plugs exhibiting

excessing fouling? —

Correct the

fouling

condition Go to Step 30

22 Verfiy repair.

Attempt to start the engine.

Is there still a problem? —Go to Step 23 Go to Step 22

23 1. Ignition OFF , install a fuel pressure gauge at the test

fitting on the fuel supply line in the engine

compartment.

CAUTION:Use a shop cloth to absorb any fuel

leakage while making the connection.

2. Check the engine and observe the fuel pressure.

Is the fuel pressure within the specified values, and

does it hold steady for 2 seconds? 285–375 kPa

(43–55 psi) Go to Step 25 Go to Step 24

24 Is any fuel pressure indicated?

—

Go to Fuel

System

Electrical Test Go to Fuel

System

Diagnosis

Step NoYesValue(s)Action

25 1. Raise the vehicle and disconnect the CKP sensor

harness.

2. Ignition ON.

3. With a test light to ground, probe the CKP ignition

feed harness terminal.

Did the light illuminate? —Go to Step 26 Go to Step 27

26 1. Ignition ON.

2. At the CKP harness connector , connect a test lamp

between the ignition and ground terminals.

Did the lamp illuminate? —Go to Step 28 Go to Step 29

27 Check the CKP High circuit between the sensor and the

ECM for a short to ground or open circuit.

Was a problem found? — Verify repair Go to Step 30

28 Replace the CKP position sensor.

Is there still a problem? —Go to Step 31 —

29 Check the CKP Low circuit between the sensor and the

ECM for: an open circuit, a short to ground, or short to

voltage.

Was the problem found? — Verify repair Go to Step 30

30 Replace the ECM. — Verify repair —

31 1. Test the fuel for contamination.

2. If a problem is found, clean the fuel system and

correct the contaminated fuel condition as

necessary. Replace the fuel filter and replace any

injectors that are not delivering fuel (see Injector

Balance Test).

Was a problem found? — Verify repair Go to Step 32

32 To diagnose the following conditions, refer to Engine

Mechanical:

DSlipped camshaft drive belt.

DLeaking or sticky valves or rings.

DExcessive valve deposits.

DLoose or worn rocker arms.

DWeak valve springs

DLeaking head gasket.

Is the action complete? — Verify repair —

FUEL SYSTEM ELECTRICAL TEST

D06RX111

Circuit Description

When the ignition switch is first turned ON, the powertrain

control module (ECM) energizes the fuel pump relay

which applies power to the in–tank fuel pump. The fuel

pump relay will remain ON as long as the engine is

running or cranking and the ECM is receiving 58X

crankshaft position pulses. If no 58X crankshaft position

pulses are present, the ECM de–energizes the fuel pump

relay within 2 seconds after the ignition is turned ON or the

engine is stopped.

The fuel pump delivers fuel to the fuel rail and injectors,

then to the fuel pressure regulator. The fuel pressure

regulator controls fuel pressure by allowing excess fuel to

be returned to the fuel tank. With the engine stopped and

ignition ON, the fuel pump can be turned ON by using a

command by the Tech 2.

Diagnostic Aids

An intermittent may be caused by a poor connection,

rubbed–through wire insulation, or a wire broken inside

the insulation. Check for the following items:

DPoor connection or damaged harness – Inspect the

ECM harness and connectors for improper mating,

broken locks, improperly formed or damaged

terminals, poor terminal–to–wire connection, and

damaged harness.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2. If the fuel pump is operating but incorrect pressure

is noted, the fuel pump wiring is OK and the ”Fuel

System Pressure Test” chart should be used for

diagnosis.

CAUTION:To reduce the risk of fire and personal

injury:

DIt is necessary to relieve fuel system pressure

before connecting a fuel pressure gauge. Refer to

Fuel Pressure Relief Procedure, below.

DA small amount of fuel may be released when

disconnecting the fuel lines. Cover fuel line

fittings with a shop towel before disconnecting, to

catch any fuel that may leak out. Place the towel in

an approved container when the procedure is

completed.

Fuel Pressure Relief Procedure

1.Remove the fuel cap.

2.Remove the fuel pump relay from the underhood

relay center.

3.Start the engine and allow it to stall.

4.Crank the engine for an additional 3 seconds.

Fuel Gauge Installation

1.Remove the shoulder fitting cap.

2.Install fuel gauge 5–8840–0378–0 to the fuel feed line

located in front of and above the right side valve

cover.

3.Reinstall the fuel pump relay.

Fuel System Electrical Test

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Read the ”Caution” above.

2. Relieve the fuel system pressure and install the fuel

pump pressure gauge to the test fitting.

3. Use a Tech 2 to command the fuel pump ON.

Is there an immediate pressure build–up which

indicates the pump is running? —Go to Step 3 Go to Step 4

31. V erify that the pump is not running by removing the

fuel filler cap and listening.

2. Command the pump ON with the Tech 2.

Did the pump turn OFF after 2 seconds? —Test

completed Go to Step 12

41. Ignition OFF.

2. Remove the fuel pump relay.

3. Ignition SW “On”, Engin Off.

4. Using a test light connected to ground, probe the

battery feed to the relay.

Did the light illuminate? —Go to Step 6 Go to Step 5

5Repair short or open battery feed to fuel pump relay.

Is the action complete? — Verify repair —

61. Connect a test light between the two wires that

connect to the fuel pump relay pull–in coil.

2. Ignition ON.

Did the test light illuminate for 2 seconds and then turn

off? —Go to Step 12 Go to Step 7

71. With a test light connected to battery (–), probe the

fuel pump relay connector at the wire which runs

from the relay pull–in coil to the ECM.

2. Ignition ON.

Did the test light illuminate for 2 seconds and then turn

off? —Go to Step 8 Go to Step 9

8Locate and repair open in the fuel pump relay ground

circuit.

Is the action complete? — Verify repair —

Step NoYesValue(s)Action

9Check for short or open between the ECM and the fuel

pump relay.

Was a problem found? — Verify repair Go to Step 10

10 1. Check the fuel pump relay circuit for a poor terminal

connection at the ECM.

2. If a problem is found, replace terminal as necessary.

Was a problem found? — Verify repair Go to Step 11

11 Replace the ECM.

Is the action complete? — Verify repair —

12 1. Reconnect the fuel pump relay.

2. Disconnect the fuel pump electrical connector at the

fuel tank.

3. Using a test light connected to ground, probe the

fuel pump feed wire (harness side).

4. Command the fuel pump ON with a Tech 2.

Did the light illuminate for 2 seconds? —Go to Step 15 Go to Step 13

13 1. Honk the horn to verify that the horn relay is

functioning.

2. Substitute the horn relay for the fuel pump relay.

3. Leave the test light connected as in step 12.

4. Command the fuel pump ON with the Tech 2.

Did the test light illuminate for 2 seconds when the fuel

pump was commanded ON? —Go to Step 17 Go to Step 14

14 1. Re–connect the horn relay in its proper location.

2. Check for a short circuit, blown fuse or open circuit

between the relay and the fuel tank.

Is the action complete? — Verify repair —

15 1. With the fuel pump electrical connector at the fuel

tank disconnected, connect a test light between the

feed wire and the ground wire (harness side).

2. Command the fuel pump ON with a Tech 2.

Did the test light illuminate for 2 seconds? —Go to Step 18 Go to Step 16

16 Repair the open circuit in the fuel pump ground wire.

Is the action complete? — Verify repair —

17 1. Re–connect the horn relay in its proper location.

2. Replace the fuel pump relay.

Is the action complete? — Verify repair —

18 Replace the fuel pump.

Is the action complete? — Verify repair —

FUEL SYSTEM DIAGNOSIS

D06RX111

Circuit Description

When the ignition switch is turned ON, the engine control

module (ECM) will turn ON the in–tank fuel pump. The

in–tank fuel pump will remain ON as long as the engine is

cranking or running and the ECM is receiving 58X

crankshaft position pulses. If there are no 58X crankshaft

position pulses, the ECM will turn the in–tank fuel pump

OFF 2 seconds after the ignition switch is turned ON or 2

seconds after the engine stops running.

The in–tank fuel pump is an electric pump within an

integral reservoir. The in–tank fuel pump supplies fuel

through an in–line fuel filter to the fuel rail assembly. The

fuel pump is designed to provide fuel at a pressure above

the pressure needed by the fuel injectors. A fuel pressure

regulator, attached to the fuel rail, keeps the fuel available

to the fuel injectors at a regulated pressure. Unused fuel is

returned to the fuel tank by a separate fuel return line.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2. Connect the fuel pressure gauge to the fuel feed

line as shown in the fuel system illustration. Wrap a

shop towel around the fuel pressure connection in

order to absorb any fuel leakage that may occur

when installing the fuel pressure gauge. With the

ignition switch ON and the fuel pump running, the

fuel pressure indicated by the fuel pressure gauge

should be 283–376 kPa (41–55 psi). This pressure

is controlled by the amount of pressure the spring

inside the fuel pressure regulator can provide.

3. A fuel system that cannot maintain a constant fuel

pressure has a leak in one or more of the following

areas:

DThe fuel pump check valve.

DThe fuel pump flex line.

DThe valve or valve seat within the fuel pressure

regulator.

DThe fuel injector(s)

4.Fuel pressure that drops off during acceleration,

cruise, or hard cornering may case a lean condition.

A lean condition can cause a loss of power, surging,

or misfire. A lean condition can be diagnosed using

a Tech 2. If an extremely lean condition occurs, the

oxygen sensor(s) will stop toggling. The oxygen

sensor output voltage(s) will drop below 500 mV.

Also, the fuel injector pulse width will increase.

IMPORTANT:Make sure the fuel system is not

operating in the ”Fuel Cut–Off Mode.”

When the engine is at idle, the manifold pressure is

low (high vacuum). This low pressure (high vacuum)

is applied to the fuel pressure regulator diaphragm.

The low pressure (high vacuum) will offset the

pressure being applied to the fuel pressure regulator

diaphragm by the spring inside the fuel pressure

regulator. When this happens, the result is lower fuel

pressure. The fuel pressure at idle will vary slightly as

the barometric pressure changes, but the fuel

pressure at idle should always be less than the fuel

pressure noted in step 2 with the engine OFF.

16. Check the spark plug associated with a particular

fuel injector for fouling or saturation in order to

determine if that particular fuel injector is leaking. If

checking the spark plug associated with a particular

fuel injector for fouling or saturation does not

determine that a particular fuel injector is leaking,

use the following procedure:

DRemove the fuel rail, but leave the fuel lines and

injectors connected to the fuel rail. Refer to Fuel Rail

Assembly in On–Vehicle Service.

DLift the fuel rail just enough to leave the fuel injector

nozzles in the fuel injector ports.

CAUTION:In order to reduce the risk of fire and

personal injury that may result from fuel spraying on

the engine, verify that the fuel rail is positioned over

the fuel injector ports and verify that the fuel injector

retaining clips are intact.

DPressurize the fuel system by connecting a 10 amp

fused jumper between B+ and the fuel pump relay

connector.

DVisually and physically inspect the fuel injector

nozzles for leaks.

17. A rich condition may result from the fuel pressure

being above 376 kPa (55 psi). A rich condition may

cause a DTC P0132 or a DTC P0172 to set.

Driveability conditions associated with rich

conditions can include hard starting (followed by

black smoke) and a strong sulfur smell in the

exhaust.

20. This test determines if the high fuel pressure is due

to a restricted fuel return line or if the high fuel

pressure is due to a faulty fuel pressure regulator.

21. A lean condition may result from fuel pressure

below 333 kPa (48 psi). A lean condition may cause

a DTC P0131 or a DTC P0171 to set. Driveability

conditions associated with lean conditions can

include hard starting (when the engine is cold),

hesitation, poor driveability, lack of power, surging,

and misfiring.

22. Restricting the fuel return line causes the fuel

pressure to rise above the regulated fuel pressure.

Command the fuel pump ON with the Tech 2. The

fuel pressure should rise above 376 kPa (55 psi) as

the fuel return line becomes partially closed.

NOTE:Do not allow the fuel pressure to exceed 414 kPa

(60 psi). Fuel pressure in excess of 414 kPa (60 psi) may

damage the fuel pressure regulator.

CAUTION:To reduce the risk of fire and personal

injury:

DIt is necessary to relieve fuel system pressure

before connecting a fuel pressure gauge. Refer to

Fuel Pressure Relief Procedure, below.

DA small amount of fuel may be released when

disconnecting the fuel lines. Cover fuel line

fittings with a shop towel before disconnecting, to

catch any fuel that may leak out. Place the towel in

an approved container when the procedure is

completed.

Fuel Pressure Relief Procedure

1.Remove the fuel cap.

2.Remove the fuel pump relay from the underhood

relay center.

3.Start the engine and allow it to stall.

4.Crank the engine for an additional 3 seconds.

Fuel Gauge Installation

1.Remove the shoulder fitting cap.

2.Install fuel gauge 5–8840–0378–0 to the fuel feed line

located on the upper right side of the engine near the

EGR valve.

3.Reinstall the fuel pump relay.

Fuel System Diagnosis

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Turn the ignition OFF.

2. Turn the air conditioning system OFF.

3. Relieve fuel system pressure and install the fuel

pressure gauge.

4. Turn the ignition ON.

NOTE: The fuel pump will run for approximately 2

seconds. Use the Tech 2 to command the fuel pump

ON.

5. Observe the fuel pressure indicated by the fuel

pressure gauge with the fuel pump running.

Is the fuel pressure within the specified limits? 283–376 kPa

(41–55 psi) Go to Step 3 Go to Step 17

3NOTE: The fuel pressure will drop when the fuel pump

stops running, then it should stabilize and remain

constant.

Does the fuel pressure indicated by the fuel pressure

gauge remain constant? —Go to Step 4 Go to Step 12

41. When the vehicle is at normal operating

temperature, turn the ignition ON to build fuel

pressure and observe the measurement on the

gauge.

2. Start the engine and observe the fuel pressure

gauge.

Did the reading drop by the amount specified after the

engine was started? 21–105 kPa

(3–15 psi) Go to Step 5 Go to Step 9

5Is fuel pressure dropping off during acceleration,

cruise, or hard cornering? —Go to Step 6 Check for

improper fuel

6Visually and physically inspect the following items for a

restriction:

DThe in–pipe fuel filter.

DThe fuel feed line.

Was a restrication found? — Verify repair Go to Step 7

7Remove the fuel tank and visually and physically

inspect the following items:

DThe fuel pump strainer for a restriction.

DThe fuel line for a leak.

DVerify that the correct fuel pump is in the vehicle.

Was a problem found in any of these areas? — Verify repair Go to Step 8

8Replace the fuel pump.

Is the action complete? — Verify repair —

91. Disconnect the vacuum hose from the fuel pressure

regulator.

2. With the engine idling, apply 12–14 inches of

vacuum to the fuel pressure regulator.

Does the fuel pressure indicated by the fuel pressure

gauge drop by the amount specified? 21–105 kPa

(3–15 psi) Go to Step 10 Go to Step 11

Step NoYesValue(s)Action

10 Locate and repair the loss of vacuum to the fuel

pressure regulator.

Is the action complete? — Verify repair —

11 Replace the fuel pressure regulator.

Is the action complete? — Verify repair —

12 1. Run the fuel pump with the Tech 2.

2. After pressure has built up, turn off the pump and

clamp the supply hose shut with suitable locking

pliers which will not damage the hose.

Does the fuel pressure indicated by the fuel pressure

gauge remain constant? —Go to Step 13 Go to Step 15

13 Visually inspect the fuel supply line and repair any

leaks.

Was a problem found? — Verify repair Go to Step 14

14 Remove the fuel tank and inspect for leaky hose or

in–tank fuel line.

Was a problem found? — Verify repair Go to Step 8

15 1. If the pliers are still clamped to the fuel supply hose,

remove the locking pliers.

2. With suitable locking pliers which will not damage

the hose, clamp the fuel return line to prevent fuel

from returning to the fuel tank.

3. Run the fuel pump with the Tech 2.

4. After pressure has built up, remove power to the

pump.

Does the fuel pressure indicated by the fuel pressure

gauge remain constant? —Go to Step 11 Go to Step 16

16 Locate and replace any leaking fuel injector(s).

Is the action complete? — Verify repair —

17 Is the fuel pressure indicated by the fuel pressure

gauge above the specified limit? 376 kPa (55

psi) Go to Step 18 Go to Step 21

18 1. Relieve the fuel pressure. Refer to the Fuel

Pressure Relief.

2. Disconnect the fuel return line from the fuel rail.

3. Attach a length of flexible hose to the fuel rail return

outlet passage.

4. Place the open end of the flexible hose into an

approved gasoline container.

5. Run the fuel pump with the Tech 2.

6. Observe the fuel pressure indicated by the fuel

pressure gauge with the fuel pump running.

Is the fuel pressure within the specified limits? 290–376 kPa

(42–55 psi) Go to Step 19 Go to Step 20

19 Locate and correct the restriction in the fuel return line.

Is the action complete? — Verify repair —

20 Visually and physically inspect the fuel rail outlet

passages for a restriction.

Was a restriction found? — Verify repair Go to Step 11

StepNoYesValue(s)Action

21 Is the fuel pressure indicated by the fuel pressure

gauge above the specified value? 0 kPa (0 psi) Go to Step 22 Go to Step 23

22 1.Command the fuel pump ON with the Tech 2.

2.Using suitable pliers which will not damage the fuel

hose, gradually apply pressure with the pliers to

pinch the flexible fuel return hose closed.

CAUTION:Do not let the fuel pressure exceed

the second specified value.

Does the fuel pressure indicated by the fuel pressure

gauge rise above the first specified value? 414 kPa (60

psi) Go to Step 11 Go to Step 7

23 1. Command the fuel pump ON with the Tech 2.

2. Remove the fuel filler cap and listen for the sound of

the fuel pump running.

3. Turn the pump off.

Was the fuel pump running? —Go to Step 7

Go to Fuel

System

Electrical Test

Chart

IDLE AIR CONTROL (IAC) SYSTEM CHECK

D06RX112

Circuit Description

The engine control module (ECM) controls engine idle

speed with the idle air control (IAC) valve. T o increase idle

speed, the ECM retracts the IAC valve pintle away from

its seat, allowing more air to bypass the throttle bore. To

decrease idle speed, it extends the IAC valve pintle

towards its seat, reducing bypass air flow. A Tech 2 will

read the ECM commands to the IAC valve in counts.

Higher counts indicate more air bypass (higher idle).

Lower counts indicate less air is allowed to bypass (lower

idle).

Diagnostic Aids

A slow , unstable, or fast idle may be caused by a non-IAC

system problem that cannot be overcome by the IAC

valve. Out of control range IAC Tech 2 counts will be

above 60 if idle is too low, and zero counts if idle is too

high. The following checks should be made to repair a

non-IAC system problem:

DVacuum leak (high idle) – If idle is too high, stop the

engine. Fully extend (low) IAC with the Tech 2. Start

the engine. If idle speed is above 800 RPM, locate

and correct the vacuum leak, including the PCV

system. Check for binding of the throttle blade or

linkage.

DLean heated oxygen sensor signal (high air/fuel ratio)

– The idle speed may be too high or too low. Engine

speed may vary up and down, and disconnecting the

IAC valve does not help. Diagnostic trouble codes

P0131, P0151, P0171, may be set. Tech 2 oxygen

(O2) voltage will be less than 100 mV (0.1 V). Check

for low regulated fuel pressure, water in fuel, or a

restricted injector.

DRich heated oxygen sensor signal (low air/fuel ratio) –

The idle speed will be too low. Tech 2 IAC counts will

usually be above 80. The system is obviously rich

and may exhibit black smoke in the exhaust.

Tech 2 O2 voltage will be fixed at about 750 mV (0.75

V). Check for high fuel pressure, or a leaking or

sticking injector. A silicon-contaminated heated

oxygen sensor will show an O2 voltage slow to

respond on Tech 2.

DThrottle body – Remove the IAC valve and inspect the

bore for foreign material.

DIAC valve electrical connections – IAC valve

connections should be carefully checked for proper

contact.

DPCV valve – An incorrect or faulty PCV valve may

result in an incorrect idle speed. Refer to

Diagnosis,

Rough Idle, Stalling.

If intermittent poor driveability or

idle symptoms are resolved by disconnecting the

IAC, carefully recheck the connections and valve

terminal resistance, or replace the IAC.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart.

1. The Tech 2 is used to extend and retract the IAC

valve. Valve movement is verified by an engine

speed change. If no change in engine speed

occurs, the valve can be resettled when removed

from the throttle body.

2. This step checks the quality of the IAC movement in

step 1. Between 700 revolutions per minute (RPM)

and about 1500 RPM, the engine speed should

change smoothly with each flash of the tester light

in both extend and retract. If the IAC valve is

retracted beyond the control range (about 1500

RPM), it may take many flashes to extend the IAC

valve before engine speed will begin to drop. This

is normal on certain engines. Fully extending the

IAC may cause engine stall. This may be normal.

Idle Air Control (IAC) System Check

Step Action Value(s) Yes No

11. Ignition “OFF.”

2. Connect the Tech 2.

3. Set the parking brake.

4. Block the wheels.

5. Turn the air conditioning “OFF.”

6. Idle the engine in Park (A/T) or Neutral (M/T).

7. Operate the IAC test.

8. The engine speed should decrease and increase as

the IAC is cycled.

Does the RPM change? —Go to

Step 2

Go to

Step 3

2RPM should change smoothly.

Does the RPM change within the range specified? 700-1500

RPM —Go to

Step 3

3Check the IAC passages.

Are the IAC passages OK? —Go to

Step 4

Go to

Step 5

4Clear any obstruction from the IAC passages.

Is the action complete? — Verify repair —

5Replace the IAC. Refer to

On-V ehicle Service, Idle Air

Control Valve.

Is the action complete? — Verify repair —

EXHAUST GAS RECIRCULATION (EGR) SYSTEM CHECK

D06RX113

Circuit Description

A properly operating exhaust gas recirculation (EGR)

system will directly affect the air/fuel requirements of the

engine. Since the exhaust gas introduced into the air/fuel

mixture is an inert gas (contains very little or no oxygen),

less fuel is required to maintain a correct air/fuel ratio.

Introducing exhaust gas into the combustion chamber

lowers combustion temperatures and reduces the

formation of oxides of nitrogen (NOx) in the exhaust gas.

Lower combustion temperatures also prevent detonation.

If the EGR pintle were to stay closed, the inert exhaust

gas would be replaced with air and the air/fuel mixture

would be leaner. The powertrain control module (ECM)

would compensate for the lean condition by adding fuel,

resulting in higher long term fuel trim values.

Diagnostic Aids

The EGR valve chart is a check of the EGR system. An

EGR pintle constantly in the closed position could cause

detonation and high emissions of NOx. It could also result

in high long term fuel trim values in the open throttle cell,

but not in the closed throttle cell. An EGR pintle constantly

in the open position would cause rough idle. Also, an EGR

valve mounted incorrectly (rotated 180°) could cause a

rough idle without setting an EGR DTC. Check for the

following items:

DEGR passages – Check for restricted or blocked EGR

passages.

DManifold absolute pressure sensor – A manifold

absolute pressure sensor may shift in calibration

enough to affect fuel delivery. Refer to Manifold

Absolute Pressure Output Check.

Exhaust Gas Recirculation (EGR) System Check

Step Action Value(s) Yes No

1Check the EGR valve for looseness.

Is the EGR valve loose? —Go to Step 2 Go to Step 3

2Tighten the EGR valve.

Is the action complete? — Verify repair —

31. Place the transmission selector in Park or Neutral.

2. Start the engine and idle until warm (”Closed Loop”).

3. Using a Tech 2, command EGR ”50% ON.”

Does the engine idle rough and lose RPMs? —

EGR system

working

properly. No

problem

found. Go to Step 4

41. Engine OFF.

2. Ignition ON.

3. Using a test light to ground, check the EGR harness

between the ignition feed and ground.

Does the test light illuminate? —Go to Step 6 Go to Step 5

5Repair the EGR harness ignition feed.

Was the problem corrected? — Verify repair Go to Step 6

61. Remove the EGR valve.

2. Visually and physically inspect the EGR valve

pintle, valve passages and adapter for excessive

deposits, obstructions or any restrictions.

Does the EGR valve have excessive deposits,

obstructions or any restrictions? —Go to Step 7 Go to Step 8

7Clean or replace EGR system components as

necessary.

Was the problem corrected? — Verify repair Go to Step 8

81. Ground the EGR valve metal case to battery (–).

2. Using a T ech 2, command EGR ON and observe the

EGR valve pintle for movement.

Does the EGR valve pintle move according to

command? —Go to Step 9 Go to DTC

P0404 chart

91. Remove the EGR inlet and outlet pipes from the

intake and exhaust manifolds.

2. Visually and physically inspect manifold EGR ports

and EGR inlet and outlet pipes for blockage or

restriction caused by excessive deposits or other

damage.

Do the manifold EGR ports or inlet and outlet pipes

have excessive deposits, obstructions, or any

restrictions? —Go to Step 10

EGR system

working

properly. No

problem

found.

10 Clean or replace EGR system components as

necessary.

Is the action complete? — Verify repair —

MANIFOLD ABSOLUTE PRESSURE (MAP) OUTPUT CHECK

D06RX114

Circuit Description

The manifold absolute pressure (MAP) sensor measures

the changes in the intake MAP which result from engine

load (intake manifold vacuum) and engine speed

changes; and converts these into a voltage output. The

powertrain control module (ECM) sends a 5–volt

reference voltage to the MAP sensor. As the MAP

changes, the output voltage of the sensor also changes.

By monitoring the sensor output voltage, the ECM knows

the MAP. A lower pressure (low voltage) output voltage

will be about 1–2 volts at idle. Higher pressure (high

voltage) output voltage will be about 4–4.8 volts at wide

open throttle. The MAP sensor is also used, under certain

conditions, to measure barometric pressure, allowing the

ECM to make adjustments for different altitudes. The

ECM uses the MAP sensor to diagnose proper operation

of the EGR system, in addition to other functions.

Test Description

IMPORTANT:Be sure to use the same diagnostic test

equipment for all measurements.

The number(s) below refer to the step number(s) on the

Diagnostic Chart:

1.When you compare the Tech 2 readings to a known

good vehicle, it is important to compare vehicles

that use MAP sensors that have the same part

number.

2.Applying 34 kPa (10 Hg) vacuum to the MAP sensor

should cause the voltage to be 1.5–2.1 volts less

than the voltage at step 1. Upon applying vacuum to

the sensor, the change in voltage should be

instantaneous. A slow voltage change indicates a

faulty sensor.

3.Check the vacuum hose to the sensor for leaking or

restriction. Be sure that no other vacuum devices

are connected to the MAP hose.

IMPORTANT:Make sure the electrical connector

remains securely fastened.

4. Disconnect the sensor from the bracket. Twist the

sensor with your hand to check for an intermittent

connection. Output changes greater than 0.10 volt

indicate a bad sensor.

Manifold Absolute Pressure (MAP) Output Check

Step Action Value(s) Yes No

11. Turn the ignition OFF and leave it OFF for 15

seconds.

2. Ignition ON. Do not crank engine.

3. The Tech 2 should indicate a manifold absolute

pressure (MAP) sensor voltage.

4. Compare this scan reading to the scan reading of a

known good vehicle obtained using the exact same

procedure as in Steps 1–4.

Is the voltage reading the same +/– 0.40 volt? —Go to Step 2 Go to Step 5

21. Disconnect the vacuum hose at the MAP sensor

and plug the hose.

2. Connect a hand vacuum pump to the MAP sensor.

3. Start the engine.

4. Apply 34 kPa (10 Hg) of vacuum and note the

voltage change.

Is the voltage change 1.5–2.1 volts less than step 1? —Go to Step 3 Go to Step 4

3Check the sensor hose for leakage or restriction.

Does the hose supply vacuum to the MAP sensor only? —Go to Step 5 Go to Step 4

4Repair the hose to ensure the hose supplies vacuum to

the MAP sensor only.

Is the action complete? — Verify repair —

5Check the sensor connection.

Is the sensor connection good? —Go to Step 6 Go to Step 7

6Refer to On–Vehicle Service, MAP Sensor.

Is the action complete? — Verify repair —

7Repair the poor connection.

Is the action complete? — Verify repair —

ECM DIAGNOSTIC TROUBLE CODES

The following table lists the diagnostic trouble codes

supported by this vehicle application. If any DTCs not

listed here are displayed by a Scan Tool, the Tech 2 data

may be faulty; notify the Tech 2 manufacturer of any

DTCs displayed that are not included in the following

table.

ECM Diagnostic Trouble Codes

DTC Description Type Illuminate MIL

P0106 MAP Circuit/Range Performance Problem BYes

P0107 MAP Sensor Circuit Low Input AYes

P0108 MAP Sensor Circuit High Input AYes

P0112 IAT Sensor Circuit Low Input AYes

P0113 IAT Sensor Circuit High Input AYes

P0117 ECT Sensor Circuit Low Input AYes

P0118 ECT Sensor Circuit High Input AYes

P0121 TP Sensor Circuit Range/Performance Problem D No

P0122 TP Sensor Circuit Low Input AYes

P0123 TP Sensor Circuit High Input AYes

P0131 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1) AYes

P0132 O2 Sensor Circuit High Voltage (Bank 1 Sensor 1) AYes

P0134 O2 Sensor Circuit No Activity Detected (Bank Sensor 1) AYes

P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1) BYes

P0171 Fuel Trim System Too Lean (Bank 1) BYes

P0172 Fuel Trim System Too Rich (Bank 1) BYes

P0201 Injector Circuit Malfunction – Cylinder 1 AYes

P0202 Injector Circuit Malfunction – Cylinder 2 AYes

P0203 Injector Circuit Malfunction – Cylinder 3 AYes

P0204 Injector Circuit Malfunction – Cylinder 4 AYes

P0325 Knock Sensor Circuit Malfunction BYes

P0327 Knock Sensor Circuit Low Input BYes

P0336 CKP Sensor Circuit Range/Performance BYes

P0337 CKP Sensor Circuit Low Input BYes

P0341 CMP Sensor Circuit Range/Performance BYes

P0342 CMP Sensor Circuit Low Input BYes

P0351 Ignition Coil ”A” Primary/Secondary AYes

P0352 Ignition Coil ”B” Primary/Secondary AYes

P0401 EGR Flow Insufficient Detected AYes

P0402 EGR Excessive Flow Detected BYes

P0404 EGR Circuit Range/Performance BYes

P0405 EGR Sensor Circuit Low AYes

P0406 EGR Sensor Circuit High AYes

P0443 EVAP Control System Purge Control Valve Circuit Malfunction AYes

P0480 Cooling Fan 1 Control Circuit Malfunction D No

P0481 Cooling Fan 2 Control Circuit Malfunction D No

P0502 VSS Circuit Low Input BYes

P0506 Idle Control System RPM Lower than expected BYes

DTC Illuminate MILTypeDescription

P0507 Idle Control System RPM Higher than expected BYes

P0563 System Voltage High AYes

P0601 Internal Control Module Memory Check Sum Error AYes

P1106 MAP Sensor Circuit Intermittent High Voltage D No

P1107 MAP Sensor Circuit Intermittent Low Voltage D No

P1111 IAT Sensor Circuit Intermittent High Voltage D No

P1112 IAT Sensor Circuit Intermittent Low Voltage D No

P1114 ECT Sensor Circuit Intermittent Low Voltage D No

P1115 ECT Sensor Circuit Intermittent High Voltage D No

P1121 TP Sensor Circuit Intermittent High Voltage D No

P1122 TP Sensor Circuit Intermittent Low Voltage D No

P1171 Fuel System Lean During Acceleration AYes

P1404 EGR Closed Valve BYes

P1625 PCM Unexpected Reset DYes

P1627 PCM A/D Conversion Malfunction AYes

P1635 5 Volt Reference Voltage Circuit Malfunction AYes

P1640 ODM Output Circuit Fault D No

DIAGNOSTIC TROUBLE CODE (DTC) P0106 MANIFOLD ABSOLUTE

PRESSURE (MAP) CIRCUIT/RANGE PERFORMANCE PROBLEM

D06RX114

Circuit Description

The manifold absolute pressure (MAP) sensor responds

to changes in intake manifold pressure. The MAP sensor

signal voltage to the engine control module (ECM) varies

from below 2 volts at idle (low manifold pressure) to above

4 volts with the ignition ON engine not running or at

wide–open throttle (high manifold pressure).

A ”speed density” method of determining engine load is

used on the 2.2L engine. This is calculated using inputs

from the MAP sensor, RPM, CKP Sensor, and the Intake

Air Temperature (IAT) sensor. The MAP sensor is the

main sensor used in this calculation, and measuring

engine load is its main function. The MAP sensor is also

used to determine manifold pressure changes while the

exhaust gas recirculation (EGR) flow test diagnostic is

being run, to determine engine vacuum level for some

other diagnostics and to determine barometric pressure

(BARO). Refer to DTC P0401.

The ECM monitors the MAP signals for voltages outside

the normal range (10–104 kpa) of the MAP sensor. If the

ECM detects a MAP signal voltage that is excessively

low, Diagnostic Trouble Code P0106 will be set.

Diagnostic Trouble Code P0106 is a Type B Code.

Conditions for Setting the DTC

DNo ECT, CKP, EGR, EVAP, MAP orTP sensor DTC’s

present.

DEngine speed is steady, changing less than 20 RPM.

DThrottle position is steady, throttle angle changes less

than 5%.

DEGR flow rate is steady, changing less than 2%.

DIAC valve counts are steady, changing less than 3

counts.

DEngine speed is between 1000 RPM and 4000 RPM.

DECT is above –10°C (14°F).

DNo change in brake switch, A/C clutch, 3 or power

steering pressure switch status.

The above conditions are met for longer than 1.5 seconds

and the following condition is met in two consecutive trips:

DActual MAP value varies more than 10 kPa.

DThe MAP value must vary for a total of 10 seconds over

a 20–second period of time that the samples were

monitored.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe ECM will default to a BARO value of 79.3 kPa.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0106 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0106 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DThe MAP sensor shares a 5 Volt Reference with the TP

sensor and Fuel Pressure sensor.

If these codes are also set, it could indicate a

problem with the 5 Volt reference circuit.

DThe MAP sensor shares a ground with the TP sensor

and Fuel Pressure sensor.

DDamaged harness – Inspect the wiring harness for

damage; an open circuit, a short to ground, or a short

to voltage. If the harness appears to be OK, observe

the MAP display on the Tech 2 while moving

connectors and wiring harnesses related to the sensor.

A change in the display will indicate the location of the

fault.

If Diagnostic Trouble Code P0106 cannot be duplicated,

the information included in the Failure Records data can

be useful in determining vehicle mileage since the

Diagnostic Trouble Code was last set. If it is determined

that the Diagnostic Trouble Code occurs intermittently,

performing the Diagnostic Trouble Code P1106 or P1107

Diagnostic Chart may isolate the cause of the fault.

DTC P0106 MAP Circuit/Range Performance Problem

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON, engine OFF

2. Review and record Tech 2 Failure Records data,

then clear the DTC’s.

3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor ”DTC” info for Diagnostic

Trouble Code P0106.

Does the Tech 2 indicate that DTC P0106 ran and

passed? —Go to Step 3 Go to Step 4

31. Check for the following condition:

DVacuum hoses disconnected, damaged, or

incorrectly routed?

DIntake manifold vacuum leaks;

DVacuum leaks at throttle body;

DVacuum leaks at EGR valve flange and pipes;

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair

Refer to

Diagnostic

Aids

41. Disconnect the Manifold Absolute Pressure (MAP)

sensor electrical connector.

2. Observe the MAP value displayed on the Tech 2.

Is the MAP value near the specified value? 0 V 10.3 kPa Go to Step 6 Go to Step 5

5Check the MAP sensor signal circuit; between the MAP

sensor and the Engine Control Module (ECM), for a

short to voltage? — Verify repair Go to Step 12

6Check the MAP sensor circuit, between the MAP

sensor and the ECM, the following conditions:

DA short to ground

DAn open circuit

Was the problem found? — Verify repair Go to Step 7

Step NoYesValue(s)Action

7Check the 5 volt signal circuit, between the MAP

sensor and the ECM, for the following conditions:

DAn open circuit

DA short to ground

DA short to voltage

Was the problem found? — Verify repair Go to Step 8

81. Ignition OFF.

2. Place a fused jumper between the MAP sensor

circuit and the 5 volt signal circuit, both at the wiring

harness’ MAP sensor connector.

3. Ignition ON, engine OFF.

4. Observe the MAP value displayed on the Tech 2?

Does the Tech 2 read the following value? (if no, start

with the diagnosis chart for other sensors in the circuit

and see if 5V returns.) 5 volts 104

kPa Go to Step 9 Go to Step 12

9Check the MAP sensor ground circuit, between the

MAP sensor and the ECM, for the following conditions:

DAn open circuit

DA short to ground

DA short to voltage

Was the problem found? — Verify repair Go to Step 10

10 1. Ignition OFF.

2. Place a Digital Multimeter (DVM), set to measure

voltage, between the ground circuit and the 5 volt

signal circuit, both at the wiring harness’ MAP

sensor connector.

3. Ignition ON, engine OFF.

5 volts

Does the DVM read the following value? —Go to Step 11 Go to Step 12

11 Replace the MAP sensor.

Verify repair. ———

12 Replace the ECM. ———

DIAGNOSTIC TROUBLE CODE (DTC) P0107 MANIFOLD ABSOLUTE

PRESSURE (MAP) SENSOR CIRCUIT LOW INPUT

D06RX114

Circuit Description

The manifold absolute pressure (MAP) sensor responds

to changes in intake manifold pressure. The MAP sensor

signal voltage to the powertrain control module (ECM)

varies from below 2 volts at idle (low manifold pressure) to

above 4 volts with the ignition ON, engine not running or at

wide–open throttle (high manifold pressure).

A ”speed density” method of determining engine load is

used on the 2.2L engine. This is calculated using inputs

from the MAP sensor, the CKP Sensor, and the Intake Air

Temperature (IAT) sensor. The MAP sensor is the main

sensor used in this calculation, and measuring engine

load is its main function. The MAP sensor is also used to

determine manifold pressure changes while the exhaust

gas recirculation (EGR) flow test diagnostic is being run,

to determine engine vacuum level for some other

diagnostics and to determine barometric pressure

(BARO). Refer to DTC P0401.

The ECM monitors the MAP signals for voltages outside

the normal range (10–104 kpa) of the MAP sensor. If the

ECM detects a MAP signal voltage that is excessively

low, Diagnostic Trouble Code P0107 will be set. DTC

P0107 is a Type A Code.

Conditions for Setting the DTC

DNo TP sensor Diagnostic Trouble Codes present.

DEngine is running.

DSystem voltage greater than 11 volts.

DThrottle angle is above 0% if engine speed is less than

or equal to 1300 RPM.

DThrottle angle is above 5% if engine speed is above

1300 RPM.

DThe MAP sensor indicates manifold absolute pressure

below 11 kPa for a total of approximately 10 seconds

over a 16–second period.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

DThe ECM will default to a BARO value of 79.3 kPa.

DThe ECM will use a MAP value based on speed density

calculation.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history DTC P0107 will clear after 40 consecutive

warm–up cycles have occurred without a fault.

DDiagnostic Trouble Code P0107 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DThe MAP sensor shares a 5 Volt Reference with the TP

sensor and Fuel Pressure sensor.

If these codes are also set, it could indicate a

problem with the 5 Volt reference circuit.

DThe MAP sensor shares a ground with the TP sensor

and Fuel Pressure sensor.

DDamaged harness – Inspect the wiring harness for

damage, shorts to ground, shorts to battery positive,

and open circuits. If the harness appears to be OK,

observe the MAP display on the Tech 2 while moving

connectors and wiring harnesses related to the sensor.

A change in the display will indicate the location of the

fault.

DA faulty 5 volt reference circuit could also set a TP

Sensor Diagnostic Trouble Code because the two

sensors share the same 5 volt reference pin at the

ECM.

If Diagnostic Trouble Code P0107 cannot be duplicated,

the information included in the Failure Records data can

be useful in determining vehicle mileage since the

Diagnostic Trouble Code was last set. If it is determined

that the Diagnostic Trouble Code occurs intermittently,

performing the Diagnostic Trouble Code P0107

Diagnostic Chart may isolate the cause of the fault.

DTC P0107 – MAP Sensor Circuit Low Input

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON, engine OFF.

2. With the throttle closed, observe the MAP value

displayed on the Tech 2.

Is the MAP value near the specified value? 0V 10.3 kPa

at sea level Go to Step 4 Go to Step 3

31. Ignition ON, engine OFF.

2. Review and record Tech 2 Failure Records data.

3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor «Diagnostic T rouble Code”

info for Diagnostic Trouble Code P0107.

Does the Tech 2 indicate Diagnostic Trouble Code

P0107 failed? —Go to Step 4

Refer to

Diagnostic

Aids

41. Ignition OFF.

2. Disconnect the MAP sensor electrical connector.

3. Jumper the 5 volt reference circuit and the MAP

signal together at the MAP sensor harness

connector.

4. Ignition ON.

5. Observe the MAP value displayed on the Tech 2.

Is the MAP value near the specified value? (if no, start

with the diagnosis chart for other sensors in the circuit

and see if 5V returns.) 5 V 104 kPa Go to Step 10 Go to Step 5

51. Disconnect the jumper.

2. Connect a fused jumper between the 5 Volt signal

circuit and the MAP sensor signal circuit at the MAP

sensor harness connector.

3. Observe the MAP value displayed on the Tech 2.

Is the MAP value near the specified value? 5 V 104 kPa Go to Step 6 Go to Step 8

Step NoYesValue(s)Action

61. Ignition OFF.

2. Disconnect the ECM and check the 5 volt reference

circuit for an open or short to ground.

3. If the 5 volt reference circuit is open or shorted to

ground, repair it as necessary.

Was the 5 volt reference circuit open or shorted to

ground? —Verify repair Go to Step 7

7Check the 5 volt reference circuit for a poor connection

at the ECM and replace the terminal if necessary.

Did the terminal require replacement? — Verify repair Go to Step 11

81. Ignition OFF.

2. Disconnect the ECM, and check the MAP signal

circuit for an open, short to ground, or short to the

sensor ground circuit.

3. If the MAP sensor signal circuit is open or shorted to

ground, repair it as necessary.

W as the MAP signal circuit open or shorted to ground? —Verify repair Go to Step 9

9Check the MAP sensor signal circuit for a poor

connection at the ECM and the MAP sensor; replace

the terminal if necessary.

Did the terminal require replacement? — Verify repair Go to Step 11

10 Replace the MAP sensor.

Is the action complete? — Verify repair —

11 Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0108 MANIFOLD ABSOLUTE

PRESSURE (MAP) CIRCUIT HIGH INPUT

D06RX114

Circuit Description

The manifold absolute pressure (MAP) sensor responds

to changes in intake manifold pressure. The MAP sensor

signal voltage to the powertrain control module (ECM)

varies from below 2 volts at idle (low manifold pressure) to

above 4 volts with the ignition ON, engine not running or at

wide–open throttle (high manifold pressure).

A ”speed density” method of determining engine load is

used on the 2.2L engine. This is calculated using inputs

from the MAP sensor, RPM, CKP Sensor, and the Intake

Air Temperature (IAT) sensor. The MAP sensor is the

main sensor used in this calculation, and measuring

engine load is its main function. The MAP sensor is also

used to determine manifold pressure changes while the

exhaust gas recirculation (EGR) flow test diagnostic is

being run, to determine engine vacuum level for some

other diagnostics and to determine barometric pressure

(BARO). Refer to DTC P0401.

The ECM monitors the MAP signals for voltages outside

the normal range (10–104 kpa) of the MAP sensor. If the

ECM detects a MAP signal voltage that is excessively

low, Diagnostic Trouble Code P0108 will be set. DTC

P0108 is a Type A Code.

Conditions for Setting the DTC

DNo TP sensor Diagnostic Trouble Codes present.

DEngine is running.

DThrottle position is below 2.7% if engine speed is below

1000 RPM.

DThrottle position is below 10% if engine speed is above

1000 RPM.

DThe MAP sensor indicates manifold absolute pressure

above 90 kPa for a total of approximately 10 seconds

over a 16–second period.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe ECM will default to a BARO value of 79.3 kPa.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0108 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0108 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DThe MAP sensor shares a 5 Volt Reference with the TP

sensor and Fuel Pressure sensor.

If these codes are also set, it could indicate a

problem with the 5 Volt reference circuit.

DThe MAP sensor share a ground with the TP sensor

and Fuel Pressure sensor.

DDamaged harness – Inspect the wiring harness for

damage; an open circuit, a short to ground, or a short

to voltage. If the harness appears to be OK, observe

the MAP display on the Tech 2 while moving

connectors and wiring harnesses related to the sensor.

A change in the display will indicate the location of the

fault.

If Diagnostic Trouble Code P0108 cannot be duplicated,

the information included in the Failure Records data can

be useful in determining vehicle mileage since the

Diagnostic Trouble Code was last set.

DTC P0108 MAP Sensor Circuit High Input

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. If the engine idle is rough, unstable or incorrect,

repair the idle problem before using this chart. Refer

to Symptoms section.

2. With the engine idling, note the MAP value on the

Tech 2.

Is the MAP reading above the specified value? About 4V 90

kPa Go to Step 4 Go to Step 3

31. Ignition ON engine OFF

2. Review and record Tech 2 Failure Records data,

then clear the DTC’s.

3. Operate the vehicle within Failure Records

conditions as noted.

4. Using the Tech 2, monitor ”DTC” info for Diagnostic

Trouble Code P0108.

Does the Tech 2 indicate that DTC P0108 failed this

ignition? —Go to Step 4

Refer to

Diagnostic

Aids

41. Ignition OFF.

2. Disconnect the MAP sensor electrical connector.

3. Ignition ON.

4. Observe the MAP value displayed on the Tech 2.

Is the MAP value near the specified value? (if no, start

with the diagnosis chart for other sensors in the circuit

and see if 5V returns.) 0 V 10.3 kPa Go to Step 5 Go to Step 6

5Check the MAP sensor signal circuit; between the MAP

sensor and the Engine Control Module (ECM), for a

short to voltage.

Was the problem found? — Verify repair Go to Step 12

6Check the MAP sensor circuit, between the MAP

sensor and the ECM, the following conditions:

DA short to ground

DAn open circuit

Was the problem found? — Verify repair Go to Step 7

7Check the 5 volt signal circuit, between the MAP

sensor and the ECM for the following conditions:

DAn open circuit

DA short to ground

DA short to voltage

Was the problem found? — Verify repair Go to Step 8

Step NoYesValue(s)Action

81. Ignition OFF.

2. Place a fused jumper between the MAP sensor

circuit and the 5 volt signal circuit, both at the wiring

harness’ MAP sensor connector.

3. Ignition ON, Engine OFF.

4. Observe the MAP value displayed on the Tech 2?

Does the Tech 2 read the following value? 5 volts 104

kPa Go to Step 9 Go to Step 12

9Check the MAP sensor ground circuit, between the

MAP sensor and the ECM, for the following conditions:

DAn open circuit

DA short to ground

DA short to voltage

Was the problem found? — Verify repair Go to Step 10

10 1. Ignition OFF.

2. Place a Digital Multimeter (DVM), set to measure

voltage, between the ground circuit and the 5 volt

signal circuit, both at the wiring harness’ MAP

sensor connector.

3. Ignition ON, Engine OFF.

Does the DVM read the following value? 5 Volts Go to Step 11 Go to Step 12

11 Replace the MAP sensor.

Verify repair. ———

12 Replace the ECM.

Verify repair. ———

DIAGNOSTIC TROUBLE CODE (DTC) P0112 INTAKE AIR TEMPERATURE (IAT)

SENSOR CIRCUIT LOW INPUT

D06RX116

Circuit Description

The intake air temperature (IAT) sensor is a thermistor

which measures the temperature of the air entering the

engine. The engine control module (ECM) applies 5 volts

through a pull–up resistor to the IAT sensor. When the

intake air is cold, the sensor resistance is high and the

ECM will monitor a high signal voltage on the IAT signal

circuit. If the intake air is warm, the sensor resistance is

lower, causing the ECM to monitor a lower voltage.

Diagnostic Trouble Code P0112 will set when the ECM

detects an excessively low signal voltage (short to

ground) on the intake air temperature sensor signal

circuit. DTC P0112 is a Type A Code.

Conditions for Setting the DTC

DThe engine has been running for over 2 minutes.

DVehicle speed is greater than 48 km/h (30 mph).

DIA T signal voltage less than 0.10 volts for a total of 12.5

seconds over a 25–second period of time.

The above conditions are met for at least 2 seconds.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

DThe ECM will use a default IAT valve based on ECM

inputs and engine run time.

DThe ECM will store conditions which were present

when the DTC was set as Freeze Frame and in the

Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history DTC P0112 will clear after 40 consecutive

warm–up cycles have occurred without a fault.

DDTC P0112 can be cleared by using the Scan Tool’s

”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage, shorts to ground, shorts to battery and open

circuits. If the harness appears to be OK, observe the

IA T display on the T ech 2 while moving connectors and

wiring harnesses related to the IAT sensor. A change

in the IAT display will indicate the location of the fault.

If Diagnostic Trouble Code P0112 cannot be duplicated,

the information included in the Failure Records data can

be useful in determining vehicle mileage since the

Diagnostic Trouble Code was last set.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2. Verifies that the fault is present.

3.If Diagnostic Trouble Code P0112 can be repeated

only by duplicating the Failure Records condition,

refer to the Temperature vs. Resistance Value table.

The table may be used to test the IAT sensor at

various temperatures to evaluate the possibility of

a ”shifted” sensor that may be stored above or

below a certain temperature. If this is the case,

replace the IAT sensor. If the IAT sensor appears

to be OK, the fault is intermittent; refer to

Diagnostic Aids.

Intake Air Temperature Sensor

°C°F OHMS

Temperature vs. Resistance Values (approximate)

100 212 177

80 176 332

60 140 667

45 113 1188

35 95 1802

25 77 2796

15 59 4450

5 41 7280

–5 23 12300

–15 5 21450

–30 –22 52700

–40 –40 100700

DTC P0112 Intake Air Temperature (IAT) Sensor Circuit Low Input

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON, engine OFF.

2. Using a Tech 2, monitor the intake air temperature

(IAT).

Is the intake air temperature greater than the specified

value? 148°C

(283°F) Go to Step 4 Go to Step 3

31. Ignition ON, engine OFF. Review and record Tech 2

Failure Records data.

2. Operate the vehicle within Failure Records

conditions as noted.

3. Using a Tech 2, monitor the ”DTC” info for

Diagnostic Trouble Code P0112.

Does the Tech 2 indicate DTC P0112 failed this

ignition? —Refer to Test

Description

Refer to

Diagnostic

Aids

41. Ignition OFF.

2. Disconnect the IAT sensor electrical connector.

3. Ignition ON.

4. Observe the intake air temperature on the Tech 2.

Is the intake air temperature below the specified value? –38°C

(–36°F) Go to Step 6 Go to Step 5

51. Ignition OFF.

2. Disconnect the ECM electrical connectors.

3. Check the IAT sensor signal circuit for a short to

ground.

Is the IAT sensor signal circuit shorted to ground? —Verify Repair Go to Step 7

6Replace the IAT sensor.

Is the action complete? —Verify Repair —

7Replace the ECM.

Is the action complete? —Verify Repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0113 INTAKE AIR TEMPERATURE (IAT)

SENSOR CIRCUIT HIGH INPUT

D06RX118

Circuit Description

The intake air temperature (IAT) sensor is a thermistor

which measures the temperature of the air entering the

engine. The engine control module (ECM) applies 5 volts

through a pull–up resistor to the IAT sensor. When the

intake air is cold, the sensor resistance is high and the

ECM will monitor a high signal voltage on the IAT signal

circuit. If the intake air is warm, the sensor resistance is

lower causing the ECM to monitor a lower voltage.

Diagnostic Trouble Code P0113 will set when the ECM

detects an excessively high signal voltage on the intake

air temperature sensor signal circuit. DTC P0113 is a

Type A Code.

Conditions for Setting the DTC

DThe engine has been running for over 4 minutes.

DVehicle speed is less than 32 km/h (20 mph).

DECT signal temperature is above 60°C (140°F).

DMass air flow is less than 20g/second.

DIAT signal voltage almost 5 volts which indicates an

intake air temperature less than –39°C (–38°F) for a

total of 12.5 seconds over a 25–second period.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

DThe ECM will use a default IAT valve based on ECM

inputs and engine run time.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0113 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0113 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage, shorts to ground, shorts to battery positive,

and open circuits. If the harness appears to be OK,

observe the IAT display on the Tech 2 while moving

connectors and wiring harnesses related to the IAT

sensor. A change in the IAT display will indicate the

location of the fault.

If Diagnostic Trouble Code P0113 cannot be duplicated,

the information included in the Failure Records data can

be useful in determining vehicle mileage since the

Diagnostic Trouble Code was last set.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2.Verifies that the fault is present.

3.If Diagnostic Trouble Code P0113 can be repeated

only by duplicating the Failure Records conditions,

refer to the ”Temperature vs. Resistance Values”

table.

The table may be used to test the IAT sensor at

various temperatures to evaluate the possibility of

a ”shifted” sensor that may be open above or

below a certain temperature. If this is the case,

replace the IAT sensor. If the IAT sensor appears

to be OK, the fault is intermittent; refer to

Diagnostic Aids.

Intake Air Temperature Sensor

°C°F OHMS

Temperature vs. Resistance Values (approximate)

100 212 177

80 176 332

60 140 667

45 1131188

35 95 1802

25 77 2796

15 59 4450

5 41 7280

–5 23 12300

–15 5 21450

–30 –22 52700

–40 –40 100700

DTC P0113 Intake Air Temperature (IAT) Sensor Circuit High Input

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Ignition ON, engine OFF. Observe the ”Intake Air

Temp” display on the Tech 2.

Is the ”Intake Air Temp” below the specified value? 5V –38°C

(–36°F) Go to Step 4 Go to Step 3

31. Ignition ON, engine OFF.

2. Review and record Tech 2 Failure Records data

parameters.

3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor «Diagnostic T rouble Code”

info for Diagnostic Trouble Code P0113.

Does the Tech 2 indicate Diagnostic Trouble Code

P0113 failed? —Refer to Test

Description

Refer to

Diagnostic

Aids

41. Ignition OFF.

2. Disconnect the IAT sensor electrical connector.

3. Jumper the IA T signal circuit and the sensor ground

circuit together at the IAT sensor harness

connector.

4. Ignition ON.

5. Observe the ”Intake Air Temp” display on the Tech

Is the ”Intake Air Temp” at the specified value? 0V 140°C

(284°F) Go to Step 6 Go to Step 5

51. Jumper the IAT signal circuit at the IAT sensor

harness connector to chassis ground.

2. Observe the ”Intake Air Temp” display on the Tech

Is the ”Intake Air Temp” at the specified value? 0V 140°C

(284°F) Go to Step 7 Go to Step 8

Step NoYesValue(s)Action

6Check for poor connections at the IAT sensor and

replace terminals if necessary.

Did any terminals require replacement? —Verify Repair Go to Step 10

71. Ignition OFF.

2. Disconnect the ECM, and check the IAT sensor

ground circuit for an open.

3. If the IAT sensor ground circuit is open, repair it as

necessary.

Was the IAT sensor ground circuit open? — Verify repair Go to Step 9

81. Ignition OFF.

2. Disconnect the ECM, and check the IAT signal

circuit for an open.

3. If the IAT sensor signal circuit is open, repair it as

necessary.

Was the IAT signal circuit open? — Verify repair Go to Step 9

9Check for a poor sensor ground or IAT signal circuit

terminal connection at the ECM and replace

terminal(s) if necessary.

Did any of the terminals need to be replaced? — Verify repair Go to Step 11

10 Replace the IAT sensor

Is the action complete? — Verify repair —

11 Replace the ECM

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0117 ENGINE COOLANT

TEMPERATURE (ECT) SENSOR CIRCUIT LOW INPUT

D06RX117

Circuit Description

The engine coolant temperature (ECT) sensor is a

thermistor mounted in the engine coolant stream. The

engine control module (ECM) applies a voltage (about 5

volts) through a pull–up resistor to the ECT signal circuit.

When the engine coolant is cold, the sensor (thermistor)

resistance is high, therefore the ECM will measure a high

signal voltage. As the engine coolant warms, the sensor

resistance becomes lower, and the ECT signal voltage

measured at the ECM drops. With a fully warmed–up

engine, the ECT signal voltage should measure about 1.5

to 2.0 volts. DTC P0117 is a Type A Code.

Conditions for Setting the DTC

DEngine running time is longer than two minutes.

DThe ECT sensor signal indicates an engine coolant

temperature greaterthan 150°C (302°F) (about 0.14

V) for a total of 12.5 seconds overa 25–second period.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

DThe ECM will substitute the ECT reading with a default

engine coolant temperature value. The default value is

based on start–up intake air temperature and running

time.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0117 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0117 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage, shorts to ground, shorts to battery positive,

and open circuits. If the harness appears to be OK,

observe the ECT display on the Tech 2 while moving

connectors and wiring harnesses related to the ECT

sensor. A change in the ECT display will indicate the

location of the fault.

If Diagnostic Trouble Code P0117 cannot be duplicated,

the information included in the Failure Records data can

be useful in determining vehicle mileage since the

Diagnostic Trouble Code was last set. If it is determined

that the Diagnostic Trouble Code occurs intermittently,

performing the Diagnostic Trouble Code P1114

Diagnostic Chart may isolate the cause of the fault.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2.Verifies that the fault is present.

3.If Diagnostic Trouble Code P0117 can be repeated

only by duplicating the Failure Records conditions,

refer to the ”Temperature vs. Resistance Values”

table.

The table may be used to test the ECT sensor at

various temperatures to evaluate the possibility of

a ”shifted” sensor that may be shorted above or

below a certain temperature. If this is the case,

replace the ECT sensor. If the ECT sensor

appears to be OK, the fault is intermittent; refer to

Diagnostic Aids.

Intake Air Temperature Sensor

°C°F OHMS

Temperature vs. Resistance Values (approximate)

100 212 177

80 176 332

60 140 667

45 1131188

35 95 1802

25 77 2796

15 59 4450

5 41 7280

–5 23 12300

–15 5 21450

–30 –22 52700

–40 –40 100700

DTC P0117 – Engine Coolant Temperature (ECT) Sensor Circuit Low Input

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON engine OFF.

2. Observe the ”Eng Cool T emp” display on the T ech 2.

Is the ”Eng Cool Temp” below the specified value? 139°C

(282°F) Go to Step 4 Go to Step 3

31. Ignition ON engine OFF.

2. Review and record Tech 2 Failure Records data.

3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor ”DTC” info for DTC P0117.

Does the Tech 2 indicate DTC P0117 failed this

ignition? —Go to Step 4

Refer to

Diagnostic

Aids

41. Disconnect the ECT sensor electrical connector.

2. Observe the ”Eng Cool T emp” display on the T ech 2.

Is the ”Eng Cool Temp” at or below the specified value? –39°C

(–38°F) Go to Step 6 Go to Step 5

51. Ignition OFF.

2. Disconnect the ECM and check the ECT signal

circuit for a short to ground or a short to the sensor

ground circuit.

3. If the ECT signal circuit is shorted, repair it as

necessary.

Was the ECT signal circuit shorted to ground? — Verify repair Go to Step 7

6Replace the ECT sensor.

Is the action complete? — Verify repair —

7Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0118 ENGINE COOLANT

TEMPERATURE (ECT) SENSOR CIRCUIT HIGH INPUT

D06RX117

Circuit Description

The engine coolant temperature (ECT) sensor is a

thermistor mounted in the engine coolant stream. The

engine control module (ECM) applies a voltage (about 5

volts) through a pull–up resistor to the ECT signal circuit.

When the engine coolant is cold, the sensor (thermistor)

resistance is high, therefore the ECM will measure a high

signal voltage. As the engine coolant warms, the sensor

resistance becomes less, and the ECT signal voltage

measured at the ECM drops. With a fully warmed up

engine, the ECT signal voltage should measure about 1.5

to 2.0 volts. If the ECM detect a continuous open in the

ECT sensor or circuit, then a code P0118 will set. DTC

P0118 is a type A code.

Conditions for Setting the DTC

DEngine running time is longer than 2.5 minutes.

DThe ECT sensor signal indicates an engine coolant

temperature of –39°C (–38°F) or less (about 5 volts)

for a total of 12.5 seconds over a 25–second period.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

DThe ECM will substitute the ECT reading with a default

engine coolant temperature value. The default value is

based on start–up intake air temperature and running

time.

DThe ECM will store conditions which were present

when the DTC was set as Freeze Frame and in the

Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0118 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0118 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage, shorts to ground, shorts to battery positive,

and open circuit. If the harness appears to be OK,

observe the ECT display on the Tech 2 while moving

connectors and wiring harnesses related to the ECT

sensor. A change in the ECT display will indicate the

location of the fault.

If Diagnostic Trouble Code P0118 cannot be duplicated,

the information included in the Failure Records data can

be useful in determining vehicle mileage since the

Diagnostic Trouble Code was last set. If it is determined

that the Diagnostic Trouble Code occurs intermittently,

performing the DTC P1115 Diagnostic Chart may isolate

the cause of the fault.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2.Verifies that the fault is present.

3.If Diagnostic Trouble Code P0118 can be repeated

only by duplicating the Failure Records condition,

refer to the ”Temperature vs. Resistance Value”

table.

The table may be used to test the ECT sensor at

various temperatures to evaluate the possibility of

a ”shifted” sensor that may be shorted above or

below a certain temperature. If this is the case,

replace the ECT sensor. If the ECT sensor

appears to be OK, the fault is intermittent; refer to

Diagnostic Aids.

Intake Air Temperature Sensor

°C°F OHMS

Temperature vs. Resistance Values (approximate)

100 212 177

80 176 332

60 140 667

45 113 1188

35 95 1802

25 77 2796

15 59 4450

5 41 7280

–5 23 12300

–15 5 21450

–30 –22 52700

–40 –40 100700

DTC P118 – ECT Sensor Circuit High Input

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON engine OFF.

2. Observe the ”Eng Cool T emp” display on the T ech 2.

Is the ”Eng Cool Temp” below the specified value? –39°C

(–38°F) Go to Step 4 Go to Step 3

31. Ignition ON engine OFF.

2. Review and record Tech 2 Failure Records data.

3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor the ”DTC” info for

Diagnostic Trouble Code P0118.

Does the Tech 2 indicate Diagnostic Trouble Code

P0118 failed? —Refer to Test

Description

Refer to

Diagnostic

Aids

41. Disconnect the ECT sensor electrical connector.

2. Jumper the ECT signal circuit and the sensor

ground circuit together at the ECT sensor harness

connector.

3. Observe the ”Eng Cool T emp” display on the T ech 2.

Is the ”Eng Cool T emp” at or above the specified value? 140°C

(284°F) Go to Step 6 Go to Step 5

51. Jumper the ECT signal circuit at the ECT sensor

harness connector to chassis ground.

2. Observe the ”Eng Cool T emp” display on the T ech 2.

Is the ”Eng Cool T emp” at or above the specified value? 140°C

(284°F) Go to Step 7 Go to Step 8

6Check for poor connections at the ECT sensor and

replace terminals if necessary.

Did any terminals require replacement? — Verify repair Go to Step

71. Ignition OFF.

2. Disconnect the ECM, and check the ECT sensor

ground circuit for an open.

3. If the ECT sensor ground circuit is open, repair it as

necessary.

Was the ECT sensor ground circuit open? — Verify repair Go to Step 9

81. Ignition OFF.

2. Disconnect the ECM, and check the ECT signal

circuit for an open.

3. If the ECT sensor signal circuit is open, repair it as

necessary.

Was the ECT signal circuit open? — Verify repair Go to Step 9

9Check for a poor sensor ground or ECT signal circuit

terminal connection at the ECM and replace

terminal(s) if necessary.

Did any of the terminals need to be replaced? — Verify repair Go to Step

10 Replace the ECT sensor.

Is the action complete? — Verify repair —

11 Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0121 THROTTLE POSITION (TP)

SENSOR CIRCUIT RANGE/PERFORMANCE PROBLEM

D06RX118

Circuit Description

The throttle position (Throttle Position) sensor circuit

provides a voltage signal that changes relative to throttle

blade angle. The signal voltage will vary from about 0.25

volts at closed throttle to about 4.75 volts at wide open

throttle (WOT).

The Throttle Position (TP) signal is used by the

powertrain control module (ECM) for fuel control and

most of the ECM–controlled outputs. The ECM monitors

throttle position and compares actual throttle positions

from the TP sensor to a predicted TP value calculated

from engine speed. If the ECM detects an out–of–range

condition, then a DTC code P0121 will set. DTC P0121 is

type A code.

Conditions for Setting the DTC

DThe Engine is running.

DNo MAP, ECT, TP, CKP, EGR, EVAP or DTC’s are set.

DIAC is between 10 and 160 counts.

DECT is above –10°C (14°F).

DThe MAP value changes by less than 2 kPa.

All the above mentioned conditions are met, and one of

the following conditions occurs for a total of 12.5 seconds

over a 25–second period of time.

Stuck High–

DMAP value is below 55 kPa.

DActual TP value is greater than the ECM’s estimated

TP value (Estimated TP value is based on MAP and

RPM).

Stuck Low–

DMAP value is below 50 kPa.

DActual TP value is less than the ECM’s estimated TP

value (Estimated TP value is based on MAP and

RPM).

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

DThe ECM will use a default throttle position based on

MAP and RPM.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0121 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDTC P0121 can be cleared by using the Scan Tool’s

”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DSkewed MAP signal or faulty MAP sensor – An

incorrect MAP signal may cause the ECM to incorrectly

calculate the predicted TP sensor value during high

engine load situations. Check for an unusually low

MAP reading. This condition can cause DTC P0121 to

be set.

DThe TP sensor shares a 5 Volt reference with the MAP

sensor and Fuel Pressure sensor.

If these codes are also set, it could indicate a

problem with the 5 Volt reference circuit.

DThe TP sensor shares a ground with the MAP sensor

and the Fuel Pressure sensor.

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; an open circuit, a short to ground, or a short

to voltage. If the harness appears to be OK, observe

the MAP display on the Tech 2 while moving

connectors and wiring harnesses related to the sensor.

A change in the display will indicate the location of the

fault.

If DTC P0121 cannot be duplicated, the information

included in the Failure Records data can be useful in

determining vehicle mileage since the DTC was last set. If

it is determined that the DTC occurs intermittently,

performing the DTC P1122 or P1121 Diagnostic Chart

may isolate the cause of the fault.

DTC P0121 TP Sensor/Range Performance Problem

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON engine OFF

2. Review and record Tech 2 Failure Records data,

then clear the DTC’s.

3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor ”DTC” info for DTC P0121.

Does the Tech 2 indicate that DTC P0121 ”Ran and

Passed?” —

Refer to

Diagnostic

Aids Go to Step 3

31. Ignition ON, engine OFF.

2. Monitor the TP value on the T ech 2 while moving the

throttle between 0% and 100%.

Does the TP value on the Tech 2 move smoothly from

0% (0.25 volts) to 100% (4.75 volts)? (if no, start with

the diagnosis chart for other sensors in the circuit and

see if 5V returns.) —Go to Step 4 Go to Step 11

41. Ignition OFF.

2. Disconnect the Throttle Position (TP) Sensor

electrical connector, located on the RH side of the

Throttle body.

3. Start the vehicle, and monitor the TP value with the

Tech 2.

Does the TP value on the T ech 2 hold steadily within the

given range? 0–0.25 volts

0% Go to Step 6 Go to Step 5

5Check the TP sensor signal circuit; between the TP

sensor and the Engine Control Module (ECM), for a

short to voltage.

Was the problem found? — Verify repair Go to Step 12

6Check the TP sensor circuit, between the TP sensor

and the ECM, the following conditions:

DA short to ground

DAn open circuit

Was the problem found? — Verify repair Go to Step 7

Step NoYesValue(s)Action

7Check the 5 volt signal circuit, between the TP sensor

and the ECM, for the following conditions:

DAn open circuit

DA short to ground

DA short to voltage

Was the problem found? — Verify repair Go to Step 8

81. Ignition OFF.

2. Place a fused jumper between the TP sensor circuit

and the 5 volt signal circuit both at the wiring

harness’ TP sensor connector.

3. Ignition ON, Engine OFF.

4. Observe the TP value displayed on the Tech 2?

Does the Tech 2 read the following value? about 5 volts

100% Go to Step 9 Go to Step 12

9Check the TP sensor ground circuit, between the TP

sensor and the ECM, for the following conditions:

DAn open circuit

DA short to ground

DA short to voltage

Was the problem found? — Verify repair Go to Step 10

10 1. Ignition OFF.

2. Place a Digital Multimeter (DVM), set to measure

voltage, between the ground circuit and the 5 volt

signal circuit, both at the wiring harness’ TP sensor

connector.

3. Ignition ON, Engine OFF.

Does the DVM read the following value? about 5 volts Go to Step 11 Go to Step 12

11 Replace the TP sensor.

Verify repair. ———

12 Replace the ECM.

Verify repair. ———

DIAGNOSTIC TROUBLE CODE (DTC) P0122 THROTTLE POSITION (TP)

SENSOR CIRCUITLOW INPUT

D06RX118

Circuit Description

The throttle position (TP) sensor circuit provides a voltage

signal that changes relative to throttle blade angle. The

signal voltage will vary from below 1 volt at closed throttle

to about 4 volts at wide open throttle(WOT).

The TP signal is used by the engine control module

(ECM) for fuel control and most of the ECM–controlled

outputs. If the ECM detect a continuous short to ground

in the TP sensor or circuit, then a code P0122 will set.

Diagnostic Trouble Code P0122 is type A code.

Conditions for Setting the DTC

DThe ignition is ON.

DThrottle Position sensor signal voltage is less than 0.22

volt for a total of 0.78 second over a 1.5–second period.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

DThe ECM will use a default throttle position based on

MAP and RPM.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0122 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0122 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DThe TP sensor shares a 5 V olt reference with the MAP

sensor and Fuel Pressure sensor.

If these codes are also set, it could indicate a

problem with the 5 Volt reference circuit or

components itself.

DThe TP sensor share a ground with the MAP and the

Fuel Pressure sensor.

DDamaged harness – Inspect the wiring harness for

damage, shorts to ground, shorts to battery positive,

and open circuits. If the harness appears to be OK,

observe the throttle position display on the T ech 2 while

moving connectors and wiring harnesses related to the

TP sensor. A change in the display will indicate the

location of the fault.

If Diagnostic Trouble Code P0122 cannot be duplicated,

the information included in the Failure Records data can

be useful in determining vehicle mileage since the

Diagnostic Trouble Code was last set. If it is determined

that the Diagnostic Trouble Code occurs intermittently,

performing the Diagnostic Trouble Code P1122

Diagnostic Chart may isolate the cause of the fault.

DTC P0122 – TP Sensor Circuit Low Input

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON engine OFF.

2. With the throttle closed, observe the ”Throttle

Position Sensor” display on the Tech 2.

Is the ”Throttle Position Sensor” below the specified

value? 0.22 V Go to Step 4 Go to Step 3

31. Ignition ON engine OFF.

2. Review and record Tech 2 Failure Records data.

3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor the “Diagnostic Trouble

Code” info for Diagnostic Trouble Code P0122.

Does the Tech 2 indicate DTC P0122 failed? —Go to Step 4

Refer to

Diagnostic

Aids

41. Ignition OFF.

2. Disconnect the TP sensor electrical connector.

3. Jumper the 5 volt reference circuit and the Throttle

Position signal together at the Throttle Position

sensor harness connector.

4. Ignition ON.

Observe the ”Throtle Position Sensor” display on the

Tech 2.

Is the ”Throttle Position Sensor” at the specified value? 5 V Go to Step

10 Go to Step 5

51. Disconnect jumper.

2. Connect a test light between B+ and the Throttle

Position sensor signal circuit at the Throttle Position

sensor harness connector.

Observe the ”Throttle Position Sensor” display on the

Tech 2.

Is the ”Throttle Position Sensor” at the specified value?

(if no, start with the diagnosis chart for other sensors in

the circuit and see if 5V returns.) 5 V Go to Step 6 Go to Step 8

61. Ignition OFF.

2. Disconnect the ECM and check the 5 volt reference

circuit for an open or short to ground.

3. If the 5 volt reference circuit is open or shorted to

ground, repair it as necessary.

Was the 5 volt reference circuit open or shorted to

ground? —Verify repair Go to Step 7

7Check the 5 volt reference circuit for a poor connection

at the ECM and replace the terminal if necessary.

Did the terminal require replacement? — Verify repair Go to Step

Step NoYesValue(s)Action

81. Ignition OFF.

2. Disconnect the ECM, and check the TP signal

circuit for an open, short to ground, or short to the

sensor ground circuit.

3. If the TP sensor signal circuit is open or shorted to

ground, repair it as necessary.

Was the TP signal circuit open or shorted to ground? — Verify repair Go to Step 9

9Check the TP sensor signal circuit for a poor

connection at the ECM and replace the terminal if

necessary.

Did the terminal require replacement? — Verify repair Go to Step

10 Check the TP sensor signal circuit for a poor

connection at the TP sensor and replace the terminal if

necessary.

Did the terminal require replacement? — Verify repair Go to Step

11 Replace the TP sensor.

Is the action complete? — Verify repair —

12 Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0123 THROTTLE POSITION (TP)

SENSOR CIRCUIT HIGH INPUT

D06RX118

Circuit Description

The throttle position (TP) sensor circuit provides a voltage

signal that changes relative to throttle blade angle. The

signal voltage will vary from below 1 volt at closed throttle

to about 4 volts at wide open throttle (WOT).

The TP signal is used by the engine control module

(ECM) for fuel control and most of the ECM–controlled

outputs. If the ECM detect a continuous open in the TP

sensor or circuit, then a code P0123 will set. DTC P0123

is a type A code.

Conditions for Setting the DTC

DThe ignition is ON.

DThrottle Position sensor signal voltage is greater than

4.78 volts for a total of 0.78 second over a 1.5–second

period.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

DThe ECM will store conditions which were present

when the DTC was set as Freeze Frame and in the

Failure Records data.

DThe ECM will use a default throttle position based on

MAP and RPM.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0123 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0123 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DThe TP sensor shares a 5 V olt reference with the MAP

sensor and Fuel Pressure sensor.

If these codes are also set, it could indicate a

problem with the 5 Volt reference circuit or

components itself.

DThe TP sensor share a ground with the MAP and the

Fuel Pressure sensor.

DDamaged harness – Inspect the wiring harness for

damage, shorts to ground, shorts to battery positive

and open circuits. If the harness appears to be OK,

observe the Throttle Position sensor display on the

Tech 2 while moving connectors and wiring harnesses

related to the TP sensor. A change in the display will

indicate the location of the fault.

DFaulty Throttle Position sensor – With the ignition key

ON engine OFF observe the TP sensor display on the

Tech 2 while slowly depressing the accelerator to wide

open throttle. If a voltage over 4.88 volts is seen at any

point in normal accelerator travel, replace the TP

sensor.

If Diagnostic Trouble Code P0123 cannot be duplicated,

the information included in the Failure Records data can

be useful in determining vehicle mileage since the

Diagnostic Trouble Code was last set. If it is determined

that the Diagnostic Trouble Code occurs intermittently,

performing theDiagnostic Trouble Code P1121

Diagnostic Chart may isolate the cause of the fault.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

7.Components that share the TP sensor 5 volt

reference circuit include the following devices:

DEGR valve

DMAP sensor

Disconnect the component while observing the

Throttle Position sensor display on the Tech 2. If

the reading changes drastically when this

component is disconnected, replace the

component that affected the reading.

DTC P0123 – TP Sensor Circuit High Input

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON, engine OFF.

2. With the throttle closed, observe the ”Throttle

Position Sensor” display on the Tech 2.

Is the ”Throttle Position Sensor” above the specified

value? 4.78 V Go to Step 4 Go to Step 3

31. Ignition ON, engine OFF.

2. Review and record Tech 2 Failure Records data.

3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor “Diagnostic T rouble Code”

info for Diagnostic Trouble Code P0123.

Does the Tech 2 indicate Diagnostic Trouble Code

P0123 failed. —Go to Step 4

Refer to

Diagnostic

Aids

41. Disconnect the Throttle Position sensor electrical

connector.

2. Observe the ”Throttle Position Sensor” display on

the Tech 2.

Is the ”Throttle Position Sensor” near the specified

value? (if no, start with the diagnosis chart for other

sensors in the circuit and see if 5V returns.) 0 V Go to Step 5 Go to Step 6

5Probe the sensor ground circuit at the Throttle Position

sensor harness connector with a test light connected to

B+.

Is the test light ON? —Go to Step 7 Go to Step

61. Ignition OFF disconnect the ECM.

2. Ignition ON engine OFF.

3. Check for a short to voltage on the TP sensor signal

circuit.

4. If the TP sensor signal circuit is shorted, repair it as

necessary.

Was the TP sensor signal circuit shorted? — Verify repair Go to Step

Step NoYesValue(s)Action

71. Ignition ON.

2. Monitor the ”Throttle Position Sensor” Tech 2

display while disconnecting each of the

components that share the 5 volt reference circuit

(one at a time).

3. If the ”Throttle Position Sensor” Tech 2 display

changes, service the component(s) that caused the

display to change when disconnected.

Does disconnecting any of these components cause

the ”Throttle Position Sensor” display to change? — Verify repair Go to Step 8

81. Ignition OFF disconnect the ECM.

2. Ignition ON, engine OFF.

3. Check for a short to B+ on the 5 volt reference

circuit.

4. If the 5 volt reference circuit is shorted, repair it as

necessary.

Was the 5 volt reference circuit shorted? — Verify repair Go to Step 9

9Check for poor electrical connections at the Throttle

Position sensor and replace terminals if necessary.

Did any terminals require replacement? — Verify repair Go to Step

10 1. Ignition OFF.

2. Disconnect the ECM, and check for an open sensor

ground circuit to the Throttle Position sensor.

3. If a problem is found, repair it as necessary.

Was the sensor ground circuit to the Throttle Position

sensor open? — Verify repair Go to Step

11 Replace the Throttle Position sensor.

Is the action complete? — Verify repair —

12 Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0131 O2 SENSOR CIRCUIT LOW

VOLTAGE (BANK 1 SENSOR 1)

D06RX119

Circuit Description

The engine control module (ECM) supplies a bias voltage

of about 450 mV between the heated oxygen sensor

(HO2S) signal and low circuits. When measured with a 10

megaW digital voltmeter, this may display as low as 350

mV. The oxygen sensor varies the voltage within a range

of about 1000 mV when the exhaust is rich, down through

about 10 mV when exhaust is lean. The ECM constantly

monitors the HO2S signal during ”Closed Loop” operation

and compensates for a rich or lean condition by

decreasing or increasing injector pulse width as

necessary. If the Bank 1 HO2S 1 voltage remains

excessively low for an extended period of time,

Diagnostic Trouble Code P0131 will be set. DTC P0131 is

a type A code.

Conditions for Setting the DTC

DNo related Diagnostic Trouble Codes.

DVehicle is operating in ”Closed Loop”.

DEngine coolant temperature is above 60°C (140°F)

D”Closed Loop” commanded air/fuel ratio is between

14.5 and 14.8.

DThrottle angle is between 3% and 19%.

All above conditions met for 0.3 seconds and the following

condition is met:

DBank 1 HO2S 1 signal voltage remains below 22 mV

during normal ”Closed Loop” operation for a total of

76.5 seconds over a 90–second period of time.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

DThe ECM will store conditions which were present

when the DTC was set as Freeze Frame and in the

Failure Records data.

D”Open Loop” fuel control will be in effect.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0131 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0131 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DHeated oxygen sensor wiring – The sensor pigtail may

be routed incorrectly and/or contacting the exhaust

system. Also, check for shorts to ground, shorts to

battery positive and open circuits.

DPoor ECM to engine block grounds.

DFuel pressure – The system will go lean if pressure is

too low. The ECM can compensate for some decrease.

However, if fuel pressure is too low, a Diagnostic

Trouble Code P0131 may be set. Refer to Fuel System

Diagnosis.

DLean injector(s) – Perform ”Injector Balance Test.”

DVacuum leaks – Check for disconnected or damaged

vacuum hoses and for vacuum leaks at the intake

manifold, throttle body, EGR system, and PCV system.

DExhaust leaks – An exhaust leak may cause outside air

to be pulled into the exhaust gas stream past the

HO2S, causing the system to appear lean. Check for

exhaust leaks that may cause a false lean condition to

be indicated.

DFuel contamination – Water, even in small amounts,

can be delivered to the fuel injectors. The water can

cause a lean exhaust to be indicated. Excessive

alcohol in the fuel can also cause this condition. For the

procedure to check for fuel contamination, Refer to

Fuel System Diagnosis.

If none of the above conditions are present, replace the

affected HO2S.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

3. Diagnostic Trouble Code P0131 failing during

operation may indicate a condition described in the

”Diagnostic Aids” above. If the Diagnostic Trouble

Code P0131 test passes while the Failure Records

conditions are being duplicated, an intermittent

condition is indicated.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic T rouble Code to

be set occurs. This may assist in diagnosing the

condition.

DTC P0131 – O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? — Go to Step 2

Go to OBD

System

Check

21. Install the Tech 2.

2. Run the engine at operating temperature.

3. Operate the vehicle within the parameters specified

under ”Conditions for Setting the Diagnostic

Trouble Code” criteria included in Diagnostic

Support.

4. Using a Tech 2, monitor Bank 1 HO2S 1 voltage.

Does the Bank 1 HO2S 1 voltage remain below the

specified value? 300 mV Go to Step 4 Go to Step 3

31. Ignition ON engine OFF review and record Tech 2

Failure Records data and note parameters.

2. Operate the vehicle within Failure Records

conditions as noted.

3. Using a Tech 2, monitor “Diagnostic T rouble Code”

info for Diagnostic Trouble Code P0131 until the

Diagnostic Trouble Code P0131 test runs.

Note test result.

Does Tech 2 indicate DTC P0131 failed this ignition? — Go to Step 4

Refer to

Diagnostic

Aids

41. Turn the ignition OFF.

2. Disconnect the ECM.

3. Check the Bank 1 HO2S 1 high and low circuits for a

short to ground or a short to the heater ground

circuit.

Are the Bank 1 HO2S 1 signal circuits shorted to

ground? — Go to Step 5 Go to Step 6

5Repair the Bank 1 HO2S 1 signal circuit.

Is the action complete? — Verify repair —

61. Turn the ignition OFF HO2S 1 and ECM

disconnected.

2. Check for continuity between the high and low

signal circuits.

Was there continuity between the high and low circuits? — Go to Step 7 Go to Step 8

7Repair the short between the high and low circuits.

Is the action complete? — Verify repair —

81. Ignition OFF.

2. Reconnect the ECM, leave the sensor

disconnected.

3. Ignition ON.

Does the Tech 2 indicate Bank 1 HO2S 1 voltage near

the specified value? 430–450 mV

Refer to

Diagnostic

Aids Go to Step 9

9Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0132 O2 SENSOR CIRCUIT HIGH

VOLTAGE (BANK 1 SENSOR 1)

D06RX119

Circuit Description

The engine control module (ECM) supplies a bias voltage

of about 450 mV between the heated oxygen sensor

(HO2S) signal and low circuits. When measured with a 10

megaW digital voltmeter, this may display as low as 320

mV. The oxygen sensor varies the voltage within a range

of about 1000 mV when the exhaust is rich, down through

about 10 mV when exhaust is lean. The ECM constantly

monitors the HO2S signal during ”Closed Loop” operation

and compensates for a rich or lean condition by

decreasing or increasing injector pulse width as

necessary. If the Bank 1 HO2S 1 voltage remains

excessively high for an extended period of time,

Diagnostic Trouble Code P0132 will be set. DTC P0132 is

a type A code.

Conditions for Setting the DTC

DNo related Diagnostic Trouble Codes.

DEngine coolant temperature is above 60°C (140°F).

D”Closed Loop” commanded air/fuel ratio is between

14.5 and 14.8.

DThrottle angle is between 3% and 19%.

All above conditions met for 0.3 seconds or vehicle in

Decelleration Fuel Cut–Off (DFCO) mode for 3 seconds,

and one of the following two conditions met:

DBank 1 HO2S 1 signal voltage remains above 952 mV

during normal ”Closed Loop” operation for a total of

76.5 seconds over a 90–second period.

DBank 1 HO2S 1 signal voltage remains above 500 mV

during ”deceleration fuel cutoff mode” (DFCO)

operation for 5 seconds.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

DThe ECM will store conditions which were present

when the DTC was set as Freeze Frame and in the

Failure Records data.

D”Open Loop” fuel control will be in effect.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0132 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0132 can be cleared by

using the Scan Tool’s ”Clear Info” function or by

disconnecting the ECM battery feed.

Diagnostic Aids

Check the following items:

DFuel pressure – The system will go rich if pressure is

too high. The ECM can compensate for some

increase. However, if fuel pressure is too high, a

Diagnostic Trouble Code P0132 may be set. Refer to

Fuel System Diagnosis.

DPerform ”Injector Balance Test” – Refer to Fuel System

Diagnosis.

DCheck the EVAP canister for fuel saturation – If full of

fuel, check canister control and hoses. Refer to

Evaporative (EVAP) Emission Control System.

DCheck for a leak in the fuel pressure regulator

diaphragm by checking the vacuum line to the

regulator for the presence of fuel.

DAn intermittent TP sensor output will cause the system

to go rich due to a false indication of the engine

accelerating.

DSilicon contamination of the HO2S can also cause a

high HO2S voltage to be indicated. This condition is

indicated by a powdery white deposit on the portion of

the HO2S exposed to the exhaust stream. If

contamination is noticed, replace the affected HO2S.

DOperate the vehicle while monitoring the HO2S voltage

with a Tech 2. If the HO2S voltage is limited within a

range between 300 mV to 600 mV, check the HO2S

high and low circuit wiring and associated terminal

connections. If the wiring and connections are OK,

replace the HO2S.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

3. Diagnostic Trouble Code P0132 failing during

”deceleration fuel cutoff mode” operation may

indicate a condition described in the ”Diagnostic

Aids” above. If the Diagnostic Trouble Code P0132

test passes while the Failure Records conditions are

being duplicated, an intermittent condition is

indicated. Reviewing the Failure Records vehicle

mileage since the diagnostic test last failed may

help determine how often the condition that caused

the Diagnostic Trouble Code to be set occurs. This

may assist in diagnosing the condition.

DTC P0132 – O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Install the Tech 2.

2. Run the engine at operating temperature.

3. Operate the vehicle within parameters specified

under ”Conditions for Setting the DTC” included in

Diagnostic Support.

4. Using a Tech 2, monitor Bank 1 HO2S 1 voltage.

Does the Bank 1 HO2S 1 voltage remain above the

specified value?

952 mV (500

mV in

deceleration

fuel cutoff

mode) Go to Step 4 Go to Step 3

31. Ignition ON review and record Tech 2 Failure

Records data.

2. Operate the vehicle within Failure Records

conditions as noted.

3. Using a Tech 2, monitor “Diagnostic T rouble Code”

info for Diagnostic Trouble Code P0132 until the

Diagnostic Trouble Code P0132 test runs.

4. Note the test result.

Does the Tech 2 indicate Diagnostic Trouble Code

P0132 failed this ignition? —

Refer to

Diagnostic

Aids Go to Step 4

41. Ignition OFF.

2. Disconnect Bank 1 HO2S 1.

3. Ignition ON.

4. At HO2S 1 connector (ECM side) use a Digital

Voltmeter (DVM) to measure voltages at the high

and low signal terminals.

Are the voltages in the specified range? 5–14 V Go to Step 5 Go to Step 6

5Repair short to voltage in signal circuit. — Verify repair —

61. Ignition OFF.

2. Disconnect the ECM connector.

3. Check for damage to the ECM pins and terminals.

Was a problem found? — Verify repair Go to Step 7

71. Ignition ON, engine OFF.

2. Disconnect Bank 1 HO2S 1 and jumper the HO2S

high and low circuits (ECM side) to ground.

3. Using a Tech 2, monitor Bank 1 HO2S 1 voltage.

Is Bank 1 HO2S 1 voltage below the specified value? 10 mV Go to Step 8 Go to Step 9

8Replace Bank 1 HO2S 1.

Is the action complete? — Verify repair —

9Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0134 O2 SENSOR CIRCUIT NO

ACTIVITY DETECTED (BANK 1 SENSOR 1)

D06RX119

Circuit Description

The engine control module (ECM) supplies a bias voltage

of about 450 mV between the heated oxygen sensor

(HO2S) high and low circuits. When measured with a 10

MW digital voltmeter, this may display as low as 320 mV.

The oxygen sensor varies the voltage within a range of

about 1000 mV when the exhaust is rich, down through

about 10 mV when exhaust is lean. The ECM constantly

monitors the HO2S signal during ”Closed Loop” operation

and compensates for a rich or lean condition by

decreasing or increasing injector pulse width as

necessary. If the Bank 1 HO2S 1 voltage remains at or

near the 450 mV bias for an extended period of time,

Diagnostic T rouble Code P0134 will be set, indicating an

open sensor signal or sensor low circuit. DTC P0134 is a

type B code.

Conditions for Setting the DTC

DNo related Diagnostic Trouble Codes.

DEngine run time is longer than 120 seconds.

DOxygen sensor heater has been determined to be

functioning properly, and the oxygen sensor has

warmed to operating temperature.

All the above conditions are met and the following

condition is met:

DBank 1 HO2S 1 signal voltage remains between 400

mV and 500 mV for a total of 76.5 seconds over a

90–second period of time.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the second time the fault is detected.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

D”Open Loop” fuel control will be in effect.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0134 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0134 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection or damaged harness – Inspect the

harness connectors for backed–out terminals,

improper mating, broken locks, improperly formed or

damaged terminals, poor terminal–to–wire

connection, and damaged harness.

DFaulty HO2S heater or heater circuit – With the ignition

ON engine OFF after a cooldown period, the HO2S 1

voltage displayed on the Tech 2 is normally 455–460

mV. A reading over 1000 mV indicates a signal line

shorted to voltage. A reading under 5 mV indicates a

signal line shorted to ground or signal lines shorted

together. Disconnect the HO2S and connect a test light

between the HO2S ignition feed and heater ground

circuits. If the test light does not light for 2 seconds

when the ignition is turned on, repair the open ignition

feed or sensor ground circuit as necessary. If the test

light lights and the HO2S signal and low circuits are

OK, replace the HO2S.

DIntermittent test – With the ignition ON monitor the

HO2S signal voltage while moving the wiring harness

and related connectors. If the fault is induced, the

HO2S signal voltage will change. This may help isolate

the location of the malfunction.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic Trouble Code to

be set occurs. This may assist in diagnosing the

condition.

DTC P0134 – O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Install the Tech 2.

2. Run the engine at operating temperature.

3. Operate the engine above 1200 RPM for three

minutes.

Does the Tech 2 indicate Bank 1 HO2S 1 voltage

varying outside the specified values? 400–500 mV Go to Step 3 Go to Step 4

31. Ignition ON, engine OFF review and record Tech 2

Failure Records data and note parameters.

2. Operate the vehicle within Failure Records

conditions as noted.

3. Using a Tech 2, monitor “Diagnostic T rouble Code”

info for Diagnostic Trouble Code P0134 until the

Diagnostic Trouble Code P0134 test runs.

4. Note the test result.

Does the Tech 2 indicate Diagnostic Trouble Code

P0134 failed this ignition? —Go to Step 4

Refer to

Diagnostic

Aids

4Check for a damaged harness.

Was a problem found? — Verify repair Go to Step 5

5Check for poor Bank 1 HO2S 1 high and low circuit

terminal connections at the Bank 1 HO2S 1 harness

connector and replace terminal(s) if necessary.

Did any terminals require replacement? — Verify repair Go to Step 6

6Check for poor Bank 1 HO2S 1 high and low circuit

terminal connections at the ECM and replace terminals

if necessary.

Did any terminals require replacement? — Verify repair Go to Step 7

71. Ignition OFF.

2. With the ECM disconnected, check continuity of the

Bank 1 HO2S 1 high circuit.

3. If the Bank 1 HO2S 1 high circuit measures over 0.5

W, repair open or poor connection as necessary.

Was a Bank 1 HO2S 1 high circuit problem found and

corrected? — Verify repair Go to Step 8

Step NoYesValue(s)Action

81. Ignition OFF.

2. With the ECM disconnected, check continuity of the

Bank 1 HO2S 1 low circuit.

3. If the Bank 1 HO2S 1 low circuit measures over 5 W,

repair open or poor connection as necessary.

Was a Bank 1 HO2S 1 low circuit problem found and

corrected? —Verify repair Go to Step 9

91. Ignition ON, engine OFF.

2. Disconnect Bank 1 HO2S 1 and jumper the HO2S

high and low circuits (ECM side) to ground.

3. Using a Tech 2, monitor Bank 1 HO2S 1 voltage.

Is Bank 1 HO2S 1 voltage approximately equal to the

specified value? 10 mV Go to Step 10 Go to Step 11

10 Replace Bank 1 HO2S 1.

Is the action complete? — Verify repair —

11 Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0135 O2 SENSOR HEATER CIRCUIT

MALFUNCTION

D06RX119

Circuit Description

Heated oxygen sensors are used to minimize the amount

of time required for “Closed Loop” fuel control operation

and to allow accurate catalyst monitoring. The oxygen

sensor heater greatly decreases the amount of time

required for fuel control sensors Bank 1 HO2S 1.

The engine control module (ECM) will run the heater test

only after a cold start (determined by engine coolant and

intake air temperature at the time of start–up) and only

once during an ignition cycle. When the engine is started

the ECM will monitor the HO2S voltage. When the HO2S

voltage indicates a sufficiently active sensor, the ECM

looks at how much time has elapsed since start–up. If the

ECM determines that too much time was required for the

Bank 1 HO2S 1 to become active, a Diagnostic Trouble

Code P0135 will set. DTC P0135 is a type B code.

Conditions for Setting the DTC

DNo related Diagnostic Trouble Codes.

DIntake air temperature (IAT) is less than 32°C (90°F)

at start–up.

DEngine coolant temperature (ECT) is less than 32°C

(90°F) at start–up.

DIAT and ECT are within 5°C (9°F) of each other at

start–up.

DIgnition voltage is between 11 and 16.6 V.

DAverage calculated air flow is less than 18 g/second

during sample period.

DThrottle angle is less than 40%.

DBank 1 HO2S 1 voltage does not change more than

148 mV from the bias voltage (between 400 mV and

500 mV) for a longer amount of time than it should. The

maximum amount of time to come up to operating

range is 240 seconds. This warm–up time depends on

the engine coolant temperature at start–up and intake

air temperature at start–up.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0135 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0135 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive

and open circuits. If the harness appears to be OK,

observe the ECT display on the Tech 2 while moving

connectors and wiring harnesses related to the sensor.

A change in the display will indicate the location of the

fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic Trouble Code to

be set occurs. This may assist in diagnosing the

condition.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2.The HO2S should be allowed to cool before

performing this test. If the HO2S heater is

functioning, the signal voltage will gradually increase

or decrease as the sensor element warms. If the

heater is not functioning, the HO2S signal will

remain near the 450 mV bias voltage.

4.Ensures that the ignition feed circuit to the HO2S is

not open or shorted. The test light should be

connected to a good chassis ground, in case the

HO2S low or HO2s heater ground circuit is faulty.

5.Checks the HO2S heater ground circuit.

6.Checks for an open or shorted HO2S heater

element.

10.An open HO2S signal or low circuit can cause the

HO2S heater to appear faulty. Check these circuits

before replacing the sensor.

DTC P0135 – O2 Sensor Heater Circuit Malfunction

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2NOTE: If the engine has just been operating, allow

engine to cool for about one half hour before

proceeding.

1. Ignition OFF, engine OFF.

2. Install a Tech 2.

3. Ignition ON engine OFF monitor the Bank 1 HO2S 1

voltage.

Does the HO2S voltage go from bias voltage to above

and below the specified values?

Above 650

mV or below

250 mV

Refer to

Diagnostic

Aids Go to Step 3

3Inspect the fuse for the Bank 1 HO2S 1 ignition feed.

Is the fuse open? —Go to Step 15 Go to Step 4

41. Ignition OFF.

2. Raise the vehicle.

3. Disconnect the Bank 1 HO2S 1 electrical connector.

4. Using a test light connected to a good ground (do

not use Bank 1 HO2S 1 heater ground or Bank 1

HO2S 1 low), probe the ignition feed circuit at the

Bank 1 HO2S 1 electrical connector (ECM harness

side).

Does the test light illuminate? —Go to Step 5 Go to Step 7

5Connect the test light between the Bank 1 HO2S 1

ignition feed and the Bank 1 HO2S 1 heater ground.

Does the test light illuminate? —Go to Step 6 Go to Step 8

Step NoYesValue(s)Action

61. Allow the HO2S to cool for at least 10 minutes.

2. Using a Digital Voltmeter (DVM), measure the

resistance between the Bank 1 HO2S 1 ignition

feed and the Bank 1 HO2S 1 heater ground at the

Bank 1 HO2S 1 pigtail.

Is the HO2S heater resistance within the specified

values? 3–6 ohms Go to Step 9 Go to Step 10

7Repair the open Bank 1 HO2S 1 ignition feed circuit to

Bank 1 HO2S 1.

Is the action complete? — Verify repair —

8Repair the open Bank 1 HO2S 1 heater ground circuit

to Bank 1 HO2S 1.

Is the action complete? — Verify repair —

91. Check for a poor connection at the Bank 1 HO2S 1

harness terminals.

2. If a poor connection is found, replace terminals.

Was a poor connection found? — Verify repair Go to Step 10

10 Check for a poor Bank 1 HO2S 1 high or low circuit

terminal connection at the Bank 1 HO2S 1 harness

connector and replace terminal(s) if necessary.

Did any terminals require replacement? — Verify repair Go to Step 11

11 1. Ignition OFF.

2. Disconnect the ECM and check the continuity of the

Bank 1 HO2S 1 signal circuit and the Bank 1 HO2S

1 low circuit.

3. If the Bank 1 HO2S 1 high circuit or HO2S low circuit

measures over 5 W, repair open or poor connection

as necessary.

Was a problem found? — Verify repair Go to Step 12

12 Check for a poor Bank 1 HO2S 1 low circuit terminal

connection at the ECM and replace the terminal if

necessary.

Did the terminal require replacement? — Verify repair Go to Step 13

13 Check for a poor Bank 1 HO2S 1 high circuit terminal

connection at the ECM and replace the terminal if

necessary.

Did the terminal require replacement? — Verify repair Go to Step 14

14 Replace the Bank 1 HO2S 1.

Is the action complete? — Verify repair —

15 Locate and repair the short to ground in Bank 1 HO2S 1

ignition feed circuit and replace the fault fuse.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0171 SYSTEM TOO LEAN (BANK 1)

D06RX119

Circuit Description

To provide the best possible combination of driveability,

fuel economy, and emission control, a ”Closed Loop”

air/fuel metering system is used. While in ”Closed Loop”,

the engine control module (ECM) monitors the Bank 1

HO2S 1 signal and adjusts fuel delivery based upon the

HO2S signal voltage. A change made to fuel delivery will

be indicated by the long and short term fuel trim values

which can be monitored with a Tech 2. Ideal fuel trim

values are around 0%; if the HO2S signal indicates a lean

condition the ECM will add fuel, resulting in fuel trim

values above 0%. If a rich condition is detected, the fuel

trim values will be below 0%, indicating that the ECM is

reducing the amount of fuel delivered. If an excessively

lean condition is detected on Bank 1, the ECM will set

Diagnostic T rouble Code P0171. DTC P0171 is a type B

code.

The ECM’s maximum authority to control long term fuel

trim allows a range between –14% and +20%. The ECM

monitors fuel trim under various engine speed/load fuel

trim cells before determining the status of the fuel trim

diagnostic.

Conditions for Setting the DTC

DNo Tech 2 test is being run.

DNone of the following: EGR Diagnostic Trouble Codes,

HO2S Diagnostic Trouble Codes, (response,

transition, open, low volts, no activity), TP sensor

Diagnostic Trouble Codes, MAP Diagnostic Trouble

Codes, IAT Diagnostic Trouble Codes, canister purge

Diagnostic Trouble Codes, EVAP Diagnostic Trouble

Codes, injector circuit Diagnostic Trouble Codes, or

misfire Diagnostic Trouble Codes.

DEngine coolant temperature is between 65°C (149°F)

and 104°C (219°F).

DIntake air temperature is between –40°C (–40°F) and

120°C (248°F).

DManifold absolute pressure is between 23.75 kPa and

99 kPa.

DEngine speed is between 400 and 6000 RPM.

DBarometric pressure is greater than 72.3 kPa.

DSystem voltage is greater than 9.5v.

DEngine is operating in ”Closed Loop”.

DThe average of the short term fuel trim samples is

greater than 0.97 and the average of adaptive index

multiplier samples is greater than 1.21.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0171 will clear

after 40 consecutivewarm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0171 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive

and open circuits. If the harness appears to be OK,

observe the Bank 1 HO2S 1 display on the Tech 2 while

moving connectors and wiring harnesses related to the

engine harness. A change in the display will indicate

the location of the fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic Trouble Code to

be set occurs. This may assist in diagnosing the

condition.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2.Diagnostic Trouble Codes other than P0171 may

indicate a condition present which may cause a lean

condition. If this is the case, repairing the condition

which caused the other Diagnostic Trouble Code will

most likely correct the Diagnostic Trouble Code

P0171.

4.If the Diagnostic Trouble Code P0171 test passes

while the Failure Records conditions are being

duplicated, the lean condition is intermittent. Refer

to Diagnostic Aids or Symptoms for additional

information on diagnosing intermittent problems.

DTC P0171 – System Too Lean (Bank 1)

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Are any DTCs set other than P0171?

—

Go to the

applicable

DTC charts

and repair the

other DTCs

before

proceeding

with this

chart. Go to Step 3

31. Start the engine and operate the vehicle in ”Closed

Loop”.

2. Observe the ”BANK 1 L.T. FUEL TRIM” and display

on the Tech 2.

Are the displayed values greater than the specified

values? L.T. Fuel

Trim: 20% Go to Step 5 Go to Step 4

41. Review and record the T ech 2 Failure Records data.

2. Clear the Diagnostic Trouble Code P0171 and

operate the vehicle to duplicate the Failure Records

conditions.

3. Monitor the Tech 2 “Diagnostic Trouble Code” info

for Diagnostic T rouble Code P0171 while operating

the vehicle to duplicate the Failure Records

conditions.

4. Continue operating the vehicle until the Diagnostic

Trouble Code P0171 test runs and note the test

result.

Does the Tech 2 indicate Diagnostic Trouble Code

P0171 failed this ignition? —Go to Step 5

The lean

condition is

not present. If

a driveability

symptom still

exists, refer

to Symptoms

section.

5Visually and physically inspect the vacuum hoses for

disconnects, splits, kinks, improper routing and

improper connections and repair any problem found.

Did your inspection reveal a problem requiring repair? —Verify repair Go to Step 6

6Visually and physically inspect the crankcase

ventilation valve for proper installation and repair any

problem found (refer to Crankcase Ventilation

System).

Did your inspection reveal a problem requiring repair? —Verify repair Go to Step 7

7Start the engine and note the idle quality.

Is a high or unsteady idle being experienced? —Go to Step 8 Go to Step

8With the engine idling, observe the ”IDLE AIR

CONTROL” display on the Tech 2.

Is the displayed value above the specified value? Above 5

counts Go to Step

10 Go to Step 9

91. Visually and physically inspect the throttle body,

intake manifold, EGR valve and the EGR feed pipe

for vacuum leaks.

2. Repair any vacuum leaks as necessary.

Did your inspection reveal a vacuum leak? — Verify repair Go to Step

Step NoYesValue(s)Action

10 Perform the ”Idle Air Control (IAC) Valve Check” and

correct any IAC problem as necessary.

Did this test isolate a problem requiring repair? — Verify repair Go to Step

11 Check the fuel for excessive water, alcohol, or other

contaminants (see Diagnosis in Engine Fuel for the

procedure) and correct the contaminated fuel condition

if present (see Engine Fuel).

Was the fuel contaminated? — Verify repair Go to Step

12 1. Visually and physically inspect the ECM injector

grounds, power grounds and sensor grounds to

ensure that they are clean, tight, and in their proper

locations.

2. If a faulty ground condition is present, correct it as

necessary.

Did your inspection reveal a condition requiring repair? —Verify repair Go to Step

13 Perform the procedure in ”Fuel System Pressure Test”

and repair fuel system problem if necessary.

Did the test isolate a condition requiring repair? — Verify repair Go to Step

14 Perform the ”Evaporative Emissions Control (EVAP)

Canister Purge Valve Check” and repair EVAP system

problem if necessary.

Did the test isolate a problem? — Verify repair Go to Step

15 1. Visually and physically inspect the intake manifold,

injector O–rings, EGR adapter, EGR valve and the

EGR feed pipes for vacuum leaks.

2. Repair any problem that is found.

Did your inspection reveal a problem? — Verify repair Go to Step

16 Visually and physically inspect the Bank 1 exhaust

manifold for leaks and loose or missing hardware and

correct any problem found.

Did your inspection reveal a problem? — Verify repair Go to Step

17 Perform the ”Injector Balance Test,” and correct any

problem found (refer to Fuel Metering System).

Did the test isolate a problem? — Verify repair Go to Step

18 1. Visually and physically inspect the Bank 1 HO2S 1

to ensure that it is installed securely and that the

Bank 1 HO2S 1 pigtail and wiring harness are not

contacting the exhaust or otherwise damaged.

2. If a problem is found, correct it as necessary.

Did your inspection reveal a problem? — Verify repair

Refer to

Diagnostic

Aids

DIAGNOSTIC TROUBLE CODE (DTC) P0172 SYSTEM TOO RICH (BANK 1)

D06RX119

Circuit Description

To provide the best possible combination of driveability,

fuel economy, and emission control, a ”Closed Loop”

air/fuel metering system is used. While in ”Closed Loop”,

the engine control module (ECM) monitors the Bank 1

heated oxygen sensor (HO2S) 1 and adjusts fuel delivery

based upon the HO2S signal voltages. A change made to

fuel delivery will be indicated by the long and short term

fuel trim values which can be monitored with a Tech 2.

Ideal fuel trim values are around 0%; if the HO2S signals

are indicating a lean condition the ECM will add fuel,

resulting in fuel trim values above 0%. If a rich condition is

detected, the fuel trim values will be below 0%, indicating

that the ECM is reducing the amount of fuel delivered. If

an excessively rich condition is detected on Bank 1, the

ECM will set Diagnostic Trouble Code P0172. DTC

P0172 is a type B code.

The ECM’s maximum authority to control long term fuel

trim allows a range between –14% and +20%. The ECM’s

maximum authority to control short term fuel trim allows a

range between –11% and +20%. The ECM monitors fuel

trim under various engine speed/load fuel trim cells

before determining the status of the fuel trim diagnostic.

Conditions for Setting the DTC

DNo Tech 2 test is being run.

DNone of the following was set: EGR Diagnostic Trouble

Codes, HO2S Diagnostic Trouble Codes, (response,

transition, open, low volts, no activity), TPS Diagnostic

Trouble Codes, MAP Diagnostic Trouble Codes, IAT

Diagnostic Trouble Codes, canister purge Diagnostic

Trouble Codes, EVAP Diagnostic Trouble Codes,

injector circuit Diagnostic Trouble Codes, or misfire

Diagnostic Trouble Codes.

DEngine coolant temperature is between 65°C (149°F)

and 104°C (219°F).

DIntake air temperature is between –40°C (–40°F) and

120°C(248°F).

DManifold absolute pressure is between 23.75 kPa and

99 kPa.

DSystem voltage is greater than 9.5 volts.

DEngine speed is between 400 and 6000 RPM.

DBarometric pressure is greater than 72.3 kPa.

DEngine is operating in ”Closed Loop”.

DThe average of the long term full trim samples is less

than 1.03 and the average of the adaptive index

multiplier samples is less than or equal to 0.82.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0172 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0172 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive

and open circuits. If the harness appears to be OK,

observe the Bank 1 HO2S 1 display on the Tech 2 while

moving connectors and wiring harnesses related to the

engine harness. A change in the display will indicate

the location of the fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the DTC to be set occurs. This

may assist in diagnosing the condition.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2.Diagnostic Trouble Codes other than P0172 may

indicate a condition present which may cause a lean

condition. If this is the case, repairing the condition

which caused the other DTC will most likely correct

the DTC P0172.

4.If the Diagnostic Trouble Code P0172 test passes

while the Failure Records conditions are being

duplicated, the rich condition is intermittent. Refer to

Diagnostic Aids or Symptoms for additional

information on diagnosing intermittent problems.

DTC P0172 – System Too Rich (Bank 1)

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Are any Diagnostic Trouble Codes set other than

P0172?

—

Go to the

applicable

DTC charts

and repair the

other DTCs

before

proceeding

with this

chart. Go to Step 3

31. Start the engine and operate the vehicle in ”Closed

Loop”.

2. Observe ”BANK 1 L.T. FUEL TRIM” display on the

Tech 2.

Are the displayed values more negative than the

specified values? L.T. Fuel

Trim: –14% Go to Step 5 Go to Step 4

41. Review and record the T ech 2 Failure Records data.

2. Clear the Diagnostic Trouble Code P0172 and

operate the vehicle to duplicate the Failure Records

conditions.

3. Monitor the Tech 2 “Diagnostic Trouble Code” info

for Diagnostic T rouble Code P0172 while operating

the vehicle to duplicate the Failure Records

conditions.

4. Continue operating the vehicle until the Diagnostic

T rouble Code P0172 test runs and note test result.

Does the Tech 2 indicate Diagnostic Trouble Code

P0172 failed this ignition? —Go to Step 5

The rich

condition is

not present. If

a driveability

symptom still

exists, refer

to Symptoms.

5Visually and physically inspect the air filter element and

replace it if necessary.

Did the air filter require replacement? — Verify repair Go to Step 6

6Visually and physically inspect the air intake duct for

collapse or restriction and repair if necessary.

Did your inspection reveal a condition requiring repair? —Verify repair Go to Step 7

7Start the engine and note the idle quality.

Is a low or unsteady idle being experienced? —Go to Step 8 Go to Step

8With the engine idling, observe the ”IDLE AIR

CONTROL” display on the Tech 2.

Is the ”IDLE AIR CONTROL” value below the specified

value? Below 100

counts Go to Step

10 Go to Step 9

91. Ignition OFF.

2. Physically inspect the throttle body bore, throttle

plate, and IAC passages for coking and foreign

objects.

3. If a problem was found, repair as necessary.

Did your inspection reveal a condition requiring repair? —Verify repair Go to Step

Step NoYesValue(s)Action

10 1. Perform the ”Idle Air Control (IAC) Valve Check.”

2. If a problem is found, repair as necessary.

Did the test isolate a problem requiring repair? — Verify repair Go to Step

11 1. Disconnect the vacuum hose from the fuel pressure

regulator and inspect the hose for the presence of

fuel.

2. If fuel is present in the vacuum hose, replace the

fuel pressure regulator (refer to Fuel Metering

System).

Did the fuel pressure regulator require replacement? — Verify repair Go to Step

12 Ignition ON engine OFF monitor the TP Angle display

on the Tech 2 while slowly depressing the accelerator

pedal.

Does the TP Angle display increase steadily and

evenly from minimum value at closed throttle to

maximum value at wide–open throttle?

Minimum 0%

Maximum

100% Go to Step

13 Go to Step

13 1. Perform the ”Fuel System Pressure Test.”

2. If the test isolates a problem, repair as necessary

(refer to Engine Fuel or Fuel Metering System).

Did the test isolate a problem requiring repair? — Verify repair Go to Step

14 1. Perform the ”Evaporative Emissions Control

(EVAP) Canister Purge Valve Check.”

2. If the test isolates a problem, repair as necessary.

Did the test isolate a problem requiring repair? — Verify repair Go to Step

15 1. Perform the ”Injector Balance Test.”

2. If the test isolates a problem, repair as necessary

(refer to Fuel Metering System).

Did the test isolate a problem requiring repair? — Verify repair Go to Step

16 1. Remove and visually/physically inspect the Bank 1

HO2S 1 for silicon contamination. This will be

indicated by a powdery white deposit on the portion

of the HO2S that is exposed to the exhaust stream.

2. If contamination is evident on the Bank 1 HO2S 1,

replace the contaminated sensors.

Did the sensor require replacement? — Verify repair

Refer to

Diagnostic

Aids

17 1. Check the TP sensor mounting screws and tighten

or replace them as necessary if they are loose or

missing.

2. If the screws are OK, replace the TP sensor.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0201 INJECTOR CIRCUIT

MALFUNCTION – CYLINDER 1

D06RX120

Circuit Description

The engine control module (ECM) has four individual

injector driver circuits. Each controls an injector. When a

driver circuit is grounded by the ECM, the injector is

activated. The ECM monitors the current in each driver

circuit. The ECM measures a voltage drop through a fixed

resistor and controls it. The voltage on each driver is

monitored to detect a fault. If the voltage is not what the

ECM expects to monitor on the circuit, a Diagnostic

Trouble Code is set. This Diagnostic Trouble Code is also

set if an injector driver is shorted to voltage. DTC P0201

is a type A code.

Conditions for Setting the DTC

DThe battery voltage is more than 9 volts.

DEngine is running.

DFuel pump is ON.

DThe injector voltage does not equal the ignition voltage

when the injector is commanded OFF or the injector

voltage does not equal 0 volts when the injector is

commanded ON.

DThe above conditions are met for 5 seconds.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

D”Open Loop” fuel control will be in effect.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn OFF the MIL on the third consecutive

trip cycle in which the diagnostic has been run and the

fault is no longer present.

DA history Diagnostic Trouble Code P0201 will clear

after 40 consecutive warm–up cycles occur without a

fault.

DDiagnostic Trouble Code P0201 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

An injector driver circuit that is open or shorted to voltage

will cause a Diagnostic T rouble Code P0201 to set. It will

also cause a misfire due to an inoperative injector. A

misfire Diagnostic Trouble Code will also be set indicating

which cylinder is inoperative.

Long term and short term fuel trims that are excessively

high or low are a good indication that an injector is faulty.

Use Fuel Injector Coil Test Procedure to check for faulty

injectors.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

3.This step determines if Diagnostic Trouble Code

P0201 is the result of a hard failure or an

intermittent condition.

5. This step tests the harness wiring and ECM control

of the injectors using a test light.

The fuel injector test connector is a gray 5 pin

connector at the right rear of the valve cover. It

can be identified by a blue connector lock which is

tethered to the harness.

5–8840–2606–0 is a test light with one light for

each cylinder. The test light fits on the injector test

connector.

If the test light is ON steady before cranking the

engine as well as while cranking the engine, then

the injector driver circuit is shorted to voltage.

If the test light blinks, the ECM and the wiring to

the injectors are OK. Fuel Injector Coil Test

Procedure will check if the injectors are faulty.

7. Because the test light was ON steady, voltage to the

injector is OK, but the driver circuit is grounded at all

times. This step determines if the circuit is shorted

to ground or the ECM is faulty.

901RX032

13. Normal injector resistance is slightly more than if

tested directly at the injector because it includes

resistance of the harness wires. The normal value is

about 13.5 W.

DTC P0201 – Injector Circuit Malfunction – Cylinder 1

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Will the engine start?

—Go to Step 3

Go to Engine

Cranks But

Will Not Run

Chart

31. Install the Tech 2. Clear the Diagnostic Trouble

Code.

2. Idle the engine for one minute.

Does Diagnostic Trouble Code P0201 reset? —Go to Step 5 Go to Step 4

41. Review the Freeze Frame data with the ignition ON

and the engine OFF and note the parameters.

2. Operate the vehicle within the Freeze Frame

conditions as noted.

Does P0201 reset? —Go to Step 5

Go to

Diagnostic

Aids

51. Ignition OFF.

2. Disconnect the injector test connector.

3. Install the injector test light 5–8840–2606–0 on the

injector test connector.

4. Crank the engine while observing the light for

cylinder 1.

Does the injector test light blink? —

Go to Fuel

Injector Coil

Test

Procedure Go to Step 6

Step NoYesValue(s)Action

6Note whether the injector test light was OFF or ON

steady in step 5.

Was the test light ON steady while cranking the

engine? —Go to Step 7 Go to Step

71. Disconnect the ECM connector for the affected

injectors.

2. With a test light connected to B+, probe the affected

injector driver circuit.

Does the test light illuminate? —Go to Step 8 Go to Step 9

8Repair short to ground in the injector driver circuit.

Is the action complete? —

Go to OBD

System

Check —

9Replace the ECM.

Is the action complete? —

Go to OBD

System

Check —

10 1. Disconnect the injector test connector.

2. Ignition ON.

3. Use a test light connected to ground to probe each

terminal on the ECM side of the injector test

connector. Only the Ign+ terminal should illuminate

the test light.

Besides the Ign+, did any other terminal illuminate the

test light? —Go to Step

11 Go to Step

11 Repair the short to voltage in the injector driver circuit. —Verify repair —

12 1. Disconnect the injector test connector.

2. Ignition ON.

3. Use a test light connected to ground to probe each

pin on the injector side of the connector.

Did any terminal illuminate the test light? —Go to Step

11 Go to Step

13 1. Disconnect the injector test connector.

2. Ignition OFF.

3. Clip one lead of an ohmmeter to the ignition pin on

the injector side of the test connector.

4. T ouch the other lead to each of the other four pins in

the test connector, one pin at a time.

Instead of normal injector resistance, did the ohmmeter

indicate an open in one of the injector circuits? —Go to Step

14 Go to Step

14 Repair the open circuit or open injector. — Verify repair —

15 Check for an open circuit between the injector test

connector and the ECM connector for the Injector 1

control circuit.

Was there an open circuit? —Go to Step

16 Go to Step 9

16 Repair the open circuit. — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0202 INJECTOR CIRCUIT

MALFUNCTION – CYLINDER 2

D06RX120

Circuit Description

The engine control module (ECM) has four individual

injector driver circuits. Each controls an injector. When a

driver circuit is grounded by the ECM, the injector is

activated. The ECM monitors the current in each driver

circuit. The ECM measures a voltage drop through a fixed

resistor and controls it. The voltage on each driver is

monitored to detect a fault. If the voltage is not what the

ECM expects to monitor on the circuit, a Diagnostic

Trouble Code is set. This Diagnostic Trouble Code is also

set if an injector driver is shorted to voltage. DTC P0202

is a type A code.

Conditions for Setting the DTC

DThe battery voltage is greater than 9 volts.

DEngine is running.

DFuel pump is ON.

DThe injector voltage does not equal the ignition voltage

when the injector is commanded OFF or the injector

voltage does not equal 0 volts when the injector is

commanded ON.

DThe above conditions are met for 5 seconds.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

D”Open Loop” fuel control will be in effect.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn OFF the MIL on the third consecutive

trip cycle in which the diagnostic has been run and the

fault is no longer present.

DA history Diagnostic Trouble Code P0202 will clear

after 40 consecutive warm–up cycles occur without a

fault.

DDiagnostic Trouble Code P0202 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

An injector driver circuit that is open or shorted to voltage

will cause a Diagnostic T rouble Code P0202 to set. It will

also cause a misfire due to an inoperative injector. A

misfire Diagnostic Trouble Code will also be set indicating

which cylinder is inoperative.

Long term and short term fuel trims that are excessively

high or low are a good indication that an injector is faulty.

Use Fuel Injector Coil Test Procedure to check for faulty

injectors.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

3.This step determines if Diagnostic Trouble Code

P0202 is the result of a hard failure or an

intermittent condition.

5.This step tests the harness wiring and ECM control

of the injectors using a test light.

The fuel injector test connector is a gray 5 pin

connector at the right rear of the valve cover. It

can be identified by a blue connector lock which is

tethered to the harness.

5–8840–2606–0 is a test light with one light for

each cylinder. The test light fits on the injector test

connector.

If the test light is ON steady before cranking the

engine as well as while cranking the engine, then

the injector driver circuit is shorted to voltage.

If the test light blinks, the ECM and the wiring to

the injectors are OK. Fuel Injector Coil Test

Procedure will check if the injectors are faulty.

7.Because the test light was ON steady, voltage to the

injector is OK, but the driver circuit is grounded at all

times. This step determines if the circuit is shorted

to ground or the ECM is faulty.

901RX033

13. Normal injector resistance is slightly more than if

tested directly at the injector because it includes

resistance of the harness wires. The normal value is

about 13.5 W.

DTC P0202 – Injector Circuit Malfunction – Cylinder 2

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Will the engine start?

—Go to Step 3

Go to Engine

Cranks But

Will Not Run

Chart

31. Install the Tech 2. Clear the Diagnostic Trouble

Code.

2. Idle the engine for one minute.

Does Diagnostic Trouble Code P0202 reset? —Go to Step 5 Go to Step 4

41. Review the Freeze Frame data with the ignition ON

and the engine OFF and note the parameters.

2. Operate the vehicle within the Freeze Frame

conditions as noted.

Does P0202 reset? —Go to Step 5

Go to

Diagnostic

Aids

51. Ignition OFF.

2. Disconnect the injector test connector.

3. Install the injector test light 5–8840–2606–0 on the

injector connector.

4. Crank the engine while observing the light for

cylinder 2.

Does the injector test light blink? —

Go to Fuel

Injector Coil

Test

Procedure Go to Step 6

Step NoYesValue(s)Action

6Note whether the injector test light was OFF or ON

steady in step 5.

Was the test light ON steady while cranking the

engine? —Go to Step 7 Go to Step

71. Disconnect the ECM connector for the affected

injectors.

2. With a test light connected to B+, probe the affected

injector driver circuit.

Does the test light illuminate? —Go to Step 8 Go to Step 9

8Repair short to ground in the injector driver circuit.

Is the action complete? —

Go to OBD

System

Check —

9Replace the ECM.

Is the action complete? —

Go to OBD

System

Check —

10 1. Disconnect the injector test connector.

2. Ignition ON.

3. Use a test light connected to ground to probe each

terminal on the ECM side of the injector test

connector. Only the Ign+ terminal should illuminate

the test light.

Besides the Ign+, did any other terminal illuminate the

test light? —Go to Step

11 Go to Step

11 Repair the short to voltage in the injector driver circuit. —Verify repair —

12 1. Disconnect the injector test connector.

2. Ignition ON.

3. Use a test light connected to ground to probe each

pin on the injector side of the connector.

Did any terminal illuminate the test light? —Go to Step

11 Go to Step

13 1. Disconnect the injector test connector.

2. Ignition OFF.

3. Clip one lead of an ohmmeter to the ignition pin on

the injector side of the test connector.

4. T ouch the other lead to each of the other four pins in

the test connector, one pin at a time.

Instead of normal injector resistance, did the ohmmeter

indicate an open in one of the injector circuits? —Go to Step

14 Go to Step

14 Repair the open circuit or open injector. — Verify repair —

15 Check for an open circuit between the injector test

connector and the ECM connector for the Injector 2

control circuit.

Was there an open circuit? —Go to Step

16 Go to Step 9

16 Repair the open circuit. — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0203 INJECTOR CIRCUIT

MALFUNCTION – CYLINDER 3

D06RX120

Circuit Description

The engine control module (ECM) has four individual

injector driver circuits. Each controls an injector. When

the driver circuit is grounded by the ECM, the injector is

activated. The ECM monitors the current in each driver

circuit. The ECM measures a voltage drop through a fixed

resistor and controls it. The voltage on each driver is

monitored to detect a fault. If the voltage is not what the

ECM expects to monitor on the circuit, a Diagnostic

Trouble Code is set. This Diagnostic Trouble Code is also

set if an injector driver is shorted to voltage. DTC P0203

is a type A code.

Conditions for Setting the DTC

DThe battery voltage is greater than 9 volts.

DEngine is running.

DFuel pump is ON.

DThe injector voltage does not equal the ignition voltage

when the injector is commanded OFF or the injector

voltage does not equal 0 volts when the injector is

commanded ON.

DThe above conditions are met for 5 seconds.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

D”Open Loop” fuel control will be in effect.

DThe ECM will store conditions which were present

when the DTC was setas Freeze Frame and in the

Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn OFF the MIL on the third consecutive

trip cycle in which the diagnostic has been run and the

fault is no longer present.

DA history Diagnostic Trouble Code P0203 will clear

after 40 consecutive warm–up cycles occur without a

fault.

DDiagnostic Trouble Code P0203 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

An injector driver circuit that is open or shorted to voltage

will cause a Diagnostic T rouble Code P0203 to set. It will

also cause a misfire due to an inoperative injector. A

misfire Diagnostic Trouble Code will also be set indicating

which cylinder is inoperative.

Long term and short term fuel trims that are excessively

high or low are a good indication that an injector is faulty.

Use Fuel Injector Coil Test Procedure to check for faulty

injectors.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

3.This step determines if Diagnostic Trouble Code

P0203 is the result of a hard failure or an

intermittent condition.

5.This step tests the harness wiring and ECM control

of the injectors using a test light.

The fuel injector test connector is a gray 5 pin

connector at the right rear of the valve cover. It

can be identified by a blue connector lock which is

tethered to the harness.

5–8840–2606–0 is a test light with one light for

each cylinder. The test light fits on the injector test

connector.

If the test light is ON steady before cranking the

engine as well as while cranking the engine, then

the injector driver circuit is shorted to voltage.

If the test light blinks, the ECM and the wiring to

the injectors are OK. Fuel Injector Coil Test

Procedure will check if the injectors are faulty.

7.Because the test light was ON steady, voltage to the

injector is OK, but the driver circuit is grounded at all

times. This step determines if the circuit is shorted

to ground or the ECM is faulty.

901RX034

13. Normal injector resistance is slightly more than if

tested directly at the injector because it includes

resistance of the harness wires. The normal value is

about 13.5 W.

DTC P0203 – Injector Circuit Malfunction – Cylinder 3

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Will the engine start?

—Go to Step 3

Go to Engine

Cranks But

Will Not Run

Chart

31. Install the Tech 2. Clear the Diagnostic Trouble

Code.

2. Idle the engine for one minute.

Does Diagnostic Trouble Code P0203 reset? —Go to Step 5 Go to Step 4

41. Review the Freeze Frame data with the ignition ON

and the engine OFF and note the parameters.

2. Operate the vehicle within the Freeze Frame

conditions as noted.

Does P0203 reset? —Go to Step 5

Go to

Diagnostic

Aids

51. Ignition OFF.

2. Disconnect the injector test connector.

3. Install the injector test light 5–8840–2606–0 on the

injector connector.

4. Crank the engine while observing the light for

cylinder 3.

Does the injector test light blink? —

Go to Fuel

Injector Coil

Test

Procedure Go to Step 6

Step NoYesValue(s)Action

6Note whether the injector test light was OFF or ON

steady in step 5.

Was the test light ON steady while cranking the

engine? —Go to Step 7 Go to Step

71. Disconnect the ECM connector for the affected

injectors.

2. With a test light connected to B+, probe the affected

injector driver circuit.

Does the test light illuminate? —Go to Step 8 Go to Step 9

8Repair short to ground in the injector driver circuit.

Is the action complete? —

Go to OBD

System

Check —

9Replace the ECM.

Is the action complete? —

Go to OBD

System

Check —

10 1. Disconnect the injector test connector.

2. Ignition ON.

3. Use a test light connected to ground to probe each

terminal on the ECM side of the injector test

connector. Only the Ign+ terminal should illuminate

the test light.

Besides the Ign+, did any other terminal illuminate the

test light? —Go to Step

11 Go to Step

11 Repair the short to voltage in the injector driver circuit. —Verify repair —

12 1. Disconnect the injector test connector.

2. Ignition ON.

3. Use a test light connected to ground to probe each

pin on the injector side of the connector.

Did any terminal illuminate the test light? —Go to Step

11 Go to Step

13 1. Disconnect the injector test connector.

2. Ignition OFF.

3. Clip one lead of an ohmmeter to the ignition pin on

the injector side of the test connector.

4. T ouch the other lead to each of the other four pins in

the test connector, one pin at a time.

Instead of normal injector resistance, did the ohmmeter

indicate an open in one of the injector circuits? —Go to Step

14 Go to Step

14 Repair the open circuit or open injector. — Verify repair —

15 Check for an open circuit between the injector test

connector and the ECM connector for the Injector 3

control circuit.

Was there an open circuit? —Go to Step

16 Go to Step 9

16 Repair the open circuit. — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0204 INJECTOR CIRCUIT

MALFUNCTION – CYLINDER 4

D06RX120

Circuit Description

The engine control module (ECM) has four individual

injector driver circuits. Each controls an injector. When

the driver circuit is grounded by the ECM, the injector is

activated. The ECM monitors the current in each driver

circuit. The ECM measures a voltage drop through a fixed

resistor and controls it. The voltage on each driver is

monitored to detect a fault. If the voltage is not what the

ECM expects to monitor on the circuit, a Diagnostic

Trouble Code is set. This Diagnostic Trouble Code is also

set if an injector driver is shorted to voltage. DTC P0204 is

a type A code.

Conditions for Setting the DTC

DThe battery voltage is greater than 9 volts.

DEngine is running.

DFuel pump is ON.

DThe injector voltage does not equal the ignition voltage

when the injector is commanded OFF or the injector

voltage does not equal 0 volts when the injector is

commanded ON.

DThe above conditions are met for 5 seconds.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

D”Open Loop” fuel control will be in effect.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn OFF the MIL on the third consecutive

trip cycle in which the diagnostic has been run and the

fault is no longer present.

DA history Diagnostic Trouble Code P0204 will clear

after 40 consecutive warm–up cycles occur without a

fault.

DDiagnostic Trouble Code P0204 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

An injector driver circuit that is open or shorted to voltage

will cause a Diagnostic T rouble Code P0204 to set. It will

also cause a misfire due to an inoperative injector. A

misfire Diagnostic Trouble Code will also be set indicating

which cylinder is inoperative.

Long term and short term fuel trims that are excessively

high or low are a good indication that an injector is faulty.

Use Fuel Injector Coil Test Procedure to check for faulty

injectors.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

3.This step determines if Diagnostic Trouble Code

P0204 is the result of a hard failure or an

intermittent condition.

5.This step tests the harness wiring and ECM control

of the injectors using a test light.

The fuel injector test connector is a gray 5 pin

connector at the right rear of the valve cover. It

can be identified by a blue connector lock which is

tethered to the harness.

5–8840–2606–0 is a test light with one light for

each cylinder. The test light fits on the injector test

connector.

If the test light is ON steady before cranking the

engine as well as while cranking the engine, then

the injector driver circuit is shorted to voltage.

If the test light blinks, the ECM and the wiring to

the injectors are OK. Fuel Injector Coil Test

Procedure will check if the injectors are faulty.

7. Because the test light was ON steady, voltage to the

injector is OK, but the driver circuit is grounded at all

times. This step determines if the circuit is shorted

to ground or the ECM is faulty.

901RX035

13. Normal injector resistance is slightly more than if

tested directly at the injector because it includes

resistance of the harness wires. The normal value is

about 13.5 W.

DTC P0204 – Injector Circuit Malfunction – Cylinder 4

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Will the engine start?

—Go to Step 3

Go to Engine

Cranks But

Will Not Run

Chart

31. Install the Tech 2. Clear the DTC.

2. Idle the engine for one minute.

Does DTC P0204 reset? —Go to Step 5 Go to Step 4

41. Review the Freeze Frame data with the ignition ON

and the engine OFF and note the parameters.

2. Operate the vehicle within the Freeze Frame

conditions as noted.

Does P0204 reset? —Go to Step 5

Go to

Diagnostic

Aids

51. Ignition OFF.

2. Disconnect the injector test connector.

3. Install the injector test light 5–8840–2606–0 on the

injector connector.

4. Crank the engine while observing the light for

cylinder 4.

Does the injector test light blink? —

Go to Fuel

Injector Coil

Test

Procedure Go to Step 6

6Note whether the injector test light was OFF or ON

steady in step 5.

Was the test light ON steady while cranking the

engine? —Go to Step 7 Go to Step

Step NoYesValue(s)Action

71. Disconnect the ECM connector for the affected

injectors.

2. With a test light connected to B+, probe the affected

injector driver circuit.

Does the test light illuminate? —Go to Step 8 Go to Step 9

8Repair short to ground in the injector driver circuit.

Is the action complete? —

Go to OBD

System

Check —

9Replace the ECM.

Is the action complete? —

Go to OBD

System

Check —

10 1. Disconnect the injector test connector.

2. Ignition ON.

3. Use a test light connected to ground to probe each

terminal on the ECM side of the injector test

connector. Only the Ign+ terminal should illuminate

the test light.

Besides the Ign+, did any other terminal illuminate the

test light? —Go to Step

11 Go to Step

11 Repair the short to voltage in the injector driver circuit. —Verify repair —

12 1. Disconnect the injector test connector.

2. Ignition ON.

3. Use a test light connected to ground to probe each

pin on the injector side of the connector.

Did any terminal illuminate the test light? —Go to Step

11 Go to Step

13 1. Disconnect the injector test connector.

2. Ignition OFF.

3. Clip one lead of an ohmmeter to the ignition pin on

the injector side of the test connector.

4. T ouch the other lead to each of the other four pins in

the test connector, one pin at a time.

Instead of normal injector resistance, did the ohmmeter

indicate an open in one of the injector circuits? —Go to Step

14 Go to Step

14 Repair the open circuit or open injector. — Verify repair —

15 Check for an open circuit between the injector test

connector and the ECM connector for the Injector 3

control circuit.

Was there an open circuit? —Go to Step

16 Go to Step 9

16 Repair the open circuit. — — Verify repair

DIAGNOSTIC TROUBLE CODE (DTC) P0325 KNOCK SENSOR (KS) CIRCUIT

MALFUNCTION

D06RX121

Circuit Description

The knock sensor (KS) system is used to detect engine

detonation. The knock sensor produced an AC voltage

signal. The knock sensor sends this signal to the ECM.

The amplitude and the frequency of the AC voltage signal

depends upon the knock level being detected. The ECM

will then retard the spark timing based on the signals from

the Knock Sensor. DTC P0325 is a type B code.

Conditions for Setting the DTC

DEngine run time is greater than 10 seconds.

DNo P0327 Diagnostic Trouble Code set.

DEngine speed is above 2500 rpm.

All the above mentioned conditions are met, and the

following conditions are met for 8.75 seconds within a 10

second monitoring period:

DAny of the four A/D voltages exceeds 1.5625 Volts.

DInstantaneous A/D delta Voltage falls below 0.019531

Volts.

Action Taken When the DTC Sets

DThe Malfunction Indicator Lamp (MIL) will illuminate

the second time the fault is detected.

DThe ECM will record operating conditions at the time

the diagnostic fails.

DA history Diagnostic Trouble Code is stored.

DThe ECM will use a calculated spark retard value in

order to minimize the knock during the conditions when

the knock is likely to occur. The calculated value will

vary based on the engine speed and load.

Conditions for Clearing the MIL/DTC

DThe MIL will turn off after 3 consecutive ignition cycles

in which the diagnostic runs without a fault.

DA history Diagnostic Trouble Code will clear after 40

consecutive warm up cycles without a fault.

DA Tech 2 can clear the Diagnostic Trouble Codes.

Diagnostic Aids

Correct any abnormal engine noise before using the

diagnostic table.

Check for an open ignition feed circuit.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

1. The Powertrain OBD System Check prompts the

technician to complete some basic checks and store

the freeze frame data and failure records data on

the Tech 2 if applicable. This creates an electronic

copy of the data taken when the malfunction

occurred. The information is then stored on the

Tech 2 for later reference.

2. If the conditions for the test as described above are

met, a Diagnostic Trouble Code P0325 will set and

MIL will illuminate.

4. If the engine has an internal knock or audible noise

that causes a knocking type noise on the engine

block, the knock sensor may be responding to the

noise.

6. The Tech 2 displays knock sensor activity in counts,

approximately 20–50 at idle. The counts should

increase when engine speed is increased and the

counts should decrease when engine speed is

decreased.

7. Any circuitry, that is suspected as causing the

complaint, should be thoroughly checked for backed

out terminals, improper mating, broken locks,

improperly formed or damaged terminals, poor

terminal to wiring connections or physical damage

to the wiring harness.

8. If the KS module was previously replaced and the

Diagnostic Trouble Code resets, a malfunctioning

ECM is indicated.

9. Checking the internal resistance of the knock sensor

verifies if the knock sensor or the wiring to the

knock sensor is OK.

DTC P0325 KS Circuit Malfunction

Step Action Value(s) YesNo

1Was the Powertrain ”On–Board Diagnostic (OBD)

System Check” performed?

——Go to Step 2

Go to

Powertrain

OBD System

Check

21. Start the engine.

2. Install a Tech 2.

3. Clear the Diagnostic Trouble Codes.

4. Run the engine at slightly more than 10% throttle

angle.

Does the Malfunction Indicator Lamp (MIL) illuminate? —Go to Step 4 Go to Step 3

31. Turn the ignition switch ON, with engine OFF.

2. Review the Freeze Frame data and note the

parameters.

3. Operate the vehicle within the Conditions and

Conditions for Setting the DTC as noted.

Does the Malfunction Indicator Lamp (MIL) illuminate? —Go to Step 4 Go to Step

4Listen to the engine while raising and lowering the

engine speed.

Is a knock or audible noise present? —Go to Step 5 Go to Step 6

5Repair the mechanical engine problem or a loose

bracket or component.

Is the action complete? —Go to Step

13 —

6Slowly increase the engine speed to the specified

value.

Does the KS Activity increase with the engine speed? 2500 RPM Go to Step 7 Go to Step

7Check for a poor connection at the ECM connector,

Knock sensor signal circuit and repair as necessary.

Was a repair necessary? —Go to Step

13 Go to Step 8

8Replace the ECM.

Is the action complete? —Go to Step

13 —

91. Turn the ignition switch OFF.

2. Disconnect the ECM connectors at the ECM.

3. With a Digital Voltmeter (DVM) connected to

ground, measure the resistance of the knock

sensor through the knock sensor signal circuit.

Is the measured value within the specified value? 90K – 110K WGo to Step 7 Go to Step

Step NoYesValue(s)Action

10 Check the knock sensor electrical connector for a poor

connection and repair as necessary.

Was a repair necessary? —Go to Step

13 Go to Step

11 Check the knock sensor signal circuit for an open or a

short to ground or to voltage and repair as necessary.

Was a repair necessary? —Go to Step

13 Go to Step

12 Replace the Knock Sensor (KS).

Is the action complete? —Go to Step

13 —

13 1. Using the Tech 2, clear the Diagnostic Trouble

Codes.

2. Start the engine and idle at normal operating

temperature.

3. Operate the vehicle within the conditions for setting

this Diagnostic Trouble Code as specified in the

supporting text.

Does the Tech 2 indicate that this diagnostic has ran

and passed? —Go to Step

14 Go to Step 2

14 Check is any additional Diagnostic T rouble Codes are

set.

Are any Diagnostic T rouble Codes displayed that have

not been diagnosed? —

Go to

applicable

DTC table System OK

DIAGNOSTIC TROUBLE CODE (DTC) P0327 KNOCK SENSOR (KS) CIRCUIT

LOW INPUT

D06RX121

Circuit Description

The ECM uses the Knock Sensor (KS) in order to detect

engine detonation. This allows the ECM to retard the

Ignition Control (IC) spark timing based on the KS signal

the ECM receives. The circuitry within the knock sensor

pulls down the ECM–supplied 5 volt signal, so that under

a no knock condition the signal on the KS circuit

measures about 1.3 volts. The knock sensors produce an

AC signal that rides on the 1.3 volts DC. The signal’s

amplitude and frequency are dependent upon the amount

of the knock being experienced.

The ECM determines whether the knock is occurring by

comparing the signal level on the KS circuit with a voltage

level on the noise channel. The noise channel allows the

CM to reject any false knock signal by indicating the

amount of normal engine mechanical noise present. The

normal engine noise varies depending on the engine

speed and load. Then the ECM determines that an

abnormally high noise channel voltage level is being

experienced, a Diagnostic Trouble Code P0327 sets.

This DTC is a type B DTC.

Conditions for Setting the DTC

A/D Test

The following conditions are met for 7.5 seconds within a

10 second monitoring period:

DEngine speed is equal to or greater than 2000 RPM.

DA/D Voltage is less than or equal to 0.0977 Volts.

Gain Test

The following conditions are met for 7.5 seconds within a

10 second monitoring period:

DEngine speed is greater than 2500 RPM.

DGain is equal to or greater than 23.875 dB.

Action Taken When the DTC Sets

DThe ECM will illuminate the MIL the second time the

fault is detected.

DThe ECM will store the conditions which were present

then the Diagnostic Trouble Code set.

DThe ECM will use a calculated spark retard value in

order to minimize the knock during the conditions when

the knock is likely to occur. The calculated value will

vary based on the engine speed and load.

Conditions for Clearing the MIL/DTC

DA history Diagnostic Trouble Code will clear after 40

consecutive warm–up cycles have occurred without a

fault.

DThe T ech 2 ”Clear Info” will clear the Diagnostic Trouble

Code.

Diagnostic Aids

Check for the following conditions:

A poor connection at the ECM. Inspect the knock sensor

and the ECM connectors for: , broken locks, improperly

formed or damaged terminals.

DBacked out terminals

DBroken locks

DImproperly formed or damaged terminals

Also, check the wiring harness for: shorts to ground,

shorts to battery positive, and open circuits.

DA misrouted harness. Inspect the knock sensor

harness in order to ensure that it is not routed too close

to high voltage wires such as spark plug leads.

DImproper Knock Sensor torque specification. Torque

the Knock Sensor to 19N·m (1.9kg·m/14 lbs·ft). Refer

to Fastener Notice.

Review the Fail Records vehicle mileage since the

diagnostic test last failed in order to help determine how

often the conditions that caused the DTC to set occur.

This may assist in diagnosing the condition.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2. Ensures that the fault is present.

6. Ensures that the knock sensor is capable of

detecting detonation.

DTC P0327 KS Circuit Low Input

Step Action Value(s) YesNo

1Was the Powertrain ”On–Board Diagnostic (OBD)

System Check” performed?

—Go to Step 2

Go to

Powertrain

OBD System

Check

21.Operate the engine within the conditions specified

in the diagnostic support Conditions for Setting the

DTC.

2.Using a Tech 2, monitor theDiagnostic Trouble

Code information for Diagnostic Trouble Code

P0327 until the Diagnostic Trouble Code P0327 test

runs.

3.Observe the test results.

Does the Tech 2 indicate the DTC P0327 failed this

ignition? —Go to Step 4 Go to Step 3

31.Turn ON the Ignition leaving the engine OFF.

2.Review the Tech 2 Fail Records data.

IMPORTANT:Before clearing the DTCs, use the Tech

2 to record the Freeze Frame and the Failure Records

for reference. This data will be lost when the Clear Info

function is used.

4. Record the Tech 2 Fail Records data.

5. Operate the vehicle within the Fail Records

conditions.

6. Using a Tech 2, monitor the DTC info for the DTC

P0327 until the DTC P0327 test runs.

7. Observe the test results.

Does the Tech 2 indicate the DTC P0327 Failed This

Ignition? —Go to Step 4

Go to

Diagnostic

Aids

41. Disconnect the KS Sensor electrical connector.

2. Using a Digital Voltmeter (DVM), measure the

voltage between the KS signal circuit at the knock

sensor harness connectors and ground.

Is the voltage at the specified value? Approx. 5.0 V Go to Step 5 Go to Step 8

5Measure the resistance of the KS sensor by connecting

the between the KS sensor terminal and the engine

block.

Is the resistance of the KS sensor near the specified

value? 100K WGo to Step 6 Go to Step 9

Step NoYesValue(s)Action

61. Check the KS signal circuit for a poor terminal

connection at the knock sensor.

2. If a problem is found, repair as necessary. Refer to

Wiring Repairs in Engine Electrical.

Was a problem found? —Go to Step 7 Go to Step 9

71. Re–Connect the KS Sensor in order to monitor the

voltage between the KS sensor terminal and the

engine ground.

2. Tap on the engine lift bracket, near the KS Sensor,

while observing the signal indicated on the Tech 2.

Is any signal indicated on the while tapping on the

engine lift bracket? —Go to Step

11 Go to Step 8

81. Turn OFF the ignition.

2. Disconnect the ECM.

3. Turn ON the ignition.

4. Check the KS signal circuit between the ECM and

the KS sensor connector for an open, a short to

voltage, or a short to ground.

5. If a wiring problem is found, repair as necessary.

Was a problem found? —Go to Step

11 Go to Step

9Replace the KS Sensor. Refer to Knock Sensor.

Is the action complete? —Go to Step

11 —

10 Replace the ECM.

Is the action complete? —Go to Step

11 —

11 1. Using the T ech 2, select the DTC and the Clear Info.

2. Start the engine.

3. Idle at the normal operating temperature.

4. Select the DTC and the Specific.

5. Enter the DTC number which was set.

6. Operate the vehicle within the conditions for setting

this DTC as specified in the supporting text.

Does the Tech 2 indicate that this diagnostic ran and

passed? —Go to Step

12 Go to Step 2

12 Using the Tech 2, select the Capture Info and the

Review Info.

Are any DTCs displayed that have not been

diagnosed? —

Go to

applicable

DTC table System OK

DIAGNOSTIC TROUBLE CODE (DTC) P0336 CRANKSHAFT POSITION (CKP)

SENSOR CIRCUIT RANGE/PERFORMANCE

D06RX122

Circuit Description

The 58X reference signal is produced by the crankshaft

position (CKP) sensor . During one crankshaft revolution,

58 crankshaft pulses will be produced. The engine control

module (ECM) uses the 58X reference signal to calculate

engine RPM and crankshaft position. The ECM

constantly monitors the number of pulses on the 58X

reference circuit and compares them to the number of

camshaft position (CMP) signal pulses being received. If

the ECM receives an incorrect number of pulses on the

58X reference circuit, Diagnostic Trouble Code P0336 will

set. Diagnostic Trouble Code P0336 is a type B code.

Conditions for Setting the DTC

DEngine is running.

DExtra or missing pulse is detected between

consecutive 58X reference pulses.

DAbove condition is detected in 10 of 100 crankshaft

rotations.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0336 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0336 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

An intermittent may be caused by a poor connection,

rubbed–through wire insulation or a wire broken inside the

insulation. Check for:

DPoor connection – Inspect the ECM harness and

connectors for improper mating, broken locks,

improperly formed or damaged terminals, and poor

terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive

and open circuits. If the harness appears to be OK,

disconnect the ECM, turn the ignition on and observe

a voltmeter connected to the 58X reference circuit at

the ECM harness connector while moving connectors

and wiring harnesses related to the ECM. A change in

voltage will indicate the location of the fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic T rouble Code to

be set occurs. This may assist in diagnosing the

condition.

DTC P0336 – CKP Sensor Circuit Range/Performance

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Attempt to start the engine.

Does the engine start?

—Go to Step 3

Refer to

Engine

Cranks But

Will Not Run

chart

31. Review and record Failure Records information.

2. Clear Diagnostic Trouble Code P0336.

3. Start the engine and idle for 1 minute.

4. Observe Diagnostic Trouble Codes.

Is Diagnostic Trouble Code P0336 set? —Go to Step 4

Refer to

Diagnostic

Aids

41. Disconnect the ECM and CKP sensor.

2. Check for an open or a short to ground in the 58X

reference circuit between the CKP sensor

connector and the ECM harness connector.

3. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 5

51. Reconnect the ECM and CKP sensor.

2. Connect a Digital Voltmeter (DVM) to measure

voltage on the 58X reference circuit at the ECM

connector.

3. Observe the voltage while cranking the engine.

Is the voltage near the specified value? 2.5 V Go to Step 8 Go to Step 6

6Check the connections at the CKP sensor and replace

the terminals if necessary.

Did any terminals require replacement? — Verify repair Go to Step 7

7Replace the CKP sensor.

Is the action complete? — Verify repair —

8Check connections at the ECM and replace the

terminals if necessary.

Did any terminals require replacement? — Verify repair Go to Step 9

9Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0337 CRANKSHAFT POSITION (CKP)

SENSOR CIRCUIT LOW INPUT

D06RX122

Circuit Description

The 58X reference signal is produced by the crankshaft

position (CKP) sensor . During one crankshaft revolution,

58 crankshaft reference pulses will be produced. The

engine control module (ECM) uses the 58X reference

signal to calculate engine RPM and crankshaft position.

The ECM constantly monitors the number of pulses on

the 58X reference circuit and compares them to the

number of camshaft position (CMP) signal pulses being

received. If the ECM does not receive pulses on the 58X

reference circuit, Diagnostic Trouble Code P0337 will set.

Diagnostic Trouble Code P0337 is a type B code.

Conditions for Setting the DTC

DNo camshaft position (CMP) sensor DTCs are set.

DEngine cranking.

DCrankshaft position (CKP) sensor signal is not present

between two cam pulses.

DCKP reference pulse is not detected within 24 CMP

pulses.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0337 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0337 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

An intermittent may be caused by a poor connection,

rubbed–through wire insulation or a wire broken inside the

insulation. Check for:

DPoor connection – Inspect the ECM harness and

connectors for improper mating, broken locks,

improperly formed or damaged terminals, and poor

terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive

and open circuits. If the harness appears to be OK,

disconnect the ECM, turn the ignition on and observe

a voltmeter connected to the 58X reference circuit at

the ECM harness connector while moving connectors

and wiring harnesses related to the ECM. A change in

voltage will indicate the location of the fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic T rouble Code to

be set occurs. This may assist in diagnosing the

condition.

DTC P0337 – CKP Sensor Circuit Low Input

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Disconnect the CKP sensor.

2. Ignition ON.

3. Using a Digital Voltmeter (DVM), verify that 5 V

reference and ground are being supplied at the

sensor connector (ECM side).

Are 5 V and ground being supplied to the sensor? —Go to Step 5 Go to Step 3

31. Ignition ON.

2. With a DVM, backprobe the ECM connector 5 V

reference and ground connections.

Are 5 V reference and ground available at the ECM? —Go to Step 4 Go to Step 9

4Check 5 V reference or ground between the CKP

sensor and ECM and repair the open circuit, short to

ground or short to voltage.

Is the action complete? — Verify repair —

51. Ignition OFF.

2. Disconnect the ECM and CKP sensor.

3. Check for an open or a short to ground in the 58X

reference circuit between the CKP sensor

connector and the ECM harness connector.

4. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 6

61. Reconnect the ECM and CKP sensor.

2. Connect a DVM to measure voltage on the 58X

reference circuit at the ECM connector.

3. Observe the voltage while cranking the engine.

Is the voltage near the specified value? 2.5 V Go to Step 9 Go to Step 7

7Check the connections at the CKP sensor and replace

the terminals if necessary.

Did any terminals require replacement? — Verify repair Go to Step 8

8Replace the CKP sensor.

Is the action complete? — Verify repair —

9Check the connections at the ECM and replace the

terminals if necessary.

Did any terminals require replacement? — Verify repair Go to Step

10 Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0341 CAMSHAFT POSITION (CMP)

SENSOR CIRCUIT RANGE/PERFORMANCE

D06RX123

Circuit Description

The camshaft position (CMP) sensor signal is produced

by the CMP sensor pulses when the engine is running and

crankshaft position (CKP) sync pulses are also being

received. The engine control module (ECM) uses the

CMP signal pulses to initiate sequential fuel injection. The

ECM constantly monitors the number of pulses on the

CMP signal circuit and compares the number of CMP

pulses to the number of 58X reference pulses received. If

the ECM receives an incorrect number of pulses on the

CMP reference circuit, Diagnostic Trouble Code P0341

will set and the ECM will initiate injector sequence without

the CMP signal with a one in four chance that injector

sequence is correct. The engine will continue to start and

run normally, although the misfire diagnostic will be

affected if a misfiring condition occurs. DTC P0341 is a

type B code.

Conditions for Setting the DTC

DThe engine is running (CMP reference pulses are

being received).

DAbove condition fails for 10 occurrences within 100 test

samples (15.6 m/s).

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe ECM will initiate injector sequence without the

CMP signal with a one in four chance that injector

sequence is correct.

DThe ECM will store conditions which were present

when the Diagnostic Trouble Code (DTC) was set as

Freeze Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code (DTC) P0341 will

clear after 40 consecutive warm–up cycles have

occurred without a fault.

DDiagnostic T rouble Code (DTC) P0341 can be cleared

by using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

DIf a CKP Diagnostic Trouble Code (DTC) is also

indicated, there may be a problem with the ground

circuit because the CMP ground is spliced to the CKP

ground wire.

DIf a fuel injector Diagnostic T rouble Code (DTC) is also

indicated, there may be a problem with the power

supply to the CMP. The wire supplying CMP power is

spliced to the wire supplying power to the fuel injectors.

An intermittent may be caused by a poor connection,

rubbed–through wire insulation or a wire broken inside the

insulation. Check for the following conditions:

DPoor connection – Inspect the ECM harness and

connectors for improper mating, broken locks,

improperly formed or damaged terminals, and poor

terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive

and open circuits. If the harness appears to be OK,

disconnect the ECM, turn the ignition ON and observe

a voltmeter connected to the CMP signal circuit at the

ECM harness connector while moving connectors and

wiring harnesses related to the CMP sensor. A change

in voltage will indicate the location of the fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic Trouble Code

(DTC) to be set occurs. This may assist in diagnosing the

condition.

DTC P0341 – CMP Sensor Circuit Range/Performance

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON.

2. Review and record Tech 2 Failure Records data.

3. Operate the vehicle within the Failure Records

conditions as noted.

4. Using a Tech 2, monitor ”DTC” information for DTC

P0341 until the DTC P0341 test runs.

Does the T ech 2 indicate DTC P0341 failed this ignition

cycle? —Go to Step 3

Refer to

Diagnostic

Aids

31. Monitor voltage on the CMP signal circuit while

cranking the engine.

Does the voltage toggle between the specified values? 0–4 V Go to Step 4 Go to Step 7

4Check for a poor connection of the CMP signal wire at

the ECM terminal.

Was a poor connection found? —Go to Step 5 Go to Step 6

5Repair the damaged pin or terminal at the ECM. — Verify repair —

6Replace the ECM

Is the repair complete? — — Verify repair

71. Disconnect the CMP connector from the CMP

Sensor.

2. Ignition ON.

3. At the CMP connector, use a Digital Voltmeter

(DVM) to check the voltage between the voltage

signal wire and sensor ground.

Does the DVM indicate the specified value? B+ Go to Step

12 Go to Step 8

81. Ignition ON.

2. Use a DVM to measure between the ground and the

CMP positive connector.

Does the DVM indicate the specified value? B+ Go to Step

10 Go to Step 9

9Repair the open circuit.

Is the repair complete? — Verify repair —

10 1. Ignition ON.

2. Use a DVM to measure at the CMP connector

between the battery + and the CMP ground wire.

Does the DVM indicate the specified value? B+ Go to Step

12 Go to Step

11 Repair the open ground wire.

Is the repair complete? — Verify repair —

Step NoYesValue(s)Action

12 Use an ohmmeter to check continuity of the signal wire

between the CMP and the ECM.

Was there an open circuit? —Go to Step

13 Go to Step

13 Repair the open signal wire.

Is the action complete? — Verify repair —

14 1. Ignition ON.

2. Check the signal wire for a short to ground or a short

to voltage.

Was a problem found? —Go to Step

15 Go to Step

15 Repair the signal circuit problem.

Is the action complete? — Verify repair —

16 Replace the CMP Sensor.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0342 CAMSHAFT POSITION (CMP)

SENSOR CIRCUIT LOW INPUT

D06RX123

Circuit Description

The camshaft position (CMP) sensor signal is produced

by the CMP sensor pulses when the engine is running and

crankshaft position (CKP) sync pulses are also being

received. The ECM uses the CMP signal pulses to initiate

sequential fuel injection. The ECM constantly monitors

the number of pulses on the CMP signal circuit and

compares the number of CMP pulses to the number of

58X reference pulses received. If the ECM does not

receive pulses on the CMP reference circuit, Diagnostic

Trouble Code (DTC) P0342 will set and the ECM will

initiate injector sequence without the CMP signal with a

one in four chance that injector sequence is correct. The

engine will continue to start and run normally, although

the misfire diagnostic will be affected if a misfiring

condition occurs. Diagnostic Trouble Code (DTC) P0342

is a type B code.

Conditions for Setting the DTC

DThe engine is running.

DThe CMP sensor signal is not received by the ECM

once every 4 cylinders.

DThe above condition occurs for 10 seconds.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe ECM will initiate injector sequence without the

CMP signal with a one in four chance that injector

sequence is correct.

DThe ECM will store conditions which were present

when the Diagnostic Trouble Code (DTC) was set as

Freeze Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code (DTC) P0342 will

clear after 40 consecutive warm–up cycles have

occurred without a fault.

DDiagnostic T rouble Code (DTC) P0342 can be cleared

by using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

DIf a CKP Diagnostic Trouble Code (DTC) is also

indicated, there may be a problem with the ground

circuit because the CMP ground is spliced to the CKP

ground wire.

DIf a fuel injector Diagnostic T rouble Code (DTC) is also

indicated, there may be a problem with the power

supply to the CMP. The wire supplying CMP power is

spliced to the wire supplying power to the fuel injectors.

An intermittent may be caused by a poor connection,

rubbed–through wire insulation or a wire broken inside the

insulation. Check for the following:

DPoor connection – Inspect the ECM harness and

connectors for improper mating, broken locks,

improperly formed or damaged terminals, and poor

terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive

and open circuits. If the harness appears to be OK,

disconnect the ECM, turn the ignition ON and observe

a voltmeter connected to the CMP signal circuit at the

ECM harness connector while moving connectors and

wiring harnesses related to the CMP sensor. A change

in voltage will indicate the location of the fault.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

2.Ensures that the fault is present.

DTC P0342 – Camshaft Position Sensor Circuit Low Input

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON.

2. Review and record Tech 2 Failure Records data.

3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor ”DTC” information for DTC

P0342 until the DTC P0342 test runs.

Did the Tech 2 indicate DTC P0342 failed this ignition

cycle? —Go to Step 3

Refer to

Diagnostic

Aids

31. Use a Digital Voltmeter (DVM) to monitor voltage on

the CMP signal circuit while cranking the engine.

Does the voltage toggle between the specified values? 0–4 V Go to Step 4 Go to Step 7

4Check for a poor connection of the CMP signal wire at

the ECM terminal.

Was a poor connection found? —Go to Step 5 Go to Step 6

5Repair the damaged pin or terminal at the ECM. — Verify repair —

6Replace the ECM.

Is the repair complete? — Verify repair —

71. Disconnect the CMP connector from the CMP

Sensor.

2. Ignition ON.

3. At the CMP connector, check the voltage between

the voltage signal wire and sensor ground.

Does the DVM indicate the specified value? B+ Go to Step

12 Go to Step 8

81. Ignition ON.

2. Use a DVM to measure between the ground and the

CMP positive connector.

Does the DVM indicate the specified value? B+ Go to Step

10 Go to Step 9

9Repair the open circuit.

Is the repair complete? — Verify repair —

10 1. Ignition ON.

2. Use a DVM to measure at the CMP connector

between the battery + and the CMP ground wire.

Does the DVM indicate the specified value? B+ Go to Step

12 Go to Step

11 Repair the open ground wire.

Is the repair complete? — Verify repair —

Step NoYesValue(s)Action

12 Use an ohmmeter to check continuity of the signal wire

between the CMP and the ECM.

Was there an open circuit? —Go to Step

13 Go to Step

13 Repair the open signal wire.

Is the action complete? — Verify repair —

14 1. Ignition ON.

2. Check the signal wire for a short to ground or a short

to voltage.

Was a problem found? —Go to Step

15 Go to Step

15 Repair the signal circuit problem.

Is the action complete? — Verify repair —

16 Replace the CMP Sensor.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0351 IGNITION COIL ”A”

PRIMARY/SECONDARY CIRCUIT MALFUNCTION

D06RX124

Circuit Description

The ignition control circuit provides a zero volt or a 5 volt

signal to the ignition control module. The normal circuit

voltage is zero volts. When the module receives the 5 volt

signal from the engine control module (ECM), it provides

a ground path for the B+ voltage supplied to the ignition

primary coil. When the ECM turns off the 5 volts to the

module, the module will remove the ground path of the

ignition primary coils; causing the magnetic field

produces a voltage in the secondary coils which fires the

spark plug.

The circuit between the ECM and the ignition control

module is monitored for an open circuit, short to voltage,

and short to ground. When the ECM detects a problem in

the ignition control circuit, it will set DTC P0351. DTC

P0351 is a type A code.

Conditions for Setting the DTC

DIgnition ON.

DOutput voltage is not equal to 5 volts when output is

ON.

DOutput voltage is not equal to 0 volt when output is

OFF.

DTwenty test failures within 40 samples of continuous

circuit monitoring.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

DThe ECM will store conditions which were present

when the DTC was set as Freeze Frame and in the

Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history DTC P0351 will clear after 40 consecutive

warm–up cycles have occurred without a fault.

DDTC P0351 can be cleared by using the Scan Tool’s

”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at the ECM – Inspect the harness

connectors for backed–out terminals, improper

mating, broken locks, improperly formed or damaged

terminals, and poor terminal–to–wire connections.

DDamaged harness – Inspect the wiring harness for

damage; Open circuits, shorts to ground, or shorts to

V oltage. If the harness appears to be OK, observe the

Tech 2 display related to DTC P0351 while moving the

connector and wiring related to the ignition system. A

change in the display will indicate the location of the

fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This

may assist in diagnosing the condition.

DTC P0351 Ignition Coil ”A” Primary/Secondary Circuit Malfunction

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Check for a faulty connection or damaged terminals at

the ignition control module.

Was a problem found? —Verify Repair Go to Step 3

3Check for a faulty connection or damaged terminals at

the ECM connector.

Was a problem found? —Verify Repair Go to Step 4

41. Ignition OFF.

2. Disconnect the ECM and the ignition control

module.

3. Check the ignition control circuit for a short to

voltage.

Was a problem found? —Verify Repair Go to Step 5

5Check the ignition control circuit for a short to voltage.

Was a problem found? —Verify Repair Go to Step 6

6Check for an open in the ignition control circuit.

Was a problem found? —Verify Repair Go to Step 7

7Replace the ignition control module.

Verify repair.

Is there still a problem? —Go to Step 8 —

8Replace the ECM.

Is the repair complete? —Verify Repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0352 IGNITION COIL ”B”

PRIMARY/SECONDARY CIRCUIT MALFUNCTION

D06RX124

Circuit Description

The ignition control circuit provides a zero volt or a 5 volt

signal to the ignition control module. The normal circuit

voltage is zero volts. When the module receives the 5 volt

signal from the engine control module (ECM), it provides

a ground path for the B+ voltage supplied to the ignition

primary coil. When the ECM turns off the 5 volts to the

module, the module will remove the ground path of the

ignition primary coils; causing the magnetic field

produces a voltage in the secondary coils which fires the

spark plug.

The circuit between the ECM and the ignition control

module is monitored for an open circuit, short to voltage,

and short to ground. When the ECM detects a problem in

the ignition control circuit, it will set DTC P0352. DTC

P0352 is a type A code.

Conditions for Setting the DTC

DIgnition ON.

DOutput voltage is not equal to 5 volts when output is

ON.

DOutput voltage is not equal to 0 volt when output is

OFF.

DTwenty test failures within 40 samples of continuous

circuit monitoring.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

DThe ECM will store conditions which were present

when the DTC was set as Freeze Frame and in the

Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history DTC P0352 will clear after 40 consecutive

warm–up cycles have occurred without a fault.

DDTC P0352 can be cleared by using the Scan Tool’s

”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at the ECM – Inspect the harness

connectors for backed–out terminals, improper

mating, broken locks, improperly formed or damaged

terminals, and poor terminal–to–wire connections.

DDamaged harness – Inspect the wiring harness for

damage; Open circuits, shorts to ground, or shorts to

V oltage. If the harness appears to be OK, observe the

Tech 2 display related to DTC P0351 while moving the

connector and wiring related to the ignition system. A

change in the display will indicate the location of the

fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This

may assist in diagnosing the condition.

DTC P0352 Ignition Coil ”B” Primary/Secondary Circuit Malfunction

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Check for a faulty connection or damaged terminals at

the ignition control module.

Was a problem found? —Verify Repair Go to Step 3

3Check for a faulty connection or damaged terminals at

the ECM connector.

Was a problem found? —Verify Repair Go to Step 4

41. Ignition OFF.

2. Disconnect the ECM and the ignition control

module.

3. Check the ignition control circuit for a short to

voltage.

Was a problem found? —Verify Repair Go to Step 5

5Check the ignition control circuit for a short to voltage.

Was a problem found? —Verify Repair Go to Step 6

6Check for an open in the ignition control circuit.

Was a problem found? —Verify Repair Go to Step 7

7Replace the ignition control module.

Verify repair.

Is there still a problem? —Go to Step 8 —

8Replace the ECM.

Is the repair complete? —Verify Repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0401 EXHAUST GAS RECIRCULATION

(EGR) FLOW INSUFFICIENT DETECTED

D06RX113

Circuit Description

The engine control module (ECM) tests the exhaust gas

recirculation (EGR) system during deceleration by

momentarily commanding the EGR valve to open while

monitoring the manifold absolute pressure (MAP) sensor

signal. When the EGR valve is opened, the ECM monitors

the change in MAP input signal. The ECM compares the

MAP change to a RPM vs. BARO table. When the ECM

interprets the change in MAP to be out of limits, the ECM

will set DTC P0401. The number of test samples required

to accomplish this may vary according to the severity of

the detected flow error.

Normally, the ECM will only allow one EGR flow test

sample to be taken during an ignition cycle. To aid in

verifying a repair, the ECM allows twelve test samples

during the first ignition cycle following a T ech 2 ”Clear Info”

or a battery disconnect. Between nine and twelve

samples should be sufficient for the ECM to determine

adequate EGR flow and pass the EGR test. DTC P0401

is a type A code.

Conditions for Setting the DTC

DNo TP sensor, VSS, EVAP Purge, IAC, IAT sensor,

MAP sensor , EGR Pintle Position sensor , ECT sensor ,

misfire DTCs set.

DBarometric pressure is above 72 kPa.

DEngine coolant temperature is greater than 60°C

(140°F).

DSystem voltage is between 11.5 and 16 volts.

DVehicle speed is greater than 23 km/h (14 mph).

DIAC position is steady, changing less than 5 counts.

DA/C clutch status is unchanged.

Start Test

DTP angle is less than 0.8%.

DEGR duty cycle is less than 1%.

DMAP is steady, changing less than 1 kPa.

DEngine speed is between 1200 RPM and 2000 RPM.

DCompensated MAP between 10.3 kPa and 49.8 kPa.

Run Test

DDelta MAP is recorded during valve open conditions.

DEGR valve is ramped over a time interval.

Run Test will be aborted if any of the following are true:

DVehicle speed changes by greater than 16 km/h

(10mph).

DEngine RPM changes by greater than 100 rpm.

DEGR is opened less than 95% of the commanded

amount.

During the Start Test and the Run Test, the EGR is closed

then opened. The associated change in MAP is

compared with the ECM’s expected change value. If the

difference between the two values exceeds the ECM’s

internal limit, a Diagnostic Trouble Code P0401 will set.

DTC P0401 is a type A code.

NOTE: Several deceleration cycles will be necessary to

run a sufficient number of EGR flow tests to determine a

”pass” or ”fail” condition.

Action Taken When the DTC Sets

DThe Malfunction Indicator Lamp (MIL) will illuminate

the first time the fault is detected.

DA history Diagnostic Trouble Code is stored.

DA history Diagnostic Trouble Code will clear after 40

consecutive warm up cycles without a fault.

DThe MIL will turn OFF after three consecutive ignition

cycles in which the diagnostic runs without a fault.

Conditions for Clearing the DTC

DThe MIL will turn OFF after three consecutive ignition

cycles in which the diagnostic runs without a fault.

DA history Diagnostic Trouble Code will clear after 40

consecutive warm up cycles without a fault.

DDiagnostic T rouble Codes can be cleared by using the

Tech 2.

Diagnostic Aids

Check for the following conditions:

DPoor connection or damaged harness – Inspect the

wiring harness for damage. If the harness appears to

be OK, observe the Actual EGR Position display on the

Tech 2 while moving connectors and wiring harnesses

related to the EGR valve. A change in the display will

indicate the location of the fault.

DEnsure EGR valve is correctly mounted. See

On–Vehicle Service.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic T rouble Code to

be set occurs. This may assist in diagnosing the

condition.

NOTE: If the EGR valve shows signs of excessive heat,

check the exhaust system for blockage (possibly a

plugged catalytic converter) using the ”Restricted

Exhaust System Check.”

DTC P0401 – Exhaust Gas Recirculation Flow Insufficient Detected

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Start the engine.

2. Monitor the MAP signal with a Tech 2 while idling.

3. While idling, depress the accelerator pedal about

halfway down and immediately let the engine return

to idle.

Did the MAP value on the Tech 2 show an immediate

large change? —Go to Step 4 Go to Step 3

3Replace the MAP sensor. — Verify repair —

41. Inspect the exhaust system for modification of

original installed parts or leaks.

2. If a problem was found, repair exhaust system as

necessary.

Was a condition present that required repair? —Go to Step 7 Go to Step 5

51. Remove the EGR valve.

2. Visually and physically inspect the pintle, valve

passages and the adapter for excessive deposits or

any kind of a restriction.

3. If a problem if found, clean or replace EGR system

components as necessary.

Was a condition present that required repair? —Go to Step 7 Go to Step 6

61. Remove the EGR inlet and outlet pipes from the

exhaust manifold and the intake manifold.

2. Inspect the manifold EGR ports and the EGR inlet

and outlet pipes for a blockage caused by excessive

deposits or other damage.

3. If a problem is found, correct the condition as

necessary.

Was a condition present that required repair? —Go to Step 7

Refer to

Diagnostic

Aids

71. Review and record the T ech 2 Failure Records data.

2. Clear Diagnostic Trouble Code and monitor the

Tech 2 System Info Screen while operating the

vehicle as specified in ”Diagnostic Aids.”

3. Using a Tech 2, monitor “Diagnostic T rouble Code”

info for Diagnostic Trouble Code P0401 until the

Diagnostic Trouble Code P0401 test runs.

4. Note the test result.

Does the Tech 2 indicate Diagnostic Trouble Code

P0401 failed this ignition? — — Repair

complete

DIAGNOSTIC TROUBLE CODE (DTC) P0402 EXHAUST GAS RECIRCULATION

(EGR) EXCESSIVE FLOW DETECTED

D06RX113

Circuit Description

The Engine Control Module (ECM) closes the Exhaust

Gas Recirculation (EGR) system on engine start–up to

test for excessive (any) flow. If the ECM determines that

EGR flow occurred on start–up, in two consecutive trips,

then DTC P0402 will set. DTC P0402 is a type B code.

Conditions for Setting the DTC

DIntake Air Temperature (IAT) is above 5°C (41°F).

DEngine RPM is less than 500 RPM.

DEGR Pintle Position if greater than 55 counts.

The above mentioned conditions must be met for 0.6

seconds during engine start–up on two consecutive trips.

Diagnostic Aids

Check for the following conditions:

DPoor connection or damaged harness – Inspect the

wiring harness for damage. If the harness appears to

be OK, observe the Actual EGR Position display on the

Tech 2 while moving connectors and wiring harnesses

related to the EGR valve. A change in the display will

indicate the location of the fault.

DEnsure EGR valve is correctly mounted. See

On–Vehicle Service.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the DTC to be set occurs. This

may assist in diagnosing the condition.

NOTE: If the EGR valve shows signs of excessive heat,

check the exhaust system for blockage (possible a

plugged catalytic converter) using the ”Restricted

Exhaust System Check.”

DTC P0402 EGR Excessive Flow Detected

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Review and record the T ech 2 Failure Records data.

2. Clear Diagnostic Trouble Code and monitor the

Tech 2 System Info Screen while operating the

vehicle as specified in ”Diagnostic Aids.”

3. Using a Tech 2, monitor “Diagnostic T rouble Code”

info for Diagnostic Trouble Code P0401 until the

Diagnostic Trouble Code P0401 test runs.

4. Note the test result.

Does the Tech 2 indicate Diagnostic Trouble Code

P0401 failed this ignition? —

Go to

Diagnostic

Aids Go to Step 3

31. Inspect the exhaust system for modification of

original installed parts or leaks.

2. If a problem was found, repair exhaust system as

necessary.

Was a condition present that required repair? — Verify repair Go to Step 4

41. Remove the EGR valve.

2. Visually and physically inspect the pintle, valve

passages and the adapter for excessive deposits or

any kind of a restriction.

3. If a problem if found, clean or replace EGR system

components as necessary.

Was a condition present that required repair? — Verify repair Go to Step 5

51. Remove the EGR inlet and outlet pipes from the

exhaust manifold and the intake manifold.

2. Inspect the manifold EGR ports and the EGR inlet

and outlet pipes for a blockage caused by excessive

deposits or other damage.

3. If a problem is found, correct the condition as

necessary.

Was a condition present that required repair? — Verify repair

Refer to

Diagnostic

Aids

DIAGNOSTIC TROUBLE CODE (DTC) P0404 EXHAUST GAS RECIRCULATION

(EGR) CIRCUIT RANGE/PERFORMANCE

D06RX113

Circuit Description

An Exhaust Gas Recirculation (EGR) system is used to

lower Oxides of Nitrogen (NOx) emission levels caused

by high combustion temperatures. It accomplishes this

by feeding small amounts of exhaust gases back into the

combustion chamber. When the air/fuel mixture is diluted

with the exhaust gases, combustion temperatures are

reduced.

A linear EGR valve is used on this system. The linear

EGR valve is designed to accurately supply exhaust

gases to the engine without the use of intake manifold

vacuum. The valve controls exhaust flow going into the

intake manifold from the exhaust manifold through an

orifice with a ECM controlled pintle. The ECM controls

the pintle position using inputs from the Throttle Position

(TP) and Manifold Absolute Pressure (MAP) sensors.

The ECM then commands the EGR valve to operate

when necessary by controlling an ignition signal through

the ECM. This can be monitored on a Tech 2 as the

Desired EGR Position.

The ECM monitors the results of its command through a

feedback signal. By sending a 5 volt reference and a

ground to the EGR valve, a voltage signal representing

the EGR valve pintle position is sent to the ECM. This

feedback signal can also be monitored on a Tech 2 and is

the actual position of the EGR pintle. The Actual EGR

position should always be near the commanded or

Desired EGR Position.

If the ECM detects a large difference between the

desired EGR position and actual EGR position, then

Diagnostic T rouble Code P0404 will set. DTC P0404 is a

type B code.

Conditions for Setting the DTC

DIAT is greater than 5°C (41°F).

DEGR commanded ON (Desired EGR Position is

greater than 0%).

DActual EGR Position differs from Desired EGR

Position by more than 15% for 5 seconds.

Action Taken When the DTC Sets

DMalfunction Indicator Lamp (MIL) will illuminate the

second time the fault is detected.

DThe ECM will record operating conditions at the time

the diagnostic fails.

DA history Diagnostic Trouble Code is stored.

DThe EGR Valve is disabled.

Conditions for Clearing the MIL/DTC

DThe MIL will turn OFF after three consecutive ignition

cycles in which the diagnostic runs without a fault.

DDiagnostic T rouble Code(s) can be cleared by using a

Tech 2.

Diagnostic Aids

Due to the moisture associated with exhaust systems, the

EGR valve may freeze and stick in colder weather at

times. After the vehicle is brought into a warm shop for

repairs, the valve warms and the problem disappears. By

watching the Actual EGR and Desired EGR Positions on

a cold vehicle with a Tech 2, the fault can be verified

easily. Check the freeze frame data to determine if the

Diagnostic Trouble Code was set when the vehicle was

cold by viewing the Engine Coolant Temperature (ECT).

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

1. The Powertrain OBD System Check prompts the

technician to complete some basic checks and store

the freeze frame and failure records data on the

Tech 2 if applicable. This created an electronic copy

of the data taken when the fault occurred. The

information is then stored on the Tech 2 for later

reference.

2. Commanding the EGR valve open determines

whether the EGR system can control the EGR valve

accurately and if the fault if present.

3. When the EGR valve electrical connector is

disconnected, the Tech 2 should display the Actual

EGR Position as 0%. If is does not, the fault lies

either in the EGR signal circuit or the ECM.

4. A test light, when connected to ground, will glow

dimly when the EGR valve is commanded to 25%,

and brighter as the EGR valve is commanded to

100%. If the test light flashes, check the sensor

ground for an open.

5. An open or poor connection condition may have

caused this Diagnostic Trouble Code to set. Be

sure to check the terminals for being backed out,

improperly formed or damaged, and for poor

tension.

7. The test light will have glowed brightly in the

previous step if the EGR control circuit was shorted

to B+ and the Actual EGR Position on the Tech 2

will display 100%. A test light that did not illuminate,

indicates that the circuit may be open or shorted to

ground.

9. If the EGR valve 5 volt reference is shorted to

voltage, the DVM will read battery voltage and

additional Diagnostic Trouble Codes may be set and

engine performance will be poor.

13. Although the circuitry acted correctly when

checked, a problem may still lie within the terminals

which would not show up in probe type testing. Be

sure to check the terminals for being backed out,

improperly formed or damaged, and for poor

tension.

17. All circuits to the EGR valve are OK at this point.

The fault lies internally in the EGR valve and

therefore must be replaced. Be sure all gasket

material is removed from the EGR mounting

surface. Even a small amount of material may

cause a Diagnostic Trouble Code P0401 to set. For

on vehicle service of the EGR Valve, refer to EGR

Valve.

18. Check the terminals for being backed out,

improperly formed or damaged, and for poor

tension.

19. Clearing the Diagnostic Trouble Codes is a very

important step for this diagnostic. The clearing

function allows the EGR valve to relearn a new

pintle position as the old position was inaccurate

due to the malfunction that caused the Diagnostic

Trouble Code. The Diagnostic Trouble Code must

be cleared with the ignition switch ON, with the

engine OFF or when the engine is idling. If the

ECM sees a EGR command, the new pintle position

will not be learned.

DTC P0404 EGR Circuit Range/Performance

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed?

—Go to Step 2

Go to

Powertrain

OBD System

Check

21. Turn the ignition switch ON, with the engine OFF.

2. Install a Tech 2.

3. Command the EGR valve to the specified values.

Does the Actual EGR Position follow the Desired EGR

Position? 25%, 50%,

75%, 100% Go to Step

19 Go to Step 3

31. Turn the ignition switch ON, with the engine OFF.

2. Disconnect the EGR valve electrical connector.

3. With a test light connected to B+, probe the ground

circuit to the EGR valve.

Does the light illuminate? —Go to Step 4 Go to Step 5

41. Connect the test light to ground.

2. Probe the EGR control circuit to the EGR valve.

3. Command the EGR valve to the specified values

using a Tech 2.

As the command is raised, does the test light glow

brighter, flash or maintain a steady glow? 25%, 50%,

75%, 100% Go to Step 6 Go to Step 7

5Repair the open or poor connection in the EGR ground

circuit.

Is the action complete? —Go to Step

19 —

6With the test light still connected to ground, probe the

signal circuit.

Is the action complete? —Go to Step 8 Go to Step 9

7With the test light still connected to ground, again probe

the control circuit without commanding the EGR valve

with the Tech 2.

Does the test light illuminate? —Go to Step

10 Go to Step

8Check the signal circuit for a short to voltage and repair

as necessary.

Was a repair necessary? —Go to Step

19 Go to Step

9With a Digital Voltmeter (DVM) connected to ground,

probe the 5 V reference circuit.

Is the voltage measured near the specified value? 5 V Go to Step

13 Go to Step

10 Check the control circuit for a short to voltage and

repair as necessary.

Was a repair necessary? —Go to Step

19 Go to Step

11 Connect the test light to B+ and again probe the control

circuit.

Does the light illuminate? —Go to Step

15 Go to Step

12 Replace the ECM.

Is the action complete? —Go to Step

19 —

Step NoYesValue(s)Action

13 Check the EGR ground circuit for a poor connection or

proper terminal tension at the ECM and repair as

necessary.

Was a repair necessary? —Go to Step

19 Go to Step

14 Check the 5 V reference circuit for a short to voltage

and repair as necessary.

Was a repair necessary? —Go to Step

19 Go to Step

15 Check the control circuit for a short to ground and repair

as necessary?

Was a repair necessary? —Go to Step

19 Go to Step

16 Check the control circuit for an open or poor connection

at the EGR valve electrical connector and repair as

necessary.

Was a repair necessary? —Go to Step

19 Go to Step

17 Replace the EGR valve.

Is the action complete? —Go to Step

19 —

18 Check the ECM electrical connector for a poor

connection and repair as necessary.

Was a repair necessary? —Go to Step

19 Go to Step

19 1. Using the Tech 2, clear Diagnostic Trouble Codes.

2. Start engine and idle at normal operating

temperature.

3. Operate vehicle within the conditions for setting this

Diagnostic Trouble Code as specified in the

supporting text.

Does the Tech 2 indicate that this diagnostic ”Ran and

Passed?” —Verify repair Go to Step 2

DIAGNOSTIC TROUBLE CODE (DTC) P0405 EXHAUST GAS RECIRCULATION

(EGR) SENSOR CIRCUIT LOW

D06RX113

Circuit Description

An Exhaust Gas Recirculation (EGR) system is used to

lower Oxides of Nitrogen (NOx) emission levels caused

by high combustion temperatures. It accomplishes this

by feeding small amounts of exhaust gases back into the

combustion chamber . When the air/fuel mixture is diluted

with the exhaust gases, combustion temperatures are

reduced.

A linear EGR valve is used on this system. The linear

EGR valve is designed to accurately supply exhaust

gases to the engine without the use of intake manifold

vacuum. The valve controls exhaust flow going into the

intake manifold form the exhaust manifold through an

orifice with a ECM controlled pintle. The ECM controls

the pintle position using inputs from the Throttle Position

(TP) and Manifold Absolute Pressure (MAP) sensors.

The ECM then commands the EGR valve to operate

when necessary by controlling an ignition signal through

the ECM. This can be monitored on a Tech 2 as the

Desired EGR Position.

The ECM monitors the results of its command through a

feedback signal. By sending a 5 volt reference and a

ground to the EGR valve, a voltage signal representing

the EGR valve pintle position is sent to the ECM. This

feedback signal can also be monitored on a Tech 2 and is

the actual position of the EGR pintle. The Actual EGR

Position should always be near the commanded or

Desired EGR Position.

If the ECM detects a continuous short to ground in the

signal circuit or the sensor , then Diagnostic Trouble Code

P0405 will set. DTC P0405 is a type A code.

Conditions for Setting the DTC

DIAT is greater than 5°C (41°F).

DThe ECM sees less than 0.10 voltage from the EGR

valve sensor.

DA malfunction is present for 10 seconds.

Action Taken When the DTC Sets

DThe Malfunction Indicator Lamp (MIL) will illuminate

the first time the malfunction is detected.

DThe ECM will record operating conditions at the time

the diagnostic fails.

DA history Diagnostic Trouble Code is stored.

DThe EGR Valve is disabled.

Conditions for Clearing the MIL/DTC

DThe MIL will turn OFF after three consecutive ignition

cycles in which the diagnostic runs without a fault.

DA history Diagnostic Trouble Code will clear after 40

consecutive warm up cycles without a fault.

DDiagnostic T rouble Codes can be cleared by using the

Tech 2.

Diagnostic Aids

Due to the moisture associated with exhaust systems, the

EGR valve may freeze and stick in colder weather at

times. After the vehicle is brought into a warm shop for

repairs, the valve warms and the problem disappears. By

watching the Actual EGR and Desired EGR Positions on

a cold vehicle with a Tech 2, the fault can be verified

easily. Check the freeze frame data to determine if the

Diagnostic Trouble Code set when the vehicle was cold

by viewing the Engine Coolant Temperature (EGR).

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

1. The Powertrain OBD System Check prompts the

technician to complete some basic checks and store

the freeze frame and failure records data on the

Tech 2 if applicable. This creates an electronic copy

of the data taken when the fault occurred. The

information is then stored on the Tech 2 for later

reference.

2. Commanding the EGR valve open determines

whether the EGR system can control the EGR valve

accurately and if the fault is present.

3. If the EGR valve 5 volt reference is shorted to

ground, the DVM will read no voltage and an

additional Diagnostic Trouble Code will be set and

engine performance will be poor. When this circuit

is open, only a Diagnostic Trouble Code P0405 will

be set.

4. Jumping the 5 volt reference circuit to the signal

circuit checks the signal circuit and ECM. The Tech

2 should display the Actual EGR Position as 100% if

the signal circuit and ECM are OK.

6. Although the ECM and circuitry acted correctly in the

previous step, a problem may still lie within the

terminals which would not show up in probe type

testing. Check the terminals for being backed out,

improperly formed or damaged, and for poor

tension.

10. All circuits to the EGR valve are OK at this point.

The fault lies internally in the EGR valve and

therefore must be replaced. Be sure all gasket

material is removed from the EGR mounting

surface. Even a small amount of material may

cause a Diagnostic Trouble Code P0405 to set.

Refer the EGR Valve for on vehicle service of the

EGR valve.

14. Check the terminals for being backed out,

improperly formed or damaged, and for poor

tension.

DTC P0405 – EGR Sensor Circuit Low

Step Action Value(s) Yes No

1Was the Powertrain On–Board Diagnostic (OBD)

System Check performed?

—Go to Step 2

Go to

Powertrain

OBD System

Check

21. Turn the ignition switch ON, with the engine OFF.

2. Install a Tech 2.

3. Command the EGR valve to the specified values.

Does the Actual EGR Position follow the Desired EGR

Position? 25%, 50%,

75%, 100% Go to Step

15 Go to Step 3

31. Turn the ignition switch ON, with the engine OFF.

2. Disconnect the EGR valve electrical connector.

3. With a Digital Voltmeter (DVM) connected to

ground, probe the 5 V reference circuit to the EGR

valve.

Does the DVM read near the specified value? 5 V Go to Step 4 Go to Step 5

4Jumper the EGR valve 5 volt reference circuit to the

signal circuit.

Does the Actual EGR Position display the specified

value? 100% Go to Step 6 Go to Step 7

51. Connect the test light to B+.

2. Probe the 5 V reference circuit to the EGR valve.

Does the test light illuminate? —Go to Step 8 Go to Step 9

Step NoYesValue(s)Action

6Check the 5 V reference and signal circuit’s for a poor

connection or proper terminal tension and repair as

necessary.

Was a repair necessary? —Go to Step

15 Go to Step

71. Connect the test light to B+.

2. Probe the signal circuit to the EGR valve.

Does the light illuminate? —Go to Step

11 Go to Step

8Check for a short to ground in the EGR valve 5 V

reference circuit and repair as necessary.

Was a repair necessary? —Go to Step

15 Go to Step

9Check for an open in the EGR valve 5 V reference

circuit and repair as necessary.

Was a repair necessary? —Go to Step

15 Go to Step

10 Replace the EGR valve.

Is the action complete? —Go to Step

15 —

11 Check for a short to ground in the EGR valve signal

circuit and repair as necessary.

Was a repair necessary? —Go to Step

15 Go to Step

12 Check for an open in the EGR valve signal circuit and

repair as necessary.

Was a repair necessary? —Go to Step

15 Go to Step

13 Replace the ECM.

Is the action complete? —Go to Step

15 —

14 Check the affected circuit for a poor connection or

proper terminal at the ECM and repair as necessary.

Was a repair necessary? —Go to Step

15 Go to Step

15 1. Using the Tech 2, clear the Diagnostic Trouble

Codes.

2. Start engine and idle at normal operating

temperature.

3. Operate vehicle within the conditions for setting this

Diagnostic Trouble Code as specified in the

supporting text.

Does the Tech 2 indicate that this diagnostic ran and

passed? —Verify repair Go to Step 2

DIAGNOSTIC TROUBLE CODE (DTC) P0406 EXHAUST GAS RECIRCULATION

(EGR) SENSOR CIRCUIT HIGH

D06RX113

Circuit Description

An Exhaust Gas Recirculation (EGR) system is used to

lower Oxides of Nitrogen (NOx) emission levels caused

by high combustion temperatures. It accomplishes this by

feeding small amounts of exhaust gases back into the

combustion chamber . When the air/fuel mixture is diluted

with the exhaust gases, combustion temperatures are

reduced.

A linear EGR valve is used on this system. The linear

EGR valve is designed to accurately supply exhaust

gases to the engine without the use of intake manifold

vacuum. The valve controls exhaust flow going into the

intake manifold form the exhaust manifold through an

orifice with a ECM controlled pintle. The ECM controls the

pintle position using inputs from the Throttle Position (TP)

and Manifold Absolute Pressure (MAP) sensors. The

ECM then commands the EGR valve to operate when

necessary by controlling an ignition signal through the

ECM. This can be monitored on a Tech 2 as the Desired

EGR Position.

The ECM monitors the results of its command through a

feedback signal. By sending a 5 volt reference and a

ground to the EGR valve, a voltage signal representing

the EGR valve pintle position is sent to the ECM. This

feedback signal can also be monitored on a Tech 2 and is

the actual position of the EGR pintle. The Actual EGR

Position should always be near the commanded or

Desired EGR Position.

If the ECM detects a continuous short to ground in the

signal circuit or the sensor, then DTC P0406 will set.

Diagnostic Trouble Code P0406 is a type A code.

Conditions for Setting the DTC

DIAT is greater than 5°C (41°F).

DThe ECM sees less than 0.10 voltage from the EGR

valve sensor.

DA malfunction is present for 10 seconds.

Action Taken When the DTC Sets

DThe Malfunction Indicator Lamp (MIL) will illuminate.

DThe ECM will record operating conditions at the time

the diagnostic fails.

DA history Diagnostic Trouble Code is stored.

DThe EGR Valve is disabled.

Conditions for Clearing the MIL/DTC

DThe MIL will turn OFF after three consecutive ignition

cycles in which the diagnostic runs without a fault.

DA history Diagnostic Trouble Code will clear after 40

consecutive warm–up cycles without a fault.

DDiagnostic Trouble Code(s) can be cleared by using

the Tech 2.

Diagnostic Aids

Due to the moisture associated with exhaust systems, the

EGR valve may freeze and stick in colder weather at

times. After the vehicle is brought into a warm shop for

repairs, the valve warms and the problem disappears. By

watching the Actual EGR and Desired EGR Positions on

a cold vehicle with a Tech 2, the fault can be verified

easily. Check the freeze frame data to determine if the

Diagnostic Trouble Code set when the vehicle was cold

by viewing the Engine Coolant Temperature (EGR).

DTC P0406 EGR Sensor Circuit High

Step Action Value(s) YesNo

1Was the Powertrain ”On–Board Diagnostic (OBD)

System Check” performed?

—Go to Step 2

Go to

Powertrain

OBD System

Check

21. Turn the ignition switch ON, with the engine OFF.

2. Review and record Tech 2 Failure Records data,

then clear the DTC’s.

3. Operate the vehicle within the Failure Records

conditions as noted.

4. Using the Tech 2, monitor ”DTC” info for DTC

P0406.

Does the Tech 2 indicate DTC P0406 ”Ran and

Passed?” —

Refer to

Diagnostic

Aids Go to Step 3

31. Ignition OFF.

2. Disconnect the Linear Exhaust Gas Recirculation

(EGR) Valve from the wiring harness.

3. Ignition ON, Engine OFF.

4. Using a Digital Voltmeter (DVM), check for voltage

on the ignition feed circuit at the Linear Exhaust Gas

Recirculation (EGR) Valve wiring harness

connector.

Does the DVM read the following value? 12 Volts Go to Step 6 Go to Step 4

4Check the ignition feed circuit, between the EGR

sensor and the ”Engine IG.” fuse, for the following

conditions:

DAn open circuit

DA short to ground

Was the problem found? — Verify repair —

5Using a DVM, check the resistance of the EGR

solenoid.

Does the DVM read the following value? less then 5 WGo to Step 6 Go to Step 14

6Check the EGR solenoid valve Low circuit, between the

EGR sensor and the ECM, for the following conditions:

DAn open circuit

DA short to ground

DA short to voltage

Was the problem found? — Verify repair Go to Step 15

71. Ignition OFF.

2. Disconnect the Linear Gas Recirculation (EGR)

Valve from the wiring harness.

3. Ignition ON, Engine OFF.

4. Observe the EGR value on the Tech 2.

Does the Tech 2 display the following value(s)? 0 Volts 0% Go to Step 9 Go to Step 8

Step NoYesValue(s)Action

8Check the EGR position feedback circuit, between the

EGR sensor and the ECM, for the following conditions:

DAn open circuit

DA short to ground

DA short to voltage

Was the problem found? — Verify repair Go to Step 15

91. Ignition ON, Engine OFF.

2. Using a Digital Voltmeter (DVM), check for voltage

on the 5 volt Reference signal circuit at the Linear

Exhaust Gas Recirculation (EGR) Valve wiring

harness connector.

Does the DVM read the following value? about 5 volts Go to Step 11 Go to Step 10

10 Check the 5 volt Reference signal circuit, between the

EGR and the ECM, for the following conditions:

DAn open circuit

DA short to ground

DA short to voltage

Was the problem found? — Verify repair Go to Step 11

11 1. Ignition OFF.

2. Place a DVM between the 5 volt Reference signal

circuit and the 5 volt signal return (ground) circuit at

the EGR wiring harness connector.

3. Ignition ON, Engine OFF.

Does the DVM read the following value? about 5 volts Go to Step 13 Go to Step 12

12 Check the 5 volt signal return (ground) circuit, between

the EGR and the ECM, for the following conditions:

DAn open circuit

DA short to ground

DA short to voltage

Was the problem found? — Verify repair Go to Step 15

13 1. Ignition OFF.

2. Place a fused jumper wire between the 5 volt

Reference signal circuit and the EGR valve position

feedback circuit at the EGR wiring harness

connector.

3. Ignition ON, Engine OFF.

4. Observe the EGR value on the Tech 2.

Does the Tech 2 display the following value(s)? 5 volts 100% Go to Step 14 Go to Step 15

14 Replace the Linear Exhaust Gas Recirculation (EGR)

Valve.

Verify Repair. ———

15 Replace the ECM.

Verify repair. ———

DIAGNOSTIC TROUBLE CODE (DTC) P0443 EVAPORATIVE EMISSION (EVAP)

CONTROL SYSTEM PURGE CONTROL VALVE CIRCUIT MALFUNCTION

D06RX115

Circuit Description

The Engine Control Module (ECM) controls the

Evaporative Emission (EVAP) Canister Purge Solenoid

Valve through the use of a control (ground) circuit. If the

ECM commands the Purge solenoid to maximum duty

cycle (100%) but the voltage remains High (12 Volts); or, if

the ECM commands the Purge solenoid to minimum duty

cycle (0%) but the voltage remains Low (0 volts), then

DTC P0443 will set. DTC P0443 is a type A code.

Conditions for Setting the DTC

DIgnition voltage is greater than 10 volts

DEngine run time is greater than 32 seconds

The above mentioned conditions are met and one of the

following two conditions are met for 25 seconds within a

50 seconds test sample:

DECM senses voltage is High with the EVAP Canister

Purge Solenoid commanded ON.

DECM senses voltage is Low with the EVAP Canister

Purge Solenoid commanded OFF.

Action Taken When the DTC Sets

DThe ECM will illuminate the Malfunction Indicator Lamp

(MIL) the first time the fault is detected.

DThe ECM will store the conditions that were present

when the DTC was set as Freeze Frame and in Failure

Records.

Conditions for Clearing the MIL/DTC

DThe ECM will turn OFF the MIL after three consecutive

trips without a reported failure.

DA History DTC will clear after 40 consecutive trips

without a reported failure.

DThe DTC can be cleared using the Scan Tool’s ”Clear

Info” function.

Diagnostic Aids

DPoor connections , or a damaged harness – Inspect the

harness connectors for: backed–out terminals,

improper mating or damaged terminals. Also check for

open circuits, shorts to ground, and shorts to voltage.

DTC P0443 EVAP Control System Purge Control Valve Circuit Malfunction

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON, Engine OFF.

2. Review and record Tech 2 Failure Records data,

then clear the DTC’s.

3. Operate the vehicle within the Failure Records

conditions as noted.

4. Using the Tech 2, monitor ”DTC” info for DTC

P0443.

Does the Tech 2 indicate DTC P0443 ”Ran and

Passed?” —

Refer to

Diagnostic

Aids Go to Step 3

31. Ignition OFF.

2. Disconnect the EVAP Canister Purge Solenoid from

the wiring harness connector from the EVAP

Canister Purge Solenoid.

3. Ignition ON, Engine OFF.

4. Using a Digital Voltmeter (DVM), check for voltage

on the ”Engine IG.” Fuse pin of the EVAP Canister

Purge Solenoid wiring harness connector.

Does the DVM read the following value? 12 Volts Go to Step 5 Go to Step 4

4Check the suspect circuit between the EVAP Canister

Purge Solenoid connector and the ”Engine IG.” Fuse

for the following conditions:

DA short to ground

DAn open circuit

DA short to voltage

Was the problem found? — Verify repair —

5Using a DVM, check the resistance of the EVAP

Canister Purge Solenoid.

Does the DVM read the following value? less than 5 WGo to Step 6 Go to Step 7

61. Ignition OFF.

2. Disconnect the Engine Control Module (ECM)

connectors from the ECM.

3. Check the EVAP Canister Purge Solenoid control

circuit between the ECM and EV AP Canister Purge

Solenoid for the following conditions:

DA short to ground

DAn open circuit

DA short to voltage

Was the problem found? — Verify repair Go to Step 8

7Replace the EVAP Canister Purge Solenoid.

Verify Repair. ———

8Replace the ECM. ———

DIAGNOSTIC TROUBLE CODE (DTC) P0480 COOLING FAN 1 CONTROL

CIRCUIT MALFUNCTION

060RX090

Circuit Description

The Engine Control Module (ECM) controls the

engagement of the cooling fan Low speed through the

use of a relay and a control circuit. If the ECM commands

the fan to Low speed and then senses that the fan did not

turn ON, or if the ECM commands the fan OFF from Low

speed and then senses that the fan did not turn OFF, the

ECM will set a DTC P0480. DTC P0480 is a type D code.

Conditions for Setting the DTC

DIgnition voltage is greater than 10 volts.

DEngine run time is greater than 32 seconds.

The above conditions are met and one of the following

conditions are met for 25 seconds within a 50 second test

sample:

DECM sensed voltage is High with the Low Speed Fan

OFF.

DECM sensed voltage is Low with the Low Speed Fan

ON.

Action Taken When the DTC Sets

DThe ECM will not turn on the Malfunction Indicator

Lamp.

DThe ECM will store the conditions that were present

when the DTC was set as Freeze Frame and in Failure

Records.

Conditions for Clearing the DTC

DA history DTC will clear after 40 consecutive trips

without a reported failure.

DThe DTC can be cleared using the Scan Tool’s Clear

Info” function.

Diagnostic Aids

DPoor connections or a damaged harness – Inspect the

harness connectors for: backed out terminals,

improper mating or damaged terminals. Also check for

open circuits, shorts to ground, and shorts to voltage.

DTC P0480 Cooling Fan 1 Control Circuit Malfunction

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON, Engine OFF.

2. Review and record Tech 2 Failure Records data,

then clear the DTCs.

3. Operate the vehicle within the Failure Records

conditions as noted.

4. Using the Tech 2, monitor ”DTC” info for DTC

P0480.

Does the Tech 2 indicate that DTC P0480 ”Ran and

Passed?” —

Refer to

Diagnostic

Aids Go to Step 3

31. Ignition OFF.

2. Remove the Low Fan Relay from the Underhood

Electrical Center.

3. Ignition OFF.

4. Using a Digital Voltmeter (DVM), check for voltage

on the ”ELEC. FAN” Fuse pin of the Low fan Relay

connector.

Does the DVM read the following value? 12 Volts Go to Step 4 Go to Step 3

41. Ignition ON.

2. Using a DVM, check for voltage on the ”ENGINE

FAN” Fuse pin of the Low Fan Relay connector.

Does the DVM read the following value? 12 Volts Go to Step 6 Go to Step 5

5Check the suspect circuit between the Low Fan Relay

connector and Fuse for the following conditions:

DA short to ground

DAn open circuit

DA short to voltage

Was the problem found? — Verify repair —

61. Ignition OFF.

2. Disconnect the Engine Control Module (ECM)

connectors from the ECM.

3. Check the Low Fan Relay control circuit between

the ECM and Underhood Electrical Center for the

following conditions:

DA short to ground

DAn open circuit

DA short to voltage

Was the problem found? — Verify repair Go to Step 7

71. Reinstall the Low Fan Relay.

2. Using a fused jumper, ground the Low Fan Relay

control circuit at the ECM connector.

3. Ignition ON, Engine OFF.

Does the fan run at low speed? —Go to Step 9 Go to Step 8

Step NoYesValue(s)Action

8Replace the Low Fan Relay.

Is the action complete? — Verify repair —

9Replace the ECM.

Verify repair. ———

DIAGNOSTIC TROUBLE CODE (DTC) P0481 COOLING FAN 2 CONTROL

CIRCUIT MALFUNCTION

060RX090

Circuit Description

The Engine Control Module (ECM) controls the

engagement of the cooling fan Low speed through the

use of a relay and a control circuit. If the ECM commands

the fan to Low speed and then senses that the fan did not

turn ON, or if the ECM commands the fan OFF from Low

speed and then senses that the fan did not turn OFF, the

ECM will set a DTC P0481. DTC P0481 is a type D code.

Conditions for Setting the DTC

DIgnition voltage is greater than 10 volts.

DEngine run time is greater than 32 seconds.

The above conditions are met and one of the following

conditions are met for 25 seconds within a 50 second test

sample:

DECM sensed voltage is High with the High Speed Fan

OFF.

DECM sensed voltage is High with the High Speed Fan

ON.

Action Taken When the DTC Sets

DThe ECM will not turn on the Malfunction Indicator

Lamp.

DThe ECM will store the conditions that were present

when the DTC was set as Freeze Frame and in Failure

Records.

Conditions for Clearing the DTC

DA history DTC will clear after 40 consecutive trips

without a reported failure.

DThe DTC can be cleared using the Scan Tool’s ”Clear

Info” function.

Diagnostic Aids

DPoor connections or a damaged harness – Inspect the

harness connectors for: backed out terminals,

improper mating or damaged terminals. Also check for

open circuits, shorts to ground, and shorts to voltage.

DTC P0481 Cooling Fan 2 Control Circuit Malfunction

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON, Engine OFF.

2. Review and record Tech 2 Failure Records data,

then clear the DTCs.

3. Operate the vehicle within the Failure Records

conditions as noted.

4. Using the Tech 2, monitor ”DTC” info for DTC

P0480.

Does the Tech 2 indicate that DTC P0480 ”Ran and

Passed?” —

Refer to

Diagnostic

Aids Go to Step 3

31. Ignition OFF.

2. Remove the Low Fan Relay from the Underhood

Electrical Center.

3. Ignition OFF.

4. Using a Digital Voltmeter (DVM), check for voltage

on the ”ELEC. FAN” Fuse pin of the Low fan Relay

connector.

Does the DVM read the following value? 12 Volts Go to Step 4 Go to Step 3

41. Ignition ON.

2. Using a DVM, check for voltage on the ”ENGINE

FAN” Fuse pin of the Low Fan Relay connector.

Does the DVM read the following value? 12 Volts Go to Step 6 Go to Step 5

5Check the suspect circuit between the Low Fan Relay

connector and Fuse for the following conditions:

DA short to ground

DAn open circuit

DA short to voltage

Was the problem found? — Verify repair —

61. Ignition OFF.

2. Disconnect the Engine Control Module (ECM)

connectors from the ECM.

3. Check the Low Fan Relay control circuit between

the ECM and Underhood Electrical Center for the

following conditions:

DA short to ground

DAn open circuit

DA short to voltage

Was the problem found? — Verify repair Go to Step 7

71. Reinstall the High Fan Relay.

2. Using a fused jumper, ground the High Fan Relay

control circuit at the ECM connector.

3. Ignition ON, Engine OFF.

Does the fan run at High speed? —Go to Step 9 Go to Step 8

Step NoYesValue(s)Action

8Replace the High Fan Relay.

Is the action complete? — Verify repair —

9Replace the ECM.

Verify repair. ———

DIAGNOSTIC TROUBLE CODE (DTC) P0502 VEHICLE SPEED SENSOR (VSS)

CIRCUIT LOW INPUT

D06RX125

Circuit Description

The vehicle speed sensor has a magnet rotated by the

transmission output shaft. Attached to the sensor is a hall

effect circuit that interacts with the magnetic field created

by the rotating magnet. A 12–volt operating supply for the

speed sensor hall circuit is supplied from the meter fuse.

The VSS pulses to ground the 5–volt signal sent from the

engine control module (ECM) on the reference circuit.

The ECM interprets vehicle speed by the number of

pulses to ground per second on the reference circuit.

DTC P0502 is a type B code.

Conditions for Setting the DTC

DEngine is running.

DEngine coolant temperature is above 60°C (140°F).

DSystem voltage is between 10 and 16 volts.

When the above conditions are met, one of the following

tests will run:

Decel Test

DMAP is less than 35 kPa.

DThrottle Position is less than 0.8%.

DEngine Speed is between 1500 RPM and 3500 RPM.

The Decel Test will fail if vehicle speed is less than 8 km/h

(5mph).

The Decel T est will pass if vehicle speed is greater than 24

km/h (15mph).

Power Test

DMAP is greater than 50 kPa.

DThrottle Position is between 25% and 70%.

DEngine Speed is between 2700 RPM and 4400 RPM.

The Power T est will fail if vehicle speed is less than 8 km/h

(5 mph).

The Power Test will pass if vehicle speed is greater than

8km/h (5mph) without any VSS DTC’s present, or if

vehicle speed is greater than 49 km/h (30mph) with VSS

Diagnostic Trouble Codes present.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the second time the fault is detected.

DBase shift logic on RPM only.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0502 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0502 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

DPoor connection at ECM: Inspect harness connectors

for backed out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal to wire connection.

DDamaged harness: Inspect the wiring harness to the

EVAP vent solenoid, the EVAP purge solenoid, and the

fuel tank pressure sensor for an intermittent open or

intermittent short circuit.

DTC P0502 – VSS Circuit Low Input

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition OFF.

2. Disconnect the VSS connector.

3. Using a test light to battery +, probe the connector

ground wire.

Did the light illuminate? —Go to Step 4 Go to Step 3

3Repair the open in the sensor ground circuit. — Verify repair —

41. Ignition ON, sensor disconnected.

2. Using a Digital Voltmeter (DVM), measure at the

VSS connector between ground and voltage

supply.

Was the measurement near the specified value? Battery

voltage Go to Step 6 Go to Step 5

5Repair the open or short to ground in the VSS sensor

circuit. —Verify repair —

61. Ignition OFF.

2. Check the BLU/BLK wire between the VSS sensor

connector and the ECM for the following conditions:

DAn open circuit

DA short to ground

Was the faulty condition located? — Verify repair Go to Step 9

7Using a DVM, measure the resistance between the

VSS sensor body and transmission case (ground).

Is the resistance above the specified value? 10 K WVerify repair Go to Step 9

81. Remove the VSS from the transmission case.

2. Visually inspect the VSS for damage.

Does the VSS appear to be OK? — Verify repair —

9Replace the VSS. — Verify repair —

10 Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0506 IDLE CONTROL SYSTEM RPM

LOWER THAN EXPECTED

D06RX112

Circuit Description

The engine control module (ECM) controls engine idle

speed by adjusting the position of the idle air control (IAC)

motor pintle. The IAC is a bi–directional stepper motor

driven by two coils. The ECM applies current to the IAC

coils in steps (counts) to extend the IAC pintle into a

passage in the throttle body to decrease air flow. The

ECM reverses the current to retract the pintle, increasing

air flow. This method allows highly accurate control of idle

speed and quick response to changes in engine load. If

the ECM detects a condition where too low of an idle

speed is present and the ECM is unable to adjust idle

speed by increasing the IAC counts, DTC P0506 will set,

indicating a problem with the idle control system. DTC

P0506 is a type B code.

Conditions for Setting the DTC

DNo intrusive tests being run.

DEngine run time is more than 125 seconds.

DNo TPS, VSS, ECT, EGR, MAP, IAT, low voltage, fuel

system or canister purge Diagnostic Trouble Codes

are set.

DBarometric pressure is greater than 72.7 kPa.

DCanister purge duty cycle is above 0%.

DEngine coolant temperature (ECT) is above 50°C

(122°F).

DIntake air temperature above –40°C (–40°F).

DMAP is less than 60 kPa.

DIgnition voltage is between 9.5 volts and 16 volts.

DThe throttle is closed.

DAll conditions are met for 10 seconds.

DEngine speed is at least 100 RPM lower than desired

idle, based upon ECM expectations.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DDiagnostic Trouble Code P0506 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM or IAC motor – Inspect

harness connectors for backed–out terminals,

improper mating, broken locks, improperly formed or

damaged terminals, and poor terminal–to–wire

connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive,

and open circuits.

DRestricted air intake system – Check for a possible

collapsed air intake duct, restricted air filter element, or

foreign objects blocking the air intake system.

DThrottle body – Check for objects blocking the IAC

passage or throttle bore, excessive deposits in the IAC

passage and on the IAC pintle, and excessive deposits

in the throttle bore and on the throttle plate.

DLarge vacuum leak – Check for a condition that causes

a large vacuum leak, such as an incorrectly installed or

faulty PCV valve or brake booster hose disconnected.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic Trouble Code to

be set occurs. This may assist in diagnosing the

condition.

DTC P0506 – Idle Control System RPM Lower Than Expected

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Are any other Diagnostic Trouble Codes set?

—

Go to other

Diagnostic

Trouble Code

first Go to Step 3

31. Start the engine.

2. T urn all accessories OFF (A/C, rear defroster, etc.)

3. Using a T ech 2, command RPM up to 1500, down to

500, and then up to 1500 while monitoring ”Engine

Speed” on the Tech 2.

Does the ”Engine Speed” remain within the specified

value of ”Desired Idle” for each RPM command? +/–50 RPM

No trouble

found. Go to

Diagnostic

Aids Go to Step 4

41. Check the following circuits for an open, short to

voltage, short to ground, or poor connection at the

PCM:

DIAC ”A” low

DIAC ”A” high

DIAC ”B” low

DIAC ”B” high

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 5

5Visually/physically inspect for the following conditions:

DThrottle body tampering (adjustment screw plug

removed).

DRestricted air intake system. Check for a possible

collapsed air intake duct, restricted air filter

element, or foreign objects blocking the air intake

system.

DThrottle body. Check for objects blocking the IAC

passage or throttle bore, excessive deposits in

the IAC passage and on the IAC pintle, and

excessive deposits in the throttle bore and on the

throttle plate.

Do any of the above require a repair? —

Refer to

appropriate

section for

on–vehicle

service Go to Step 6

61. Check for a poor connection at the IAC harness

connector.

2. If a problem is found, replace faulty terminals as

necessary.

Was a problem found? — Verify repair Go to Step 7

Step NoYesValue(s)Action

7Using a Digital Voltmeter (DVM), check the IAC valve

solenoids (A and B) for the following conditions:

DAn open circuit

DA short to ground (the IAC body)

DA short together

Was the problem found? —Go to Step 8 Go to Step 9

8Replace the IAC valve.

Is the action complete? — Verify repair —

9Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0507 IDLE CONTROL SYSTEM RPM

HIGHER THAN EXPECTED

D06RX112

Circuit Description

The engine control module (ECM) controls engine idle

speed by adjusting the position of the idle air control (IAC)

motor pintle. The IAC is a bi–directional stepper motor

driven by two coils. The ECM applies current to the IAC

coils in steps (counts) to extend the IAC pintle into a

passage in the throttle body to decrease air flow. The

ECM reverses the current to retract the pintle, increasing

air flow. This method allows highly accurate control of idle

speed and quick response to changes in engine load. If

the ECM detects a condition where too high of an idle

speed is present and the ECM is unable to adjust idle

speed by increasing the IAC counts, Diagnostic Trouble

Code P0507 will set, indicating a problem with the idle

control system. DTC P0507 is a type B code.

Conditions for Setting the DTC

DNo intrusive tests being run.

DEngine run time is more than 125 seconds.

DNo TPS, VSS, ECT, EGR, MAP, IAT, low voltage, fuel

system or canister purge DTCs are set.

DBarometric pressure is greater than 72.7 kPa.

DCanister purge duty cycle is above 0%.

DIntake air temperature above –40°C (–40°F).

DEngine coolant temperature (ECT) is above 50°C

(122°F).

DIgnition voltage is between 9.5 volts and 16 volts.

DThe throttle is closed.

DAll conditions are met for 10 seconds.

DMAP is less than 60 kPa.

DEngine speed is at least 200 RPM lower than desired

idle, based upon PCM’s expectations.

Action Taken When the DTC Sets

DThe PCM will illuminate the malfunction indicator lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe PCM will store conditions which were present

when the DTC was set as Freeze Frame and in the

Failure Records data.

Conditions for Clearing the MIL/DTC

DThe PCM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0507 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0507 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at PCM or IAC motor – Inspect

harness connectors for backed–out terminals,

improper mating, broken locks, improperly formed or

damaged terminals, and poor terminal–to–wire

connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive,

and open circuits.

DVacuum leak – Check for a condition that causes a

vacuum leak, such as disconnected or damaged

hoses, leaks at EGR valve and EGR pipe to intake

manifold, leak at the throttle body, a faulty or incorrectly

installed PCV valve, leaks at the intake manifold, etc.

DThrottle body – Check for sticking throttle plate. Also

inspect the IAC passage for deposits or objects which

will not allow the IAC pintle to fully extend or properly

seat.

If Diagnostic Trouble Code P0507 cannot be duplicated,

reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic Trouble Code to

be set occurs. This may assist in diagnosing the

condition.

DTC P0507 – Idle Control System RPM Higher Than Expected

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Are any other Diagnostic Trouble Codes set?

—

Go to other

Diagnostic

Trouble Code

first Go to Step 3

31. Start the engine.

2. T urn all accessories OFF (A/C, rear defroster, etc.)

3. Using a T ech 2, command RPM up to 1500, down to

500, and then up to 1500 while monitoring ”Engine

Speed” on the Tech 2.

Does the ”Engine Speed” remain within the specified

value of ”Desired Idle” for each RPM command? +/–50 RPM

No trouble

found. Go to

Diagnostic

Aids Go to Step 4

41. Check the following circuits for an open, short to

voltage, short to ground, or poor connection at the

PCM:

DIAC ”A” low

DIAC ”A” high

DIAC ”B” low

DIAC ”B” high

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 5

5Visually/physically inspect for the following conditions:

DVacuum leaks

DThrottle body tampering (adjustment screw plug

removed).

DThrottle plate or throttle shaft for binding.

DAccelerator and cruise control cables for being

mis–adjusted or for binding.

DFaulty, missing, or incorrectly installed PCV

valve.

Do any of the above require a repair? —

Refer to

appropriate

section for

on–vehicle

service Go to Step 6

61. Check for a poor connection at the IAC harness

connector.

2. If a problem is found, replace faulty terminals as

necessary.

Was a problem found? — Verify repair Go to Step 7

Step NoYesValue(s)Action

7Using a Digital Voltmeter (DVM), check the IAC valve

solenoids (A and B) for the following conditions:

DAn open circuit

DA short to ground (the IAC body)

DA short together

Was the problem found? —Go to Step 8 Go to Step 9

8Replace the IAC valve.

Is the action complete? — Verify repair —

9Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0563 SYSTEM VOLTAGE HIGH

D06RX127

Circuit Description

The engine control module (ECM) monitors the system

voltage on the ignition feed terminals to the ECM. A

system voltage Diagnostic Trouble Code will set

whenever the voltage is above a calibrated value. DTC

P0563 is a type A code.

Conditions for Setting the DTC

DIgnition ON.

DSystem voltage is above 16.

Action Taken When the DTC Sets

DThe ECM will not illuminate the malfunction indicator

lamp (MIL) for the first time the malfunction is detected.

DThe ECM will store as Failure Records conditions

which were present when the Diagnostic Trouble Code

was set. This information will not be stored as Freeze

Frame data.

Conditions for Clearing the MIL/DTC

DA history Diagnostic Trouble Code P0563 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0563 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for a faulty charging system components.

DTC P0563 System Voltage High

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition OFF, engine OFF.

2. Using a Digital Voltmeter (DVM), measure the

battery voltage at the battery.

Is the battery voltage greater than the specified value? 16 V Go to Step 3 Go to Step 4

31. Charge the battery and clean the battery terminals.

2. Clean the battery ground cable connection if

corrosion is indicated.

Is the battery voltage greater than the specified value? 16 V Replace

battery Go to Step 4

41. Turn OFF all the accessories.

2. Install the Tech 2.

3. Select the ignition voltage parameter on the data

list.

4. Start the engine and raise the engine speed to 2000

RPM.

Is the voltage above the specified value? 16 V Go to Step 5 Go to Step 6

5Replace or repair the generator (see Charging

System).

Is a malfunction present? — Verify repair —

6Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P0601 INTERNAL CONTROL MODULE

MEMORY CHECK SUM ERROR

014RX002

Circuit Description

The engine control module (ECM) used in this vehicle

utilizes an electrically erasable programmable read–only

memory (EEPROM). The EEPROM contains program

information and the calibrations required for engine,

transmission, and powertrain diagnostics operation.

Unlike the PROM used in past applications, the EEPROM

is not replaceable.

If the ECM detects a check sum error then DTC P0601 will

set. DTC P0601 is a type A code.

Conditions for Setting the DTC

DThe ECM detects an internal program fault (check sum

error).

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the malfunction is detected.

DThe ECM will store conditions which were present

when the Diagnostic Trouble Code was set in the

Failure Records data only.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P0601 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P0601 can be cleared by

using the Scan Tool’s ”Clear Info” function.

DTC P0601 Internal Control Module Memory Check Sum Error

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Replace the ECM.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P1106 MANIFOLD ABSOLUTE

PRESSURE (MAP) SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE

D06RX114

Circuit Description

The manifold absolute pressure (MAP) sensor responds

to changes in intake manifold pressure. The MAP sensor

signal voltage to the ECM varies from below 2 volts at idle

(low manifold pressure) to above 4 volts with the ignition

ON, engine not running or at wide–open throttle (high

manifold pressure).

A ”speed density” method of determining engine load is

used on the 2.2L engine. This is calculated using inputs

from the MAP sensor, RPM, the CKP sensor, and the

Intake Air Temperature (IAT) sensor. The MAP sensor is

the main sensor used in this calculation, and measuring

engine load is its main function.

The MAP sensor is also used to determine manifold

pressure changes while the linear EGR flow test

diagnostic is being run, to determine engine vacuum level

for some other diagnostics and to determine barometric

pressure (BARO). Refer to Diagnostic Trouble Code 401.

The ECM compares the MAP sensor signal to a

calculated MAP based on throttle position and various

other engine load factors. If the ECM detects a MAP

signal that is intermittently above the calculated value,

Diagnostic Trouble Code P1106 will set. DTC P1106 is a

type D code.

Conditions for Setting the DTC

DNo TP sensor Diagnostic Trouble Codes are present.

DEngine is running.

DThrottle angle is below 2.7% if engine speed is below

1000 RPM.

DThrottle angle is below 10% if engine speed is above

1000 RPM.

DThe MAP sensor indicates an intermittent manifold

absolute pressure above 90 kPa for a total of

approximately 5 seconds over a 16–second period of

time.

Action Taken When the DTC Sets

DThe ECM will not illuminate the malfunction indicator

lamp (MIL).

DThe ECM will store conditions which were present

when the Diagnostic Trouble Code was set as Failure

Records data only. This information will not be stored

as Freeze Frame data.

Conditions for Clearing the DTC

DA history Diagnostic Trouble Code P1106 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P1106 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DLeaking or plugged vacuum supply line to the MAP

sensor.

DInspect ECM harness connectors for backed–out

terminals, improper mating, broken locks, improperly

formed or damaged terminals, and poor

terminal–to–wire connection.

DThe MAP sensor shares a 5 Volt Reference with the TP

sensor and Fuel Pressure sensor.

If these codes are also set, it could indicate a

problem with the 5 Volt reference circuit.

DThe MAP sensor shares a ground with the TP sensor

and Fuel Pressure sensor.

DInspect the wiring harness for damage; shorts to

ground, shorts to battery positive, and open circuits. If

the harness appears to be OK, observe the MAP

display on the Tech 2 while moving connectors and

wiring harnesses related to the sensor. A change in the

display will indicate the location of the fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic Trouble Code to

be set occurs. This may assist in diagnosing the

condition.

DTC P1106 – MAP Sensor Circuit Intermittent High Voltage

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Is DTC P0108 also set?

—

Go to DTC

P0108 chart

first Go to Step 3

3Are Diagnostic Trouble Code P0463, and/or P1121

also set? —Go to Step 6 Go to Step 4

4Check for a poor sensor ground circuit terminal

connection at the MAP sensor.

Was a problem found? —Go to Step 9 Go to Step 5

5Check the MAP signal circuit between the MAP sensor

connector and the ECM for an intermittent short to

voltage.

Was a problem found? —Go to Step

10 Go to Step 8

6Check for an intermittent short to voltage on the 5 volt

reference circuit between the ECM and the following

components:

DFuel Tank Vapor Pressure Sensor

DTP sensor

Was a problem found? —Go to Step

10 Go to Step 7

7Check for a poor sensor ground circuit terminal

connection at the ECM.

Was a problem found? —Go to Step 9 Go to Step 8

8Check for an intermittent open or a faulty splice in the

sensor ground circuit.

Was a problem found? (if no, start with the diagnosis

chart for other sensors in the circuit and see if 5V

returns.) —Go to Step

Refer to

Diagnostic

Aids

9Replace the faulty harness connector terminal for the

sensor ground circuit.

Is the action complete? — Verify repair —

10 Locate and repair the intermittent open/short circuit in

the wiring harness as necessary.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P1107 MANIFOLD ABSOLUTE

PRESSURE (MAP) SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

D06RX114

Circuit Description

The manifold absolute pressure (MAP) sensor responds

to changes in intake manifold pressure. The MAP sensor

signal voltage to the engine control module (ECM) varies

from below 2 volts at idle (low manifold pressure) to above

4 volts with the ignition ON, engine not running or at

wide–open throttle (high manifold pressure).

A ”speed density” method of determining engine load is

used on the 2.2l engine. This is calculated using inputs

from the MAP sensor, the CKP sensor, and the Intake Air

Temperature (IAT) sensor. The MAP sensor is the main

sensor used in this calculation, and measuring engine

load is its main function.

The MAP sensor is also used to determine manifold

pressure changes while the linear EGR flow test

diagnostic is being run, to determine engine vacuum level

for some other diagnostics and to determine barometric

pressure (BARO). Refer to DTC P0401.

The ECM compares the MAP sensor signal to a

calculated MAP based on throttle position and various

other engine load factors. If the ECM detects a MAP

signal that is intermittently below the calculated value,

DTC P1107 will set. DTC P1107 is a type D code.

Conditions for Setting the DTC

DNo TP sensor Diagnostic Trouble Codes are present.

DEngine is running.

DThrottle angle is below 0% if engine speed is less than

1300 RPM.

DThrottle angle is below 5% if engine speed is above

1300 RPM.

DThe MAP sensor indicates an intermittent manifold

absolute pressure above 11 kPa for a total of

approximately 5 seconds over a 16–second period of

time.

Action Taken When the DTC Sets

DThe ECM will not illuminate the malfunction indicator

lamp (MIL).

DThe ECM will store conditions which were present

when the Diagnostic Trouble Code was set as Failure

Records data only. This information will not be stored

as Freeze Frame data.

Conditions for Clearing the DTC

DA history Diagnostic Trouble Code P1107 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P1107 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DThe MAP sensor shares a 5 Volt Reference with the TP

sensor and Fuel Pressure sensor.

If these codes are also set, it could indicate a

problem with the 5 Volt reference circuit.

DThe MAP sensor shares a ground with the TP sensor

and Fuel Pressure sensor.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive,

and open circuits. If the harness appears to be OK,

observe the MAP display on the Tech 2 while moving

connectors and wiring harnesses related to the sensor.

A change in the display will indicate the location of the

fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic Trouble Code to

be set occurs. This may assist in diagnosing the

condition.

DTC P1107 – MAP Sensor Circuit Intermittent Low Voltage

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Is DTC P0107 also set?

—

Go to DTC

P0107 chart

first Go to Step 3

3Is DTC P1122 and/or P0462 also set? —Go to Step 6 Go to Step 4

4Check for a poor 5 volt reference circuit terminal

connection at the MAP sensor.

Was a problem found? —Go to Step 9 Go to Step 5

5Check the MAP signal circuit between the MAP sensor

connector and the PCM for an intermittent open or

short to ground.

Was a problem found? —Go to Step

10 Go to Step 8

6Check for an intermittent short to ground on the 5 volt

reference circuit between the ECM and the following

components:

DFuel Tank Vapor Pressure Sensor

DTP sensor

Was a problem found? —Go to Step

10 Go to Step 7

7Check for a poor 5 volt reference terminal connection at

the ECM.

Was a problem found? —Go to Step 9 Go to Step 8

8Check for an intermittent open or a faulty splice in the 5

volt reference circuit.

Was a problem found? (if no, start with the diagnosis

chart for other sensors in the circuit and see if 5V

returns.) —Go to Step

Refer to

Diagnostic

Aids

9Replace the faulty harness connector terminal for the 5

volt reference circuit and/or the MAP signal circuit as

necessary.

Is the action complete? — Verify repair —

10 Repair the intermittent open/short circuit in the wiring

harness as necessary.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P1111 INTAKE AIR TEMPERATURE (IAT)

SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE

D06RX117

Circuit Description

The intake air temperature (IAT) sensor is a thermistor

which measures the temperature of the air entering the

engine. The engine control module (ECM) applies 5 volts

through a pull–up resistor to the IAT sensor. When the

intake air is cold, the sensor resistance is high and the

ECM will monitor a high signal voltage on the IAT signal

circuit. If the intake air is warm, the sensor resistance is

lower causing the ECM to monitor a lower voltage.

Diagnostic Trouble Code P1111 will set when the ECM

intermittently detects an excessively high signal voltage

on the intake air temperature sensor signal circuit. DTC

P1111 is a type D code.

Conditions for Setting the DTC

DThe engine has been running for over 4 minutes.

DVehicle speed is less than 32 km/h (20 mph).

DEngine coolant temperature is above 60°C (140°F).

DCalculated air flow is less than 20g/second.

DIAT signal voltage indicates an intake air temperature

intermittently less than –39°C (–38°F) (4.94 volts) for

approximately 2.5 seconds over a 25–second period of

time.

Action Taken When the DTC Sets

DThe ECM will substitute a default value for intake air

temperature.

DThe ECM will store conditions which were present

when the Diagnostic Trouble Code set as Failure

Records data only. This information will not be stored

as Freeze Frame data.

DDiagnostic Trouble Code P1111 does not illuminate the

MIL.

Conditions for Clearing the DTC

DA history DTC P1111 will clear after 40 consecutive

warm–up cycles have occurred without a fault.

DDiagnostic Trouble Code P1111 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive,

and open circuits. If the harness appears to be OK,

observe the IAT display on the Tech 2 while moving

connectors and wiring harnesses related to the IAT

sensor. A change in the IAT display will indicate the

location of the fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic T rouble Code to

be set occurs. This may assist in diagnosing the

condition.

Intake Air Temperature Sensor

°C°FW

Temperature vs. Resistance Values (approximate)

100 212 177

80 176 332

60 140 667

45 113 1188

35 95 1802

25 77 2796

15 59 4450

5 41 7280

–5 23 12300

–15 5 21450

–30 –22 52700

–40 –40 100700

DTC P1111 – IAT Sensor Circuit Intermittent High Voltage

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Is DTC P0113 also set?

—

Go to DTC

P0113 chart

first Go to Step 3

31. Check for a poor sensor ground circuit terminal

connection at the IAT sensor.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 4

41. Check for a poor IAT signal circuit terminal

connection at the IAT sensor.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 5

51. Check the IA T signal circuit between the IA T sensor

connector and the ECM for an intermittent open.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 6

61. Check the IA T signal circuit between the IA T sensor

connector and the ECM for an intermittent short to

voltage.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 7

71. Check for a poor sensor ground circuit terminal

connection at the ECM.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 8

81. Check for an intermittent open or a faulty splice in

the sensor ground circuit.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair

Refer to

Diagnostic

Aids

DIAGNOSTIC TROUBLE CODE (DTC) P1112 INTAKE AIR TEMPERATURE (IAT)

SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

D06RX117

Circuit Description

The intake air temperature (IAT) sensor is a thermistor

which measures the temperature of the air entering the

engine. The engine control module (ECM) applies 5 volts

through a pull–up resistor to the IAT sensor. When the

intake air is cold, the sensor resistance is high and the

ECM will monitor a high signal voltage on the IAT signal

circuit. If the intake air is warm, the sensor resistance

becomes lower, causing the ECM to monitor a lower

voltage. Diagnostic Trouble Code P1 1 12 will set when the

ECM intermittently detects an excessively low signal

voltage on the intake air temperature sensor signal

circuit. DTC P1112 is a type D code.

Conditions for Setting the DTC

DThe engine has been running for over 2 minutes.

DVehicle speed is greater than 48 km/h (30 mph).

DIAT signal voltage is greater than 148°C (298°F)

(about 0.10 volt) for a total of 2.5 seconds over a

25–second period of time.

Action Taken When the DTC Sets

DThe ECM will not illuminate the malfunction indicator

lamp (MIL).

DThe ECM will store conditions which were present

when the Diagnostic Trouble Code set as Failure

Records data only. This information will not be stored

as Freeze Frame data.

DThe ECM will substitute a default value for intake air

temperature.

Conditions for Clearing the DTC

DA history Diagnostic Trouble Code P1112 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P1112 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive,

and open circuits. If the harness appears to be OK,

observe the IAT display on the Tech 2 while moving

connectors and wiring harnesses related to the IAT

sensor. A change in the IAT display will indicate the

location of the fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic T rouble Code to

be set occurs. This may assist in diagnosing the

condition.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart.

2.Verifies that the fault is present.

3.If DTC P1112 can be repeated only by duplicating

the Failure Records conditions, refer to the

”Temperature vs. Resistance Value Chart.”

The chart may be used to test the IAT sensor at

various temperatures to evaluate the possibility of

a ”shifted” sensor that may be shorted above or

below a certain temperature. If this is the case,

replace the IAT sensor.

Intake Air Temperature Sensor

°C°FW

Temperature vs. Resistance Values (approximate)

100 212 177

80 176 332

60 140 667

45 1131188

35 95 1802

25 77 2796

15 59 4450

5 41 7280

–5 23 12300

–15 5 21450

–30 –22 52700

–40 –40 100700

DTC P1112 – IAT Sensor Circuit Intermittent Low Voltage

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Is DTC P0112 also set?

—

Go to DTC

P0112 chart

first Go to Step 3

31. Check the IA T signal circuit between the IA T sensor

connector and the PCM for an intermittent short to

ground.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair

Refer to

Diagnostic

Aids

DIAGNOSTIC TROUBLE CODE (DTC) P1114 ENGINE COOLANT

TEMPERATURE (ECT) SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

D06RX117

Circuit Description

The engine coolant temperature (ECT) sensor is a

thermistor mounted in the engine coolant stream. The

engine control module (ECM) applies a voltage (about 5.0

volts) through a pull–up resistor to the ECT signal circuit.

When the engine coolant is cold, the sensor (thermistor)

resistance is high, therefore the ECM will measure a high

signal voltage. As the engine coolant warms, the sensor

resistance becomes less, and the ECT signal voltage

measured at the ECM drops. With a fully warmed up

engine, the ECT signal voltage should measure about 1.5

to 2.0 volts. If the ECM detects an ECT signal that is

intermittently below the range of the ECT sensor,

Diagnostic Trouble Code P1114 will set. DTC P1114 is a

type D code.

Conditions for Setting the DTC

DEngine run time longer than 2 minutes.

DThe ECT sensor signal is intermittently greater than

150°C (302°F) (about 0.10 volt) for a total of 10

seconds over a 100–second period.

Action Taken When the DTC Sets

DThe ECM will not illuminate the malfunction indicator

lamp (MIL).

DThe ECM will store conditions which were present

when the Diagnostic Trouble Code set as Failure

Records data only. This information will not be stored

as Freeze Frame data.

Conditions for Clearing the DTC

DA history Diagnostic Trouble Code P1114 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P1114 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive,

and open circuits. If the harness appears to be OK,

observe the ECT display on the Tech 2 while moving

connectors and wiring harnesses related to the ECT

sensor. A change in the ECT display will indicate the

location of the fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic T rouble Code to

be set occurs. This may assist in diagnosing the

condition.

Engine Coolant Temperature Sensor

°C°FW

Temperature vs. Resistance Values (approximate)

100 212 177

80 176 332

60 140 667

45 1131188

35 95 1802

25 77 2796

15 59 4450

5 41 7280

–5 23 12300

–15 5 21450

–30 –22 52700

–40 –40 100700

DTC P1114 – ECT Sensor Circuit Intermittent Low Voltage

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Is DTC P0117 also set? —Go to DTC

P0117 first Go to Step 3

31. Check the ECT signal circuit between the ECT

sensor connector and the ECM for an intermittent

short to ground.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair

Refer to

Diagnostic

Aids

DIAGNOSTIC TROUBLE CODE (DTC) P1115 ENGINE COOLANT

TEMPERATURE (ECT) SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE

D06RX117

Circuit Description

The engine coolant temperature (ECT) sensor is a

thermistor mounted in the engine coolant stream. The

engine control module (ECM) applies a voltage (about 5.0

volts) through a pull–up resistor to the ECT signal circuit.

When the engine coolant is cold, the sensor (thermistor)

resistance is high, therefore the ECM will measure a high

signal voltage. As the engine coolant warms, the sensor

resistance becomes less, and the ECT signal voltage

measured at the ECM drops. With a fully warmed up

engine, the ECT signal voltage should measure about 1.5

to 2.0 volts. If the PCM detects an ECT signal that is

intermittently above the range of the ECT sensor,

Diagnostic Trouble Code P1115 will set. Diagnostic

Trouble Code P1115 is a type D code.

Conditions for Setting the DTC

DEngine run time longer than 180 seconds.

DThe ECT sensor signal is intermittently greater than

–39°C (–38°F) (4.94 volts) for a total of 10 seconds

over a 100–second period.

Action Taken When the DTC Sets

DThe ECM will not illuminate the malfunction indicator

lamp (MIL).

DThe ECM will store conditions which were present

when the Diagnostic Trouble Code set as Failure

Records data only. This information will not be stored

as Freeze Frame data.

Conditions for Clearing the DTC

DA history Diagnostic Trouble Code P1115 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P1115 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive,

and open circuits. If the harness appears to be OK,

observe the ECT display on the Tech 2 while moving

connectors and wiring harnesses related to the ECT

sensor. A change in the ECT display will indicate the

location of the fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the Diagnostic T rouble Code to

be set occurs. This may assist in diagnosing the

condition.

Engine Coolant Temperature Sensor

°C°FW

Temperature vs. Resistance Values (approximate)

100 212 177

80 176 332

60 140 667

45 113 1188

35 95 1802

25 77 2796

15 59 4450

5 41 7280

–5 23 12300

–15 5 21450

–30 –22 52700

–40 –40 100700

DTC P1115 ECT Sensor Circuit Intermittent High Voltage

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Is DTC P0118 also set? —Go to DTC

P0118 first Go to Step 3

31. Check for a poor sensor ground circuit terminal

connection at the ECT sensor.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 4

41. Check for a poor ECT signal circuit terminal

connection at the ECT sensor.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 5

51. Check the ECT signal circuit between the ECT

sensor connector and the ECM for an intermittent

open.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 6

61. Check the ECT signal circuit between the ECT

sensor connector and the ECM for an intermittent

short to voltage.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 7

71. Check for a poor sensor ground circuit terminal

connection at the ECM.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 8

81. Check for an intermittent open or a faulty splice in

the sensor ground circuit.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair

Refer to

Diagnostic

Aids

DIAGNOSTIC TROUBLE CODE (DTC) P1121 THROTTLE POSITION (TP)

SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE

D06RX118

Circuit Description

The throttle position (TP) sensor circuit provides a voltage

signal that changes relative to the throttle blade angle.

The signal voltage will vary from less than 1 volt at closed

throttle to more than 4 volts at wide open throttle (WOT).

The TP signal is used by the engine control module

(ECM) for fuel control and for most of the ECM controlled

outputs. If the ECM detects a TP signal that is

intermittently above the range of the TP sensor,

Diagnostic Trouble Code P1 121 will be set. DTC P1121 is

a type D code.

Conditions for Setting the DTC

DThe ignition is ON.

DTP sensor indicates a throttle position voltage

intermittently greater than 4.88 volts for a total of 0.15

seconds over a 1.5–second period.

Action Taken When the DTC Sets

DThe ECM will not illuminate the malfunction indicator

lamp (MIL).

DThe ECM will store conditions which were present

when the Diagnostic Trouble Code set as Failure

Records data only. This information will not be stored

as Freeze Frame data.

Conditions for Clearing the DTC

DA history Diagnostic Trouble Code P1121 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P1121 can be cleared by

using the Scan Tool’s ”Clear Info” function or by

disconnecting the ECM battery feed.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect the harness

connectors for backed–out terminals, improper

mating, broken locks, improperly formed or damaged

terminals, and poor terminal–to–wire connection.

DThe TP sensor shares a 5 V olt reference with the MAP

sensor and Fuel Pressure sensor.

If these codes are also set, it could indicate a

problem with the 5 Volt reference circuit or

components itself.

DThe TP sensor share a ground with the MAP and the

Fuel Pressure sensor.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive,

and open circuits. If the harness appears to be OK,

observe the throttle position display on the T ech 2 while

moving connectors and wiring harnesses related to the

TP sensor. A change in the display will indicate the

location of the fault.

If Diagnostic Trouble Code P1121 cannot be duplicated,

reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help to determine how often

the condition that caused the Diagnostic Trouble Code to

be set occurs. This may assist in diagnosing the

condition.

DTC P1121 – TP Sensor Circuit Intermittent High Voltage

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Is Diagnostic Trouble Code P0123 also set? —Go to DTC

P0123 first Go to Step 3

3Is Diagnostic Trouble Code P1106 also set? —Go to Step 6 Go to Step 4

4Check for a poor sensor ground circuit terminal

connection at the TP sensor.

Was a problem found? —Go to Step 9 Go to Step 5

5Check the TP signal circuit between the TP sensor

connector and the ECM for an intermittent short to

voltage.

Was a problem found? —Go to Step

10 Go to Step 8

6Check for an intermittent short to voltage on the 5 volt

reference circuit between the ECM and the following

components:

DMAP Sensor

Was a problem found? —Go to Step

10 Go to Step 7

7Check for a poor sensor ground terminal connection at

the ECM.

Was a problem found? —Go to Step 9 Go to Step 8

8Check for an intermittent open or a faulty splice in the

sensor ground circuit.

Was a problem found? (if no, start with the diagnosis

chart for other sensors in the circuit and see if 5V

returns.) —Go to Step

Refer to

Diagnostic

Aids

9Replace the faulty harness connector terminal for the

sensor ground circuit.

Is the action complete? — Verify repair —

10 Repair intermittent open/short circuit in wiring harness

as necessary.

Is the action complete? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P1122 THROTTLE POSITION (TP)

SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

D06RX118

Circuit Description

The throttle position (TP) sensor circuit provides a voltage

signal that changes relative to the throttle blade angle.

The signal voltage will vary from less than 1 volt at closed

throttle to more than 4 volts at wide open throttle (WOT).

The TP signal is used by the engine control module

(ECM) for fuel control and for most of the ECM controlled

outputs. If the ECM detects a TP signal that is

intermittently above the range of the TP sensor,

Diagnostic Trouble Code P1 122 will be set. DTC P1122 is

a type D code.

Conditions for Setting the DTC

DThe ignition is ON.

DTP sensor indicates a throttle position signal

intermittently less than 0.10 volt for a total of 0.15

seconds over a 1.5–second period.

Action Taken When the DTC Sets

DThe ECM will not illuminate the malfunction indicator

lamp (MIL).

DThe ECM will store conditions which were present

when the Diagnostic Trouble Code set as Failure

Records data only. This information will not be stored

as Freeze Frame data.

Conditions for Clearing the DTC

DA history Diagnostic Trouble Code P1122 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P1122 can be cleared by

using the Scan Tool’s ”Clear Info” function or by

disconnecting the ECM battery feed.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect the harness

connectors for backed–out terminals, improper

mating, broken locks, improperly formed or damaged

terminals, and poor terminal–to–wire connection.

DDamaged harness – Inspect the wiring harness for

damage; shorts to ground, shorts to battery positive,

and open circuits. If the harness appears to be OK,

observe the throttle position display on the T ech 2 while

moving connectors and wiring harnesses related to the

TP sensor. A change in the display will indicate the

location of the fault.

DThe TP sensor shares a 5 V olt reference with the MAP

sensor and Fuel Pressure sensor.

If these codes are also set, it could indicate a

problem with the 5 Volt reference circuit or

components itself.

DThe TP sensor share a ground with the MAP and the

Fuel Pressure sensor.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help to determine how often

the condition that caused the Diagnostic Trouble Code to

be set occurs. This may assist in diagnosing the

condition.

DTC P1122 – TP Sensor Circuit Intermittent Low Voltage

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Is DTC P0122 also set? —Go to DTC

P0122 first Go to Step 3

3Is DTC P1107 also set? —Go to Step 6 Go to Step 4

4Check for a poor 5 volt reference circuit or TP signal

circuit terminal connection at the TP sensor.

Was a problem found? —Go to Step 9 Go to Step 5

5Check the TP signal circuit between the TP sensor

connector and the ECM for an intermittent short to

ground.

Was a problem found? —Go to Step

10 Go to Step 8

6Check for an intermittent short to ground on the 5 volt

reference circuit between the ECM and the following

components:

DMAP Sensor

Was a problem found? —Go to Step 9 Go to Step 8

7Check for a poor 5 volt reference circuit terminal

connection at the ECM.

Was a problem found? —Go to Step 9 Go to Step 8

8Check for an intermittent open or a faulty splice in the 5

volt reference circuit.

Was a problem found? (if no, start with the diagnosis

chart for other sensors in the circuit and see if 5V

returns.) —Go to Step

Refer to

Diagnostic

Aids

9Replace the faulty harness connector terminal(s) for

the 5 volt reference circuit and/or the TP signal circuit

as necessary.

Is the action complete?

—

Repair

complete. If a

driveability

symptom still

exists, refer

to Symptoms. —

10 Repair intermittent open/short circuit in wiring harness

as necessary.

Is the action complete?

—

Repair

complete. If a

driveability

symptom still

exists, refer

to Symptoms. —

DIAGNOSTIC TROUBLE CODE (DTC) P1171 FUEL SYSTEM LEAN DURING

ACCELERATION

D06RX119

Circuit Description

The engine control module (ECM) internal circuitry can

identify if the vehicle fuel system is capable of supplying

adequate amounts of fuel during heavy acceleration

(power enrichment). The ECM monitors the voltage of the

oxygen sensor during power enrichment. When a power

enrichment mode of operation is requested during

”Closed Loop” operation (by heavy acceleration), the

ECM will provide more fuel to the engine. Under these

conditions the ECM should detect a ”rich” condition (high

oxygen sensor voltage). If this ”rich” exhaust is not

detected at this time, a Diagnostic Trouble Code P1171

will set. A plugged fuel filter or restricted fuel line can

prevent adequate amounts of fuel from being supplied

during power enrichment mode. DTC P1171 is a type A

code.

Conditions for Setting the DTC

DNo related Diagnostic Trouble Codes.

DEngine is operating in ”Closed Loop”.

DEngine coolant temperature is above 60°C (140°F).

DWhile in ”power enrichment” mode the oxygen sensor

voltage remains below 400 mV for 3 seconds.

Action Taken When the DTC Sets

DThe ECM will illuminate the malfunction indicator lamp

(MIL) the first time the fault is detected.

DThe ECM will store conditions which were present

when the Diagnostic T rouble Code was set as Freeze

Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history Diagnostic Trouble Code P1171 will clear

after 40 consecutive warm–up cycles have occurred

without a fault.

DDiagnostic Trouble Code P1171 can be cleared by

using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

DA restricted fuel filter or fuel line can supply adequate

amounts of fuel at idle, but may not be able to supply

enough fuel during heavy acceleration.

DWater or alcohol in the fuel may cause low HO2S

voltage during acceleration.

DCheck for faulty or plugged fuel injector(s).

DCheck for low fuel.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart:

4. When the engine is idling or at steady cruise, the

HO2S voltage should vary from between

approximately 100 mV to 900 mV. During ”power

enrichment” mode, more fuel is needed and the

HO2S voltage should rise above 447 mV. This step

checks to see if the HO2S is operating properly.

5. Wrap a shop towel around the fuel pressure

connector to absorb any small amount of fuel

leakage that may occur when installing the gauge.

Ignition ON, pump pressure should be 235–320

kPa.

7. Add Caution: Use correct pliers so damage to fuel

lines will not occur.

DTC P1171 – Fuel System Lean During Acceleration

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Are any component–related Diagnostic Trouble Codes

set? —

Go to

component

DTC charts Go to Step 3

31. Check the vehicle’s fuel tank for an adequate

amount of fuel.

2. Add fuel to the vehicle’s fuel tank if the tank is almost

empty.

Was fuel added to the vehicle’s fuel tank? —Go to Step 4 Go to Step 5

41. Using a Tech 2, observe HO2S 1 voltage while

running warm engine(75°C–95°C [167°F–203°F])

at 1200 RPM.

2. HO2S 1 voltage should vary within the specified

range.

Does the voltage toggle back and forth within the

specified range? 100– 900 mV

Go to

Diagnostic

Aids Go to Step 5

51. Disconnect the fuel pump relay and crank the

engine to relieve the fuel pressure.

2. Install the fuel pressure gauge.

3. Start the engine and idle at normal operating

temperature.

4. Disconnect the vacuum line going to the fuel

pressure regulator.

With the engine running, is the fuel pressure within the

specified range? 284– 325 kPa

Go to OBD

System

Check Go to Step 6

6Check for restricted fuel lines or restricted in–line filter .

Was a problem found? — Verify repair Go to Step 7

71. Ignition OFF.

2. Ignition ON, engine OFF.

3. Using a Tech 2, enable the fuel pump to operate.

4. Using pliers, slowly close the return line (do not

exceed the first specified value).

Using the pliers, can the fuel pressure be manipulated

to exceed the second specified value? 414 kPa 325

kPa

Go to

Diagnostic

Aids Go to Step 8

8Check for:

DFaulty fuel pump

DRestricted fuel pump strainer (sock)

DIncorrect fuel pump

DIncorrect fuel being used

DHot fuel — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) 1404 EXHAUST GAS RECIRCULATION

(EGR) CLOSED VALVE

D06RX113

Circuit Description

The engine control module (ECM) monitors the exhaust

gas recirculation(EGR) valve pintle position input to

ensure that the valve responds properly to commands

from the ECM to detect a fault if the pintle position sensor

and control circuits are open or shorted. If the ECM

detects a pintle position signal voltage below the normal

range of the pintle position sensor, or a signal voltage that

is not within a tolerance considered acceptable for proper

EGR control system operation, the ECM will set a DTC

P1404.

Conditions for Setting the DTC

DIAT is above 5°C (41°)

DEGR actual position is 16 counts below the EGR low

threshold for at least 6.3 seconds.

Action Taken When the DTC Sets

DThe ECM will illuminate the Malfunction Indicator Lamp

(MIL) after the second consecutive trip in which the

fault is detected.

DThe ECM will store conditions which were present

when the DTC was set as Freeze Frame and in the

Failure Records data.

Conditions for Clearing the MIL/DTC

DThe ECM will turn the MIL OFF on the third consecutive

trip cycle during which the diagnostic has been run and

the fault condition is no longer present.

DA history DTC P1404 will clear after 40 consecutive

warm up cylcles without a fault.

DDTC P1404 can be cleared by using the Scan Tool’s

”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DExcessive deposits on EGR valve pintle or seat –

Check for deposits that may interfere with the EGR

valve pintle extending completely or cause the pintle to

stick.

DPoor connection or damaged harness – Inspect the

wiring harness for damage. If the harness appears to

be OK, observe the EGR actual position display on the

Tech 2 while moving connectors and wiring harnesses

related to the EGR valve. A change in the display will

indicate the location of the fault.

Reviewing the Failure Records vehicle mileage since the

diagnostic test last failed may help determine how often

the condition that caused the DTC to be set occurs. This

may assist in diagnosing the condition.

NOTE: If the EGR valve show signs of excessive heat,

check the exhaust system for blockage (possible a

plugged catalytic converter) using the ”Restricted

Exhaust System Check”.

DTC P1404 EGR Closed Valve

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check

performed? —Go to Step 2

Go to OBD

System

Check

21. Turn the ignition switch ON, with the engine OFF.

2. Review and record the T ech 2 Failure Records data,

the clear the DTCs.

3. Operate the vehicle within the Failure Records

conditions noted.

4. Using the Tech 2, monitor ”DTC” info for DTC

P1404.

Does the Tech 2 indicate DTC P1404 ”Ran and

Passed” —

Refer to

Diagnostic

Aids Go to Step 3

31. Ignition OFF.

2. Disconnect the Linear Exhaust Gas Recirculation

(EGR) Valve from the wiring harness.

3. Ignition ON, Engine OFF.

4. Using a Digital Voltmeter (DVM), check for voltage

on the Ignition feed circuit at the Linear Exhaust Gas

Recirculation (EGR) Valve wiring harness

connector.

Does the DVM read the following value? 12 volts Go to Step 6 Go to Step 4

4Check the Ignition feed circuit, between the EGR

sensor and the ”Engine IG.” fuse, for the following

conditions:

DAn Open circuit

DA short to ground

Was the problem found? — Verify repair —

5Using a DVM, check the resistance of the EGR

solenoid.

Does the DVM read the following value? less than 5 WGo to Step 6 Go to Step 14

6Check the EGR solenoid valve Low circuit, between the

EGR sensor and the ECM, for the following conditions:

DAn Open circuit

DA short to ground

Was the problem found? — Verify repair Go to Step 15

71. Ignition OFF.

2. Disconnect the Linear Exhaust Gas Recirculation

(EGR) Valve from the wiring harness.

3. Ignition ON, Engine OFF.

4. Observe the EGR value on the Tech 2.

Does the Tech 2 display the following value(s)? 0 volts 0% Go to Step 9 Go to Step 8

8Check the EGR position feedback circuit, between the

EGR sensor and the ECM, for the following conditions:

DAn Open circuit

DA short to ground

Was the problem found? — Verify repair Go to Step 15

Step NoYesValue(s)Action

91. Ignition ON, engine OFF.

2. Using a Digital Voltmeter (DVM), check for voltage

on the 5 volt Reference signal circuit at the Linear

Exhaust Gas Recirculation (EGR) Valve wiring

harness connector.

Does the DVM read the following value? about 5 volts Go to Step 11 Go to Step 10

10 Check the 5 volt reference signal circuit, between the

EGR and the ECM, for the following conditions:

DAn Open circuit

DA short to ground

Was the problem found? — Verify repair Go to Step 11

11 1. Ignition OFF.

2. Place a DVM between the 5 volt reference signal

circuit and the 5 volt signal return (ground) circuit at

the EGR wiring harness connector.

3. Ignition ON, Engine OFF.

Does the DVM read the following value? about 5 volts Go to Step 13 Go to Step 12

12 Check the 5 volt signal return (ground) circuit, between

the EGR and the ECM, for the following conditions:

DAn Open circuit

DA short to ground

Was the problem found? — Verify repair Go to Step 15

13 1. Ignition OFF.

2. Place a fused jumper wire between the 5 volt

reference signal circuit and the EGR valve position

feedback circuit at the EGR wiring harness

connector.

3. Ignition ON, Engine OFF.

4. Observe the EGR value on the Tech 2.

Does the Tech 2 display the following value? 5 volts 100% Go to Step 14 Go to Step 15

14 Replace the Linear Exhaust Gas Recirculation (EGR)

Value.

Verify repair. ———

15 Replace the ECM.

Verify repair. ———

DIAGNOSTIC TROUBLE CODE (DTC) P1625 ECM UNEXPECTED RESET

014RX002

Circuit Description

The engine control module (ECM) monitors unexpected

ECM reset. This will not turn on MIL light on, only records

code DTC P1625.

Conditions for Setting the DTC

DClock or COP (Computer Operating Properly) reset.

Action Taken When the DTC Sets

DThe ECM will not illuminate the malfunction indicator

lamp (MIL).

DThe ECM will store conditions which were present

when the DTC was set as Failure Records only. This

information will not be stored as Freeze Frame data.

Conditions for Clearing the DTC

DThe ECM will turn the MIL “OFF” on the third

consecutive trip cycle during which the diagnostic has

been run and the fault condition is no longer present.

DA history DTC P1625 will clear after 40 consecutive

warm-up cycles have occurred without a fault.

DDTC P1625 can be cleared by using the Tech 2 “Clear

Info” function or by disconnecting the ECM battery

feed.

Diagnostic Aids

Check for the following conditions:

DP1625 alone stored does not need diagnosis. Clear

DTC code.

NOTE: DTC P1625 is a DTC to record a ECM reset

history. If DTC P1625 is not reset and no engine

abnormality is found after clearance of DTC, it is not

necessary to do any farther processing.

DTC P1625–ECM Unexpected Reset

Step Action Value(s) YesNo

1Was the “On-Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition is “On”.

2. Install the Tech 2.

3. Start the engine at let it Idle.

4. On the Tech 2, select “DTC info”.

Does the Tech 2 indicate DTC P1625 failed? —Go to Step 3

Go to

Diagnostic

Aids

31. Ignition is “On”.

2. Clear DTC P1625 by using the Tech 2 “Clear Info”.

3. Start the engine at let it Idle.

4. On the Tech 2, select “DTC info”.

Does the Tech 2 indicate DTC P1625 failed? —Go to Step 4

Go to

Diagnostic

Aids

41. Check for aftermarket electronics, such as

transceiver stereos, and anti theft devices, they

may radiate EMI into the control system if they are

improperly installed. (This may cause a false

sensor reading and turn on the MIL.)

2. If a problem is found, repair as necessary.

Was the problem found? — Verify repair —

DIAGNOSTIC TROUBLE CODE (DTC) P1627 PCM A/D CONVERSION

MALFUNCTION

014RX002

Circuit Description

The Engine Control Module (ECM) monitors the 5 volt

reference signal when the Ignition is ON. If the ECM

senses an Analog to Digital (A/D) conversion error within

the ECM, then DTC P1627 will set. DTC P1627 is a type A

code.

Conditions for Setting the DTC

DEngine is running.

DAny A/D DTC’s set.

Action Taken When the DTC Sets

DThe ECM will illuminate the Malfunction Indicator Lamp

(MIL) the first time the fault is detected.

DThe ECM will store the conditions that were present

when the DTC was set as Freeze Frame and in Failure

Records.

Conditions for Clearing the MIL/DTC

DThe ECM will turn OFF the MIL on the third consecutive

trip without a reported failure.

DA History DTC will clear after 40 consecutive trips

without a reported failure.

DThe DTC can be cleared using the Scan Tool’s ”Clear

Info” function.

Diagnostic Aids

DPoor connections, or a damaged harness – Inspect the

harness connectors for: backed–out terminals,

improper mating or damaged terminals. Also, check for

open circuits, shorts to ground, and shorts to voltage.

DTC P1627 PCM A/D Conversion Malfunction

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON, Engine OFF.

2. Review and record Tech 2 Failure Records data,

then clear the DTCs.

3. Operate the vehicle within the Failure Records

conditions as noted.

4. Using the Tech 2, monitor ”DTC” info for DTC

P1627.

Does the Tech 2 indicate DTC P1627 ”Ran and

Passed?” —

Refer to

Diagnostic

Aids Go to Step 3

3Check the suspect 5 volt reference circuit(s) for the

following conditions:

DA short to ground

DAn open circuit

DA short to voltage

Was the problem found? — Verify repair Go to Step 4

4Replace the ECM. ———

DIAGNOSTIC TROUBLE CODE (DTC) P1635 5 VOLT REFERENCE VOLTAGE

CIRCUIT MALFUNCTION

014RX002

Circuit Description

The Engine Control Module (ECM) monitors the 5 volt

reference signal when the Ignition is ON. If the ECM

senses the 5 volt reference signal circuit is above 5.12

volts or below 4.88 volts, then DTC P1635 will set. DTC

P1635 is a type A code.

Conditions for Setting the DTC

DIgnition voltage is greater than 6.3 volts.

DEngine is running.

The above mentioned conditions are met and one of the

following two conditions are met for 5 seconds within a 10

second test sample:

DECM senses the 5 volt reference signal circuit is above

5.12 volts.

DECM senses the 5 volt reference signal circuit is below

4.88 volts.

Action Taken When the DTC Sets

DThe ECM will illuminate the Malfunction Indicator Lamp

(MIL) the first time the fault is detected.

DThe ECM will store the conditions that were present

when the DTC was set as Freeze Frame and in Failure

Records.

Conditions for Clearing the MIL/DTC

DThe ECM will turn OFF the MIL on the third consecutive

trip without a reported failure.

DA History DTC will clear after 40 consecutive trips

without a reported failure.

DThe DTC can be cleared using the Scan Tool’s ”Clear

Info” function.

Diagnostic Aids

Poor connections, or a damaged harness – Inspect the

harness connectors for: backed–out terminals, improper

mating or damaged terminals. Also, check for open

circuits, shorts to ground, and shorts to voltage.

DTC P1635 5 Volt Reference Voltage Circuit Malfunction

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Ignition ON, Engine OFF.

2. Review and record Tech 2 Failure Records data,

then clear the DTCs.

3. Operate the vehicle within the Failure Records

conditions as noted.

4. Using the Tech 2, monitor ”DTC” info for DTC

P1635.

Does the Tech 2 indicate DTC P1635 ”Ran and

Passed?” —

Refer to

Diagnostic

Aids Go to Step 3

3Check the suspect 5 volt reference circuit(s) for the

following conditions:

DA short to ground

DAn open circuit

DA short to voltage

Was the problem found? — Verify repair Go to Step 4

4Replace the ECM. ———

DIAGNOSTIC TROUBLE CODE (DTC) P1640 ODM OUTPUT CIRCUIT FAULT

014RX002

Circuit Description

Output driver modules (ODMs) are used by the engine

control module(ECM) to turn ON many of the current

driven devices that are needed to control various engine

and transmission functions. Each ODM is capable of

controlling up to 11 separate outputs by applying ground

to the device which the ECM is commanding ON.

ODMs have the capability of diagnosing each output

circuit individually. DTC P1640 set indicates an improper

voltage level has been detected on an ODM output.

If the ECM detects an open circuit condition and a shorted

to voltage circuit condition on the same circuit at the same

time, then DTC P1640 will set. DTC P1640 is a type D

code.

Conditions for Setting the DTC

DIgnition ON.

DAbove conditions occur for at least 2.5 seconds.

DThe ECM detects an open circuit condition and a

shorted to voltage circuit condition on the same circuit

at the same time.

Action Taken When the DTC Sets

DThe ECM will not illuminate the malfunction indicator

lamp (MIL).

DThe ECM will store conditions which were present

when the DTC was set as Failure Records only. This

information will not be stored as Freeze Frame data.

Conditions for Clearing the DTC

DA history DTC P1640 will clear after 40 consecutive

warm up cycles occur without a fault.

DDTC P1640 can be cleared by using the Scan Tool’s

”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

DPoor connection at ECM – Inspect harness connectors

for backed–out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and

poor terminal to wire connection.

DDamaged harness Inspect the wiring harness for

damage. If the harness appears to be OK, disconnect

the ECM, turn the ignition ON and observe a voltmeter

connected to the MIL driver circuit at the ECM harness

connector while moving connectors and wiring

harnesses relates to the MIL. A change in voltage will

indicate the location of the fault.

DReviewing the Failure Records vehicle mileage since

the diagnostic test last failed may help determine how

often the condition that caused the DTC to be set

occurs. This may assist in diagnosing the condition.

The following ECM pins are controlled by

output driver modules (ODMs):

DA13 MIL LAMP

DA14 Rear Defogger

DB14 A/C Clutch

DB16 EVAP Canister Parge Solenoid

DA1 2 Low Fuel

DC10 Tacho Meter

DC11 Fuel Gauge

DC13 Fan Low

DC12 Fan High

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Chart.

2. The Tech 2 Driver Module Status indicates the ECM

pin that is affected.

9. The Tech 2 may indicate “short circuit” even when

the problem is an open circuit. The cause of an

open circuit may be in the component itself.

11. A short to ground on the ignition side of the

component will blow the fuse. Since the fuse was

checked in Step 2, a short to ground would be

between the affected component and the ECM.

DTC P1640 –Output Driver Module (ODM) “A” Fault

Step Action Value(s) YesNo

1Was the “On-Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

2Check the fuse for the driver circuit that was shown as

faulty.

Was the fuse blown? —Go to Step 3 Go to Step 4

31. Check for a short to ground between the fuse and

the affected component.

2. Replace the fuse after making any necessary

repairs.

Is the action complete? — Verify repair —

41. Disconnect the ECM connector for the affected

driver circuit.

Is there any damage to the ECM pin or connector? —Go to Step 5 Go to Step 6

5Repair the damaged pin or terminal.

Is the action complete? — Verify repair —

6Was the Lamp of circuit for “Check Engine”? —Go to Step 7 Go to Step 13

71. Leave the ECM connector for the lamp driver circuit

disconnected.

2. Ignition “ON.”

3. Using a DVM, check the voltage at the ECM

connector for the affected lamp driver circuit.

Was the voltage equal to the specified value? B+ Go to Step 15 Go to Step 8

81. Ignition “ON.”

2. Check for battery voltage at the fuse for the affected

lamp circuit.

Was battery voltage available at the fuse? —Go to Step 10 Go to Step 9

9Repair the open circuit between the ignition switch and

the fuse.

Is the action complete? — Verify repair —

10 1. Ignition “OFF.”

2. Disconnect the ECM connector for the affected

driver terminal.

3. Connect an ohmmeter between a good ground and

the ECM connector for the affected driver.

Did the ohmmeter indicate continuity? —Go to Step 11 Go to Step 12

11 Repair the short to ground between the affected

component and its ECM driver terminal.

Is the action complete? — Verify repair —

Step NoYesValue(s)Action

12 Repair the open circuit between the fuse and the ECM

driver terminal for the affected circuit.

Is the action complete? — Verify repair —

13 1. Connect the ECM.

2. Start the engine and let it idle.

3. Backprobe the affected terminal at the ECM with a

DVM.

Was the voltage equal to the specified value? B+ Go to Step 15 Go to Step 14

14 1. Run the engine at idle.

2. Check for battery voltage at the fuse for the affected

circuit.

Was battery voltage available at the fuse? —Go to Step 10 Go to Step 9

15 Replace the ECM.

Is the action complete? — Verify repair —

SYMPTOM DIAGNOSIS

PRELIMINARY CHECKS

Before using this section, perform the ”On–Board

Diagnostic (OBD) System Check” and verify all of the

following items:

DThe engine control module (ECM) and malfunction

indicator lamp (MIL)(Check Engine lamp) are

operating correctly.

DThere are no DTC(s) stored.

DTech 2 data is within normal operating range. Refer to

Typical Scan Data Values.

DVerify the customer complaint and locate the correct

symptom in the table of contents. Perform the

procedure included in the symptom chart.

VISUAL/PHYSICAL CHECK

Several of the symptom procedures call for a careful

visual/physical check. This can lead to correcting a

problem without further checks and can save valuable

time. This check should include the following items:

DECM grounds for cleanliness, tightness and proper

location.

DVacuum hoses for splits, kinks, and proper

connections, as shown on the ”Vehicle Emission

Control Information” label. Check thoroughly for any

type of leak or restriction.

DAir intake ducts for collapsed or damaged areas.

DAir leaks at throttle body mounting area, manifold

absolute pressure (MAP) sensor and intake manifold

sealing surfaces.

DIgnition component for cracking, hardness, and

carbon tracking.

DWiring for proper connections, pinches and cuts.

INTERMITTENTS

An intermittent problem may or may not turn on the mal-

function indicator lamp (MIL) or store a Diagnostic

Trouble Code. DO NOT use the Diagnostic Trouble Code

(DTC) charts for intermittent problems. The fault must be

present to locate the problem.

Most intermittent problems are caused by faulty electrical

connections or wiring. Perform a careful visual/physical

check for the following conditions:

DPoor mating of the connector halves or a terminal not

fully seated in the connector (backed out).

DImproperly formed or damaged terminal.

DAll connector terminals in the problem circuit should

be carefully checked for proper contact tension.

DPoor terminal–to–wire connection. This requires

removing the terminal from the connector body to

check.

Road test the vehicle with a J 39200 Digital Multimeter

connected to a suspected circuit. An abnormal voltage

when the malfunction occurs is a good indication that

there is a fault in the circuit being monitored.

Use a Tech 2 to help detect intermittent conditions.

The Scan Tools have several features that can be used to

locate an intermittent condition. Use the following feature

to find intermittent faults:

DUsing a Scan Tool’s ”Freeze Frame” buffer or ”Failure

Records” buffer can aid in locating an intermittent

condition. Review and record the information in the

freeze frame or failure record associated with the

intermittent DTC being diagnosed. The vehicle can

be driven within the conditions that were present

when the DTC originally set.

To check for loss of diagnostic code memory, disconnect

the MAP sensor and idle the engine until the MIL (Check

Engine lamp) comes on. Diagnostic Trouble Code P0107

should be stored and kept in memory when the ignition is

turned OFF. If not, the ECM is faulty. When this test is

completed, make sure that you clear the Diagnostic

Trouble Code P0107 from memory.

An intermittent MIL (Check Engine lamp) with no stored

Diagnostic Trouble Code may be caused by the following:

DIgnition coil shorted to ground and arcing at ignition

wires or plugs.

DMIL (Check Engine lamp) wire to ECM shorted to

ground.

DPoor ECM grounds. Refer to the ECM wiring

diagrams.

Check for improper installation of electrical options such

as lights, cellular phones, etc. Check all wires from the

ECM to the ignition coils for poor connections.

Check for an open diode across the A/C compressor

clutch and check for other open diodes (refer to wiring

diagrams in Electrical Diagnosis).

If problem has not been found, refer to ECM Connector

Symptom tables.

HARD START SYMPTOM

DEFINITION:

Engine cranks, but does not start for a long time. Does

eventually run, or may start but immediately stalls.

Step Action Value(s) YesNo

1Was the ”On–Board Diagnostic (OBD) System Check”

performed? —Go to Step 2

Go to OBD

System

Check

21. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom? — Verify repair Go to Step 3

3Was a visual/physical check performed?

—Go to Step 4

Go to Visual /

Physical

Check

4Check engine coolant temperature (ECT) sensor for

shift in value.

1. After 8 hours with the hood up and the engine not

running, connect the Tech 2.

2. Ignition ON, engine not running.

3. Using the Tech 2, compare Engine Coolant

Temperature to Intake Air Temperature.

Are ECT and IAT within the specified value of each

other? ± 5°C (± 9°F) Go to Step 8 Go to Step 5

51. Using a Tech 2, display the engine coolant

temperature and note the value.

2. Check the resistance of the engine coolant

temperature sensor.

3. For resistance specifications, refer to Temperature

vs. Resistance chart in DTC P0118.

Is the actual resistance near the resistance value in the

chart for the temperature that was noted? —Go to Step 7 Go to Step 6

6Replace the ECT sensor.

Is the action complete? — Verify repair —

7Locate and repair high resistance or connection in the

ECT signal circuit or the ECT signal circuit or the ECM

sensor ground. — Verify repair —

8Check for a faulty , plugged, or incorrectly installed PCV

valve.

Was a problem found? — Verify repair Go to Step 9

9Visually/Physically inspect the secondary ignition

wires. Check for the following conditions:

DVerify that all ignition wire resistance are less than

the specified value.

DVerify that ignition wires are correctly routed to

eliminate cross–firing.

DV erify that ignition wires are not arcing to ground.

Spraying the secondary ignition wires with a light

mist of water may help locate an intermittent

problem.

Was a problem found? 22.4 k WVerify repair Go to Step 10

Step NoYesValue(s)Action

10 Check for proper ignition voltage output with a spark

tester5-8840-0383-0.

Was a problem found? — Verify repair Go to Step 11

11 1. Remove the spark plugs and check for gas or oil

fouling cracks, wear, improper gap, burned

electrodes, heavy deposits, or improper heat range.

2. If spark plugs are fouled, the cause of fouling must

be determined before replacing the spark plugs.

Was a problem found? — Verify repair Go to Step 12

12 Check for a loose ignition control module ground.

Was a problem found? — Verify repair Go to Step 13

13 1. Check the ignition coil secondary resistance.

2. Replace the coil if it is not within the specified range

of resistance.

Did the coil require replacement? 9 kW–12 kWVerify repair Go to Step 14

14 Check IAC operation. Perform the procedure in the

diagnostic chart DTC P0506, Step 6.

Was a problem found? — Verify repair Go to Step 15

15 Check for water or alcohol contaminated fuel.

Was a problem found? — Verify repair Go to Step 16

16 Perform the procedure in Fuel System Pressure T est to

determine if there is a problem with fuel delivery.

Was a problem found? — Verify repair Go to Step 17

17 Check for the following engine mechanical problems

(refer to Engine Mechanical):

DLow compression

DLeaking cylinder head gaskets

DWorn camshaft

DCamshaft drive belt slipped or stripped

Was a problem found? — Verify repair Go to Step 18

18 1. Review all diagnostic procedures within this table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:

DVisual/physical inspection

DTech 2 data

DFreeze Frame data/Failure Records buffer

DAll electrical connections within a suspected

circuit and/or system

Was a problem found? — Verify repair

Contact

Technical

Assistance

SURGES AND/or CHUGGLES SYMPTOM

DEFINITION:

Engine power variation under steady throttle or cruise.

Feels like the vehicle speeds up and slows down with no

change in the accelerator pedal.

Step Action Value(s) YesNo

1Was the On–Board Diagnostic (OBD) System Check

performed? —Go to Step 2

Go to OBD

System

Check

21. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom? — Verify repair Go to Step 3

3Was a visual/physical check performed?

—Go to Step 4

Go to Visual /

Physical

Check

4Be sure that the driver understands A/C compressor

operation as explained in the owner ’s manual. Inform

the customer how the A/C clutch operate.

Is the customer experiencing a normal condition? —System OK Go to Step 5

5Check the fuel control Heated Oxygen Sensor

(HO2S1). When monitored on the Tech 2, the H02S1

should respond quickly to different throttle positions. If

it doesn’t check for silicon or other contaminants from

fuel or use of improper RTV sealant. The sensors may

have a white powdery coating. Silicone contamination

sends a rich exhaust signal which causes the ECM to

command an excessively lean air/fuel mixture.

Was a problem found? — Verify repair Go to Step 6

6Check the fuel pressure. Refer to Fuel System

Pressure Test.

Was a problem found? — Verify repair Go to Step 7

7 Monitor ”Long Term Fuel Trim” on the Tech 2.

Is ”Long Term Fuel Trim” in the negative range (rich

condition)? —Go to Step 8 Go to Step 9

8Check items that can cause the engine to run rich.

Refer to Diagnostic Aids in DTC P0172.

Was a problem found? — Verify repair Go to Step 10

9Check items that can cause the engine to run lean.

Refer to Diagnostic Aids in DTC P0171.

Was a problem found? — Verify repair Go to Step 10

10 Check for proper ignition voltage output with the spark

tester 5-8840-0383-0.

Was a problem found? — Verify repair Go to Step 11

11 Check for a loose ignition control module ground.

Was a problem found? — Verify repair Go to Step 12

Step NoYesValue(s)Action

12 Visually/Physically inspect the secondary ignition

wires. Check for the following conditions.

DVerify that all ignition wire resistance are less than

the specified value.

DVerify that ignition wires are correctly routed to

eliminated cross–firing.

DV erify that ignition wires are not arcing to ground.

Spraying the secondary ignition wires with a light

mist of water may help to locate an intermittent

problem.

Was a problem found? 22.4 WVerify repair Go to Step 13

13 1. Check ignition coil secondary resistance.

2. Replace the coil if it is not within the specified range

of resistance.

Did the coil require replacement? 9 kW– 12 kWVerify repair Go to Step 14

14 1. Remove the spark plugs and check for gas or oil

fouling, cracks, wear, improper gap, burned

electrodes, heavy deposits or improper heat range.

2. If spark plugs are fouled, the cause of fouling must

be determined before replacing the spark plugs.

Was a problem found? — Verify repair Go to Step 15

15 1. Check the injector connectors.

2. If any of the connectors are connected at an

improper cylinder, correct as necessary.

Was a problem found? — Verify repair Go to Step 16

16 Check the ECM grounds to verify that they are clean

and tight. Refer to the ECM wiring diagrams in

Electrical Diagnosis.

Was a problem found? — Verify repair Go to Step 17

17 Visually/physically check the vacuum hoses for splits,

kinks and proper connections and routing as shown on

the ”Vehicle Emission Control Information” label.

Was a problem found? — Verify repair Go to Step 18

18 Check the exhaust system for a possible restriction:

Ddamaged or collapsed pipes

Dinternal muffler failure

DRefer to Restricted Exhaust System Check to

measure back pressure and determine if the

catalytic converter is plugged. — Verify repair Go to Step 19

19 1. Review all the diagnostic procedures within this

table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:

DVisual/physical inspection.

DTech 2 data.

DFreeze Frame data/Failure Records buffer.

DAll electrical connections within a suspected

circuit and/or system.

Was a problem found? — Verify repair

Contact

Technical

Assistance

LACK OF POWER, SLUGGISH OR SPONGY SYMPTOM

DEFINITION:

Engine delivers less than expected power. Little or no

increase in speed when accelerator pedal is pushed down

part–way.

Step Action Value(s) YesNo

1Was the On–Board Diagnostic (OBD) System Check

performed? —Go to Step 2

Go to OBD

System

Check

21. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom? — Verify repair Go to Step 3

3Was a visual/physical check performed?

—Go to Step 4

Go to Visual /

Physical

Check

41. Remove and check the air filter element for dirt or

restrictions. Refer to Air Intake System in

On–Vehicle Service.

2. Replace the air filter element if necessary.

Was a problem found? — Verify repair Go to Step 5

5Check for proper ignition voltage output with the spark

tester 5-8840-0385-0.

Was a problem found? — Verify repair Go to Step 6

61. Remove the spark plugs and check gas or oil

fouling, cracks, wear, improper gap, burned

electrodes, heavy deposits or improper heat range.

2. If spark plugs are fouled, the cause of fouling must

be determined before replacing the spark plugs.

Was a problem found? — Verify repair Go to Step 7

7Check the fuel pressure. Refer to Fuel System Test.

Was a problem found? — Verify repair Go to Step 8

8Check for water or alcohol contaminated fuel.

Was a problem found? — Verify repair Go to Step 9

9Check the ECM grounds to verify that they are clean

and tight. Refer to the ECM wiring diagrams in

Electrical Diagnosis.

Was a problem found? — Verify repair Go to Step 10

10 Check the exhaust system for a possible restriction:

DDamaged or collapsed pipes

DInternal muffler failure

DRefer to Restricted Exhaust System Check to

measure backpressure and determine if the

catalytic converter is plugged.

Was a problem found? — Verify repair Go to Step 11

Step NoYesValue(s)Action

11 Check for the following engine mechanical problems:

DLow compression

DLeaking cylinder head gasket

DWorn or incorrect camshaft

DLoose timing belt

Was a problem found? — Verify repair Go to Step 12

12 1. Review all the diagnostic procedures within this

table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:

DVisual/physical inspection.

DTech 2 data

DFreeze Frame data/Failure Records buffer.

DAll electrical connections within suspected

circuit and/or system.

Was a problem found? — Verify repair

Contact

Technical

Assistance

DETONATION/SPARK KNOCK SYMPTOM

DEFINITION:

A mild to severe ping, usually worse under acceleration.

The engine makes sharp metallic knocks that change

with throttle opening.

Step Action Value(s) YesNo

1Was the On–Board Diagnostic (OBD) System Check

performed? —Go to Step 2

Go to OBD

System

Check

21. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom? — Verify repair Go to Step 3

3Was a visual/physical check performed?

—Go to Step 4

Go to Visual /

Physical

Check

41. If Tech 2 readings are normal and there are no

engine mechanical faults, fill the fuel tank with a

known quality gasoline that has a minimum octane

rating of 87. Refer to Typical Scan Values.

2. Re–evaluate the vehicle performance.

Is detonation present? —Go to Step 5 Verify repair

51. Check for obvious overheating problems:

DLow engine coolant.

DRestricted air flow to radiator, or restricted

water flow through radiator.

DIncorrect coolant solution. It should be a 50/50

mix of approved antifreeze/water.

DIncorrect EGR operation. Refer to DTC

P0401.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 6

6Check fuel pressure. Refer to Fuel System Pressure

Test.

Was a problem found? — Verify repair Go to Step 7

7Check items that can cause an engine to run lean.

Refer to Diagnostic Aids in DTC P0171.

Was a problem found? — Verify repair Go to Step 8

8Check spark plugs for proper heat range. Refer to

General Information.

Were incorrect spark plugs installed? — Verify repair Go to Step 9

91. Remove excessive carbon buildup with a top engine

cleaner. Refer to instructions on the top engine

cleaner can.

2. Re–evaluate vehicle performance.

Is detonation still present? —Go to Step 10 Verify repair

Step NoYesValue(s)Action

10 Check for an engine mechanical problem. Perform a

cylinder compression check. Refer to Engine

Mechanical.

Was a problem found? — Verify repair Go to Step 11

11 1. Review all diagnostic procedures within this table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:

DVisual/physical inspection

DTech 2 data

DFreeze Frame data/Failure Records buffer

DAll electrical connections within a suspected

circuit and/or system

Was a problem found? — Verify repair

Contact

Technical

Assistance

ROUGH, UNSTABLE, OR INCORRECT IDLE, STALLING SYMPTOM

DEFINITION:

Engine runs unevenly at idle. If severe, the engine or

vehicle may shake. Engine idle speed may vary in RPM.

Either condition may be severe enough to stall the engine.

Step Action Value(s) YesNo

1Was the On–Board Diagnostic (OBD) System Check

performed? —Go to Step 2

Go to OBD

System

Check

21. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom? — Verify repair Go to Step 3

3Was a visual/physical check performed, including the

rotor, ignition coil and secondary ignition wires? —Go to Step 4

Go to Visual /

Physical

Check

4Verify that the EGR valve is not mounted backwards.

Was a problem found? — Verify repair Go to Step 5

51. Check for incorrect idle speed. Ensure that the

following conditions are present:

DEngine fully warm.

DAccessories are OFF.

2. Using a Tech 2, monitor IAC position.

Is the IAC position within the specified values?

Between 10

and 50

counts Go to Step 8 Go to Step 7

61. Visually/physically inspect for the following

conditions:

DRestricted air intake system. Check for a

restricted air filter element, or foreign objects

blocking the air intake system.

DCheck for objects blocking the IAC passage or

throttle bore, excessive deposits in the IAC

passage and on the IAC pintle, and excessive

deposits in the throttle bore and on the throttle

plate.

DCheck for a condition that causes a large

vacuum leak, such as an incorrectly installed

or faulty crankcase ventilation valve brake

booster hose.

Was a problem found? — Verify repair Go to Step 7

7Using a T ech 2, monitor TP angle with the engine idling.

Is the TP angle at the specified value and steady? 0% Go to Step 8

For further

diagnosis,

refer to DTC

P0123

8Check for proper ignition voltage output with the spark

tester 5-8840-0383-0.

Was a problem found? — Verify repair Go to Step 9

91. Remove the spark plugs and check for gas or oil

fouling, cracks, wear, improper gap, burned

electrodes, heavy deposits or improper heat range.

2. If spark plugs are fouled, the cause of the fouling

must be determined before replacing the spark

plugs.

Was a problem found? — Verify repair Go to Step 10

Step NoYesValue(s)Action

10 Check for a loose ignition control module ground. Refer

to Electrical Ignition System.

Was a problem found? — Verify repair Go to Step 11

11 Monitor ”Long Term Fuel Trim” on the Tech 2.

Is ”Long Term Fuel Trim” in the negative range (rich

condition)? —Go to Step 12 Go to Step 13

12 Check the items that can cause the engine to run rich.

Refer to Diagnostic Aids in DTC P0172.

Was a problem found? — Verify repair Go to Step 13

13 Is ”Long Term Fuel Trim” significantly in the positive

range (lean condition)?

——Go to Step 14 Go to Step 15

14 Check items that can cause the engine to run leading.

Refer to ”Diagnostic Aids” in DTC P0171.

Was a problem found? — Verify repair Go to Step 14

15 Check the injector connections. If any of the injectors

are connected to an incorrect cylinder, correct as

necessary.

Was a problem found? — Verify repair Go to Step 16

16 Perform the Injector Coil/Balance Test.

Was a problem found? — Verify repair Go to Step 17

17 1. Check the following engine mechanical problems:

DLow compression

DLeaking cylinder head gasket

DWorn or incorrect camshaft

DSticking or leaking valves

DValve timing

DBroken valve springs

DCamshaft drive belt slipped or stripped.

Was a problem found? — Verify repair Go to Step 18

18 1. Check for faulty motor mounts. Refer to Engine

Mechanical for inspection of mounts.

2. If a problem is found, repair as necessary.

Was a problem found? — Verify repair Go to Step 19

19 1. Review all diagnostic procedures within this table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:

DVisual/physical inspection

DTech 2 data

DFreeze Frame data/Failure Records buffer

DAll electrical connections within a suspected

circuit and/or system

Was a problem found? — Verify repair

Contact

Technical

Assistance

POOR FUEL ECONOMY SYMPTOM

DEFINITION:

Fuel economy, as measured by an actual road test, is

noticeably lower than expected. Also, economy is

noticeably lower than it was on this vehicle at one time,

as previously shown by an actual road test.

Step Action Value(s) YesNo

1Was the On–Board Diagnostic (OBD) System Check

performed? —Go to Step 2

Go to OBD

System

Check

21. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom? — Verify repair Go to Step 3

3Was a visual/physical check performed?

—Go to Step 4

Go to Visual /

Physical

Check

4Check owner’s driving habits.

DIs the A/C ON full time (defroster mode ON)?

DAre tires at the correct pressure?

DAre excessively heavy loads being carried?

DIs acceleration too much, too often? —Go to Step 5 Go to Step 6

5Review the items in Step 4 with the customer and

advise as necessary.

Is the action complete? —System OK —

61. Visually/physically check: Vacuum hoses for splits,

kinks, and improper connections and routing as

shown on the ”Vehicle Emission Control

Information” label.

Was a problem found? — Verify repair Go to Step 7

7Remove and check the air filter element for dirt or for

restrictions.

Was a problem found? — Verify repair Go to Step 8

81. Remove the spark plugs and check for gas or oil

fouling, cracks, wear, improper gap, burned

electrodes of heavy deposits.

2. Is spark plugs are fouled, the cause of fouling must

be determined before replacing the spark plugs.

Was a problem found? — Verify repair Go to Step 9

9Check for low engine coolant level.

Was a problem found? — Verify repair Go to Step 10

10 Check for an incorrect or faulty engine thermostat.

Refer to Engine Cooling.

Was a problem found? — Verify repair Go to Step 11

11 Check for low engine compression. Refer to Engine

Mechanical.

Was a problem found? — Verify repair Go to Step 12

Step NoYesValue(s)Action

12 Check for excessive exhaust system back–pressure.

Refer to Restricted Exhaust System Check. Possible

problems could be:

DDamaged or collapsed pipes.

DInternal muffler failure.

DPlugged catalytic converter.

Was a problem found? — Verify repair Go to Step 13

13 Check for proper calibration of the speedometer.

Does the speed indicated on the speedometer closely

match the vehicle speed displayed on the Tech 2? —Go to Step 15 Go to Step 14

14 Diagnose and repair the inaccurate speedometer

condition as necessary . Refer to Vehicle Speed Sensor

in Electrical Diagnosis. — Verify repair —

15 Check the air intake system and the crankcase for air

leaks.

Was a problem found? — Verify repair Go to Step 16

16 1. Review all the diagnostic procedures within this

table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:

DVisual/physical inspection

DTech 2 data

DFreeze Frame data/Failure Records buffer

DAll connections within a suspected circuit

and/or system

Was a problem found? — Verify repair Go to Step 17

17 Perform the procedure in Fuel System Pressure Test.

Was the fuel pressure normal? —

Contact

Technical

Assistance Verify repair

EXCESSIVE EXHAUST EMISSIONS OR ODORS SYMPTOM

DEFINITION:

Vehicle fails an emission test. There is excessive ”rotten

egg” smell. (Excessive odors do not necessarily indicate

excessive emissions.)

Step Action Value(s) YesNo

1Was the On–Board Diagnostic (OBD) System Check

performed? —Go to Step 2

Go to OBD

System

Check

21. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom? —Go to Step 13 Go to Step 3

3Was visual/physical check performed?

—Go to Step 4

Go to Visual /

Physical

Check

4Check for vacuum leaks (vacuum lines, intake

manifold, throttle body, etc.)

Were any vacuum leaks found? —Go to Step 13 Go to Step 5

51. Check fuel cap for proper installation.

2. Secure the fuel cap if necessary.

Was a problem found? —Go to Step 13 Go to Step 6

61. Check the fuel pressure. Refer to Fuel System

Pressure Test.

Was a problem found? —Go to Step 13 Go to Step 7

71. Check for faulty, plugged or incorrectly installed

PCV valve.

2. Verify that the PCV system is not plugged.

Was a problem found? —Go to Step 13 Go to Step 8

8Check the injector connections. If any of the injectors

are connected to an incorrect cylinder, correct as

necessary.

Was a problem found? —Go to Step 13 Go to Step 9

9Perform the Injector Balance Test by Tech 2.

Was a problem found? —Go to Step 13 Go to Step 10

10 Check for a problem with the engine cooling system.

Was a problem found? —Go to Step 13 Go to Step 11

11 Check the EVAP canister for fuel loading. Refer to

Evaporative Emission Control System.

Was a problem found? —Go to Step 13 Go to Step 12

12 1. Remove excessive carbon build-up with a top

engine cleaner. Refer to the instructions on the top

engine cleaner can.

2. Perform the exhaust emission test.

Does the vehicle pass the test? —System OK Go to Step 14

13 Perform the exhaust emission test.

Does the vehicle pass the test? —System OK Go to Step 14

14 Does the exhaust emission test indicate excessive HC

levels, or is ”Long Term Fuel Trim” significantly in the

negative range (rich condition)? —Go to Step 15 Go to Step 16

Step NoYesValue(s)Action

15 1. Check items that can cause the engine to run rich.

Refer to Diagnostic Aids in DTC P0172 Diagnostic

Support.

Make any necessary repairs.

2. Perform the exhaust emission test.

Does the vehicle pass the test? —System OK Go to Step 17

16 1. Check items that can cause the engine to run lean.

Refer to Diagnostic Aids in DTC P0171.

Make any necessary repairs.

2. Perform the exhaust emission test.

Does the vehicle pass the test? —System OK Go to Step 17

17 Check the EGR system (refer to DTC P0401).

Was a problem found? — Verify repair Go to Step 18

18 Check for the following engine mechanical problems.

DLow compression

DLeaking cylinder head gasket

DWorn or incorrect camshaft

DSticking or leaking valves

DValve timing

DBroken Valve springs

Was a problem found? — Verify repair Go to Step 19

19 1. Review all the diagnostic procedures within this

table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:

DVisual/physical inspection

DTech 2 data

DFreeze Frame data/Failure Records buffer

DAll electrical connections within a suspected

circuit and/or system

Was a problem found? — Verify repair

Contact

Technical

Assistance

DIESELING, RUN–ON SYMPTOM

DEFINITION:

Engine continues to run after key is turned OFF, but runs

very rough. If engine runs smoothly, check the ignition

switch and adjustment.

Step Action Value(s) YesNo

1Was the On–Board Diagnostic (OBD) System Check

performed? —Go to Step 2

Go to OBD

System

Check

21. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom? — Verify repair Go to Step 3

3Was a visual/physical check performed?

—Go to Step 4

Go to Visual /

Physical

Check

41. Check for a short between B+ and the ignition feed

circuit.

Was a problem found? — Verify repair Go to Step 5

51. Review all the diagnostic procedures within this

table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:

DVisual/physical inspection

DTech 2 data

DFreeze Frame data/Failure Records buffer

DAll connections within a suspected circuit

and/or system

Was a problem found? — Verify repair

Contact

Technical

Assistance

BACKFIRE SYMPTOM

DEFINITION:

Fuel ignites in the intake manifold, or in the exhaust

system, making a loud popping noise.

Step Action Value(s) YesNo

1Was the On–Board Diagnostic (OBD) System Check

performed? —Go to Step 2

Go to OBD

System

Check

21. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom? — Verify repair Go to Step 3

3Was a visual/physical check performed?

—Go to Step 4

Go to Visual /

Physical

Check

4Check for proper ignition voltage output with spark

tester 5-8840-0383-0.

Was a problem found? — Verify repair Go to Step 5

51. Remove the spark plugs and check for gas or oil

fouling, cracks, wear, improper gap, burned

electrodes of heavy deposits.

2. If spark plugs are fouled, the cause of fouling must

be determined before replacing the spark plugs.

Was a problem found? — Verify repair Go to Step 6

61. Visually/physically inspect the secondary ignition

wires. Check for the following conditions:

DV erify that all ignition wire resistances are less

than the specified value.

DV erify that ignition wires are correctly routed to

eliminate cross–firing.

DVerify that ignition wires are not arcing to

ground. Spraying the secondary ignition wires

with a light mist of water may help locate an

intermittent problem.

Was a problem found? — Verify repair Go to Step 7

7Check for an intermittent ignition system malfunction:

DIntermittent CKP 58X signal.

DIntermittent ignition feed circuit or sensor ground

circuit to the crankshaft position sensor.

Was a problem found? — Verify repair Go to Step 8

8To determine if there is a problem with fuel delivery,

refer to Fuel System Diagnosis.

Was a problem found? — Verify repair Go to Step 9

91. Check for the following engine mechanical

problems:

DLow compression

DLeaking cylinder head gasket

DWorn or incorrect camshaft

DIncorrect valve timing

DSticking or leaking valves

DCamshaft drive belt slipped or stripped.

Was a problem found? — Verify repair Go to Step 10

Step NoYesValue(s)Action

10 Check the intake and exhaust manifold(s) for casting

flash. Refer to Engine Mechanical.

Was a problem found? — Verify repair Go to Step 11

11 1. Review all the diagnostic procedures within this

table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:

DVisual/physical inspection

DTech 2 data

DFreeze Frame data/Failure Records buffer

DAll electrical connections within a suspected

circuit and/or system

Was a problem found? — Verify repair

Contact

Technical

Assistance

CUTS OUT, MISSES SYMPTOM

DEFINITION:

Steady pulsation or jerking that follows engine speed;

usually more pronounced as engine load increases.

Step Action Value(s) YesNo

1Was the On–Board Diagnostic (OBD) System Check

performed? —Go to Step 2

Go to OBD

System

Check

21. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom? — Verify repair Go to Step 3

3Was a visual/physical check performed?

—Go to Step 4

Go to Visual /

Physical

Check

4Check the ECM grounds to verify that they are clean

and tight. Refer to the ECM wiring diagrams in

Electrical Diagnosis.

Was a problem found? — Verify repair Go to Step 5

5 Monitor ”Long Term Fuel Trim” on the Tech 2.

Is the ”Long Term Fuel Trim” in the negative range (rich

condition)? —Go to Step 6 Go to Step 7

6Check items that can cause the engine to run rich.

Refer to ”Diagnostic Aids” in DTC P0172.

Was a problem found? — Verify repair Go to Step 9

7Is the long term fuel trim significantly in the positive

range (lean condition)? —Go to Step 8 Go to Step 9

8Check items that can cause the engine to run lean.

Refer to Diagnostic Aids in DTC P0171.

Was a problem found? — Verify repair Go to Step 9

91. Check for incorrect idle speed. Ensure that the

following conditions are present:

DEngine fully warm.

DAccessories are OFF.

2. Using a Tech 2, monitor the IAC position.

Is the IAC position within the specified values?

Between 5

and 50

counts Go to Step 11 Go to Step 10

10 1. Visually/physically inspect for the following

conditions:

DRestricted air intake system. Check for a

restricted air filter element, or foreign objects

blocking the air intake system.

DCheck for objects blocking the IAC passage or

throttle bore, excessive deposits in the IAC

passage and on the IAC pintle, and excessive

deposits in the throttle bore and on the throttle

plate.

DCheck for a condition that causes a large

vacuum leak, such as an incorrectly installed

or faulty crankcase ventilation valve or brake

booster hose disconnected.

Was a problem found? — Verify repair Go to Step 11

Step NoYesValue(s)Action

11 Check the injector connections. If any of the injectors

are connected to an incorrect cylinder, correct as

necessary.

Was a problem found? — Verify repair Go to Step 12

12 1. Perform the Injector Coil/Balance Test.

Was a problem found? — Verify repair Go to Step 13

13 1. Check for fuel in the pressure regulator vacuum

hose.

2. If fuel is present, replace the fuel pressure regulator

assembly.

Was a problem found? — Verify repair Go to Step 14

14 Check for proper ignition voltage output with spark

tester J 26792.

Was a problem found? — Verify repair Go to Step 15

15 1. Remove spark plugs and check for gas or oil fouling,

cracks, wear, improper gap, burned electrodes of

heavy deposits.

2. If spark plugs are fouled, the cause of fouling must

be determined before replacing the spark plugs.

Was a problem found? — Verify repair Go to Step 16

16 Check for a loose ignition control module ground.

Was a problem found? — Verify repair Go to Step 17

17 Using a Tech 2, monitor the TP angle with the engine

idling.

Is the TP angle at the specified value and steady? 0% Go to Step 18

For further

diagnosis,

refer to DTC

P0123

18 Check the PCV valve for proper operation.

Was a problem found? — Verify repair Go to Step 19

19 Check for the following engine mechanical problems:

DLow compression

DLeaking cylinder head gasket

DWorn or incorrect camshaft

DIncorrect valve timing

DSticking or leaking valves

DCamshaft drive belt slipped or stripped.

Was a problem found? — Verify repair Go to Step 20

20 Check for faulty motor mounts. Refer to Engine

Mechanical for inspection of the mounts.

Was a problem found? — Verify repair Go to Step 21

21 1. Review all the diagnostic procedures within this

table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:

DVisual/physical inspection

DTech 2 data

DFreeze Frame data/Failure Records buffer

DAll electrical connections within a suspected

circuit and/or system

Was a problem found? — Verify repair

Contact

Technical

Assistance

HESITATION, SAG, STUMBLE SYMPTOM

DEFINITION:

Momentary lack of response as the accelerator is pushed

down. Can occur at any vehicle speed. Usually most

pronounced when first trying to make the vehicle move,

as from a stop sign. May cause the engine to stall if severe

enough.

Step Action Value(s) YesNo

1Was the On–Board Diagnostic (OBD) System Check

performed? —Go to Step 2

Go to OBD

System

Check

21. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom? — Verify repair Go to Step 3

3Was a visual/physical check performed?

—Go to Step 4

Go to Visual /

Physical

Check

41. Check the fuel control heated oxygen sensor

(HO2S1). The HO2S1 should respond quickly to

different to throttle positions. If it doesn’t, check for

silicon or other contaminants from fuel or use of

improper RTV sealant. The sensors may have a

white powdery coating. Silicon contamination

sends a rich exhaust signal which causes the ECM

to command an excessively lean air/fuel mixture.

Was a problem found? — Verify repair Go to Step 5

5Check the fuel pressure. Refer to Fuel System

Pressure Test.

Was a problem found? — Verify repair Go to Step 6

6Observe the ”TP angle” display on the Tech 2 while

slowly increasing throttle pedal.

Does the TP angle display steadily increase from 0% at

closed throttle to 100% at WOT? —Go to Step 7 Go to Step 13

7 Monitor ”Long Term Fuel Trim” on the Tech 2.

Is the ”Long Term Fuel Trim” in the negative range (rich

condition)? —Go to Step 8 Go to Step 9

8Check items that can cause the engine to run rich.

Refer to Diagnostic Aids in DTC P0172.

Was a problem found? — Verify repair Go to Step 10

9Check items that can cause the engine to run lean.

Refer to Diagnostic Aids in DTC P0171.

Was a problem found? — Verify repair Go to Step 10

10 Check for proper ignition voltage output with spark

tester 5-8840-0383-0. For the procedure, refer to

Electronic Ignition System.

Was a problem found? — Verify repair Go to Step 11

11 Check for a loose ignition control module ground.

Was a problem found? — Verify repair Go to Step 12

Step NoYesValue(s)Action

12 Visually/physically inspect the secondary ignition

wires. Check for the following conditions:

DVerify that all ignition wire resistances are less

than the specified value.

DValue that ignition wires are correctly routed to

eliminate cross–firing.

DV erify that ignition wires are not arcing to ground.

Spraying the secondary ignition wires with a light

mist of water may help locate an intermittent

problem.

Was a problem found? 30,000 WVerify repair Go to Step 14

13 Replace the TP sensor. — Verify repair —

14 1. Check the ignition coil secondary resistance.

2. Replace the coil if it is not within the specified value.

Was a problem found? 9 kW– 12kWVerify repair Go to Step 15

15 1. Remove the spark plugs and check for gas or oil

fouling, cracks, wear, improper gap, burned

electrodes of heavy deposits.

2. If spark plugs are fouled, the cause of fouling must

be determined before replacing the spark plugs.

Was a problem found? — Verify repair Go to Step 16

16 Check the ECM grounds to verify that they are clean

and tight. Refer to the ECM wiring diagrams in

Electrical Diagnosis.

Was a problem found? — Verify repair Go to Step 17

17 Visually/physically check vacuum hoses for splits,

kinks, and proper connections and routing as shown on

the Vehicle Emission Control Information label.

Was a problem found? — Verify repair Go to Step 18

18 1. Review all diagnostic procedures within this table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:

DVisual/physical inspection

DTech 2 data

DFreeze Frame data/Failure Records buffer

DAll electrical connections within a suspected

circuit and/or system

3. If a problem is found, repair as necessary.

Was a problem found? — Verify repair

Contact

Technical

Assistance

RESTRICTED EXHAUST SYSTEM CHECK

Step Action Value(s) YesNo

1Was the On–Board Diagnostic (OBD) System Check

performed? —Go to Step 2

Go to OBD

System

Check

21. Remove the HO2S2.

DFor removal procedures, refer to Heated

Oxygen Sensors in On–Vehicle Service.

2. Install the Exhaust Backpressure Tester in place of

the Bank 1 HO2S.

3. Idle the engine at normal operating temperature.

Does the reading on the gauge exceed the specified

value? 8.62 kPa

(1.25 psi) Go to Step 5 Go to Step 3

3With the exhaust back–pressure tester in place of

HO2S, and the engine at normal operating

temperature:

Increase the engine speed to 2000 RPM while

observing the gauge.

Does the reading exceed the amount of the value

column? 8.62 kPa

(1.25 psi) Go to Step 5 Go to Step 4

41. Re–install the HO2S2. (Refer to Heated Oxygen

Sensors in On–Vehicle Service for installation

procedure.)

2. Remove the HO2S1.

3. Install the Exhaust Back–Pressure T ester BT8515V

or equivalent in place of the HO2S1.

4. Bring the engine to normal operating temperature

while observing the gauge.

5. Increase the engine speed to 2000 RPM (allow 10

seconds for pressure build) and observe the gauge.

Did the reading exceed the specified value? 8.62 kPa

(1.25 psi) Go to Step 6 System OK

5Repair a restiction in the exhaust system after the

catalytic converter.

Possible faults include:

DCollapsed pipe

DInternal muffler failure — Verify repair —

6Replace the restricted catalytic converter. — Verify repair —

NOTE: Diagnostic Trouble Codes will be set by running

the vehicle to normal operating temperature after a cold

start with the O2 sensor disconnected. After performing

these tests, use the Tech 2 to erase the Diagnostic

Trouble Codes that were set by the lack of O2 sensor

activity.

DEFAULT MATRIX TABLE

SERVICE PROCEDURE DEFAULT

STRATEGY

A referral strategy has been established to assist the

technician with additional information when the cause of

the failure cannot be determined. If no problem is found

after performing diagnostics, then for further diagnostic

information, refer to the default matrix table.

DEFAULT MATRIX TABLE

Strategy Based Diagnostic Charts Initial Diagnosis Default Section(s)

On–Board Diagnostic (OBD) System

Check Vehicle does not enter diagnostics. Chassis Electrical

On–Board Diagnostic (OBD) System

Check Vehicle enters diagnostics and

communicates with the Tech 2. MIL is

ON in diagnostics. Engine does not

start and run.

Ignition System Check

On–Board Diagnostic (OBD) System

Check Engine starts and runs, no ECM codes

set. Customer complains of vibration. —

ECM Power and Ground Check On–Board Diagnostic (OBD) System

Check. Chassis Electrical

ECM Power and Ground Check On–Board Diagnostic (OBD) System

Check. ECM power and ground circuits

OK. Data link voltage incorrect.

Chassis Electrical

Symptoms Initial Diagnosis Default Section(s)

Intermittents 1. On–board diagnostic (OBD)

system check.

2. Careful visual/physical inspections.

Chassis Electrical

Hard Starts 1. OBD system check.

2. Sensors (ECT, MAP, TP); MAP

output chart.

3. Fuel system electrical test, fuel

system diagnosis.

4. Ignition system.

5. IAC system check.

Engine Mechanical

Ignition System Check

Exhaust System Diagnosis

Surges and/or Chuggles 1. OBD system check.

2. Heated oxygen sensors.

3. Fuel system diagnosis.

4. Ignition system.

Calibration ID ”Broadcast

Code”/Service Bulletins

Ignition System Check

Generator Output

Exhaust System Diagnosis

Lack of Power, Sluggish or Spongy 1. OBD system check.

2. Fuel system diagnosis.

3. Ignition system.

4. EGR operation.

5. EGR system check.

Refer to Exhaust System in

Engine Exhaust

TCC Operation

Calibration ID/Service Bulletins

Detonation / Spark Knock 1. OBD system check.

2. EGR operation.

3. EGR system check.

4. Fuel system diagnosis.

5. Ignition system.

Cooling System

Ignition System Check

Calibration ID/Service Bulletins

Symptoms Initial Diagnosis Default Section(s)

Hesitation, Sag, Stumble 1. OBD system check.

2. TP.

3. MAP output check.

4. Fuel system diagnosis.

5. Fuel injector and fuel injector

balance test.

6. EVAP emission canister purge

valve.

7. Ignition system.

EGR Operation

EGR System Check

Generator Output Voltage (refer

to Chassis Electrical)

Calibration ID/Service Bulletins

Ignition System Check

Cuts Out, Misses 1. OBD system check.

2. Cylinder balance test. Ignition System Check

Rough, Unstable, or Incorrect Idle,

Stalling 1. OBD system check.

2. Fuel injector and fuel injector

balance test.

3. EVAP emission canister purge

valve check.

4. Ignition system.

5. IAC operation.

6. EGR operation.

MAP Output Check

Throttle Linkage

IAC System Check

EGR System Check

A/C Clutch Control Circuit Diag-

nosis

Crankcase Ventilation System

Calibration ID/Service Bulletins

Generator Output Voltage (refer

to Chassis Electrical)

Exhaust Diagnosis

Poor Fuel Economy 1. OBD system check.

2. Careful visual/physical inspection.

3. Ignition system.

4. Cooling system.

TCC Operation

Exhaust System (refer to Engine

Exhaust)

Engine Cranks But Will Not Run 1. OBD system check. Fuel System Electrical

Diagnosis

Fuel System Diagnosis

Fuel Injector

Fuel Injector Balance Test

Excessive Exhaust Emissions or

Odors 1. OBD system check.

2. Emission test.

3. Cooling system.

4. Fuel system diagnosis.

5. Fuel injector and fuel injector

balance test.

6. EVAP emission canister purge

valve.

7. Crankcase ventilation system.

8. Ignition system.

9. MAP output check.

EGR System Check

Exhaust Diagnosis

Calibration ID/Service Bulletins

Dieseling, Run–On 1. OBD system check.

2. Careful visual/physical inspection.

3. Fuel system diagnosis.

—

Backfire 1. OBD system check.

2. Ignition system.

3. Fuel system diagnosis.

4. Fuel injector and fuel injector

balance test.

5. EGR operation, EGR system

check.

Exhaust System Diagnosis,

Intake Casting Flash, Ignition

System Check

Symptoms Initial Diagnosis Default Section(s)

Misfire 1. OBD system check.

2. Ignition system.

3. Fuel system diagnosis.

4. Fuel injector and fuel injector

balance test.

Vibrations, Transmission,

Driveshaft and Axle

Catalyst Monitor 1. OBD system check.

2. Careful visual/physical inspection.

3. Heated oxygen sensors.

Exhaust System

Fuel Trim 1. OBD system check.

2. Careful visual/physical inspection.

3. Fuel system diagnosis.

4. Heated oxygen sensors.

Exhaust System Intake Air

System

Evaporative Emissions 1. OBD system check.

2. Careful visual/physical inspection.

3. Fuel system diagnosis.

—

Heated Oxygen Sensors 1. OBD system check.

2. Careful visual/physical inspection. Exhaust System

Camshaft Position (CMP)

Sensor

Removal Procedure

1.Disconnect the negative battery cable.

2.Remove spark plug cover on top of valve cover by

removing four retaining bolts.

3.Disconnect electrical connector from the sensor.

014RX003

4.Remove drive belt. Refer to Engine Mechanical

Section.

5.Remove top harness cover installed on timing belt

cover by removing a retaining screw.

6.Remove the retaining bolts holding crankshaft pulley,

and pull crankshaft pulley while wiggling. Refer to

Engine Mechanical Section.

7.Remove the retaining screws for timing belt cover and

timing belt cover.

014RX004

8.Remove the retaining bolt for the sensor and pull up

camshaft position sensor.

014RX005

Installation Procedure

1.Insert camshaft position sensor in position.

2.Install retaining bolt.

014RX007

3.Install the timing belt cover and the retaining screws.

4.Install the crank shaft pulley and the mounting bolts.

Holes for mounting bolts are off the pitch. The pulley

can be mounted only one way to install all mounting

bolts. Tighten the bolts. Refer to Engine Mechanical

section.

5.Install the drive belt. Refer to Engine Mechanical

Section.

014RX005

6.Install the top harness cover onto timing belt cover.

7.Connect electrical connector to the sensor and

securely lock it.

8.Install the spark plug cover.

9.Connect the negative battery cable.

014RX004

Crankshaft Position (CKP)

Sensor

Removal Procedure

1.Disconnect the negative battery cable.

2.Remove the drive belt. Refer to Engine Mechanical

Section.

014RX003

3.Remove the pwer steering pump and

mounting–bracket from engine.

4.Disconnect electrical connector from the sensor.

014RX006

5.Remove the retaining bolt and sensor from the engine

block.

NOTE:Use caution to avoid any hot oil that might drip

out.

0013

Installation Procedure

1.Install the crank shaft position sensor to its position.

2.Install and tighten the mounting bolt. Refer to Engine

Mechanical Section.

0013

3.Reinstall the power steering pump and bracket to the

engine.

014RX006

4.Reinstall the accessory drive belt.

5.Connect the negative battery cable.

014RX003

EEPROM

The Electronically Erasable Programmable Read Only

Memory (EEPROM) is a permanent memory that is

physically soldered within the ECM. The EEPROM

contains program and calibration information that the

ECM needs to control Powertrain operation.

014RX002

901RX031

Functional Check

1.Perform the On–Board Diagnostic System Check.

2.Start the engine and run for least one minute.

3.Check for DTCs using Tech 2.

4.If the ECM fails to program, proceed as follow:

DEnsure that all ECM connections are OK.

DCheck the ITCS for latest version software.

DAttempt to program ECM again. If ECM still cannot

be programmed properly, replace ECM. The

replacement ECM must be programmed.

Engine Coolant Temperature

(ECT) Sensor

Removal Procedure

1.Disconnect the negative battery cable.

2.Drain enough engine coolant so that the coolant level

will be below the ECT sensor.

3.Remove electrical connector from the sensor located

on the intake manifold above the ignition coil.

4.Unscrew the sensor from the manifold.

014RX008

Installation Procedure

1.Install the sensor into the intake manifold. Do not over

tighten.

2.Connect electrical connector.

3.Add engine coolant to required level. Refer to Engine

Cooling System Section.

4.Connect the negative battery cable.

0016

Heated Oxygen Sensor (HO2S)

Removal Procedure

1.Disconnect the negative battery cable.

2.Locate the two oxygen sensors.

DBank 1 sensor 1 is mounted on the exhaust pipe

ahead of the catalytic converter.

DBank 1 sensor 2 is mounted on the exhaust pipe

behind the catalytic converter.

3.Disconnect pig tail electrical connector.

IMPORTANT:The pigtail is permanently attached to

the sensor. Be careful not to pull the wires out.

014RX010

4.Unscrew sensors form the exhaust pipe. Because of

the expansion and contraction of the metal in the

exhaust system over time, this may be difficult if the

engine temperature is below 48 degree C.

Inspection Procedure

NOTE: Both sensors are identical. Inspect each inthe

same way.

1.Inspect the pigtail and the electrical connector for

grease, dirt, corrosion and bare wire or worn

insulation.

2.Inspect the louvered end of the sensor for grease,

dirt, excessive carbon build up or other contaminants.

TS23739

Installation Procedure

NOTE: If HO2S is reinstalled after removal, special

anti–seize compound or the equivalent should be applied

to the threads. Special anti–seize compound, (P/N

5613695), is used on the HO2S threads. This compound

consists of glass beads suspended in a liquid graphite

solution. The graphite burns away with exhaust heat, but

the glass beads will remain, making the sensor easier to

remove.

1.Apply anti–seize compound or the equivalent to the

thread.

TS23739

2.Install HO2S on the exhaust pipe.

3.Tighten the sensor to 55 Nm (5.6 kg·m/40 lb ft)

4.Connect the pig tail to the wiring harness.

5.Connect the negative battery cable.

(Pre–Catalytic Converter Heater Oxygen Sensor Loca-

tion)

014RX010

(Post–Catalytic Converter Heater Oxygen Sensor

Location)

014RX009

Intake Air Temperature (IAT)

Sensor

Removal Procedure

1.Disconnect the negative battery cable.

2.The IAT sensor is located in the intake air duct

between the air filter and the throttle body.

014RX011

3.Disconnect the electrical connector from the sensor.

4.Remove the sensor from intake air duct by using a

rocking motion while pulling the sensor.

0018

Installation Procedure

1.Install the IAT sensor into intake air duct. Make sure

the sensoris pushed all the way into the intake air

duct.

2.Connect electrical connector.

3.Connect the negative battery cable.

014RX011

Manifold Absolute Pressure

(MAP) Sensor

Removal Procedure

1.Disconnect the negative battery cable.

2.Disconnect the electrical connector from the sensor.

(The MAP sensoris located on the intake manifold

behind throttle body.)

3.Remove a mounting bolt securing the sensor to the

manifold.

4.Remove the sensor from the intake manifold using

rocking motion while pulling the sensor.

014RX012

Installation Procedure

1.Push MAP sensor into the manifold. Make sure the

sensor is pushed always into its position.

2.Install a mounting bolts and tighten.

3.Connect electrical connector.

4.Connect the negative battery cable.

014RX013

Malfunction Indicator Lamp

(MIL)

Malfunction Indicator Lamp (MIL)

Refer to Instrument Panel Removal Procedure.

Engine Control Module (ECM)

Electrostatic Discharge (ESD)

Damage

Electronic components used in the control system are

often designed to carry very low voltage. Electronic

components are susceptible to damage caused by

electrostatic discharge. Less than 100 volts of static

electricity can cause damage to same electronic

components. By comparison, it takes as much as 4000

volts for a person to even feel the zap of a static

discharge. There are several way for a person to become

statically charged. The most common methods of

charging are by friction and by induction. An example of

charging by friction is a person sliding across a car seat.

Charging by induction occurs when a person with well

insulated shoes stands near a highly charged object and

momentarily touches ground. Charge of the same polarity

are drained off leaving the person highly charged with

opposite polarity. Static charge can cause damage,

therefore, it is important to use care when handling and

testing electronic components.

NOTE:To prevent possible Electrostatic Discharge

damage, follow these guidelines:

DDo not touch the control module connector pins or

soldered components on the control module circuit

board.

DDo not open the replacement part package until the

part is ready to be installed.

DBefore removing the parts from the package, ground

the package to a known good ground on the vehicle.

DIf the parts been handled while sliding across the

seat, or while sitting from standing position, or walking

a distance, touch a known good ground before

installing the parts.

014RX002

NOTE:To prevent internal ECM damage, the ignition

must be OFF position in order to disconnect or reconnect

power to the ECM (for example: battery cable. pig tail,

ECM fuse, jumper cable, etc.).

IMPORTANT:When replacing the production ECM

with a service ECM, it is important to transfer the

broadcast code and production ECM number to the

service ECM label. This will allow positive identification of

ECM parts throughout the service life of the vehicle. Do

not record this information on ECM metal cover.

Removal Procedure

1.Disconnect the negative battery cable.

2.Block the wheels.

3.Remove ashtray inner.

4.Remove a screw located behind ashtray.

014RX014

5.Pull out Face trim of console.

6.Remove two screws located inside of center console

storage box and pull up rear part of center console.

014RX015

7.Unscrew the shift knob.

8.Remove four screw holding front part of the console

and pull the console up.

9.Disconnect the red, white and blue electrical

connector at the ECM.

014RX016

10.Remove two nuts in the front of ECM.

11.Remove two nuts in the rear of ECM.

12.Pull the ECM out from dashboard.

014RX002

Installation Procedure

1.Place ECM into its position and secure by four

mounting screws.

014RX002

2.Connect all three connectors to ECM. All connectors

are color keyed. Same color male and female

connectors join together.

014RX017

3. Install the front center console and secure by four

retaining screws.

014RX016

4.Install the rear center console and secure it by two

retaining screw into storage box.

014RX015

5.Snap face plate into its position and secure it by a

screw.

6.Insert ashtray inner.

7.Insert the shift knob.

8.Connect the negative battery cable.

9.Remove wheel blocks.

014RX014

Throttle Position (TP) Sensor

Removal Procedure

1.Disconnect the negative battery cable.

2.Disconnect the TPS electrical connector.

3.Remove the two screws and TP sensor from the

throttle body.

NOTE: Do not clean the TP sensor by soaking it in

solvent. The sensor will be damaged as a result.

101RX002

Function Check

Use a Tech 2 to check the TP sensor output voltage at

closed throttle.

DThe voltage should be under 0.25 volts.

DIf the reading is greater than 0.25 volts, check the

throttle shaft to see if it is binding. Check that the

throttle cable is properly adjusted, also. Refer to

Throttle Cable Adjustment.

DIf the throttle shaft is not binding and the throttle cable

is properly adjusted, install a new TP sensor.

101RX003

Installation Procedure

1.Install the TP sensor on the throttle body with two

screws.

101RX003

2.Connect the electrical connector.

3.Connect the negative battery cable.

101RX002

Vehicle Speed Sensor (VSS)

Removal Procedure

1.Disconnect the negative battery cable.

2.VSS is located on the right side of the transmission

case just ahead of the rear propeller shaft.

Disconnect the VSS electrical connector.

3.Remove the bolt and the VSS from the transmission

case by wiggling it slightly and pulling it straight out.

IMPORTANT:Have a container ready to catch any fluid

that leaks out when the VSS is removed from the transfer

case.

014RX020

Inspection Procedure

1.Inspect the electrical connector for signs of corrosion

or warping. Replace the VSS if the electrical

connector is corroded or warped.

2.Inspect the VSS driven gear for chips, breaks, or worn

condition. Replace the VSS if the driven gear is

chipped, broken or worn.

3.Inspect the O–ring for wear, nicks, tears, or

looseness. Replace the O–ring if necessary.

014RX021

Installation Procedure

1.Install the VSS in the transmission case with the

notch for the connector facing the rear.

2.Secure the VSS with mounting bolt. Tighten the bolt to

16 Nm (12 lb ft).

014RX021

3.Connect electrical connector to the VSS.

4.Check the transmission oil level. Add oil if necessary .

5.Connect the negative battery cable.

014RX020

Air Filter

Removal Procedure

1.Disconnect electrical connector at the IAT sensor.

2.Release the four latches securing the lid to the air

cleaner housing.

3.Remove the air cleaner lid.

014RX019

4.Remove the air filter element.

014RX023

Installation Procedure

1.Install the air filter element in the air cleaner housing.

014RX023

2.Install the air cleaner lids.

3.Secure the three latches, holding the lid on the air

cleaner housing.

4.Connect the electrical connector to the IAT sensor.

014RX019

Idle Air Control (IAC) Valve

Removal Procedure

1.Disconnect the negative battery cable.

101RX002

2.Disconnect the IAC electrical connector.

3.Remove the two screws and IAC valve from the

throttle body.

NOTE:Do not clean the IAC valve by soaking it in

solvent. The valve will be damaged as a result.

014RX022

Cleaning and Inspection Procedure

DClean the IAC valve O–ring sealing surface, pintle

valve seat and air passage.

DUse carburetor cleaner and a parts cleaning brush to

remove carbon deposit. Do not use a cleaner that

contain methyl ethyl ketone. This is an extremely

strong solvent and not necessary for this type of

deposit.

DShiny spots on the pintle are normal and do not

indicate misalignment or a bent pintle shaft.

DInspect the IAC valve O–ring for cuts, cracks or

distortion. Replace the O–ring if damaged.

0006

Measurement Procedure

DIn order to install a new IAC valve, measure the

distance between the tip of the pintle and the

mounting flange. If that measurement is 28 mm or

less, the valve need no adjustment. If the

measurement is greater than 28 mm, apply finger

pressure and retract the valve. The force required to

retract the pintle on a new valve will not damage the

valve, shaft or pintle.

NOTE:Do not push or pull on the IAC valve pintle on IAC

valve that have been in service. The force required to

move the pintle may damage it.

IMPORTANT:Use an identical replacement part in

order to replace a valve. IAC valve pintle shape and

diameter are designed for the specific application.

TS23746

Installation Procedure

1.Install IAC valve on the throttle valve body with the

two screws. Tighten the screw to 1 Nm ( 9 lb in).

014RX022

2.Connect electrical connector to IAC valve.

3.Connect the negative battery cable.

101RX002

Intake Air Duct

Removal Procedure

1.Disconnect the negative battery cable.

2.Disconnect electrical connector at IAT sensor.

3.Remove the IAT sensor if necessary. Refer to Intake

Air Temperature Sensor Removal.

014RX011

4.Loosen retaining clamps at the throttle body and at

the air filter box.

5.Disconnect brake booster vacuum hose at intake

manifold and at brake booster.

014RX025

6.Remove retaining nut at the intake air duct bracket at

top of valve cover.

7.Disconnect the intake air duct from the throttle body

and at the air filter box.

014RX019

Installation Procedure

1.Connect the intake air duct at the throttle body and at

the air filter box. Make sure retaining hole is inserted

to the intake air duct bracket.

014RX019

2.Tighten retaining clamp at the throttle body and at the

air filter box.

3.Install a nut to the intake air duct bracket and tighten.

4.Connect brake booster vacuum hose to intake

manifold and to brake booster and secure them with

clamps.

014RX026

5.Install IAT sensor if necessary. Refer to Intake Air

Temperature Sensor Installation.

6.Connect electrical connector at IAT sensor.

7.Connect the negative battery cable.

014RX011

IMPORTANT:Use an identical replacement part in

order to replace a valve. IAC valve pintle shape and

diameter are designed for the specific application.

Knock Sensor

Removal Procedure

1.Disconnect negative battery cable.

2.Disconnect pig tail electrical connector at near the top

of generator.

014RX027

3. Unscrew retaining bolt from Knock Sensor located

passenger side of engine block just front of starter.

014RX028

4.Remove Knock Sensor with retaining bolt.

Installation Procedure

1.Install Knock Sensor with retaining bolt.

2.Connect pig tail electrical connector.

3.Connect battery negative cable.

014RX029

Oil Pressure Switch

Removal Procedure

1.Disconnect battery negative cable.

2.Disconnect electrical connector at Oil Pressure

Switch.

014RX030

3.Unscrew Oil Pressure Switch from Oil Filter Mounting

Housing.

014RX031

Installation Procedure

1. Install Oil Pressure Switch into Oil Filter Mounting

Housing and tighten.

2.Connect electrical connector.

3.Connect battery negative cable.

014RX028

FUEL METERING SYSTEM

Accelerator Cable Assembly

Removal Procedure

1.Loosen the adjusting nut on the cable bracket

mounting on the throttle body.

2.Remove the cable clip from holding bracket.

014RX026

3.Remove accelerator control cable (on the throttle

valve end).

101RW006

4.Remove the accelerator control cable (on the

accelerator pedal end).

5.Remove the grommet.

6.Remove the accelerator control cable.

Inspection Procedure

Check the following items, and replace the control cable if

any abnormality is found:

DThe control cable should move smoothly.

DThe control cable should not be bent or kinked.

DThe control cable should be free of damage and

corrosion.

014RX032

Installation Procedure

1.Install the accelerator control cable.

2.Install the grommet.

3.Install the accelerator control cable on the accelerator

pedal.

014RX032

4.Install the accelerator control cable on the throttle

valve.

101RW006

5.Install the cable clip to the holding bracket.

6.Adjust the accelerator cable. Refer to Accelerator

Cable Adjustment Section.

014RX026

Accelerator Cable Adjustment

Adjustment Procedure

1.Loosen the adjusting nut.

2.Loosen the jam nut.

3.Pull the outer cable while fully closing the throttle

valve.

4.Tighten the adjusting nut.

5.Tighten the jam nut.

6.Loosen the adjusting nut by three turns.

7.Tighten the jam nut again.

8.Manually operate valve.

IMPORTANT: The valve lever must return up to the

stopper screw. If the valve lever does not reach the

stopper screw, repeat the procedure again from Step 1.

014RX026

Accelerator Pedal Replacement

Removal Procedure

1.Disconnect the accelerator pedal control cable from

the acceleratorpedal assembly.

2.Remove the two screws retaining the accelerator

pedal to the bulkhead.

3.Remove the accelerator pedal from the bulkhead.

014RX033

Installation Procedure

1.Install the accelerator pedal assembly to the

bulkhead with two screws.

2.Connect the accelerator control cable to the

accelerator pedal assembly.

3.Adjust accelerator cable if necessary. Refer to

Accelerator Cable Adjustment Section.

014RX034

Fuel Filler Cap

The Fuel filter cap includes a vacuum valve and a

pressure valve. If high vacuum or pressure occurs in the

fuel tank, each valve works to adjust the pressure in order

to prevent damage to the tank at the EGR valve.

Inspection Procedure

NOTE: Replace the fuel filler cap with the same typeof

filler cap that was originally installed on the vehicle.

DCheck the seal ring in the filler cap for any abnormality

and for seal condition.

DReplace the filler cap if any abnormality is found.

TS23767

Fuel Filter

Removal Procedure

1.Disconnect the negative battery cable.

2.Remove the fuel filler cap.

041RW005

3. Disconnect the fuel lines from the fuel filter on the

engine side.

4.Disconnect the fuel line from the fuel filter on the fuel

tank side.

041RW006

5.Remove the bolt on the fuel filter holder.

6.Remove the fuel filter.

041RW007

Inspection Procedure

1.Replace the fuel filter when the following occur:

DFuel leaks from the fuel filter body

DThe fuel filter body is damaged

DThe fuel filter is clogged with dust or sediment

2.If the drain hole is clogged at filler neck is clogged with

dust, clean the drain hole with air.

041RW008

Installation Procedure

1.Install the fuel filter in the correct direction.

2.Install the bolt on the fuel filter holder.

3.Connect the fuel line on the engine side.

4.Connect the fuel line on the fuel tank side.

5.Install the fuel filler cap.

6.Connect the negative battery cable.

041RW006

Fuel Injectors

Removal Procedure

NOTE:If the fuel injectors are leaking, the engine oil may

be contaminated with fuel. Check the oil for signs of

contamination and change the oil and filter if necessary.

NOTE:Use care in removing the fuel injector in order to

prevent damage to the fuel injector electrical connector

pins or fuel injector nozzles. The fuel injector is an

electrical component and should not be immersed in any

type of cleaner as this may damage the fuel injector.

IMPORTANT:Fuel injectors are serviced as complete

assembly only.

1.Disconnect the negative battery cable.

014RX035

2.Disconnect electrical connector from fuel injector.

3.Remove the fuel rail. Refer to Fuel Rail Removal

Procedure.

014RX036

4.Remove the fuel injector retainer clip.

5.Remove fuel injector assembly from fuel rail.

6.Remove O–ring from the fuel injector.

7.Remove O–ring backup from fuel injector.

014RX037

Inspection Procedure

1.Inspect O–ring for crack, damage or leaks.

2.Replace worn or damaged O–ring.

3.Lubricate the new O–rings with engine oil before

installation.

Installation Procedure

1.Lubricate the new O–ring with engine oil.

2.Install the O–ring backup on the fuel injector.

3.Install new O–ring on the fuel injector.

4.Install all four injector on the fuel rail.

5.Use new injector retainer clip to retain the injector to

the fuel rail.

6.Coat the end of the fuel injector with engine oil.

014RX037

7.Install fuel rail assembly. Refer to Fuel Rail

Installation Procedure.

8.Connect the negative battery cable.

014RX035

Fuel Pressure Regulator

Removal Procedure

CAUTION:To reduce the risk of fire and personal

injury, it is necessary to relieve the fuel system

pressure before servicing the fuel system

components.

CAUTION:After relieving the fuel system pressure,

a small amount of fuel may be released when

servicing fuel lines or connections. Reduce the

chance of personal injury by covering the fuel line

fitting with a shop towel before disconnecting the

fittings. The towel will absorb any fuel that may leak

out. When the disconnect is completed, place the

towel in an approved container.

NOTE: Compressed air must never used to test or clean

a fuel pressure regulator , as damage to the fuel pressure

regulator may occur.

014RX035

NOTE:To prevent damage to the fuel pressure regulator,

do not immerse the pressure regulator in solvent.

1.Depressurize the fuel system. Referto Fuel Pressure

Relief Procedure.

2.Disconnect the negative battery cable.

3.Remove the fuel pump relay.

4.Disconnect the vacuum line form fuel pressure

regulator.

014RX038

5.Remove the fuel pressure regulator retaining screw.

6.Remove the fuel pressure regulator retaining bracket.

7.Remove the fuel pressure regulator from fuel rail.

014RX039

Installation Procedure

1.Insert the fuel pressure regulator into the fuel rail.

014RX039

2. Install the fuel pressure regulator retaining bracket

ant tighten with a screw.

3.Connect vacuum line onto the fuel pressure regulator.

014RX038

4.Install the fuel pump relay.

5.Connect the negative battery cable.

6.Crank the engine until it starts. Cranking the engine

may take longer than usual due to trapped air in the

fuel line.

014RX035

Fuel Pressure Relief Procedure

CAUTION:To reduce the risk of fire and personal

injury, it is necessary to relieve the fuel system

pressure before servicing the fuel system

components.

CAUTION:After relieving the fuel system pressure,

a small amount of fuel may be released when

servicing fuel lines or connections. Reduce the

chance of personal injury by covering the fuel line

fitting with a shop towel before disconnecting the

fittings. The towel will absorb any fuel that may leak

out. When the disconnect is completed, place the

towel in an approved container.

1.Remove the fuel filler cap.

041RW005

2.Remove the fuel pump relay from the underhood

relay box.

3.Start the engine and allow it to stall.

4.Crank the engine for about 30 seconds.

5.Disconnect the negative battery cable.

014RW089

Fuel Pump Assembly

Removal Procedure

1.Disconnect the negative battery cable.

2.Drain all fuel from fuel tank from filler neck.

3.Remove the fuel pump relay from the fuse and relay

box at right side of engine room.

014RW089

4.Remove fuel tank. Refer to Fuel Tank Removal

Procedure.

5. Using J–39763, twist the fuel pump counter–clock

wise to release from fuel tank.

041RX001

6.Lift fuel pump to remove from fuel tank.

041RX002

Inspection Procedure

Inspect in–tank fuel filter for tears, damage or evidence of

dirt derbies or water in the fuel. If any of these condition

exist, replace the in–tank fuel filter.

041RX003

Installation Procedure

1.Insert the fuel pump assembly into fuel tank and place

them at its position.

041RX002

2.Using J–39763, twist fuel pump assembly clock wise

into the lock.

901RX036

3.Install the fuel tank. Refer to Fuel Tank Installation

Procedure.

4.Install the fuel pump relay.

5.Connect the negative battery cable.

041RX004

Fuel Pump Relay

Removal Procedure

1.Remove the fuse and relay box cover located right

side of engine room.

2.Determine correct relay by consulting to the diagram

on the cover.

3.Insert a small screwdriver or use thumb pressure to

release the retainer of the relay.

4.Pull the relay straight up and out of the fuse and relay

box.

Installation Procedure

1.Inserts the relay into the correct place in the fuse and

relay box with the catch slot aligned to retainer.

2.Press down until the catch of retainer engages.

3.Install fuse and relay box cover.

014RW089

Fuel Rail Assembly

Removal Procedure

NOTE:

DUse care when removing the fuel rail assembly in

order to prevent damage to the injector electrical

connector terminal and the injector spray tips.

DFitting should be capped and holes plugged during

servicing to prevent dirt and other contaminants from

entering open lines and passage.

IMPORTANT:An eight–digit identification number is

stamped on side of the fuel rail. Refer to this number when

you service the fuel rail or when a replacement part is

required.

014RX035

1.Depressurize the fuel system. Refer to Fuel Pressure

Relief Procedure.

2.Disconnect the fuel inlet at the rear of the engine.

3.Disconnect the fuel return line at front of the engine.

4.Disconnect the injector electrical connectors.

5.Remove the nuts holding wiring harness onto fuel rail.

6.Remove the bolts retaining fuel rail to the intake

manifold.

Lift up the injectors carefully to separate them from intake

manifold.

Lift up the fuel rail with injectors as assembly. Do not sep-

arate the fuel injectors from fuel rail.

If an injector become separated from fuel rail, injector

backup O–ring and injector retainer clip must be replaced.

Drain residual fuel from fuel rail into an approved contain-

er.

014RX036

7.If removal of fuel pressure regulator is necessary.

Refer to Fuel Pressure Regulator Removal

Procedure.

8.If removal of fuel injector is necessary. Refer to Fuel

Injectors Removal Procedure.

014RX037

Installation Procedure

1.Install the fuel injectors if necessary. Refer to Fuel

Injector Installation Procedure.

2.Install the fuel pressure regulator if necessary. Refer

to Fuel Pressure Regulator Installation Procedure.

3.Place the fuel injector rail assembly on the manifold

and insert the injectors into each port by pushing fuel

rail.

014RX037

4. Install two fuel rail retaining bolts. Tighten fuel rail

retaining bolts to 19 Nm (14 lb ft)

5.Place wiring harness in its place and secure it with two

nuts.

6.Connect electrical connector to each fuel injector.

014RX036

7. Connect the fuel supply line securely. Do not over

tighten.

8. Connect the fuel return line securely. Do not over

tighten.

9.Connect the negative battery cable.

10.Crank the engine until it start. Cranking the engine

may take longer than usual due to trapped air in the

fuel system. Check for leak. If fuel leak is observed,

stop engine immediately. Before correct fuel leak, be

sure to depressurize system again.

014RX035

Fuel Tank

Removal Procedure

1.Disconnect the negative battery cable.

2.Remove fuel filer cap.

3.Drain the fuel from fuel filler neck.

4.Disconnect the fuel filler hose at fuel tank.

5.Disconnect the air breather hose at the fuel tank.

6.Disconnect the evaporator hose at the fuel tank.

7.Hold entire fuel tank at the bottom with stands.

8. Disconnect fuel supply lines and fuel return line at

near the fuel filter inside of body frame.

041RX005

9.Remove four bolts (two in front and two in rear)

holding fuel tank to the frame.

10.Lower tank assembly from the vehicle a little to make

access space on top.

11.Disconnect two electrical connectors at fuel pump.

041RX006

12.Remove fuel tank assembly from the vehicle.

13.Remove four nuts retaining tank under guard to the

tank.

14.Remove the tank from the guard.

041RX002

Installation Procedure

1.Secure fuel tank into under guard with four retaining

bolts, if necessary.

2.Place the fuel tank assembly onto stands.

3.Lift the fuel tank assembly near the position.

4.Connect two electrical connectors at fuel pump.

5.Lift the fuel pump to its position and secure it with four

mounting bolts. Make sure that all hoses and fuel

lines are out of way between the fuel tank and the fuel

tank bracket. Tighten the fuel tank retaining bolts to

36 Nm (27 lb ft).

041RX007

6.Connect fuel supply and return lines.

7.Connect the fuel filler hose, the air breather hose and

EVAP hose onto fuel tank and secure them with

clamps.

041RX006

8.Pour fuel into fuel tank.

9.Install fuel filler cap securely.

10.Connect the battery negative cable.

041RX005

Throttle body (TB)

Removal Procedure

1.Disconnect the negative battery cable.

2.Drain the cooling system. Refer to Cooling System.

3.Remove the air intake duct. Refer to Air Intake Duct

Removal Procedure.

4.Remove the accelerator cable from throttle. Refer to

Accelerator Cable Assembly Removal Procedure.

5.Disconnect the electrical connectors from the throttle

position sensor and the idle air control valve solenoid.

6.Disconnect all vacuum hoses below air horn.

7.Disconnect coolant lines.

014RX025

8.Remove the mounting bolts retaining the throttle body

the intake manifold.

9.Lift up the throttle body from the intake manifolds.

014RX040

10.Remove the gaskets from the intake manifolds.

11.Remove the IAC. Refer to Idle Air Control Valve

Solenoid Removal Procedure.

12.Remove TPS. Refer to Throttle Position Sensor

Removal Procedure.

Inspection Procedure

NOTE:Do not use solvent of any type when you clean the

gasket surfaces on the intake manifold and the throttle

body assembly. The gasket surface and the throttle body

assembly may be damaged as results.

1.If the throttle body gasket needs to be released,

remove any gasket material that may be stuck to the

mating surfaces of the manifold.

2.Do not leave any scratches in the aluminum casting.

014RX041

Installation Procedure

1.Install IAC valve onto the throttle body. Refer to Idle

Air Control Valve Solenoid Installation Procedure. 2.Install TPS onto the throttle body if necessary. Refer

to TPS Installation Procedure.

3.Place the gasket then the throttle body on the

manifold.

4.Install four mounting bolt. Tighten the throttle body

mounting bolt to 13.5 Nm (10 lb ft).

014RX041

5.Connect coolant line and secure them with clamps.

6.Connect all vacuum hoses and secure them with

clamps if necessary.

7.Install accelerator control cable bracket onto the

throttle body.

8.Connect accelerator control cable to throttle plate.

014RX025

9.Connect electrical connector at IAC valve and TPS.

10.Install the air intake duct. Refer to Air Intake DuctInstallation Procedure. 11.Fill the cooling system with required coolant. Refer to

Engine Cooling System.

12.Connect the negative battery cable.

101RX002

ELECTRONIC IGNITION SYSTEM

Ignition Control Module (ICM)

Removal Procedure

1.Disconnect the negative battery cable.

2.Disconnect the electrical connector from the ignition

control module.

3.Remove the two attaching screws.

4.Remove the ignition control module from the engine

block.

Installation Procedure

1.Fasten the module to the engine block with two

screws.

2.Reconnect the electrical connector.

3.Reconnect the negative battery terminal.

041RX042

Ignition Coil

Removal Procedure

1.Disconnect the negative battery cable.

2.Drain the cooling system. Refer to Engine Cooling

System.

3.Remove the heater supply and return hose.

4.Remove the coolant return hose.

5.Disconnect all four spark plug cables from the coil.

6.Disconnect electrical connector from the ignition coil.

7.Remove three mounting bolt from the ignition coil.

8.Remove the ignition coil from the bracket.

014RX043

Installation Procedure

1.Install the ignition coil onto the bracket with three

mounting bolts.

2.Connect electrical connector at the ignition coil.

3.Connect spark plug cable to the ignition coil.

4.Connect heater supply and return hose and secure

them with clamps.

5.Connect coolant return line and secure them with

clamps.

6.Fill the cooling system with required coolant. Refer to

Engine Cooling System.

7.Connect the negative battery cable.

014RX044

Spark Plugs

Removal Procedure

Type: NGK BPR6ES–11

Spark Gap : 1.05 MM (0.040”)

Spark Plug Torque : 25 Nm (2.6 kg·m/18 lb ft)

1.Disconnect the negative battery cable.

2.Remove four bolt holding spark plug cover plate to top

of valve cover, and remove the cover plate.

3.Pull ignition wire using hocks attached to end of spark

plug cable.

014RX043

4.Remove the spark plug.

014RX045

Inspection Procedure

1.Check the insulator for cracks. Replace the spark

plug if crack are present.

2.Check the electrode condition and replace the spark

plug if necessary.

014RX046

If the spark plug electrodes and insulators are fouled with

carbon or oil, the engine will not operate efficiently.

There are number of possible causes:

DFuel mixture is too rich.

DOil in the combustion chamber.

DThe spark plug gap is not set correctly.

If spark plug fouling is excessive, check the fuel and

electrical system for possible causes of trouble. If fuel and

electrical system are normal, install spark plug of a higher

heat range which have the same physical dimensions as

the original equipment spark plug.

The following symptoms are characteristics of spark

plugs that are running too hot:

DFuel mixture is too lean.

DHeat range is incorrect.

014RX047

If vehicle usage does not conform to normal driving

conditions, a more suitable spark plug may be

substituted.

If fuel and electrical system are normal, in most cases of

this sort, the problem can be corrected by using a colder

type spark plug with the same physical dimensions as the

original equipment spark plug.

3.Check the gaskets for damage and replace if

necessary.

4.Measure the spark plug gap. The specification is 1.05

mm (0.040”).

5.Adjust the spark gap by bending the grounded

electrode.

014RX048

Installation Procedure

1.Tighten the spark plug to the 25 Nm (2.6 kg·m/18 lb ft).

2.Push the spark plug cable in until it snaps in.

3.Install spark plug cover onto valve cover and secure it

with four retaining bolts.

014RX049

Spark Plug Cables

The cable contains a synthetic conductor which is easily

damaged. Never stretch or kink the cable. Disconnect the

cable from spark plug and the ignition coil.

The original equipment cables and the ignition coil are

marked to show correct location of the cables. If spark

plug cables or the ignition coil are replaced previously,

before cables are removed from the ignition coil, mark the

cables and the coil so they can be reconnected in the

same position.

014RX050

Inspection Procedure

NOTE:Never puncture the spark plug cable’s insulation

with a needle or the pointed end of a probe into the cable.

An increase in resistance would be created which would

cause the cable to become defective.

1.If the cable has broken or cracked insulation, it must

be replaced.

2.If the terminals are corroded or loose, the cable must

be replaced.

3.Check that the cable resistance does not exceed 10 k

W per foot.

014RX051

EMISSIONS Catalytic Converter

Refer to Engine Exhaust.

Air Conditioning Relay

Removal Procedure

1.Remove the fuse and relay box cover at right side of

engine room.

2.Refer to the diagram on the cover to determine which

is the correct relay.

3. Insert small screwdriver or use thumb pressure to

release the retainer of the relay.

4.Pull the relay straight up and out of the fuse and relay

box.

014RX052

Installation Procedure

1.Insert the relay into the correct place in the fuse and

relay box with the catch slot aligned to retainer.

2.Press down until the catch of retainer engages.

3.Install fuse and relay box cover.

Ignition Timing Adjustment

There is no timing adjustment. The timing signal is

furnished by the CKP and the CMP signal. ECM control

the ignition timing.

EVAP Canister Hoses

To see the routing of the EVAP canister hoses, refer to

Vehicle Emission Control Information in Diagnosis or

Emission Label located bottom side ofthe hood. Use

6148M or equivalent when you replace the EVAP canister

hoses.

EVAP Canister

Removal Procedure

1.Disconnect all hoses.

2.Remove two mounting bracket nuts.

Inspection Procedure

1.Inspect the hoses for cracks, damage and leaks.

2.Inspect the canister for damages.

014RX001

Installation Procedure

1.Install EVAP canister onto crossmember with two

mounting bolts.

2.Connect all hoses and secure them with clamps.

014RX054

Linear Exhaust Gas

Recirculation (EGR) Valve

Removal Procedure

1.Disconnect the negative battery cable.

2.Disconnect electrical connector at EGR valve.

3.Disconnect the electrical connector at Intake Air

Temperature Sensor.

4.Remove air intake duct. Refer to Air Intake Duct

Removal Procedure.

5.Remove crankshaft breather hose.

6.Remove two bolts holding EGR valve.

7.Remove EGR valve and gasket from the manifold.

057RX001

Inspection Procedure

1.Inspect the air passage for a restrtiction. If there is

restriction, remove the object. Do not use any type of

solvent, it may damage electrical system of EGR

valve.

2.Inspect restriction for valve movement. If there is

restriction remove the object.

014RX056

Installation Procedure

1.Place the gasket and EGR valve on to the intake

manifold.

2.Install mounting bolts and tighten.

3.Connect electrical connector at EGR valve

4.Connect the crankshaft breather hose and secure it

with clamps.

5.Install the air intake duct. Refer to Air Intake Duct

Installation Procedure.

6.Connect the negative battery cable.

014RX057

Wiring and Connectors

Wiring Harness Service

The control module harness electrically connects the

control module to the various solenoids, switches and

sensors in the vehicle engine compartment and

passenger compartment.

Replace wire harnesses with the proper part number

replacement.

Because of the low amperage and voltage levels utilized

in powertrain control systems, it is essential that all wiring

in environmentally exposed areas be repaired with crimp

and seal splice sleeves.

The following wire harness repair information is intended

as a general guideline only. Refer to Chassis Electrical for

all wire harness repair procedures.

ECM Connectors And Terminals

Removal Procedure

1.Remove the connector terminal retainer.

2.Push the wire connected to the affected terminal

through the connector face so that the terminal is

exposed.

3.Service the terminal as necessary.

Installation Procedure

1.Bend the tab on the connector to allow the terminal to

be pulledinto position within the connector.

2.Pull carefully on the wire to install the connector

terminal retainer.

Connectors And Terminals

Use care when probing a connector and when replacing

terminals. It is possible to short between opposite

terminals. Damage to components could result. Always

use jumper wires between connectors for circuit

checking. NEVER probe through Weather–Pack seals.

Use an appropriate connector test adapter kit which

contains an assortment of flexible connectors used to

probe terminals during diagnosis. Use an appropriate

fuse remover and test tool for removing a fuse and to

adapt the fuse holder to a meter for diagnosis.

Open circuits are often difficult to locate by sight because

oxidation or terminal misalignment are hidden by the

connectors. Merely wiggling a connector on a sensor, or

in the wiring harness, may temporarily correct the open

circuit. Intermittent problems may also be caused by

oxidized or loose connections.

Be certain of the type of connector/terminal before

making any connector or terminal repair. Weather–Pack

and Com–Pack III terminals look similar , but are serviced

differently.

Wire Harness Repair: Twisted

Shielded Cable

Removal Procedure

1.Remove the outer jacket.

2.Unwrap the aluminum/mylar tape. Do not remove the

mylar.

047

3.Untwist the conductors.

4.Strip the insulation as necessary.

048

Installation Procedure

1.Splice the wires using splice clips and rosin core

solder.

2.Wrap each splice to insulate.

3.Wrap the splice with mylar and with the drain

(uninsulated) wire.

049

4.Tape over the whole bundle to secure.

050

Twisted Leads

Removal Procedure

1.Locate the damaged wire.

2.Remove the insulation as required.

051

Installation Procedure

1.Use splice clips and rosin core solder in order to splice

the two wires together.

052

2.Cover the splice with tape in order to insulate it from

the other wires.

053

3.Twist the wires as they were before starting this

procedure.

054

4.Tape the wires with electrical tape.

055

Weather–Pack Connector

Tools Required

5-8840-0388-0 Weather–Pack II Terminal Remover

Removal Procedure

A Weather–Pack connector can be identified by a rubber

seal at the rear of the connector. This engine room

connector protects against moisture and dirt, which could

form oxidation and deposits on the terminals. This

protection is important, because of the low voltage and

the low amperage found in the electronic systems.

1.Open the secondary lock hinge on the connector.

070

2.Use tool 5-8840-0388-0 or the equivalent to remove

the pin and the sleeve terminals. Push on

5-8840-0388-0 to release.

NOTE: Do not use an ordinary pick or the terminal may

be bent or deformed. Unlike standard blade terminals,

these terminals cannot be straightened after they have

been improperly bent.

071

3.Cut the wire immediately behind the cable seal.

072

Installation Procedure

Make certain the connectors are properly seated and all

of the sealing rings are in place when you reconnect the

leads. The secondary lock hinge provides a backup

locking feature for the connector. The secondary lock

hinge is used for added reliability. This flap should retain

the terminals even if the small terminal lock tangs are not

positioned properly.

Do not replace the Weather–Pack connections with

standard connections. Read the instructions provided

with the Weather–Pack connector and terminal

packages.

1.Replace the terminal.

2.Slip the new seal onto the wire.

3.Strip 5 mm (0.2”) of insulation from the wire.

4.Crimp the terminal over the wire and the seal.

073

5.Push the terminal and the connector to engage the

locking tangs.

6.Close the secondary locking hinge.

Com–Pack III

The Com–Pack III terminal looks similar to some

Weather–Pack terminals. This terminal is not sealed and

is used where resistance to the environment is not

required. Use the standard method when repairing a

terminal. Do not use the Weather–Pack terminal tool

5-8840-0388-0 or equivalent. These will damage the

terminals.

070

Metri–Pack

Tools Required

5-8840-0632-0 Terminal Remover

Removal Procedure

Some connectors use terminals called Metri–Pack Series

150. These may be used at the engine coolant

temperature (ECT) sensor.

1.Slide the seal (1) back on the wire.

2.Insert the 5-8840-0632-0 tool or equivalent (3) in

order to release the terminal locking tang (2).

3.Push the wire and the terminal out through the

connector. If you reuse the terminal, reshape the

locking tang.

060

Installation Procedure

Metri–Pack terminals are also referred to as

”pull–to–seat” terminals.

1.In order to install a terminal on a wire, the wire must be

inserted through the seal (2) and through the

connector (3).

2.The terminal (1) is then crimped onto the wire.

3.Then the terminal is pulled back into the connector to

seat it in place.

061

GENERAL DESCRIPTION — ECM

AND SENSORS

58X Reference ECM Input

The engine control module (ECM) uses this signal from

the crankshaft position (CKP) sensor to calculate engine

RPM and crankshaft position at all speeds. The ECM

also uses the pulses on this circuit to initiate injector

pulses. If the ECM receives no pulses on this circuit, DTC

P0337 will set. If the ECM receives a number of pulses

other than the expected amount, DTC P0336 will set. The

engine will not start and run without using the 58X

reference signal.

A/C Request Signal

This signal tells the ECM when the A/C mode is selected

at the A/C control switch. The ECM uses this signal to

adjust the idle speed before turning ON the A/C clutch.

The A/C compressor will be inoperative if this signal is not

available to the ECM.

For A/C wiring diagrams and diagnosis for the A/C

electrical system, refer to A/C Clutch Circuit Diagnosis.

Crankshaft Position (CKP) Sensor

The crankshaft position (CKP) sensor provides a signal

used by the powertrain control module (ECM) to calculate

the ignition sequence. The CKP sensor initiates the 58X

reference pulses which the ECM uses to calculate RPM

and crankshaft position. For additional information,

refer to Electronic Ignition System.

0013

Camshaft Position (CMP) Sensor And

Signal

The camshaft position (CMP) sensor sends a signal to

the ECM. The ECM uses this signal as a ”sync pulse” to

trigger the injectors in the proper sequence. The ECM

uses the CMP signal to indicate the position of the #1

piston during its power stroke. The CMP allows the ECM

to calculate true sequential fuel injection (SFI) mode of

operation. If the ECM detects an incorrect CMP signal

while the engine is running, DTC P0341 will set.

If the CMP signal is lost while the engine is running, the

fuel injection system will shift to a calculated sequential

fuel injection mode based on the last fuel injection pulse,

and the engine will continue to run. It will run in the

calculated sequential mode with a 1–in–4 chance of the

injector sequence being correct.

For further information, refer to

DTC P0341

DTC P0342.

014RX007

Engine Coolant Temperature (ECT) Sensor

The engine coolant temperature (ECT) sensor is a

thermistor (a resistor which changes value based on

temperature) mounted in the engine coolant stream. Low

coolant temperature produces a high resistance of about

100,000 W at –40°C (–40°F). High temperature causes a

low resistance of about 70 W at 130°C (266°F).

The ECM supplies a 5–volt signal to the ECT sensor

through resistors internal to the ECM and then measures

the voltage after the internal resistor. This signal voltage

will be high when the engine is cold and low when the

engine is hot. By measuring the voltage, the ECM

calculates the engine coolant temperature. Engine

coolant temperature affects most of the systems that the

ECM controls.

The Tech 2 displays engine coolant temperature in

degrees. After engine start–up, the temperature should

rise steadily to about 85°C (185°F). It then stabilizes

when the thermostat opens. If the engine has not been

run for several hours (overnight), the engine coolant

temperature and intake air temperature displays should

be close to each other. A hard fault in the engine coolant

sensor circuit will set DTC P0117 or DTC P0118. An

intermittent fault will set a DTC P1114 or P1115.

0016

Electrically Erasable Programmable Read

Only Memory (EEPROM)

The electrically erasable programmable read only

memory (EEPROM) is a permanent memory chip that is

physically soldered within the ECM. The EEPROM

contains the program and the calibration information that

the ECM needs to control powertrain operation.

Unlike the PROM used in past applications, the EEPROM

is not replaceable.

Fuel Control Heated Oxygen Sensor (Pre

Catalyst)

The fuel control heated oxygen sensor (Bank 1 HO2S 1)

is mounted in the exhaust stream where it can monitor the

oxygen content of the exhaust gas. The oxygen present in

the exhaust gas reacts with the sensor to produce a

voltage output. This voltage should constantly fluctuate

from approximately 100 mV to 900 mV. The heated

oxygen sensor voltage can be monitored with a T ech 2. By

monitoring the voltage output of the oxygen sensor, the

ECM calculates the pulse width command for the

injectors to produce the proper combustion chamber

mixture.

DLow HO2S voltage is a lean mixture which will result in

a rich command to compensate.

DHigh HO2S voltage is a rich mixture which will result in

a lean command to compensate.

An open Bank 1 HO2S 1 signal circuit will set a DTC

P0134 and the Tech 2 will display a constant voltage

between 400–500 mV. A constant voltage below 300 mV

in the sensor circuit (circuit grounded) will set DTC

P0131. A constant voltage above 800 mV in the circuit will

set DTC P0132. The ECM can also detect HO2S

response problems. If the response time of an HO2S is

determined to be too slow , the ECM will store a DTC that

indicates degraded HO2S performance.

0012

Intake Air Temperature (IAT) Sensor

The intake air temperature (IAT) sensor is a thermistor

which changes its resistance based on the temperature of

air entering the engine. Low temperature produces a high

resistance of about 100,000 W at –40°C (–104°F). High

temperature causes low resistance of about 70 W at

130°C (266°F). The ECM supplies a 5–volt signal to the

sensor through a resistor internal to the ECM, and then

monitors the signal voltage. The voltage will be high when

the incoming air is cold. The voltage will be low when the

incoming air is hot. By measuring the voltage, the ECM

calculates the incoming air temperature. The IAT sensor

signal is used to adjust spark timing according to the

incoming air density.

The Tech 2 displays the temperature of the air entering

the engine. The temperature should read close to the

ambient air temperature when the engine is cold and rise

as underhood temperature increases. If the engine has

not been run for several hours (overnight), the IAT sensor

temperature and engine coolant temperature should read

close to each other. A failure in the IAT sensor circuit will

set DTC P0112, or DTC P0113.

Linear Exhaust Gas Recirculation (EGR)

Control

The ECM monitors the exhaust gas recirculation (EGR)

actual position and adjusts the pintle position accordingly.

The ECM uses information from the following sensors to

control the pintle position:

DEngine coolant temperature (ECT) sensor.

DThrottle position (TP) sensor.

DManifold Absolute Pressure (MAP) sensor.

0017

Manifold Absolute Pressure (MAP) Sensor

The manifold absolute pressure (MAP) sensor responds

to changes in intake manifold pressure (vacuum). The

MAP sensor signal voltage to the ECM varies from below

2 volts at idle (high vacuum) to above 4 volts with the

ignition ON, engine not running or at wide–open throttle

(low vacuum).

The MAP sensor is used to determine the following:

DManifold pressure changes while the linear EGR flow

test diagnostic is being run. Refer to DTC P0401.

DEngine vacuum level for other diagnostics.

DBarometric pressure (BARO).

If the ECM detects a voltage that is lower than the

possible range of the MAP sensor, DTC P0107 will be set.

A signal voltage higher than the possible range of the

sensor will set DTC P0108. The ECM can detect a shifted

MAP sensor . The ECM compares the MAP sensor signal

to a calculated MAP based on throttle position and

various engine load factors.

014RX013

Engine Control Module (ECM)

The engine control module (ECM) is located in the

passenger compartment below the center console. The

ECM controls the following:

DFuel metering system.

DIgnition timing.

DOn–board diagnostics for powertrain functions.

The ECM constantly observes the information from

various sensors. The ECM controls the systems that

affect vehicle performance. The ECM performs the

diagnostic function of the system. It can recognize

operational problems, alert the driver through the Check

Engine lamp, and store diagnostic trouble codes (DTCs).

DTCs identify the problem areas to aid the technician in

making repairs.

014RX002

ECM Function

The ECM supplies either 5 or 12 volts to power various

sensors or switches. The power is supplied through

resistors in the ECM which are so high in value that a test

light will not light when connected to the circuit. In some

cases, even an ordinary shop voltmeter will not give an

accurate reading because its resistance is too low.

Therefore, a digital voltmeter with at least 10 megW input

impedance is required to ensure accurate voltage

readings. Tool J 39200 meets this requirement.

The ECM controls output circuits such as the injectors,

IAC, cooling fan relays, etc., by controlling the ground or

the power feed circuit through transistors or through

either of the following two devices:

DOutput Driver Module (ODM)

DQuad Driver Module (QDM)

ECM Components

The ECM is designed to maintain exhaust emission levels

to government mandated standards while providing

excellent driveability and fuel efficiency. The ECM

monitors numerous engine and vehicle functions via

electronic sensors such as the throttle position (TP)

sensor, heated oxygen sensor (HO2S), and vehicle

speed sensor (VSS). The ECM also controls certain

engine operations through the following:

DFuel injector control

DIgnition control module

DEvaporative emission (EVAP) purge

DA/C clutch control

ECM Voltage Description

The ECM supplies a buffered voltage to various switches

and sensors. It can do this because resistors in the ECM

which are so high in value that a test light may not

illuminate when connected to the circuit. An ordinary shop

voltmeter may not give an accurate reading because the

voltmeter input impedance is too low . Use a 10–megohm

input impedance digital voltmeter (such as J 39200) to

assure accurate voltage readings.

The input/output devices in the ECM include

analog–to–digital converters, signal buffers, counters,

and special drivers. The ECM controls most components

with electronic switches which complete a ground circuit

when turned ON. These switches are arranged in groups

of 4 and 7, called either a quad driver module (QDM),

which can independently control up to 4 output terminals,

or Output Driver Module (ODM) which can independently

control up to 7 outputs. Not all outputs are always used.

ECM Inputs/Outputs

Inputs – Operating Conditions Read

DAir Conditioning Compressor Clutch ON or OFF

DEngine Coolant Temperature

DCrankshaft Position

DExhaust Oxygen Content

DManifold Absolute Pressure

DBattery Voltage

DThrottle Position

DFuel Tank Vapor Pressure

DFuel Tank Level

DExhaust Gas Recirculation (EGR) Feedback

DKnock

DVehicle Speed

DFuel Pump Voltage

DPower Steering Pressure

DIntake Air Temperature

DCamshaft Position

Outputs – Systems Controlled

DEVAP Canister Purge Solenoid

DExhaust Gas Recirculation (EGR)

DIgnition Control

DFuel Injector Control

DIdle Air Control

DCoolant Fan Relays

DElectric Fuel Pump Relay Compressor Clutch Relay

DAir Conditioning

DDiagnostics

–OBD II Malfunction Indicator Lamp (Check Engine

lamp)

–Data Link Connector (DLC)

–Data Output

DTachometer Signal

ECM Service Precautions

The ECM is designed to withstand normal current draws

associated with vehicle operation. Avoid over loading any

circuit. When testing for opens and shorts, do not ground

or apply voltage to any of the ECM’s circuits unless

instructed to do so. These circuits should only be tested

using digital voltmeter J 39200. The ECM should remain

connected to the ECM or to a recommended breakout

box.

014RX002

Throttle Position (TP) Sensor

The throttle position (TP) sensor is a potentiometer

connected to the throttle shaft on the throttle body. The

ECM monitors the voltage on the signal line and

calculates throttle position. As the throttle valve angle is

changed (accelerator pedal moved), the TP sensor signal

also changes. At a closed throttle position, the output of

the TP sensor is about 0.25 volts. As the throttle valve

opens, the output increases so that at wide open throttle

(WOT), the output voltage should be about 4.75 volts.

The ECM calculates fuel delivery based on throttle valve

angle (driver demand). A broken or loose TP sensor may

cause intermittent bursts of fuel from an injector and

unstable idle because the ECM thinks the throttle is

moving. A hard failure in the TP sensor 5–volt reference

or signal circuits will set either a DTC P0122 or DTC

P0123. A hard failure with the TP sensor ground circuit

may set DTC P0123 and DTC P0122. Once a DTC is set,

the ECM will use an artificial default value based on

engine RPM and mass air flow for the throttle position,

and some vehicle performance will return. A high idle may

result when either DTC P0122 or DTC P0123 is set. The

ECM can detect intermittent TP sensor faults.

101RX003

Transmission Range Switch

IMPORTANT:The vehicle should not be driven with the

transmission range switch disconnected; idle quality will

be affected.

The four inputs from the transmission range switch

indicate to the ECM which position is selected by the

transmission selector lever. This information is used for

ignition timing, EVAP canister purge, EGR and IAC valve

operation.

For more information on the transmission range switch,

refer to 4L30–E Automatic Transmission.

Vehicle Speed Sensor (VSS)

The ECM determines the speed of the vehicle by

converting a pulsing voltage signal from the vehicle speed

sensor (VSS) into miles per hour. The ECM uses this

signal to operate the speedometer.

0008

Use of Circuit Testing Tools

Do not use a test light to diagnose the powertrain

electrical systems unless specifically instructed by the

diagnostic procedures. Use Connector Test Adapter Kit J

35616 whenever diagnostic procedures call for probing

connectors.

Aftermarket Electrical And Vacuum

Equipment

Aftermarket (add–on) electrical and vacuum equipment is

defined as any equipment which connects to the vehicle’s

electrical or vacuum systems that is installed on a vehicle

after it leaves the factory. No allowances have been made

in the vehicle design for this type of equipment.

NOTE: No add–on vacuum equipment should be added

to this vehicle.

NOTE: Add–on electrical equipment must only be

connected to the vehicle’s electrical system at the battery

(power and ground).

Add–on electrical equipment, even when installed to

these guidelines, may still cause the powertrain system to

malfunction. This may also include equipment not

connected to the vehicle electrical system such as

portable telephones and radios. Therefore, the first step

in diagnosing any powertrain problem is to eliminate all

aftermarket electrical equipment from the vehicle. After

this is done, if the problem still exists, it may be diagnosed

in the normal manner.

Electrostatic Discharge Damage

Electronic components used in the ECM are often

designed to carry very low voltage. Electronic

components are susceptible to damage caused by

electrostatic discharge. Less than 100 volts of static

electricity can cause damage to some electronic

components. By comparison, it takes as much as 4000

volts for a person to feel even the zap of a static

discharge.

There are several ways for a person to become statically

charged. The most common methods of charging are by

friction and induction.

DAn example of charging by friction is a person sliding

across a vehicle seat.

DCharge by induction occurs when a person with

well–insulated shoes stands near a highly charged

object and momentarily touches ground. Charges of

the same polarity are drained off leaving the person

highly charged with the opposite polarity. Static

charges can cause damage, therefore it is important

to use care when handling and testing electronic

components.

TS23793

NOTE: To prevent possible electrostatic discharge

damage, follow these guidelines:

DDo not touch the ECM connector pins or soldered

components on the ECM circuit board.

DDo not touch any electronic sensor module

component leads.

DDo not open the replacement part package until the

part is ready to be installed.

DBefore removing the part from the package, ground

the package to a known good ground on the vehicle.

DIf the part has been handled while sliding across the

seat, while sitting down from a standing position, or

while walking a distance, touch a known good ground

before installing the part.

GENERAL DESCRIPTION — AIR

INDUCTION

Air Induction System

The air induction system filters contaminants from the

outside air, and directs the progress of the air as it is

drawn into the engine. A remote–mounted air cleaner

prevents dirt and debris in the air from entering the

engine. The air duct assembly routes filtered air to the

throttle body . Air enters the engine by the following steps:

1.Through the throttle body.

2.Into the intake manifold.

3.Through the cylinder head intake ports.

4.Into the cylinders.

028RX002

GENERAL DESCRIPTION — FUEL

METERING

Acceleration Mode

The ECM provides extra fuel when it detects a rapid

increase in the throttle position and the air flow.

Accelerator Controls

The accelerator control system is a cable–type system

with specific linkage adjustments.

Refer to Cable Adjustment.

Battery Voltage Correction Mode

When battery voltage is low, the ECM will compensate for

the weak spark by increasing the following:

DThe amount of fuel delivered.

DThe idle RPM.

CMP Signal

The ECM uses the camshaft position (CMP) sensor

signal to determine the position of the number 1 piston

during its power stroke, allowing the ECM to calculate

true sequential multiport fuel injection (SFI). Loss of this

signal will set a DTC P0341 or DTC P0342. If the CMP

signal is lost while the engine is running, the fuel injection

system will shift to a calculated sequential fuel injection

based on the last fuel injection pulse, and the engine will

continue to run. The engine can be restarted and will run

in the calculated sequential mode with the fault is present,

with a 1–in–4 chance of being correct.

Clear Flood Mode

Clear a flooded engine by pushing the accelerator pedal

down all the way. The ECM then de–energizes the fuel

injectors. The ECM holds the fuel injectors de–energized

as long as the throttle remains above 80% and the engine

speed is below 800 RPM. If the throttle position becomes

less than 80%, the ECM again begins to pulse the

injectors ON and OFF, allowing fuel into the cylinders.

Deceleration Fuel Cutoff (DFCO) Mode

The ECM reduces the amount of fuel injected when it

detects a decrease in the throttle position and the air flow.

When deceleration is very fast, the ECM may cut off fuel

completely for short periods.

Engine Speed/Vehicle Speed/ Fuel Disable

Mode

The ECM monitors engine speed. It turns off the fuel

injectors when the engine speed increases above 6000

RPM. The fuel injectors are turned back on when engine

speed decreases below 5750 RPM.

Fuel Cutoff Mode

No fuel is delivered by the fuel injectors when the ignition

is OFF. This prevents engine run–on. In addition, the

ECM suspends fuel delivery if no reference pulses are

detected (engine not running) to prevent engine flooding.

Fuel Injector

The sequential multiport fuel injection (SFI) fuel injector is

a solenoid–operated device controlled by the ECM. The

ECM energizes the solenoid, which opens a valve to allow

fuel delivery.

The fuel is injected under pressure in a conical spray

pattern at the opening of the intake valve. Excess fuel not

used by the injectors passes through the fuel pressure

regulator before being returned to the fuel tank.

A fuel injector which is stuck partly open will cause a loss

of fuel pressure after engine shut down, causing long

crank times.

0003

Fuel Metering System Components

The fuel metering system is made up of the following

parts:

DThe fuel injectors.

DThe throttle body.

DThe fuel rail.

DThe fuel pressure regulator.

DThe ECM.

DThe crankshaft position (CKP) sensor.

DThe camshaft position (CMP) sensor.

DThe idle air control (IAC) valve.

DThe fuel pump.

DThe fuel pump relay.

Basic System Operation

The fuel metering system starts with the fuel in the fuel

tank. An electric fuel pump, located in the fuel tank,

pumps fuel to the fuel rail through an in–line fuel filter. The

pump is designed to provide fuel at a pressure above the

pressure needed by the injectors. A fuel pressure

regulator in the fuel rail keeps fuel available to the fuel

injectors at a constant pressure. A return line delivers

unused fuel back to the fuel tank. Refer to Section 6C for

further information on the fuel tank, line filter, and fuel

pipes.

Fuel Metering System Purpose

The basic function of the air/fuel metering system is to

control the air/fuel delivery to the engine. Fuel is delivered

to the engine by individual fuel injectors mounted in the

intake manifold near each intake valve.

The main control sensor is the heated oxygen sensor

(HO2S) located in the exhaust system. The HO2S tells

the ECM how much oxygen is in the exhaust gas. The

ECM changes the air/fuel ratio to the engine by controlling

the amount of time that the fuel injector is ON. The best

mixture to minimize exhaust emissions is 14.7 parts of air

to 1 part of gasoline by weight, which allows the catalytic

converter to operate most efficiently. Because of the

constant measuring and adjusting of the air/fuel ratio, the

fuel injection system is called a ”Closed Loop” system.

The ECM monitors signals from several sensors in order

to determine the fuel needs of the engine. Fuel is

delivered under one of several conditions called ”modes.”

All modes are controlled by the ECM.

Fuel Pressure Regulator

The fuel pressure regulator is a diaphragm–operated

relief valve mounted on the fuel rail with fuel pump

pressure on one side and manifold pressure on the other

side. The fuel pressure regulator maintains the fuel

pressure available to the injector at three times

barometric pressure adjusted for engine load. It may be

serviced separately.

If the pressure is too low, poor performance and a DTC

P0171, or DTC P1171 will be the result. If the pressure is

too high, a DTC P0172 will be the result. For information

on diagnosing fuel pressure conditions, refer to Fuel

System Diagnosis.

014RX038

Fuel Pump Electrical Circuit

When the key is first turned ON, the ECM energizes the

fuel pump relay for two seconds to build-up the fuel

pressure quickly. If the engine is not started within two

seconds, the ECM shuts the fuel pump off and waits until

the engine is cranked. When the engine is cranked and

the 58X crankshaft position signal has been detected by

the ECM, the ECM supplies 12 volts to the fuel pump relay

to energize the electric in–tank fuel pump.

An inoperative fuel pump will cause a ”no–start” condition.

A fuel pump which does not provide enough pressure will

result in poor performance.

Fuel Rail

The fuel rail is mounted to the top of the engine and

distributes fuel to the individual injectors. Fuel is delivered

to the fuel inlet tube of the fuel rail by the fuel lines. The

fuel goes through the fuel rail to the fuel pressure

regulator. The fuel pressure regulator maintains a

constant fuel pressure at the injectors. Remaining fuel is

then returned to the fuel tank.

014RX036

Idle Air Control (IAC) Valve

The purpose of the idle air control (IAC) valve is to control

engine idle speed, while preventing stalls due to changes

in engine load. The IAC valve, mounted in the throttle

body, controls bypass air around the throttle plate. By

moving the conical valve (pintle) in (to decrease air flow)

or out (to increase air flow), a controlled amount of air can

move around the throttle plate. If the RPM is too low, the

ECM will retract the IAC pintle, resulting in more air

moving past the throttle plate to increase the RPM. If the

RPM is too high, the ECM will extend the IAC pintle,

allowing less air to move past the throttle plate,

decreasing the RPM.

The IAC pintle valve moves in small steps called counts.

During idle, the proper position of the IAC pintle is

calculated by the ECM based on battery voltage, coolant

temperature, engine load, and engine RPM. If the RPM

drops below a specified value, and the throttle plate is

closed, the ECM senses a near–stall condition. The ECM

will then calculate a new IAC pintle valve position to

prevent stalls.

If the IAC valve is disconnected and reconnected with the

engine running, the idle RPM will be wrong. In this case,

the IAC must be reset. The IAC resets when the key is

cycled ON then OFF. When servicing the IAC, it should

only be disconnected or connected with the ignition OFF.

The position of the IAC pintle valve affects engine

start–up and the idle characteristics of the vehicle. If the

IAC pintle is fully open, too much air will be allowed into

the manifold. This results in high idle speed, along with

possible hard starting and a lean air/fuel ratio. DTC

P0507 may set. If the IAC pintle is stuck closed, too little

air will be allowed in the manifold. This results in a low idle

speed, along with possible hard starting and a rich air/fuel

ratio. DTC P0506 may set. If the IAC pintle is stuck

part–way open, the idle may be high or low and will not

respond to changes in the engine load.

0006

Run Mode

The run mode has the following two conditions:

DOpen Loop

DClosed Loop

When the engine is first started, the system is in ”Open

Loop” operation. In ”Open Loop,” the ECM ignores the

signal from the heated oxygen sensor (HO2S). It

calculates the air/fuel ratio based on inputs from the TP,

ECT, and MAP sensors.

The system remains in ”Open Loop” until the following

conditions are met:

DThe HO2S has a varying voltage output showing that

it is hot enough to operate properly (this depends on

temperature).

DThe ECT has reached a specified temperature.

DA specific amount of time has elapsed since starting

the engine.

DEngine speed has been greater than a specified RPM

since start–up.

The specific values for the above conditions vary with

different engines and are stored in the programmable

read only memory (PROM). When these conditions are

met, the system enters ”Closed Loop” operation. In

”Closed Loop”, the ECM calculates the air/fuel ratio

(injector on–time) based on the signal from the HO2S.

This allows the air/fuel ratio to stay very close to 14.7:1.

Starting Mode

When the ignition is first turned ON, the ECM energizes

the fuel pump relay for two seconds to allow the fuel pump

to build up pressure. The ECM then checks the engine

coolant temperature (ECT) sensor and the throttle

position (TP) sensor to determine the proper air/fuel ratio

for starting.

The ECM controls the amount of fuel delivered in the

starting mode by adjusting how long the fuel injectors are

energized by pulsing the injectors for very short times.

Throttle Body Unit

The throttle body has a throttle plate to control the amount

of air delivered to the engine. The TP sensor and IAC

valve are also mounted on the throttle body.

Vacuum ports located behind the throttle plate provide the

vacuum signals needed by various components. Engine

coolant is directed through a coolant cavity in the throttle

body to warm the throttle valve and to prevent icing.

014RX040

GENERAL DESCRIPTION —

ELECTRONIC IGNITION SYSTEM

Camshaft Position (CMP) Sensor

The camshaft position (CMP) sensor sends a signal to

the ECM. The ECM uses this signal as a ”sync pulse” to

trigger the injectors in the proper sequence. The ECM

uses the CMP signal to indicate the position of the #1

piston during its power stroke. The CMP allows the ECM

to calculate true sequential fuel injection (SFI) mode of

operation. If the ECM detects an incorrect CMP signal

while the engine is running, DTC P0341 will set.

If the CMP signal is lost while the engine is running, the

fuel injection system will shift to a calculated sequential

fuel injection mode based on the last fuel injection pulse,

and the engine will continue to run. It will run in the

calculated sequential mode with a 1–in–4 chance of the

injector being correct.

For additional information, refer to DTC P0342.

014RX007

Crankshaft Position (CKP) Sensor

The crankshaft position (CKP) sensor provides a signal

used by the engine control module (ECM) to calculate the

ignition sequence. The sensor initiates the 58X reference

pulses which the ECM uses to calculate RPM and

crankshaft position. For additional information, refer to

Electronic Ignition System.

Electronic Ignition

The electronic ignition system controls fuel combustion

by providing a spark to ignite the compressed air/fuel

mixture at the correct time. To provide optimum engine

performance, fuel economy, and control of exhaust

emissions, the ECM controls the spark advance of the

ignition system. Electronic ignition has the following

advantages over a mechanical distributor system:

DNo moving parts.

DLess maintenance.

DRemote mounting capability.

DNo mechanical load on the engine.

DMore coil cooldown time between firing events.

DElimination of mechanical timing adjustments.

DIncreased available ignition coil saturation time.

0013

Ignition Coils

The 2.2L engine uses 2 ignition coils, 1 per 2 cylinders. A

two–wire connector provides a 12–volt primary supply

through the 15–amp ignition coil fuse, and the ground wire

is connected to a ground–switching ignition module.

Radio frequency interference produced by the coil is

controlled by a condenser which is mounted near the

ignition coil.

014RX044

Ignition Control

The ignition control (IC) spark timing is the ECM’s method

of controlling the spark advance and the ignition dwell.

The IC spark advance and the ignition dwell are

calculated by the ECM using the following inputs:

DEngine speed.

DCrankshaft position (58X reference).

DCamshaft position (CMP) sensor.

DEngine coolant temperature (ECT) sensor.

DThrottle position (TP) sensor.

DVehicle speed (vehicle speed sensor).

DECM and ignition system supply voltage.

Ignition Control Module (ICM)

The engine control module (ECM) controls engine ignition

through a solid–state switching unit called the ignition

control module (ICM). The software in the ECM uses

input from several sensors to determine the timing,

duration, and strength of the spark.

014RX042

DThe crankshaft position (CKP) sensor sends the ECM

a 58X signal related to the exact position of the

crankshaft.

0013

DThe camshaft position (CMP) sensor sends a signal

related to the position of the camshaft.

014RX007

Based on these sensor signals, as well as engine load

and engine coolant temperature information, the ECM

controls the switching function of the ICM by sending it a

5V signal. As long as the ICM receives the signal, it allows

battery voltage to the ignition coil. That voltage allows a

magnetic field to build in the coil.

When the ECM requires a spark plug to fire, it shuts off the

5V signal to the ICM grounding it internally. This triggers

the ICM to switch off the battery voltage to the ignition coil,

which causes the field to collapse. The lines of magnetic

force pass through the secondary portion of the coil as

they collapse. As they intersect the coil, they induce high

voltage in the secondary ignition circuit which travels

toward ground through the spark plug.

Ignition Control ECM Output

The ECM provides a zero volt (actually about 100 mV to

200 mV) or a 5–volt output signal to the ignition control

(IC) module. When the ignition control (IC) module

receives the 5–volt signal from the ECM, it provides a

ground path for the B+ supply to the primary side of the

coil and creates a magnetic field in the coil. When the

ECM shuts off the 5–volt signal to the ignition control

module, the ground path for the primary coil is broken.

The magnetic field collapses and induces a high voltage

secondary impulse which fires the spark plug and ignites

the air/fuel mixture.

Engine Control Module (ECM)

The ECM is responsible for maintaining proper spark and

fuel injection timing for all driving conditions. To provide

optimum driveability and emissions, the ECM monitors

the input signals from the following components in order

to calculate spark timing:

DEngine coolant temperature (ECT) sensor.

DIntake air temperature (IAT) sensor.

DThrottle position (TP) sensor.

DVehicle speed sensor (VSS).

DCrankshaft position (CKP) sensor.

Spark Plug

Although worn or dirty spark plugs may give satisfactory

operation at idling speed, they frequently fail at higher

engine speeds. Faulty spark plugs may cause poor fuel

economy, power loss, loss of speed, hard starting and

generally poor engine performance. Follow the

scheduled maintenance service recommendations to

ensure satisfactory spark plug performance. Refer to

Maintenance and Lubrication.

Normal spark plug operation will result in brown to

grayish–tan deposits appearing on the insulator portion of

the spark plug. A small amount of red–brown, yellow , and

white powdery material may also be present on the

insulator tip around the center electrode. These deposits

are normal combustion by–products of fuels and

lubricating oils with additives. Some electrode wear will

also occur.

Carbon fouling of the spark plug is indicated by dry , black

carbon (soot) deposits on the portion of the spark plug in

the cylinder. Excessive idling and slow speeds under light

engine loads can keep the spark plug temperatures so

low that these deposits are not burned off. Very rich fuel

mixtures or poor ignition system output may also be the

cause.Refer to DTC P0172.

Oil fouling of the spark plug is indicated by wet oily

deposits on the portion of the spark plug in the cylinder,

usually with little electrode wear. This may be caused by

oil during break–in of new or newly overhauled engines.

Deposit fouling of the spark plug occurs when the normal

red–brown, yellow or white deposits of combustion

by–products become sufficient to cause misfiring. In

some cases, these deposits may melt and form a shiny

glaze on the insulator around the center electrode. If the

fouling is found in only one or two cylinders, valve stem

clearances or intake valve seals may be allowing excess

lubricating oil to enter the cylinder, particularly if the

deposits are heavier on the side of the spark plug facing

the intake valve.

TS23995

Excessive gap means that the air space between the

center and the side electrodes at the bottom of the spark

plug is too wide for consistent firing. This may be due to

improper gap adjustment or to excessive wear of the

electrode during use. A check of the gap size and

comparison to the gap specified for the vehicle in

Maintenance and Lubrication will tell if the gap is too wide.

A spark plug gap that is too small may cause an unstable

idle condition. Excessive gap wear can be an indication of

continuous operation at high speeds or with engine loads,

causing the spark to run too hot. Another possible cause

is an excessively lean fuel mixture.

TS23992

Low or high spark plug installation torque or improper

seating can result in the spark plug running too hot and

can cause excessive center electrode wear. The plug and

the cylinder head seats must be in good contact for proper

heat transfer and spark plug cooling. Dirty or damaged

threads in the head or on the spark plug can keep it from

seating even though the proper torque is applied. Once

spark plugs are properly seated, tighten them to the

torque shown in the Specifications T able. Low torque may

result in poor contact of the seats due to a loose spark

plug. Overtightening may cause the spark plug shell to be

stretched and will result in poor contact between the

seats. In extreme cases, exhaust blow–by and damage

beyond simple gap wear may occur.

Cracked or broken insulators may be the result of

improper installation, damage during spark plug

re–gapping, or heat shock to the insulator material. Upper

insulators can be broken when a poorly fitting tool is used

during installation or removal, when the spark plug is hit

from the outside, or is dropped on a hard surface. Cracks

in the upper insulator may be inside the shell and not

visible. Also, the breakage may not cause problems until

oil or moisture penetrates the crack later.

TS23994

A broken or cracked lower insulator tip (around the center

electrode) may result from damage during re–gapping or

from ”heat shock” (spark plug suddenly operating too

hot).

TS23993

DDamage during re–gapping can happen if the

gapping tool is pushed against the center electrode or

the insulator around it, causing the insulator to crack.

When re–gapping a spark plug, make the adjustment

by bending only the ground side terminal, keeping the

tool clear of other parts.

D”Heat shock” breakage in the lower insulator tip

generally occurs during several engine operating

conditions (high speeds or heavy loading) and may be

caused by over–advanced timing or low grade fuels.

Heat shock refers to a rapid increase in the tip

temperature that causes the insulator material to

crack.

Spark plugs with less than the recommended amount of

service can sometimes be cleaned and re–gapped, then

returned to service. However, if there is any doubt about

the serviceability of a spark plug, replace it. Spark plugs

with cracked or broken insulators should always be

replaced.

A/C CLUTCH DIAGNOSIS

A/C Clutch Circuit Operation

A 12–volt signal is supplied to the A/C request input of the

ECM when the A/C is selected through the A/C control

switch.

The A/C compressor clutch relay is controlled through the

ECM. This allows the ECM to modify the idle air control

position prior to the A/C clutch engagement for better idle

quality. If the engine operating conditions are within their

specified calibrated acceptable ranges, the ECM will

enable the A/C compressor relay. This is done by

providing a ground path for the A/C relay coil within the

ECM. When the A/C compressor relay is enabled, battery

voltage is supplied to the compressor clutch coil. The

ECM will enable the A/C compressor clutch whenever the

engine is running and the A/C has been requested. The

ECM will not enable the A/C compressor clutch if any of

the following conditions are met:

DThe engine speed is greater than 6315 RPM.

DThe ECT is greater than 119°C (246°F).

DThe throttle is more than 80% open.

A/C Clutch Circuit Purpose

The A/C compressor operation is controlled by the engine

control module (ECM) for the following reasons:

DIt improves idle quality during compressor clutch

engagement.

DIt improves wide open throttle (WOT) performance.

DIt provides A/C compressor protection from operation

with incorrect refrigerant pressures.

The A/C electrical system consists of the following

components:

1.The A/C control switch.

2.The A/C refrigerant pressure switches.

3.The A/C compressor clutch.

4.The A/C compressor clutch relay.

5.The ECM.

A/C Request Signal

This signal tells the ECM when the A/C mode is selected

at the A/C control switch. The ECM uses this input to

adjust the idle speed before turning on the A/C clutch. The

A/C compressor will be inoperative if this signal is not

available to the ECM.

For A/C wiring diagrams and diagnosis for the A/C

electrical system, refer to A/C Clutch Circuit Diagnosis.

GENERAL DESCRIPTION —

EVAPORATIVE EMISSION (EVAP)

SYSTEM

EVAP Emission Control System Purpose

The basic evaporative emission (EVAP) control system

used on all vehicles is the charcoal canister storage

method. Gasoline vapors from the fuel tank flow into the

canister through the inlet labeled ”TANK.” These vapors

are absorbed into the activated carbon (charcoal) storage

device (canister) in order to hold the vapors when the

vehicle is not operating. The canister is purged by ECM

control when the engine coolant temperature is over 60°C

(140°F), the IAT reading is over 10°C (50°F), and the

engine has been running. Air is drawn canister through

the air inlet grid. The air mixes with the vapor and the

mixture is drawn into the intake manifold.

EVAP Emission Control System Operation

The EVAP canister purge is controlled by a solenoid valve

that allows the manifold vacuum to purge the canister.

The Engine Control Module (ECM) supplies a ground to

energize the solenoid valve (purge on). The EV AP purge

solenoid control is pulse–width modulated (PWM) (turned

on and off several times a second). The duty cycle (pulse

width) is determined by engine operating conditions

including load, throttle position, coolant temperature and

ambient temperature. The duty cycle is calculated by the

ECM. The output is commanded when the appropriate

conditions have been met. These conditions are:

DThe engine is fully warmed up.

DThe engine has been running for a specified time.

DThe IAT reading is above 10°C (50°F).

Poor idle, stalling and Poor driveability can be caused by:

DA malfunctioning purge solenoid.

DA damaged canister.

DHoses that are split, cracked, or not connected

properly.

GENERAL DESCRIPTION —

EXHAUST GAS RECIRCULATION

(EGR) SYSTEM

EGR Purpose

The exhaust gas recirculation (EGR) system is used to

reduce emission levels of oxides of nitrogen (NOx). NOx

emission levels are caused by a high combustion

temperature. The EGR system lowers the NOx emission

levels by decreasing the combustion temperature.

Linear EGR Valve

The main element of the system is the linear EGR valve.

The EGR valve feeds small amounts of exhaust gas back

into the combustion chamber . The fuel/air mixture will be

diluted and combustion temperatures reduced.

Linear EGR Control

The ECM monitors the EGR actual position and adjusts

the pintle position accordingly. The ECM uses information

from the following sensors to control the pintle position:

DEngine coolant temperature (ECT) sensor.

DThrottle position (TP) sensor.

Linear EGR Valve Operation And Results

Of Incorrect Operation

The linear EGR valve is designed to accurately supply

EGR to the engine independent of intake manifold

vacuum. The valve controls EGR flow from the exhaust to

the intake manifold through an orifice with a

ECM–controlled pintle. During operation, the ECM

controls pintle position by monitoring the pintle position

feedback signal. The feedback signal can be monitored

with a Tech 2 as ”Actual EGR Pos.” ”Actual EGR Pos.”

should always be near the commanded EGR position

(”Desired EGR Pos.”). The ECM also tests for EGR flow.

If incorrect flow is detected, DTC P0401 will set. If DTC

P0401 is set, refer to the DTC charts.

The linear EGR valve is usually activated under the

following conditions:

DWarm engine operation.

DAbove–idle speed.

Too much EGR flow at idle, cruise or cold operation may

cause any of the following conditions to occur:

DEngine stalls after a cold start.

DEngine stalls at idle after deceleration.

DVehicle surges during cruise.

DRough idle.

DDTC P0300 (misfire detected).

Too little or no EGR flow may allow combustion

temperatures to get too high. This could cause:

DSpark knock (detonation).

DEngine overheating.

DEmission test failure.

DDTC P0401 (EGR Flow Insufficient detected).

DPoor fuel economy.

0017

EGR Pintle Position Sensor

The ECM monitors the EGR valve pintle position input to

ensure that the valve responds properly to commands

from the ECM and to detect a fault if the pintle position

sensor and control circuits are open or shorted. If the

ECM detects a pintle position signal voltage outside the

normal range of the pintle position sensor, or a signal

voltage that is not within a tolerance considered

acceptable for proper EGR system operation, the ECM

will set DTC P0404.

GENERAL DESCRIPTION —

POSITIVE CRANKCASE

VENTILATION (PCV) SYSTEM

Crankcase Ventilation System Purpose

The crankcase ventilation system is used to consume

crankcase vapors in the combustion process instead of

venting them to the atmosphere. Fresh air from the

throttle body is supplied to the crankcase and mixed with

blow–by gases. This mixture is then passed through the

positive crankcase ventilation (PCV) port into the intake

manifold.

While the engine is running, exhaust gases and small

amounts of the fuel/air mixture escape past the piston

rings and enter the crankcase. These gases are mixed

with clean air entering through a tube from the air intake

duct.

028RX003

During normal, part–throttle operation, the system is

designed to allow crankcase gases to flow through the

PCV valve into the throttle body to be consumed by

normal combustion.

A plugged valve or PCV hose may cause the following

conditions:

DRough idle.

DStalling or slow idle speed.

DOil leaks.

DSludge in the engine.

A leaking PCV hose would cause:

DRough idle.

DStalling.

DHigh idle speed.

SPECIAL TOOLS

ILLUSTRATION TOOL NO.

TOOL NAME

5-8840-0285-0

(J 39200)

High Impedance

Multimeter (Digital

Voltmeter – DVM)

(1) PCMCIA Card

(2) RS232 Loop Back

Connector

(3) SAE 16/19 Adapter

(4) DLC Cable

(5) TECH–2

5-8840-0607-0

(J 34142-B)

Unpowered Test Light

5-8840-0385-0

(J 35616-A/BT-8637)

Connector Test Adapter

Kit

5-8840-0383-0

(J 26792/BT-7220-1)

Spark Tester

5-8840-0279-0

(J 23738-A)

Vacuum Pump with

Gauge

ILLUSTRATION TOOL NO.

TOOL NAME

5-8840-2640-0

(J 39194-B)

Heated Oxygen Sensor

Wrench

5-8840-0632-0

(J 35689-A)

Terminal Remover

5-8840-0388-0

(J 28742-A)

Weather Pack II

Terminal Remover

5-8840-2606-0

(J 39021-45)

Injector Test Light