SECTION 6C2-2A - DIAGNOSTIC CHARTS

CAUTION

This vehicle will be equipped with a Supplemental Restraint System (SRS). A SRS

will consist of either seat belt pre-ten sioners and a driv er’s side air bag, or seat b elt

pre-tensioners and a driver’s and front passenger’s side air bags. Refer to

CAUTIONS, Section 12M, before performing any service operation on or around SRS

components, the steering mechanism or wiring. Failure to follow the CAUTIONS

could result in SRS deployment, resulting in possible personal injury or

unnecessary SRS system repairs.

SYSTEM COMPONENT LOCATIONS

Figure 6c2-2A-1 Engine Compartment Component Locations

Figure 6C2-2A-2 System Component Locations

Figure 6C2-2A-3 Power Distribution Center

PCM WIRING DI AGRAMS

Figure 6C2-2A-4 PCM wiring diagram 1 of 8

Figure 6C2-2A-5 PCM Wiring Diagram 2 of 8

Figure 6C2-2A-6 PCM Wiring Diagram 3 of 8

Figure 6C2-2A-7 PCM Wiring Diagram 4 of 8

Figure 6C2-2A-8 PCM Wiring Diagram 5 of 8

Figure 6C2-2A-9 PCM Wiring Diagram 6 of 8

Figure 6C2-2A-10 PCM Wiring Diagram 7 of 8

Figure 6C2-2A-11 PCM Wiring Diagram 8 of 8

PCM CONNECTOR IDENTIFICATION AND VOLTAGES

Figure 6C2-2A-12 PCM Connector Identification and Voltages 1 of 3

Figure 6C2-2A-13 PCM Connector Identification and Voltages 2 of 3

Figure 6C2-2A-14 PCM Connector Identification and Voltage 3 of 3

PCM CONNECTOR TERMI NAL DEFINITIONS

PINS A1 - A12

A1 SYSTEM EARTH - This terminal should have zero volts. This circuit is connected directly to the engine earth.

A2 SYSTEM EARTH - This terminal should have zero volts. This circuit is connected directly to the engine earth.

A3 SERIAL DATA - This is a dedicated line for the Tech 2 scan tool communications. The circuit connects the

PCM, the ABS and the BCM together. The Tech 2 scan tool communicates to these modules by sending a

message to the module and requesting the module to respond. The normal voltage on this circuit is about 5

volts. When the Tech 2 scan tool is communicating with a module the voltage will be around 2.5V.

A4 IGNITION FEED - This is the ON signal to the PCM from the ignition switch circuit. The ignition feed is not the

"power supply" to the PCM. The ignition feed only tells the PCM that the ignition switch is "ON." The voltage

should be equal to the battery voltage when the key is in either the "run" or the "crank" position.

A5 NOT USED

A6 FUEL PUMP RELAY CONTROL - Whenever the ignition is turned ON the PCM energises the fuel pump

relay. If no crankshaft reference input pulses are received, the PCM turns OFF the relay. As soon as the PCM

receives crankshaft reference pulses, the PCM will turn the fuel pump relay back on.

A7 TP SENSOR 5V REFERENCE VOLTAGE - This voltage should always be 5 volts whenever the ignition is

"ON." The reference voltage is a regulated voltage from the PCM, and supplies 5 volts to the TP sensor.

A8 BATTERY VOLTAGE FEED - This supplies the PCM with full-time B+ volts. This circuit stays hot even when

the ignition is turned off. The battery voltage feed circuit receives it's voltage from the ENGINE fuse circuit.

A9 NOT USED

A10 NOT USED

A11 NOT USED

A12 NOT USED

PINS B1 - B12

B1 SYSTEM EARTH - This terminal should have zero volts. This terminal is connected directly to the engine

earth.

B2 SYSTEM EARTH - This terminal should have zero volts. The terminal is connected directly to the engine earth.

B3 A/C PRESSURE TRANSDUCER INPUT SIGNAL - The signal that is sent from the pressure transducer to the

PCM indicates to the PCM what the A/C pressure is. Depending on the A/C pressure, this signal will indicate

to the PCM if the A/C pressure is to low or to high.

B4 IAT SENSOR SIGNAL INPUT - The PCM sends a 5 volt reference to the IAT sensor. The sensor is connected

to earth. The signal voltage will vary according to incoming air temperature.

B5 ENGINE COOLANT TEMPERATURE SENSOR SIGNAL INPUT - The PCM sends a 5 volt signal voltage to

the engine coolant temperature sensor. The ECT sensor is also connected to earth. The voltage will vary with

engine coolant temperatures.

B6 TRANSMISSION FLUID TEMPERATURE (TFT) SENSOR SIGNAL - The PCM sends out a 5 volt signal

voltage to the transmission fluid temperature sensor. The sensor, being also connected to earth, will cycle the

voltage according to transmission fluid temperature. As the fluid temperature increases, the voltage seen on

terminal D15 will decrease.

B7 A/C SENSOR 5V REFERENCE VOLTAGE - This voltage should always be 5 volts whenever the ignition is

ON. It is a regulated voltage output from the PCM, and supplies 5 volts to the A/C sensor.

B8 BATTERY VOLTAGE FEED - This supplies the PCM with full time B+. This circuit stays hot even when the

ignition is turned off. It receives its voltage from the "ENGINE" fuse circuit.

B9 B10 - NOT USED

B11 TP SENSOR SIGNAL INPUT - The TP Sensor input voltage varies from 0 to 5 volts. Typically the voltage is

less than 1.25 volt at idle, and greater than 4-volts at wide open throttle.

B12 INJECTOR VOLTAGE MONITOR LINE - The injector voltage monitor line is used so that the PCM will know

the exact voltage that the fuel injectors are operating. This voltage is used to control the pulse width modulation

of the fuel injectors.

PINS C1 - C16

C1 NOT USED

C2 1-2 SHIFT SOLENOID CONTROL - The PCM either opens or earths the 1-2 shift solenoid. When the PCM

provides a path to earth, the 1-2 shift solenoid is considered ON and the voltage should read 0 volts.

C3 2-3 SHIFT SOLENOID CONTROL - The PCM either opens or earths the 2-3 shift solenoid. When the PCM

provides a path to earth, the 2-3 shift solenoid is considered ON and the voltage should read 0 volts.

C4 CANISTER PURGE - Grounds the canister purge valve circuit to enable the purging of the canister.

C5 VEHICLE SPEED SENSOR SIGNAL - The PCM alternately earths this signal when the drive wheels are

turning. This pulsing action takes place about 6250 times per kilometre. The speedometer, the BCM and the

trip computer will calculate the vehicle speed based on the time between pulses.

C6 VEHICLE SPEED SENSOR - OUTPUT SHAFT SPEED INPUT SIGNAL HIGH

The transmission has an output shaft speed sensor used by the PCM to calculate vehicle speed, and to help

determine various automatic transmission shifting functions. It is a magnetic inductive sensor that generates an

AC voltage signal sent to the PCM. If measured with the digital AC voltmeter, no voltage will appear until the

output shaft begins turning.

C7, C8, C9,C10

IDLE AIR CONTROL (IAC) VALVE - These circuits control the positioning of the pintle valve which is located

inside the IAC valve. The voltage on this circuit is difficult to predict because of so many variables.

C11 NOT USED

C12 ESC (KNOCK) SIGNAL - The knock sensor is used to detect engine detonation, and the PCM will retard the

Electronic Spark Timing (EST) based on the signal being received.

C13 3-2 SHIFT SOLENOID - The 3-2 shift solenoid is normally closed, and is pulse width modulated. The 3-2

control solenoid controls the 3-2 down shift. The PCM operates the 3-2 shift solenoid at a frequency of 50 Hz.

The solenoid is constantly fed B+ voltage. The PCM controls the time the path to earth is closed or opened.

C14 3-2 SHIFT SOLENOID FEEDBACK CIRCUIT The 3-2 shift solenoid is a normally closed solenoid which is

used to control the 3-2 down shift. The solenoid is constantly fed B+ and the PCM controls the time the path to

earth is closed. The PCM does this to provide a smooth 3-2 down shift. If the PCM senses an incorrect voltage

on this circuit when controlling the 3-2 down shift solenoid (i.e. - 0 volts with the solenoid OFF, or 12 volts with

the solenoid ON) a DTC 66 will set.

C15 TORQUE CONVERTER CLUTCH ENABLE SOLENOID - The Torque converter clutch apply solenoid is used

to smoothly engage the torque converter clutch. By varying the solenoids duty cycle, the PCM can slowly

engage the torque converter clutch, which allows a smooth TCC engagement. If the PCM senses an incorrect

voltage on this circuit when controlling the TCC PWM solenoid (i.e. - 0 volts with the solenoid OFF, or 12 volts

with the solenoid ON) a DTC 83 will set.

C16 TORQUE CONVERTER CLUTCH - PULSE WIDTH MODULATED APPLY SOLENOID CONTROL

AUTO TRANS ONLY

The PCM uses the pulse width modulated TCC apply solenoid to smoothly engage the torque converter clutch,

after the TCC enable solenoid is energised. By varying the duty cycle pulse width modulation, the PCM can

slowly engage the torque converter clutch, allowing very smooth TCC engagement.

PINS D1 - D16

D1 MASS AIR FLOW (MAF) INPUT SIGNAL -

The PCM supplies a 5-volt signal voltage to the mass air flow sensor on this circuit. The mass air flow sensor

pulses the 5-volt signal to earth. These ground pulses occur at a very fast rate - from less than 500 per second

(500 Hz) with no airflow through the sensor, to upwards of many thousands of pulses per second at high air

flow rates such as during acceleration. If measured, the voltage seen will be between 0.5 and 4.5 volts,

depending on air flow through the sensor.

D2 NOT USED

D3 CAMSHAFT POSITION INPUT SIGNAL -

This signal is used by the PCM to sequence the fuel injectors, similar to the firing order of an engine. This

allows the PCM to operate the fuel injectors in a sequential fuel injection mode.

D4 NOT USED

D5 VEHICLE SPEED SENSOR - OUTPUT SHAFT SPEED INPUT SIGNAL LOW -

The transmission has an output shaft speed sensor used by the PCM to calculate vehicle speed, and to help

determine various automatic transmission shifting functions. It is a magnetic inductive sensor that generates an

AC voltage signal sent to the PCM. If measured with the digital AC voltmeter, no voltage will appear until the

output shaft begins turning.

D6 NOT USED

D7 NOT USED

D8 NOT USED

D9 IGNITION MODULE BYPASS CONTROL - With the ignition ON and the engine OFF this terminal will have

very low voltage. As soon as the PCM receives engine RPM over 450 RPM (engine "run" threshold) the PCM

twill send 5 volts to the Ignition Module Bypass Circuit.

D10 ELECTRONIC SPARK TIMING (EST) OUTPUT - This terminal will have very low voltage with the ignition ON

and engine OFF. With the engine at idle, the voltage should be slightly more than 1 volt. As the engine RPM

increases, this voltage will also increases.

D11 REFERENCE SIGNAL LOW - This terminal should always be zero volts. This circuit is connected through the

ignition module to engine earth.

D12 REFERENCE SIGNAL HIGH - This terminal could be called the tach input. It provides the PCM with RPM and

crankshaft position information. With the ignition ON and engine OFF, the voltage will be either high or low,

depending on crankshaft position. As the crankshaft turns, the voltage will be an average of the two readings.

D13 R/H OXYGEN SENSOR SIGNAL INPUT - With the ignition ON and the engine OFF, the voltage should be

between 350 and 450 millivolts (.350 -.450 volts). This is the PCM-supplied O2 circuit "bias" voltage. With the

engine running and the O2 sensor in closed loop, the voltage should be changing between 10 - 1000 millivolts

(.010 - 1.000 volt).

D14 R/H OXYGEN SENSOR EARTH CIRCUIT - This terminal should have zero volts. This circuit is connected

directly to the engine earth. This terminal earths the PCM circuitry for the O2 voltage inside the PCM.

D15 L/H OXYGEN SENSOR SIGNAL INPUT - With the ignition ON and the engine OFF, the voltage should be

between 350 and 450 millivolts (.350 -.450 volts). This is the PCM-supplied O2 circuit "bias" voltage. With the

engine running and the O2 sensor in closed loop, the voltage should be changing between 10 - 1000 millivolts

(.010 - 1.000 volt).

D16 L/H OXYGEN SENSOR EARTH CIRCUIT - This terminal should have zero volts. This circuit is connected

directly to the engine earth. This terminal earths the PCM circuitry for the O2 voltage inside the PCM.

PINS E1 - E16

E1 FUEL INJECTOR CONTROL - With the engine OFF and the ignition ON, the voltage should be B+. With the

engine running at idle, the charging system increases the battery voltage slightly, so this voltages will increase.

With higher engine RPM or more engine load, the resulting increase in injector pulse frequency or injector

pulse width will cause this voltage to become slightly less.

E2 SAME AS E1

E3 SAME AS E1

E4 SAME AS E1

E5 SAME AS E1

E6 RANGE SIGNAL "A" - The PCM sends out a buffered B+ signal to the pressure switch assembly. The B+

signal must pass through a series of switches to earth. When the switch(es) are closed, the voltage should be

near 0. The PCM monitors this voltage to calculate the position of the manual valve.

E7 RANGE SIGNAL "B"- SAME AS E6

E8 RANGE SIGNAL "C"- SAME AS E6

E9 NOT USED

E10 NOT USED

E11 NOT USED

E12 OIL PRESSURE SWITCH - This is a earth input to the PCM from the Oil Pressure Switch indicating proper oil

pressure when the engine is running. If oil pressure is lost while the engine is running, the oil switch will open

its contacts and the earth signal to the PCM will be removed. When the PCM sees this loss of earth signal, the

PCM will command the oil lamp ON.

E13 NOT USED

E14 TRANSMISSION PRESSURE CONTROL

SOLENOID (PCS) - LOW

AUTO TRANS ONLY

The 4L60-E automatic transmission uses an electrical solenoid to control hydraulic pressure inside the

transmission. This electrical solenoid allows the PCM to control "line pressure", similar to other automatic

transmissions that use a "throttle valve" cable or vacuum modulator. The duty cycle, and amount of current

flow to the PCS, are both controlled by the PCM. By monitoring this line, the PCM can determine if the

commanded amperage has gone to the PCS and returned to the PCM.

E15 TRANSMISSION PRESSURE CONTROL

SOLENOID (PCS) - HIGH

AUTO TRANS ONLY

The duty cycle, and amount of current flow to the PCS, are controlled by the PCM. This circuit is the B+ supply

line from the PCM to the PCS. The duty cycle and amperage are controlled by the PCM.

E16 ECT/TP SENSOR EARTH - This terminal should be zero volts. This circuit is connected through the PCM to

the engine earth.

PINS F1 - F16

F1 FUEL INJECTOR CONTROL - With the engine OFF and the ignition ON, the voltage should be B+. With the

engine running at idle, the charging system increases the battery voltage slightly, so this voltages will increase.

With higher engine RPM or more engine load, the resulting increase in injector pulse frequency or injector

pulse width will cause this voltage to become slightly less.

F2 SAME AS F1

F3 SAME AS F1

F4 AIR CONDITIONING RELAY CONTROL -

When the A/C is requested, the BCM will communicate to the PCM via the serial data line, requesting A/C. The

PCM supplies the earth path on this terminal to energise the A/C control relay. The voltage will be less than 1

volt when the PCM energises the relay. When the PCM does energise the A/C control relay, the voltage will be

more than 0.1, but less than 1 volt.

F5 START RELAY CONTROL - When the PCM receives the ignition voltage from the Cranking Signal Input

circuit, the PCM will then supply the earth signal needed to energise the Start Relay Control. Once this Start

Relay Control is energised, power is supplied to the starter.

F6 ENGINE COOLING FAN - HIGH SPEED RELAY CONTROL -This terminal will have B+ until the PCM

energises the high speed cooling fan relay. The input that causes the PCM to energise the high speed fan relay

is the engine coolant temperature sensor. The PCM will also energise the high speed fan relay in the

Diagnostic Mode - i.e., ignition ON, engine stopped, and DLC diagnostic "test" enable terminal earthed.

F7 NOT USED

F8 NOT USED

F9 RANGE SIGNAL A INPUT SIGNAL

F10 RANGE SIGNAL B INPUT SIGNAL

F11 RANGE SIGNAL C INPUT SIGNAL

AUTO TRANS ONLY

Range signal "A", "B" and "C". The PCM sends out a buffered 12 volt signal to the pressure switch assembly,

located in the automatic transmission valve body. The 12 volt signal must pass through either a normally open

or normally closed switch to reach earth. When the switch(es) are closed, the signal should be near 0 volts.

The PCM monitors the status of these signals to determine which gear servo is actually receiving hydraulic

apply pressure.

F12 NORMAL / ECONOMY INPUT SIGNAL

AUTO TRANS ONLY

The PCM sends a signal of about 12 volts, and monitors the status of this circuit. In the ECONOMY position

the switch is open, the PCM voltage status signal remains high - about 12 volts, and the PCM does not allow

shift point changes. When the transmission switch is pressed to the POWER position the switch is closed and

the PCM voltage status signal is pulled low - about 0 volts. The PCM senses the zero voltage signal, and

enables power mode shifting only if other criteria are met. These criteria include throttle position and engine

speed.

F13 NOT USED

F14 DIAGNOSTIC TEST ENABLE INPUT - This terminal is connected to the DLC. When the diagnostic test

terminal is not earthed, this terminal will read 5 volts. When the DLC diagnostic test enable terminal is earthed,

the resulting zero voltage at the PCM will cause the PCM to operate in the Diagnostic Mode.

F15 PRNDL P - This circuit along with PCM circuits E6, E7, E8 indicate to the PCM what transmission gear the

driver has selected. The PCM will then send a command via the serial data line to the instrument panel cluster

to indicate to the driver what gear has been selected.

F16 INTAKE AIR TEMPERATURE / TRANSMISSION FLUID TEMPERATURE /A/C PRESSURE SENSOR

EARTH CIRCUIT - This terminal should be zero volts. It is connected through the PCM circuitry to engine

earth.

TECH 2 SCAN ENGINE DATA

The Tech 2 scan Data listed in the table may be used for comparison

1. After completing the " ON-BOARD DIAGNOSTIC SYSTEM CHECK"

2. Finding the on-board diagnostics are functioning properly and

3. No diagnostic DTCs are displayed.

A TECH 2 SCAN TOOL THAT DISPLAYS FAULTY DATA SHOULD NOT BE USED, AND THE PROBLEM

SHOULD BE REPORTED TO THE MANUFACTURER. THE USE OF A FAULTY TECH 2 SCAN TOOL CAN

RESULT IN MISDIAGNOSIS AND UNNECESSARY PARTS REPLACEMENT.

Only the parameters listed are used in this Volume for diagnosis. For more description on the values and use of the

Tech 2 scan tool to diagnosis PCM inputs, refer to the applicable diagnosis chart in this Section. If all values are

within the range illustrated, refer to "Symptoms" Charts in Section 6C2-2B.

TEST DESCRIPTION:

Number(s) below refer to number(s) on the Tech 2 Scan Data Engine Stream chart.

1. The Tech 2 scan tool "FO: DATA LIST" will display scan position's that will be displayed in order. The Tech 2

can tool will display nine (9) scan position parameters at a time. The "DOWN ARROW" button will scroll down

through all of the scan positions one at a time. After "Time From Start" parameter is displayed, pressing the

"DOWN ARROW" button again, will display scan position parameters starting at the top of the list again.

2. "Units Displayed" are the available ways of displaying what each parameter is currently operating in, or a value

that is being sensed or being output by the PCM.

3. "Typical Data Value" is separated into two parts. These displayed values are typical of a normally operating

vehicle. The ignition "ON" comparison should be performed first as this may lead to a quick identification of a

failure. The engine running data should be compared to the ignition "ON" data as a diagnostic check to make

sure the component or system is operating properly.

4. Ignition "ON" values are the typical values that should be seen on the Tech 2 scan tool with the ignition "ON,"

and engine stopped. Temperature sensors should be compared to the actual temperatures by letting the

sensor sit overnight and then comparing their values. A difference of 3-5 degrees C from the actual

temperature may indicate a problem with the sensor. Use the diagnostic aids chart for that sensor to compare

the resistance to temperature values.

5. "ENGINE RUNNING" typical data values are an average of display values recorded from normally operating

vehicles at normally operating temperature. They are intended to represent what a normally functioning system

would typically display.

TECH 2 SCAN DATA ENGINE STREAM

TYPICAL DATA VALUE !

SCAN POSITION "UNITS

DISPLAYED # IGNITION

"ON" $ENGINE RUNNING %

ENGINE SPEED RPM 0 RPM ± 100 RPM FROM DESIRED

RPM

(± 50 RPM IN DRIVE)

DESIRED IDLE

SPEED RPM 0 RPM PCM IDLE COMMAND

(VARIES WITH

TEMPERATURE)

ECT SENSOR VOLTS VOLTS Varies 1.96 V

ENG. COOLANT

TEMP DEGREES C Varies +96 C

IAT VOLTAGE VOLTS Varies Varies

IAT DEGREES C Varies Varies

MAF SENSOR

FREQUENCY Hz 0 Hz 2600-2900 Hz

MASS AIR FLOW GRAM /SEC 0 G/S 5 -10 G/S

MASS AIR FLW/CYL mG/S 0.0 mG/S 150-170 mG/S

TPS SIGNAL

VOLTAGE VOLTS 0.32 V 0.47 V

TPS ANGLE 0-100 % 0 % 0 %

RH O2 SENSOR

READY YES / NO NO YES

LH O2 SENSOR

READY YES / NO NO YES

RH O2 SENSOR mV 447

mV(varies) 100 - 1000 mV AND

VARYING

LH O2 SENSOR mV 447

mV(varies) 100 - 1000 mV AND

VARYING

ST FUEL TRIM R + 0 - 100 % 0 % + 0 % to 10%

ST FUEL TRIM L + 0 - 100 % 0 % + 0 % to 10 %

LT FUEL TRIM R + 0 - 100 % 0% + 0 % to 10%

LT FUEL TRIM L + 0 - 100 % 0 % + 0 % to 10 %

LTFT ENABLE YES / NO NO NO

FUELLING MODE OPEN /

CLOSED LOOP OPEN LOOP CLOSED LOOP

LTFT CELL CELL # 0 0

RH O2 STATUS RICH / LEAN LEAN Rich

LH O2 STATUS RICH / LEAN LEAN Rich

RH O2 CROSS CNTS COUNTS 0 0

LH O2 CROSS CNTS COUNTS 0 0

STFT DELTA 0 - 100 % 0 % 0 - 10%

LTFT DELTA 0 - 100 % 0 % 0 - 10%

DECEL FUEL CUT-

OFF NO/YES NO NO

INJ. PULSE TIME mS 27.5 mS 3-5 mS

INJECTOR VOLTAGE VOLTS 11.4 V 14.0 V

AIR / FUEL RATIO % 0.0 : 1 14.0 : 1

PURGE PWM % 0 % 0 -15 %

BATTERY VOLTAGE VOLTS 11.3 V 14.0 V

REFERENCE VOLTS VOLTS 4.99 V 4.99 V

CRANK SWITCH CRANKING/OF

FOFF OFF

TYPICAL DATA VALUE !

CAM SIGNAL MISSING

/PRESENT MISSING PRESENT

IAC POSITION STEPS 30-50

STEPS 25 -50 STEPS

LITRES / Hr LITRES/Hr 00.00 2.50 L/Hour

IDLE RPM VARIANT RPM 0 RPM 9 RPM

SPARK MODE BYPASS/EST BYPASS EST

SPARK ADVANCE DEGREES

BTDC + 0° BTDC + 18 ° BTDC

KNOCK SIGNAL KNOCK/NONE NONE NONE

KNOCK RETARD # OF DEGREES 0 ° 0 °

TCC SOLENOID ON / OFF OFF OFF

VEHICLE SPEED KM / H 0 KM/H 0 KM/H

A/C REQUEST ON /OFF OFF OFF

A/C CLUTCH ON /OFF OFF OFF

A/C PRESSURE

VOLTS VOLTS 1-2 V 1-2 V

A/C PRESSURE kPa 400 - 600

kPa 400 -600 kPa A/C OFF

800 -1000 kPa A/C ON

HIGH SPEED FAN ON / OFF OFF OFF

LOW SPEED FAN

REQUEST ON / OFF OFF ON or OFF

THEFT STATUS NO

START/START START START

STARTER RELAY OFF/ON ON ON

FUEL PUMP RELAY ON / OFF OFF ON

CRANK TIME SEC 0.0 SEC 0.5 SEC

DTC STATUS NO

DTC(s)/DTC(s)

SET

NO DTC(s) NO DTC(s)

TIME FROM START TIME 0:00:00 VARIES FROM START

PROM I.D. FOUR DIGITS Varies with

Prom

Updates

Varies with PROM Updates

CHECK

POWERTRAIN LAMP ON/OFF ON OFF

TECH 2 SCAN ENGINE DATA DESCRIPTIONS

A list of explanations for each data message displayed on the Tech 2 scan tool is listed below. This information will

assist in diagnosing emission or driveability problems. The displays can be viewed while the vehicle is being driven.

Refer to the " On-Board Diagnostic System Check" for additional informational.

ENGINE SPEED - Range 0-9999 RPM - The engine speed is computed by the PCM from the fuel control reference

input. It should remain close to desired idle under various engine loads with engine idling.

DESIRED IDLE SPEED- Range 0-3175 RPM - The idle speed that is commanded by the PCM. The PCM will

compensate for various engine loads to keep the engine at the desired idle speed.

ECT SENSOR VOLTS/ENG COOLANT TEMP- Range -40 degrees to 151 degrees C / 0 - 5 VOLTS - The

Engine Coolant Temperature (ECT) sensor is mounted in the inlet manifold. The ECT sensor measures the engine

temperature. The PCM supplies a 5 volts reference and a earth circuit to the engine coolant temperature sensor.

When the sensor is cold (internal resistance high), the PCM reads a high signal voltage. As the sensor warms

(internal resistance decreases), the voltage signal will decrease.

IAT SENSOR VOLTS/IAT - Range -40 degrees to 151 degrees C / 0 - 5 VOLTS - The PCM converts the

resistance of the intake air temperature sensor to degrees. Intake Air Temp (IAT) is used by the PCM to adjust fuel

delivery and spark timing according to incoming air density.

MAF Sensor - Range 0-10,192 Hz - The signal that is sent from the Mass Air Flow (MAF) sensor to the PCM is in

the form of a frequency output. This frequency output changes as the demand of engine air intake changes.

MASS AIR FLOW - Range 0-246 Grams/Sec. - The Mass Air Flow (MAF) sensor measures the change in the

intake air flow which results from engine load and speed changes. As intake air flow increases, the air in the inlet

manifold also increases and addition fuel is required.

MASS AIR FLOW/CYL - Range 0-1000 mG/S. - Calculated air flow per each cylinder.

TPS VOLTAGE - Range 0-5.10 Volts - Used by the PCM to determine the amount of throttle demanded by the

driver. The TPS voltage should read between 0.25 - 1.25 volts at idle to greater than 4 volts at wide open throttle.

TPS ANGLE - Range 0-100% - Computed by the PCM from the TP sensor voltage. The TP angle should read 0%

at idle to greater than 80% at Wide Open Throttle.

(RIGHT) AND (LEFT) O2 SENSOR READY - Tech 2 display s "YES" or "NO". Indicating if the oxygen sensor has

reached operating temperature.

(RIGHT or LEFT) O2 SENSOR - Range 0-1192 mV - Represents the exhaust sensor output voltage. The O2

sensor voltage should fluctuate constantly between 100 mV (Lean exhaust) and 1000 mV (Rich exhaust) when

operating in "Closed Loop."

(LEFT or RIGHT) SHORT TERM FUEL TRIM - Range -100% -0% -+ 100% - Short Term Fuel Trim represents a

short-term correction for fuel delivery by the PCM in response to the amount of time the oxygen sensor voltage is

above or below the 450 mV threshold. If the oxygen sensor voltage has mainly been below 450 mV, indicating a

lean air/fuel mixture, STFT will increase to request the PCM to reduce fuel delivery to compensate for the indicated

rich condition. Under certain conditions such as extended idle and high ambient temperatures, canister purge may

cause STFT to read less than -10%.

(LEFT or RIGHT) LONG TERM FUEL TRIM -100% - 0% - +100% - LTFT is derived by the PCM from the STFT

value and is used for long-term correction of fuel delivery. A value of 0% indicates that fuel delivery requires no

compensation to maintain a 14.7:1 air/fuel ratio. A value below 0% means that the fuel system has been rich and

fuel delivery is being reduced decreased injector pulse width to maintain a 14.7 to 1 A/F ratio. A value above 0%

indicates that a lean condition exists and the PCM has been compensating by adding fuel. LTFT tends to follow

STFT.

LTFT ENABLE - Tech 2 Displays "YES" or "NO". - The Long Term Fuel Trim is enable by the PCM when a long

term fuel correction is required. A YES indicates that the LTFT is enabled, a NO indicates that is not.

FUELLING MODE - Displays OPEN or CLOSED- "Closed Loop" displayed indicates that the PCM is controlling

the fuel delivery from the oxygen sensor voltage. In Open Loop, the PCM ignores the oxygen sensor voltage and

bases the amount of fuel to be delivered on TP Sensor, coolant, and the IAT sensor inputs only. At extremely high

temperatures, it is possible for the system to remain in Open Loop to control the catalytic converter temperatures.

LTFT CELL - Range 0-23 - LTFT cell is dependent upon engine speed and mass air flow readings. A plot of RPM

vs MAF is divided into 24 cells. LTFT cell indicates which cell is currently active.

O2 SENSOR STATUS (Left or Right) - RICH or LEAN - Indicates whether the exhaust oxygen sensor voltage is

above (rich) or below (lean) the 450 mV oxygen sensor threshold voltage. This voltage should change constantly

indicating that the PCM is controlling the air/fuel mixture properly.

O2 SENSOR CROSS COUNTS (Left or Right) - Displays the number of times the O2 Sensor voltage switches from

less than 450 mV to greater than 450 mV and then from greater than 450 mV to less than 450 mV.

STFT/LTFT DELTA - Range 0-100%. - The difference (Delta) in % of the STFT/LTFT counts from each bank. This

value is used by the PCM to determine bank to bank fuel trim balance.

DEC. FUEL CUT-OFF - Displays OFF or ON - Indicates if the PCM is in the Decel Fuel Cut-off Mode.

INJ. PULSE WIDTH - Range 0.0 - 999.9 mS. - The ON time of the injector as determined by the PCM.

INJECTOR VOLTAGE - Range 0 - 14.0 Voltage -The voltage commanded from the PCM to open the injector.

AIR FUEL RATIO - Range 0.00 : 99.99 - The reading reflects the commanded value. This should be at or near

14.7. A lower value indicates a richer commanded air fuel mixture while a higher value indicates a leaner mixture.

PURGE PWM - Range 0-100%. The duty cycle of the purge solenoid as being commanded by the PCM.

BATTERY VOLTAGE - Range 0-25.5 volts - This represents the system voltage measured by the PCM at the

ignition No. 1 feed.

REFERENCE VOLTS - Range 0-5 Volts - Indicates the voltage that is supplied to various sensors from the PCM.

CRANK SWITCH - Displays Cranking or OFF. - Indicates that the engine is cranking. The signal is used by the

PCM to prevent backfire.

CAM SIGNAL - Range MISSING/PRESENT- A signal generated by the cam sensor then sent to the PCM. The

PCM then uses this signal for piston positioning for sequential fuelling.

IDLE SPEED VARIANT - RANGE 0-9999 RPM - Indicates the variation in RPM between sampling of engine

speeds.

IAC POSITION - Range 0-255 Counts - Displays the commanded position of the idle air control pintle in counts.

The higher the number of counts, the greater the commanded idle speed. The Idle air control valve should respond

quickly to changes in engine load.

LITRES/100km - Range 0-100 - Indicates fuel consumption per litres per 100 km.

SPARK MODE - Displays "BYPASS" or "EST" - Indicates what mode of ignition timing the vehicle is operating.

SPARK ADVANCE - Range -90 Degrees to +90 Degrees - This displays the spark advance (EST) calculation

which the PCM is programming into the ignition system. The PCM computes the desired spark advance using data

such as engine temperature, engine rpm, engine load, vehicle speed, and operating mode.

KNOCK SIGNAL - Displays "KNOCK" or "NONE" - Indicates whether or not a knock signal is being detected by

the PCM. Should read "NONE" at idle.

KNOCK RETARD - Range 0 Degrees - 90 Degrees - Indicates the amount of spark advance the PCM is removing

from EST in response to the Knock sensor (ESC) signal. Should read 0 degrees at idle.

TCC ENABLE SOLENOID - Displays ON or OFF. - Indicates if the TCC enable Solenoid is commanding the TCC

ON or OFF.

VEHICLE SPEED - Range 0-255 km/h - The vehicle speed sensor signal is converted into kph and mph for

display.

A/C REQUEST - Displays YES or NO - Represents the state of the A/C request serial data input from the BCM.

A/C CLUTCH - Displays ON or OFF - Represents the commanded state of the A/C clutch control relay. Clutch

should be engaged when ON is displayed.

A/C PRESSURE SENSOR - Tech 2 Displays 0.0 - 5.0 Volts - Represents the A/C refrigerant pressure sensor

signal. The amount of pressure indicates the amount of load that the A/C compressor is placing on the engine. The

PCM uses this information to adjust idle speed and to control the cooling fan.

A/C PRESSURE - Range 0 - 3195 kPa - The kPa displayed indicates that the PCM is monitoring an A/C

Refrigerant Pressure signal voltage which is too high or too low to allow the A/C compressor clutch to engage.

HIGH SPEED FAN - Tech 2 Displays "ON" or "OFF - Indicates if the engine cooling fan high speed relay has

been commanded ON or OFF.

LOW SPEED FAN REQUEST - Tech 2 Displays "ON" or "OFF - Indicates if the engine cooling fan low speed

relay has been commanded ON or OFF.

THEFT STATUS - Displays "NO START" or " START". - Indicates the status of the Theft Deterrent System.

FUEL PUMP STATUS - Displays ON or OFF. - Indicates if the fuel pump is ON or OFF.

ENGINE CRANK TIME - Range 0 - 99.9 Seconds. - Indicates the duration of the engine crank time.

DTC STATUS - Indicates if there are any DTC's in

TIME FROM START - Displays 0:00:00. - Indicates the hours, minutes and seconds the engine has been running.

PROM I.D. - Displays a four digit number - Indicates the numerical identification of the PROM stored in the PCM.

TECH 2 SCAN TOOL TRANSM ISSION DATA

The Tech 2 scan Data listed in the table may be used for comparison

1. After completing the " ON-BOARD DIAGNOSTIC SYSTEM CHECK".

2. Finding the on-board diagnostics are functioning properly and

3. No diagnostic DTCs are displayed.

A TECH 2 SCAN TOOL THAT DISPLAYS FAULTY DATA SHOULD NOT BE USED, AND THE PROBLEM

SHOULD BE REPORTED TO THE MANUFACTURER. THE USE OF A FAULTY TECH 2 SCAN TOOL CAN

RESULT IN MISDIAGNOSIS AND UNNECESSARY PARTS REPLACEMENT.

Only the parameters listed are used in this manual for diagnosis. For more description on the values and use of the

Tech 2 scan tool to diagnosis PCM inputs, refer to the applicable diagnosis chart in this Section. If all the values are

within the range illustrated, refer to "Symptoms" Charts in Section 6C2-2B.

TEST DESCRIPTION:

Number(s) below refer to circled number(s) on the diagnostic chart.

1. The scan position refers to the Tech 2 scan tool DATA LIST that will be displayed in order.

2. "Units Displayed" are the available ways of displaying what each parameter is currently operating in, or a value

that is being sensed or being out putted by the PCM.

3. "Typical Data Value" is separated into two parts. These displayed values are typical of a normally operating

vehicle. The ignition ON comparison should be performed first as this may lead to a quick identification of a

fault. The engine running data should be compared to the ignition ON data as a diagnostic check to make sure

the component or the system is operating properly.

4. Ignition ON values are the typical values that should be seen on the Tech 2 scan tool with the ignition ON, and

the engine OFF. The temperature sensors should be compared to the actual temperatures by letting the

sensor sit overnight and then comparing their values. A difference of 3 to 5 degrees C from the actual

temperature may indicate a problem with the sensor. Use the diagnostic aids chart for that sensor to compare

the resistance to temperature values.

Some ON or OFF switches may display an abnormal state. If the chart states this position is abnormal, than

this may be caused by an open or short to earth, depending upon the normal state of the switch. Refer to the

proper Section or more information on diagnosis.

5. "ENGINE RUNNING" typical data values are an average of display values recorded from normally operating

vehicles at normally operating temperature. They are intended to represent what a normally functioning system

would typically display.

TECH 2 SCAN DATA - TRANSMISSION

DISPLAY POSITION UNITS

DISPLAYED TYPICAL DATA

IGNITION ON TYPICAL VALUE ENGINE

RUNNING

ENGINE SPEED RPM 0 RPM ± 100 RPM FROM

DESIRED RPM

(± 50 RPM IN DRIVE)

VEHICLE SPEED km/h 0 km/h 0 km/h

TPS SIGNAL VOLTS 0.50 V 0.50 V

THROTTLE ANGLE 0-100 % 0 % 0 %

ECT SENSOR V Varies Varies

COOLANT

TEMPERATURE °C Varies 96°C

TFT SENSOR V Varies Varies

TRANSMISSION

FLUID

TEMPERATURE

°C Varies Varies

TFP SWITCH A OPEN/

CLOSED OPEN 12V OPEN 12V

TFP SWITCH B OPEN/

CLOSED CLOSED 0V CLOSED 0V

TFP SWITCH C OPEN/

CLOSED OPEN 12V OPEN 12V

TFP GEAR P-N-

1-2-3-D-RP/N P/N

PRNDL SELECTED

POSITION INVALID/

P-R-N-D-LPP

1-2 SHIFT SOLENOID ON/OFF OFF ON

DISPLAY POSITION UNITS

DISPLAYED TYPICAL DATA

IGNITION ON TYPICAL VALUE ENGINE

RUNNING

2-3 SHIFT SOLENOID ON/OFF OFF ON

1-2 SHIFT SOLENOID

FEEDBACK ON/OFF OFF ON

2-3 SHIFT SOLENOID

FEEDBACK ON/OFF OFF ON

1-2 SHIFT TIME sec 0 sec 0 sec

2-3 SHIFT TIME sec 0 sec 0 sec

COMMANDED PCS Ma 0 mA 950 mA

ACTUAL PCS mA 0 mA 950 mA

PCS DUTY CYCLE % 0 mA 60%

TCC ENABLE

SOLENOID ON/OFF OFF OFF

TCC PWM SOLENOID % 0% 0%

TRANSMISSION SLIP

SPEED RPM 0 650 RPM

ECONOMY/POWER

SHIFT SWITCH Economy/

Power Economy Economy

3-2 DOWNSHIFT

ENABLED YES/NO NO NO

3-2 DOWNSHIFT

SOLENOID ON/OFF OFF ON

LONG TERM 1-2

SHIFT ADAPT kPa 0 kPa 0

LONG TERM 2-3

SHIFT SOLENOID kPa 0 kPa 0

SHORT TERM SHIFT

ADAPT kPa 0 kPa 0 kPa

ADAPT SHIFT

STATUS Enabled/

Disabled Enabled Enabled

SHIFT ADAPT CELL 0 0 0

GEAR RATIO :1 1 3.06:1

COMMANDED GEAR 1-2-3-4 3 1

BATTERY VOLTAGE V 12V 12V

TIME FROM START HH:MM:SS Varies with

engine run time Varies with

engine run time

CHECK

POWERTRAIN LAMP OFF/ON ON OFF

TECH 2 SCAN TOOL TRANSM ISSION DATA DESCRIPTIONS

A list of explanations for each data message displayed on the Tech 2 scan tool begins as follows. This information

will assist in tracking emission or driveability problems, since the displays can be viewed while the vehicle is being

driven. Refer to the " On-Board Diagnostic System Chec k " for additional informational.

ENGINE SPEED - Range 0-9999 RPM - Displays the actual engine speed, as received from the reference input

signal. Displays in increments of 1 RPM.

VEHICLE SPEED - Range 0-255 KM/H - Displays the PCM's calculation of vehicle speed as received from the

PCM. Useful for checking speedometer accuracy.

TPS SIGNAL - Range 0-5 VOLTS - This position shows the Throttle Position sensor signal input to the PCM. The

values read will be in voltage. The PCM then will calculate the throttle opening. The TP sensor voltage should be

between 0.25 - 1.25 volts with the throttle closed and greater than 4 volts at Wide Open Throttle .

TPS THROTTLE ANGLE - Range 0-100% - This display is the PCM's calculation of the percentage of throttle

opening. The TPS angle should display zero (0%) with the throttle closed and greater than 80% at Wide Open

Throttle.

ECT SENSOR VOLTS/ENG COOLANT TEMP - Range -40 degrees C to 151 degrees C/0 - 5 Volts - The PCM

supplies 5 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as

temperature changes. When the sensor is cold (internal resistance high), the PCM receives a high signal voltage

which it interprets as a cold engine. As the sensor warms (internal resistance decreases), the voltage signal will

increase indicating a warm engine.

TFT SENSOR VOLTS/TRANS FLUID TEMP - Range -40 degrees C to 151 degrees C/0 - 5 VOLTS - This

displays the temperature of the fluid in the transmission.. The TECH 2 scan tool will display TFT in voltage and in

degrees Celsius. The TFT sensor reading should read close to the air temperature when the transmission is cold,

and increases as the transmission fluid temperature increases. After the engine is started the temperature should

rise steadily to between 82 degrees C and 94 degrees C then stabilise.

TFP SWITCHES A/B/C RANGE VOLTS - Range 0-12 VOLTS - These values represent the three fluid pressure

switch assembly signals. These lines are normally high and are taken low as the fluid pressure switch interprets the

manual valve position. The sequence of these signals is decoded by the PCM to determine the appropriate gear

range.

PRNDL SELECTED POSITIONS - This value represents the decoded sequence of the Transmission Fluid

Pressure Manual Valve Position Switch Assembly (TFP). The TFP is used to determine the manual valve position.

The manual valve position is an input to the PCM used to control line pressure, TCC, and shift solenoid operation.

1-2 SHIFT SOLENOID, AND 2-3 SHIFT SOLENOID This displays the ON or OFF state of the two shift solenoids.

The shift solenoids are turned OFF or ON to change gears.

1-2 AND 2-3 SHIFT SOLENOID FEEDBACK - These values represent the true electrical state of the solenoids.

The PCM uses this information to set malfunction DTC's.

1-2 SHIFT TIME - This value represents the time taken to shift from first gear to second gear. This information is

only accurate if the shift was adaptable.

2-3 SHIFT TIME - This value represents the time taken to shift from second gear to third gear. This information is

only accurate if the shift was adaptable.

COMMANDED TFP - This value represents the commanded pressure control solenoid current. The commanded

current is determined from the manual valve position, transmission fluid temperature, transmission output speed,

shift solenoid state, TCC, A/C status, engine speed, TCC slip and the throttle position sensor. The commanded

pressure control solenoid current is then used to control the transmission line pressure.

ACTUAL TFP - This value represents the actual transmission fluid pressure control solenoid current. This value

should always be close to the desired pressure control solenoid current.

TFP DUTY CYCLE - This value represents the pressure control solenoid duty cycle. This value is determined by the

desired pressure control solenoid current.

TORQUE CONVERTER CLUTCH (TCC) SOLENOID-

This value represents the status of the Torque Converter Clutch (TCC) solenoid. This status is determined by

throttle position, transmission output speed, transmission range, engine coolant temperature, transmission fluid

temperature, and TCC slip.

TCC PWM SOLENOID - Range 0-100%. This parameter is the commanded percentage of ON time of the TCC

PWM solenoid . Approximately 90% represents an ON (energised) commanded state. Zero percent represents an

OFF (non-energised) commanded state. This commanded state is applied at a vehicle speed between

approximately 0 -16 km/h (0-10 mph).

TRANSMISSION SLIP SPEED - This displays the calculated difference between the engine RPM and the

transmission input shaft RPM. This TCC slip RPM should be within ±30 RPM to the actual engine RPM whenever

the TCC is applied.

ECONOMY/POWER SHIFT SW - This display shows the state of the economy/power switch.

3-2 SHIFT SOLENOID PWM- This value represents the duty cycle of the 3-2 downshift solenoid. This device

regulates the release of the 3-4 clutch and the apply of the 2-4 band. The duty cycle is normally about 90%, except

during a 3-2 downshift when the duty cycle drops. The duty cycle will be 0% in first gear. The duty cy cle is

determined by throttle position, vehicle speed, and the commanded gear.

3-2 SHIFT SOLENOID FEEDBACK - These values represent the true electrical state of the solenoid and circuit.

The PCM uses this information to set a DTC.

ADAPT SHIFT STATUS- This value indicates if the current shift will update the 1-2 adapt tables which are used to

modify line pressure.

SHIFT ADAPT CELL - This value displays the cell that the PCM is operating. There are three cells to adapt the

shift, these cells are: Light throttle, Medium throttle and Full throttle. These three cells are very similar to LTFT cell

used by the engine.

GEAR RATIO - This display represents the gear ratio of the commanded gear. 1st 3.06:1, 2nd 1.63:1, 3rd 1.00:1,

4th 0.69:1, Rev 2.29 :1.

COMMANDED GEAR - The gear that the PCM is commanding the transmission. In Park, the Tech 2 scan tool will

display, the commanded state of the shift.

BATTERY VOLTAGE - Range 0-25.5 VOLTS - This represents the system voltage measured by the PCM at its

ignition No. 1 feed.

TIME FROM START - Tech 2 Displays 0:00:00 - Indicates the hours, minutes and seconds the engine has been

running.

CHECK POWERTRAIN LAMP - ON/OFF - Indicates whether the lamp on the instrument panel is illuminated.

PCM V8 ENGINE DIAGNOSTIC TROUBLE CODES (DTC)

DTC DESCRIPTION ILLUMINATE

“CHECK

POWERTRAIN”

LAMP

12 No revolutions per minute signal - normal when engine is not

running No

13 Right Hand (RH) No Oxygen Sensor Signal Yes

14 Engine Coolant Temperature ECT - Signal Voltage Low Yes

15 Engine Coolant Temperature ECT - Signal Voltage High Yes

16 Engine Coolant Temperature ECT - Signal Voltage Unstable Yes

17 PCM Error - ECT Circuit No

19 Throttle Position (TP) Sensor Stuck No

21 Throttle Position (TP) - Signal Voltage High Yes

22 Throttle Position (TP) - Signal Voltage Low Yes

23 Intake Air Temperature (IAT) - Signal Voltage High No

24 No Vehicle Speed Sensor Signal Yes

25 Intake Air Temperature (IAT) - Signal Voltage Low No

26 Intake Air Temperature (IAT) - Signal Voltage Unstable No

31 Theft Deterrent Signal Missing Yes

32 Mass Air Flow (MAF) Sensor- Out Of Range Yes

35 Idle Speed Error No

36 Vacuum Leak No

41 Ignition Electronic Spark Timing (EST) Circuit Fault Yes

42 Bypass Circuit Fault Yes

43 Knock Sensor Circuit Fault No

44 Right Hand (RH) Lean Exhaust Indication Yes

45 Right Hand (RH) Rich Exhaust Indication Yes

46 No Reference Pulses While Cranking Yes

48 Camshaft Position Sensor Signal Missing No

49 Cam/Crank Sensor Signal Intermittent No

51 PROM Error Yes

54 System Voltage Unstable Yes

55 PCM Analog to Digital (A/D) Conversion Error Yes

57 Injector Voltage Monitor Fault No

63 Left Hand (LH) No Oxygen Sensor Signal Yes

64 Left Hand (LH) Lean Exhaust Indication Yes

65 Left Hand (LH) Rich Exhaust Indication Yes

76 Short Term Fuel Trim (STFT) Delta High No

78 Long Term Fuel Trim (LTFT) Delta High No

91 QDSM (Quad Driver Module) Circuit Fault No

92 Low Speed Fan No BCM Response No

93 SNEF Circuit Fault No

94 No Vehicle Speed Sensor - Manual Transmission Yes

96 A/C Pressure Sensor Circuit No

97 Canister Purge Circuit Fault No

PCM V8 TRANSMISSION DIAGNOSTIC TROUBLE CODES (DTC)

DTC DESCRIPTION ILLUMINATE

“CHECK

POWERTRAIN”

LAMP

14 Engine Coolant Temperature (ECT) - Signal Voltage Low Yes

15 Engine Coolant Temperature (ECT) - Signal voltage High Yes

21 Throttle Position (TP) Signal Voltage High Yes

22 Throttle Position (TP) Signal Voltage Low Yes

24 No Vehicle Speed Sensor Signal Yes

28 Transmission Fluid Pressure Manual Valve Position Switch

Assembly Circuit Yes

52 System Voltage Too High - Long Time Yes

53 System Voltage Too High Yes

55 PROM - Analog - Digital (A/D) Conversion Error Yes

58 Transmission Fluid Temperature (TFT) Sensor Circuit - Low

Input Yes

59 Transmission Fluid Temperature (TFT) Sensor Circuit - High

Input Yes

66 3-2 Downshift Solenoid Circuit - Fault Yes

67 Torque Converter Clutch Enable Solenoid Circuit - Electrical Yes

69 Torque Converter Clutch (TCC) Stuck ON No

73 Pressure Control Solenoid Circuit - Error No

75 System Voltage Low Yes

79 Transmission Fluid Over-Temperature Yes

81 2-3 Shift Solenoid Circuit - Error Yes

82 1-2 Shift Solenoid Circuit - Error Yes

83 Torque Converter Clutch Pulse Width Modulation Solenoid

Circuit No

85 Transmission Component Slipping No

Techline

4L60E TRANSMISSION FLUID CHECKING PROCEDURE

GENERAL INFORMATION

When adding or changing the transmission fluid, use only Dexron III. Refer to the VT Series Owner’s Handbook for

the recommended servicing intervals.

Because Dexron II transmission fluid changes colour and odour very easily, these indicators should not necessarily

be relied upon to diagnose either transmission internal condition or fluid deterioration.

Reference to the table under ‘ Transmission Fluid Checking Procedure” shows that a dark brown fluid colour,

with a delayed shift pattern, may only indicate that the fluid requires replacement and, is not a definite indication of a

potential transmission problem.

NOTE:

Do not overfill the transmission. Overfilling may cause foaming of the fluid, loss of fluid, shift complaints and

possible damage to the transmission.

TRANSMISSION FLUID COLOUR

Transmission fluid colour when new, is red. A red dy e is added so that it can be distinguished from other oils and

lubricants. The red dye is not an indicator of fluid quality and is not permanent. As the vehicle is driven, the

transmission fluid will quickly begin to look darker. The colour will then appear light brown. A dark brown colour with

a distinctively burnt odour may indicate fluid deterioration and a need for the fluid to be changed.

NOTE:

As the temperature affects the transmission fluid levels, this operation must only be performed when the

transmission is at normal operating temperature 82 - 94 followed, the result could be a false reading of the fluid

level on the dipstick. Degrees C. If the vehicle is not at normal operating temperature, and the proper checking

procedures are not

TRANSMISSION FLUID CHECKING PROCEDURE

1. Start the engine and drive the vehicle for a maximum of 24 km, or until the transmission’s normal operating

temperature is reached.

2. Park the vehicle on a level surface.

3. Move the gear selector into PARK.

4. Apply the park brake.

5. Let the engine idle for 3 minutes with all the accessories turned off.

6. Locate the red coloured dipstick in the engine compartment. Lift the locking lever then remove the dipstick.

Check the fluid colour, the fluid condition and the fluid level.

Do not check the fluid levels immediately after the vehicle has been operated under any of the following conditions.

• In high ambient temperatures above 32 °C.

• At sustained high speeds.

• In heavy city traffic during hot weather.

• Towing

• In commercial use (e.g. taxi).

If the vehicle has been operated under these conditions, turn the engine off and allow the vehicle to cool for

approximately thirty minutes. After a cool-down period, re-start the vehicle and continue from step 2.

STEP ACTION VALUE YES NO

1Check the fluid colour.

Is the fluid colour red? Go to Step 2 Go to Step 11

2Is the fluid level correct? Go to Step 20 Go to Step 3

3Check the fluid.

Is the fluid foamy? Go to Step 8 Go to Step 4

4Check the fluid level. The

proper fluid level should

be In the middle of the X-

hatch.

Is the fluid level high?

Go to Step 9 Go to Step 5

5Fluid will be low.

Add fluid to the proper

fluid level.

Is the fluid level

satisfactory?

Go to Step 6 Go to Step 1

6Check for external leaks.

Were any leaks found? Go to Step 7 Go to Step 20

7Correct the fluid leak

condition.

Is the action complete?

Go to Step 20

8Is the fluid level too high? Go to Step 9 Go to Step 10

9Remove the excess fluid

to adjust to the proper

fluid level.

Is the action complete?

Go to Step 20

10 1. Check for

contaminants in the

fluid.

2. Drain the fluid in order

to determine the

source of the

contamination.

Is the action complete?

Go to Step 15

11 Is the fluid colour non-

transparent pink? Go to Step 12 Go to Step 13

12 Replace the cooler.

Is the action complete? Go to Step 15

STEP ACTION VALUE YES NO

13 The fluid colour should be

light brown. The

Transmission fluid may

turn dark with normal use.

This does not always

indicate oxidation or

contamination.

Is the fluid colour light

brown?

Go to Step 14 Go to Step 1

14 Drain the fluid in order to

determine if the fluid is

contaminated. A very

small amount of material

in the bottom of the pan is

normal, but large pieces

of metal or other material

in the bottom of the pan

requires a transmission

overhaul.

Was the fluid

contaminated?

Go to Step 15 Go to Step 18

15 Overhaul the

transmission. Refer to

Section 7C5, UNIT

REPAIR.

Is the action complete?

Go to Step 16

16 Flush the cooler.

Is the action complete? Go to Step 17

17 Add the new fluid.

Is the action complete? Go to Step 19

18 Change the fluid and the

filter.

Is the action complete?

Go to Step 19

19 Is the fluid level

satisfactory, If not, correct

as necessary.

Is the action complete?

Go to Step 20

20 Refer to 4L60-E

Transmission Functional

Test Procedure, in

Section 7C3, Diagnosis.

Is the action complete?

Fluid Checking

Procedure

Completed

CHART A - ON-BOARD DIAGNOSTIC SYSTEM CHECK

CIRCUIT DESCRIPTION:

The On-Board Diagnostic System Check is an organised approach in identifying a problem created by a powertrain

control system malfunction. It must be the starting point for any driveability complaint diagnosis, because it directs

the service technician to the next logical step in diagnosing the complaint. Understanding the chart and using it

correctly will reduce diagnostic time and prevent the unnecessary replacement of good parts.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

1. This step is a check for the proper operation of the "Check Powertrain" lamp (MIL). The PCM should provide

serial data communication path for the "Check Powertrain" lamp, this is a bulb check. The "Check Powertrain"

lamp should be "ON." If it can do this, it confirms that the PCM has power, earth and is capable of some

functions.

If the "Check Powertrain" lamp is "OFF," this indicates a problem in the "Check Powertrain" lamp fuse circuits

or the PCM earth circuits or the PCM's serial data communication circuit or a problem with the PI cluster. Chart

A-1 will check for both ignition feed and constant battery power to the PCM and the PCM earth.

2. This check is done to see if the PCM has the capability of performing internal diagnostics. With the diagnostic

"test" terminal earthed, the "Check Powertrain" lamp, should flash a DTC 12 three times, followed by any

DTC(s) stored in memory. DTC 12 means there is no crankshaft reference signal coming to the PCM, this is

normal because the engine is not running.

3. This check is used to see if the PCM can supply serial data for Tech 2 scan tool use. If a PROM error is

present, the PCM may have been able to flash DTC 12 but not enable serial data.

4. This check is to see there are any Theft Deterrent DTC stored. If Theft Deterrent sy stem is enabled, this may

be the cause of the no crank condition.

5. This test determines if the vehicle is able to crank. If the vehicle will not crank, refer to Chart A-4.0 to diagnosis

starter cranking circuit.

7. This test is used to determine the cause of a "Cranks But Will Not Run," although the PCM is powered up, a

"Cranks But Will Not Run" symptom could exist because of a PCM problem or the vehicle electrical system.

8. Look at all the parameters to determine if one is not in a normal state with just the ignition "ON" and engine

stopped. Look at the ECT value to see if the value is shifted above or below where it should be. If so, refer

"Diagnostic Aid Chart" on DTC 14.

9. Look at all the parameters to determine that all values are within typical ranges for normal operating

temperatures at idle. Keep in mind that a basic engine problem may alter sensor value.

Techline

DIAGNOSTIC AIDS:

If the Serial Data circuit is shorted to voltage or earth, the vehicle will not crank. Check Serial Data circuit from PCM

to BCM, and from BCM to all other controllers.

STEP ACTION VALUE YES NO

11. Ignition ON engine

OFF.

2. Observe the "CHECK

POWERTRAIN" lamp.

Is the "CHECK

POWERTRAIN" lamp ON

steady?

Go to Step 2 If No "CHECK

POWERTRAIN"

lamp, Go to Chart

A-1 in this Section

----------------------

If "CHECK

POWERTRAIN"

lamp is flashing

DTC 12, Go to

Step 10

2Jumper the Data Link

Connector terminal "6" to

terminal "5".

Does the "CHECK

POWERTRAIN" lamp

flash DTC 12?

Go to Step 3 Go to Chart A-1

in this section

31. Remove the Data Link

Connector jumper.

2. Install a Tech 2 Scan

tool.

3. Ignition ON engine

OFF.

Does the Tech 2 tool

display PCM serial data?

Go to Step 4 Go to Chart A-2

in this section

41. Ignition ON engine

OFF.

2. Use the Tech 2 to

check for Theft

Deterrent DTC(s).

Are any Theft Deterrent

DTC(s) stored?

Go to the

appropriate DTC

chart

Go to Step 5

5Does the engine crank? Go to Step 6 Go to Chart A-4.0

in this Section

6Use the scan tool to

check for any other

DTC(s).

Are Any Diagnostic

Trouble Codes set?

Refer To

Applicable DTC

Chart in this

Section.

Start with lowest

DTC Number

Go to Step 7

STEP ACTION VALUE YES NO

7Does the engine start? Go to Step 8 Go to chart A-3.1

in this section

81. Ignition ON, engine

OFF.

2. Compare the Tech 2

Scan tool data values

with the typical values

shown on the Tech 2

scan data page.

Are the values within the

typical ranges?

Go to Step 9 Refer to indicated

Component(s)

System checks in

this Section

91. Run the engine until

the specified operating

temperature is

reached.

2. Run the engine at

1500 RPM's for two

minutes, then let the

engine idle.

3. Compare the Tech 2

scan data with the

typical values shown

on the scan data page.

Are all the values normal

or within their typical

ranges?

85°C Refer to

"Symptom

Diagnosis Charts"

in Section 6C1-2B

Refer to indicated

"Component(s)

System " checks

in this Section

10 Check for an earthed

diagnostic "TEST"

terminal circuit.

Was a problem found?

Verify Repair Go to Step 11

11 Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for Security

Link procedure.

Is the action complete?

Verify Repair

CHART A-1 - NO CHECK POWERTRAIN LAMP

CIRCUIT DESCRIPTION:

There should always be a steady "Check Powertrain" (MIL) lamp with the ignition ON and engine OFF. The Battery

supplies voltage directly to the "Check Powertrain" (MIL) lamp through a fused circuit. The Powertrain Control

Module (PCM) will control the (MIL) over the serial data communication circuit to the Body Control Module (BCM).

When the PCM requests the "Check Powertrain" lamp ON, the PCM will send a message over the serial data circuit

to the BCM requesting that the (MIL) be turned ON. The BCM in return will then send a message through the serial

data circuit to the instrument panel (PI) Cluster. The PI Cluster will then determine what message the BCM is

sending, and will then turn ON the "Check Powertrain" lamp when commanded.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. Fuse F13 supplies the power to the instrument panel cluster. If fuse F13 is open, the instrument panel cluster

lamps will not light.

5. If the Tech 2 scan tool can not communicate with the vehicle, there may be a problem in the serial data line.

Chart A-2 will check the serial data line.

6. If the Tech 2 scan tool is capable of commanding the MIL ON and OFF, the PCM may be at fault.

7. This checks for the proper serial data voltage to the instrument panel (PI) cluster.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check in

this Section

2Check the PI cluster fuse

(F13).

Is the fuse OK?

Go to Step 3 Go to Step 9

31. Ignition OFF.

2. Disconnect the PCM

connectors.

3. Ignition ON engine

OFF.

4. Probe the PCM battery

feed circuits (A8 and

B8) and then the

ignition feed circuit

(A4) with a test light

connected to earth on

the harness side.

Is the test light ON for all

three circuits?

Go to Step 4 Go to Step 15

41. Ignition OFF.

2. Disconnect the PCM

connectors.

3. With a test light

connected to B+,

probe the PCM earth

circuits (A1, A2 , B1,

B2).

Is the test light ON for all

four circuits?

Go to Step 5 Go to Step 16

51. Reconnect the PCM

connectors.

2. Install a Tech 2 scan

tool.

3. Ignition ON, engine

OFF.

Does the Tech 2 scan tool

display PCM serial data?

Go to Step 6 Go to Chart A-2

6With the scan tool still

connected to the DLC,

command the MIL ON

using the scan tool.

Does the MIL turn ON

when commanded ON

with the scan tool?

Go to Step 14 Go to Step 7

71. Ignition OFF.

2. Remove the PI Cluster

from the dash panel.

3. Ignition ON.

4. Using a DVM, probe

the PI Cluster

connector terminal 12

with the DVM

connected to earth.

Does the DVM display

voltage at the specified

value?

4-5 volts Go to Step 8 Go to Step 10

STEP ACTION VALUE YES NO

8Check for poor connection

at the PI Cluster

connector.

Was a problem found?

Verify Repair Go to Step 11

91. Repair the short to

earth in the PI cluster

fuse circuit.

2. Replace the fuse.

Is the action complete?

Verify Repair

10 Repair the open in the

serial data circuit from the

BCM to the PI Cluster.

Is the action complete?

Verify Repair

11 Check the "Check

Powertrain " (MIL) bulb for

an open.

Was a problem found?

Go to Step 12 Go to Step 13

12 Replace the "Check

Powertrain " (MIL) bulb.

Is the action complete?

Verify Repair

13 Replace the instrument

panel cluster.

Is the action complete?

Verify Repair

14 Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for the

Security Link procedure.

Is the action complete?

Verify Repair

15 Check for an open or a

short to earth in the power

circuit that did not light the

test light. Repair as

necessary.

Is the action complete?

Verify Repair

16 Repair the open in the

earth circuit that did not

light the test light.

Is the action complete?

Verify Repair

CHART A-2 - NO SERIAL DATA OR WILL NOT FLASH DTC 12,

MALFUNCTION INDICATOR LAM P (MI L) "CHECK POWERTRAIN" LAMP ON

STEADY

CIRCUIT DESCRIPTION:

There should always be a steady (MIL) "Check Powertrain" lamp when the ignition is ON and the engine is OFF.

The battery voltage is supplied directly to the (MIL) "Check Powertrain" lamp bulb. The Powertrain Control Module

(PCM) will control the "Check Powertrain" lamp and turn ON via the serial data communication circuit.

With the ignition ON, and the engine OFF and the diagnostic test terminal earthed, the "Check Powertrain" lamp

should flash a DTC 12, followed by any diagnostic trouble code(s) that are stored.

With the Tech 2 scan tool connected to the DLC and the ignition switch ON, the scan tool should display serial data.

If the scan tool does not display serial data, then the serial data circuit may be open or shorted.

There are several other control modules that are connected to the serial data circuit (PCM, BCM, ABS module, ECC

module, SRS module and PI cluster). Any one of these controllers could cause a fault in the serial data line. This

fault could result in the scan tool not being able to display serial data.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. This step checks if the PCM will flash a DTC 12.

3. This checks if the Tech 2 scan tool will communicate with the PCM.

4. There should be 4 to 5 volts at the DLC, terminal 9. If the voltage is higher or lower, then serial communication

will be effected. This serial data circuit is also connected to several other controllers. A problem with any one of

these other controllers, may cause serial data communication fault.

DIAGNOSTIC AIDS:

A fault with the serial data circuit, could be caused by one or more of the several controllers connected to this serial

data circuit. Isolate the fault by disconnecting each controller one at a time until the serial data communication is

restored.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check in

this Section.

21. Ignition" ON" engine

stopped.

2. Earth diagnostic

"TEST" terminal No. 6.

Does "CHECK

POWERTRAIN" lamp

flash DTC 12?

Go to Step 3 Go to Step 6

31. Connect Tech 2 scan

tool to DLC.

2. Ignition "ON", engine

stopped.

Does the Tech 2 scan tool

display PCM serial data?

No trouble found Go to Step 4

41. Ignition "ON" engine

stopped.

2. Using DVM, probe

DLC terminal 9 with

DVM connected to

earth.

Does the DVM display

voltage varying between

the

specified value?

3-5 volts Go to Step 5 Go to Step 8

5Check connections

between the DLC and the

PCM. If not OK repair, if

connection are OK,

Replace PCM,

Refer to Section 6C2-3

Service Operations, for

PCM Security link

procedure.

Is the action complete?

Verify Repair

61. Ignition "ON" engine

stopped.

2. Using DVM, probe

DLC terminal 6 with

DVM connected to

earth.

Does the DVM display

voltage at specified

value?

B+ Go to Step 13 Go to Step 12

7Replace the PI cluster.

Is the action complete? Verify Repair

8Is the voltage steady at or

above the specified

value?

5 volts Go to Step 11 Go to Step 9

91. Connect a Tech 2 scan

tool to DLC.

2. Ignition ON, engine

stopped.

Does the Tech 2 scan tool

display BCM serial data?

Go to Step 10 Go to Step 13

STEP ACTION VALUE YES NO

10 Repair the open or the

short to earth in the serial

data circuit between the

PCM and the DLC.

Is the action complete?

Verify Repair

11 Repair the short to voltage

on the serial data circuit.

NOTE:

Assure that none of the

other controllers on the

serial data circuit are

causing this voltage

problem. Unplug each

controller one at a time to

isolate a short to voltage.

Is the action complete?

Verify Repair

12 Check for an open in the

Diagnostic Test circuit

from the PCM to the DLC.

Was a problem found?

Verify Repair Go to Step 5

13 Check for a short to earth,

a short to voltage, or an

open in the serial data

line. Refer to Diagnostic

Aids.

Was a problem found?

Verify Repair Go to Step 7

NOTE:

For additional PCM wiring information refer to PCM Wiring Diagram - 2 of 8 in this section.

CHART A-3.1 - ENGINE CRANKS BUT WILL NOT RUN

CIRCUIT DESCRIPTION:

This is the first of several diagnostic charts that must be followed in order to find the cause of a no-start. These

charts assume, that the cranking motor circuit is in good working order, and that the engine will crank with adequate

RPM. These charts also assume that Diagnostic Trouble Code (DTC) 31 or DTC 46 are not set. The On-Board

Diagnostic System Check is always the starting point for all diagnostic procedures.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

1. There are a few cases where the PCM could cause a no-start. The On-Board Diagnostic System Check will

uncover any problems in the PCM power circuit and the earth circuit.

4. This is a quick check of the fuel system. The easiest place to install the pressure gauge is where the fuel pipes

come up into the engine compartment. There are 2 hoses, and the gauge must be connected to the hose or

pipe leading directly to the fuel rail. This connection is on the left (passenger) side of the fuel rail. The other

hose or pipe leads to the pressure regulator, and no pressure testing is done there. If the pressure is not as

specified, or continues to drop after the pump stops running, the Fuel System Diagnostic Chart A-4.2 in this

Section must be used.

6. Note that this check is for sufficient voltage at the spark plug wire. If, the spark plug electrodes are wet with fuel

(engine flooded), the engine may not start. A flooded engine is a symptom of some other problem. There is no

normal condition that should ever be able to flood the engine.

NOTE:

Use ST 125 spark checker or equivalent. An ST 125 requires about 25,000 volts (25 kilovolts, or 25 kV) to "spark".

Do not use a spark plug in open air earthed to the engine as an indication of sufficient "spark". Only a few kilovolts

are required to jump the gap of a spark plug outside of the engine, and that would be an inadequate test of the

ignition coil output ability.

8. At this point the Fuel system and the ignition system are OK. Continue to inspect the rest of the PCM input

sensors and outputs. Use the typical scan tool value charts, the functional test charts, and the voltage pin out

charts for additional information.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Check the power feed

fuses F14, F28, F34

and F35.

2. Check the FS Main

fuse, the FJ main fuse,

and the white fusible

link wire.

Are all of the above circuit

protectors OK?

Go to Step 3 Go to Step 7

31. Install a Tech 2 scan

tool.

2. Ignition ON engine

OFF.

3. Remove the fuel filler

cap.

4. Use the Tech 2 to

command the fuel

pump ON and OFF

while listening at the

fuel filler neck for the

fuel pump to turn ON

and OFF.

Does the fuel pump turn

ON and OFF when

commanded?

Go to Step 4 Go to Chart A-4.1

in this Section

41. Ignition OFF.

2. Remove the EFI relay

from the engine

compartment FUSE

AND RELAY CENTRE,

then crank the engine

for 15 seconds to

relieve the fuel

pressure.

3. Ignition OFF, install a

fuel pressure gauge

(Gauge to be installed

in the pressure line,

between the fuel feed

hose and the fuel inlet

line to the fuel rail, at

left rear of fuel rail.)

4. Reinstall the fuel pump

relay.

5. Turn the ignition ON

for 10 seconds.

Does the fuel pressure

hold steady between the

specified value for two

minutes?

270-350

kPa Go to Step 5 Go to Chart A-4.2

in this Section

STEP ACTION VALUE YES NO

51. Ignition OFF.

2. Disconnect the fuel

injector electrical

connectors.

3. Connect a test light

across the No.1

cylinder fuel injector

harness terminals.

4. Have a helper crank

the engine while you

observe the light.

5. Repeat the test on

cylinders No. 2 through

No. 8.

Did the test light flash on

all eight cylinders while

cranking the engine?

Go to Step 6 Go to Chart A-3.2

in this section

61. Ignition OFF.

2. Remove the spark plug

wire from the No. 1

spark plug.

3. Connect an ST125

spark tester to the No.

1 cylinder (see note

above).

4. Check for spark while

cranking the engine. A

few sparks and then

nothing is considered

no spark.

5. Continue to check for

spark on the remaining

cylinders.

Was their spark on all

eight cylinders?

Go to Step 8 Go to Chart A-8.1

in this Section

71. Repair the short to

earth in the circuit that

the circuit protector

was found open.

2. Replace the open

circuit protector.

Is the action complete?

Verify Repair

STEP ACTION VALUE YES NO

8At this point, the fuel

control system, the fuel

delivery system, and

ignition system are OK.

Check For:

• Fouled spark plugs.

The proper MAF

sensor operation. If the

engine will start with

the MAF sensor

electrical connector

disconnected refer

Chart A-6.1 in this

Section.

The proper TP sensor

circuit operation. Use

the Tech 2 scan tool to

monitor the TP sensor

signal. If the voltage is

over 2.5 volts with the

throttle closed, refer to

Chart A-6.2 in this

Section.

• A restricted exhaust

system. Loosen the

front pipe from the

exhaust manifold(s). If

the engine will start,

refer to Chart A-13 in

this Section.

An improper Engine

Coolant Temperature

(ECT) sensor

resistance. Refer to

DTC 14 DIAGNOSTIC

AIDS to check the

resistance of the ECT

sensor.

• The camshaft timing

chain slipped or

stripped, causing the

camshaft to be out-of-

time.

• Inadequate engine

compression.

• Measure the

resistance across the

terminals of each fuel

injector. Replace any

fuel injector that does

not measures between

14 and 16 Ohms.

Verify Repair

CHART A-3.2 - ENGINE CRANKS BUT WILL NOT RUN

CIRCUIT DESCRIPTION:

These charts assume, that the cranking motor circuit is in good working order, and that the engine will crank with

adequate RPM. These charts also assume that Diagnostic Trouble Code (DTC) 31 or DTC 46 are not set. The On-

Board Diagnostic System Check is always the starting point for all diagnostic procedures.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

1. Do not use this chart unless sent here from Chart A-3.1. There must be some preliminary checks done before

continuing with this chart. Failure to perform these steps could lead to an incorrect diagnosis.

2. This test both circuits for an open. Repair the open in the circuit that did not light the light.

3. This test CKT 152 for an open in the EFI relay circuit.

6. The Security Link procedure must be performed whenever the PCM or the PROM is replaced. Refer to

Section 6C2-3 SERVICE OPERATION for the Security Link procedures.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

2From Table A-3.1

1. Ignition OFF.

2. Reconnect the fuel

injector's electrical

connectors.

3. Disconnect the EFI

relay.

4. Ignition ON.

5. With a test light

connected to earth,

probe the EFI relay

harness connector

CKT 39, then CKT

1040.

Is the test light ON at both

circuits?

Go to Step 3 Go to Step 8

31. Ignition OFF.

2. EFI relay

disconnected.

3. With a test light

connected to B+,

probe EFI relay CKT

152.

Is the test light ON?

Go to Step 4 Go to Step 9

41. Ignition OFF.

2. EFI relay

disconnected.

3. Using a fused jumper

wire, jumper across

terminal 87 to terminal

30 on the EFI harness

connector.

4. Attempt to start the

engine.

Does the engine start and

continue to run?

Go to Step 7 Go to Step 5

STEP ACTION VALUE YES NO

51. Inspect CKT 481 for an

open, or a short to B+

between the EFI relay

and the fuel injectors.

2. Repair as necessary.

Was a fault found in CKT

481?

Verify Repair Go to Step 6

6Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for the

Security Link procedure

Is the action complete?

Verify Repair

7Replace the EFI relay.

Is the action complete? Verify Repair

81. Inspect the circuit that

did not turn ON the

test light for an open.

2. Repair as necessary

Is the action complete?

Verify Repair

9Repair the open in the EFI

relay earth CKT 152.

Is the action complete?

Verify Repair

CHART A-4.0 - STARTER CRANKING CIRCUIT

CIRCUIT DESCRIPTION:

When the ignition is turned to the ON position, battery power is supplied from a fusible link to the Start Relay

terminal "30". As the ignition switch is turned to the START position, power is also supplied from the ignition switch

to the PCM Cranking Signal Input terminal, and to the Start Relay terminal "85". The PCM supplies the earth signal

needed to energise the Start Relay and allows power to the starter motor.

When the PCM receives this voltage input at the Cranking Signal Input terminal, the PCM will then look for the

proper Theft Deterrent signal sent from the BCM. If the PCM has determined that the proper Theft Deterrent signal

is present, the PCM will allow the vehicle to crank. If the PCM determines that a improper Theft Deterrent signal

was sent from the BCM, or no Theft Deterrent signal was sent, the PCM will not supply a earth signal from the PCM

terminal to the Start Relay terminal "86". When the Start Relay receives this earth signal from the PCM, the relay will

be energised, allowing the starter motor to operate. This removed earth signal to the Start Relay w ill cause the

vehicle not to crank.

The cranking signal provides an input for enabling fuel cut off during a possible backfire situation. During an engine

start, when the ignition switch is released from the crank position before the engine is running, the engine may

backfire. The PCM stops all injector 12.5 milliseconds. pulses when the engine speed is less than 450 RPM, the

coolant temperature is greater than -4 degrees C, and a cranking signal is not received, but was received within the

previous 12.5 milliseconds.

If there is a fault with the PCM Start Relay circuit a DTC 91 will set.

If there is a problem with the Theft Deterrent signal from the BCM to the PCM, a DTC 31 will set.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. This step checks to see if DTC 31 or 91 is set. Either of these DTC could prevent the vehicle from cranking.

This step also verifies that if a PCM was replaced, that the Security Link procedure was performed.

3. This step checks to see if power is being applied to the starter motor. If test light lights, the problem is with the

starter motor.

12. This step checks the adjustment of the Neutral start switch.

18. Whenever replacing the PCM perform the Security Link procedure found in Section 6C2-3 SERVICE

OPERATIONS.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check in

this Section

21. Install a Tech 2 scan

tool.

2. Use the scan tool to

check for a DTC 31 or

a DTC 91.

Is a DTC 31 or a DTC 91

set?

Go to the

appropriate DTC

chart

Go to Step 3

31. Ignition OFF.

2. Using a test light,

probe the starter

solenoid terminal "S"

with test light

connected to earth.

3. Have a helper turn the

ignition switch to the

START position, note

the test light.

Does the test light

illuminate when the

ignition switch is turned to

the START position?

Refer to Section

6D2-2 ENGINE

ELECTRICAL -

STARTING

SYSTEM

Go to Step 4

4Check fuse F10 for an

open.

Was an open fuse found?

Go to Step 14 Go to Step 5

51. Remove the start relay.

2. With a test light

connected to earth

probe the start relay

harness terminal 30.

3. Turn the ignition ON.

Does the test light

illuminate??

Go to Step 6 Go to Step 16

61. With the start relay still

removed and the test

light connected to

earth probe the start

relay harness

terminal 85.

2. Turn the ignition to the

start position.

Did the test light

illuminate?

Go to Step 8 Go to Step 15

7Check for an open circuit

between the starter

solenoid and the Start

Relay.

Was a problem found?

Verify Repair Go to Step 9

STEP ACTION VALUE YES NO

81. Ignition OFF.

2. Remove the Start

Relay.

3. Connect a test light

between the relay

harness terminal 85

and terminal 86.

4. Turn the ignition switch

to the START position.

Does the test light

illuminate when the

ignition switch is turned to

the START position?

Go to Step 7 Go to Step 10

9Replace the Start Relay.

Is the action complete? Verify Repair

10 Is the vehicle equipped

with a manual

transmission?

Go to Step 11 Go to Step 13

11 1. Ignition ON engine

OFF.

2. With a test light

connected to B+,

probe both of the

circuits at the neutral

start switch.

Did the test light illuminate

at both terminals?

Go to Step 17 Go to Step 12

12 Check the adjustment of

the neutral start switch. If

the adjustment is OK,

replace the neutral start

switch.

Is the action complete?

Verify Repair

13 Check for open circuit

from the neutral start

switch to the Start Relay.

Was a problem found?

Verify Repair Go to Step 18

14 Repair the short to earth

in the faulty circuit.

Replace the fusible link or

the fuse as necessary.

Is the action complete?

Verify Repair

15 Repair the open in the

ignition circuit.

Is the action complete?

Verify Repair

16 Check for an open circuit

2 including the fusible link.

Is the action complete?

Verify Repair

17 Repair the open in circuit

434.

Is the action complete?

Verify Repair

18 Replace the PCM.

Refer to Section 6D2-3

Service Operations, for

PCM Security Link

procedure.

Is the action complete?

Verify Repair

CHART A-4.1 - FUEL PUMP ELECTRI CAL CIRCUIT

CIRCUIT DESCRIPTION:

When the ignition switch is turned ON, the Power Control Module (PCM) energises the Fuel Pump Relay control

output. The PCM will provide a B+ voltage to the Fuel Pump Relay, as long as the engine is cranking or running,

and the PCM is receiving crankshaft reference input signal pulses.

If there are no distributor reference pulses (ignition ON, engine OFF - or - engine stalled), the PCM will shut OFF

the Fuel Pump Relay within 2 seconds.

Improper electrical control of the pump will result in one or more of the following symptoms:

• Cranks, but won't run.

• Hard start.

• Cuts out, may feel like an ignition problem.

• Excessive cranking ti me.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

1. Do not use this chart unless sent here from another chart. It is important to follow this sequence.

2. The test light should light on both power feed circuits.

5. If the B+ voltage is not being supplied to the fuel pump inspect for an open circuit. The fuel pump will not

operate if B+ voltage is not supplied

13. Whenever replacing the PCM perform the Security Link procedure in Section 6C2-3 SERVICE

OPERATIONS.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check in

this Section

21. Ignition OFF.

2. Remove the fuel pump

relay.

3. Ignition ON.

4. With a test light

connected to earth,

probe the fuel pump

relay power feed

circuits (CKT 240 and

CKT 465) on the

harness side of the

fuel pump relay

connector.

Did the test light illuminate

on both of the circuits?

Go to step 3 Go to step 7

31. Ignition ON.

2. Fuel pump relay

disconnected.

3. With a test light

connected to B+,

probe the fuel pump

relay earth circuit (CKT

152) on the harness

side of the fuel pump

relay connector.

Did the test light

illuminate?

Go to Step 4 Go to step 8

STEP ACTION VALUE YES NO

41. Relay disconnected.

2. Ignition ON.

3. Using a fused jumper,

jumper the power feed

circuit, CKT 240

(terminal 3) to CKT

120 (terminal 5).

4. Listen for the fuel

pump to turn ON.

Does the fuel pump turn

ON?

Go to Step 9 Go to step 5

51. Reinstall the fuel pump

relay.

2. Install a Tech 2 scan

tool.

3. Raise the vehicle and

suitably support.

4. Disconnect the fuel

pump motor electrical

connector.

5. Ignition ON.

6. With a test light

connected to earth,

probe the fuel pump

motor power feed

circuit (CKT 120) on

the fuel pump motor

electrical connector

side.

7. Using the Tech 2, turn

the fuel pump ON and

OFF.

Does the test light turn

ON and OFF when the

fuel pump

is commanded ON and

OFF?

Go to step 6 Go to Step 10

61. Ignition OFF.

2. Disconnect the fuel

pump motor electrical

connector.

3. Using a test light

connected to B+,

probe the fuel pump

motor earth circuit

(CKT 156) on the

connector side.

Does the test light

illuminate?

Go to Step 12 Go to Step 11

STEP ACTION VALUE YES NO

7Inspect the power feed

circuit that did not light the

test light for an open or a

short to earth.

Was an open circuit

found?

Verify Repair Go to Step 13

8Repair the open, or the

short to B+ in the fuel

pump relay earth circuit

(CKT 152).

Is the action complete?

Verify Repair

9Replace the Fuel Pump

Relay.

Is the action complete?

Verify Repair

10 Repair the open or the

short to earth, in the fuel

pump motor power feed

circuit (CKT 120).

Is the action complete?

Verify Repair

11 Repair the open or the

short to B+ in the Fuel

Pump motor earth circuit

(CKT 156).

Is the action complete?

Verify Repair

12 Replace the fuel pump

motor.

Is the action complete?

Verify Repair

13 Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for the

Security Link procedure.

Is the action complete?

Verify Repair

CHART A-4.2 - FUEL DELIVERY SYSTEM

CIRCUIT DESCRIPTION:

Fuel is drawn from the tank by the electric fuel pump and is fed under pressure through a fuel filter. The fuel then

continues to the fuel rail and then is injected into the ports by the fuel injectors.

Fuel pressure in the system is governed by the fuel pressure regulator. The fuel pressure regulator maintains the

pressure between the fuel pressure inlet and the intake manifold. Excess fuel is returned to the fuel tank through

the fuel return line.

The fuel pump has a check valve to maintain pressure at the fuel rail after the pump stops running. The check valve

plays an important part in the fuel delivery system. The check valve keeps the fuel rail pressurised with fuel after the

pump is turned off. The check valve is inside the fuel pump, and is not serviceable.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. Do not use this chart unless instructed to do so from chart A-3.1. There are some preliminary procedures that

must be done before continuing on with this chart.

5. Thoroughly inspect the components mentioned for any restrictions. Even the slightest restriction can cause a

problem with the fuel flow and the fuel pressure.

6. Do not allow the fuel pressure to exceed 414 kPa as damage to the system can occur from excessive

pressures.

DIAGNOSTIC AIDS

Inspect for any obvious signs of fuel leakage. Such as fuel odours and wet spots. Also inspect the underbody fuel

lines for any sort of damage.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check

2From Table A-3.1

Did the fuel pressure read

between the specified

value than begin to lose

pressure.

270-350

kPa Go to Step 4 Go to Step 3

3Did the fuel pressure read

less than the specified

value

270 kPa Go to Step 5 Go to Step 7

41. Install a Tech 2 scan

tool.

2. Turn the ignition OFF

for 10 seconds then

ON.

3. Use the Tech 2 to turn

the fuel pump ON for

10 seconds, while

observing the fuel

pressure gauge.

4. After the fuel pump is

turned OFF, and while

the pressure is

dropping, pinch shut

the pressure side hose

at the fuel gauge

sender unit

connection.

Does the fuel pressure

hold steady?

Go to Step 9 Go to Step 6

5Inspect for a restriction in

the following components

or systems.

• A fuel pressure line

restricted between the

fuel pump and the fuel

rail.

• A fuel supply line

restricted in the fuel

tank.

• A restricted fuel filter.

• A restricted in-tank fuel

strainer.

Was a problem found?

Go to Step 10 Go to Step 11

STEP ACTION VALUE YES NO

61. Ignition OFF for 10

seconds.

2. Ignition ON.

3. Release the pressure

(supply) hose to the

fuel rail.

4. While y ou observe the

pressure gauge, turn

ON the fuel pump for

10 seconds, using the

Tech 2.

5. While the pressure is

dropping, pinch shut

the fuel return hose at

the fuel gauge sender

unit.

CAUTION:

Do not allow the fuel

pressure to exceed 414

kPa when performing this

test.

Is the fuel pressure

greater than the specified

value?

350 kPa Go to Step 7 Go to Step 8

7Replace the fuel pressure

regulator.

Is the action complete?

Verify Repair

8Locate and replace the

leaking fuel injector(s).

Is the action complete?

Verify Repair

9Repair or replace any

leaky parts in the

pressure-side of the fuel

system.

Is the action complete?

Verify Repair

10 Repair or replace the

faulty component or

system.

Is the action complete?

Verify Repair

11 Replace the fuel pump

motor.

Is the action complete?

Verify Repair

CHART A-6.1 - MAF SENSOR OUTPUT CHECK

CIRCUIT DESCRIPTION:

The signal that is sent from the Mass Air Flow (MAF) sensor is sent in the form of a frequency output. A large

quantity of air passing through the MAF sensor will be indicated as a high frequency output (such as when under

acceleration). A small quantity of air passing through the sensor will be indicated as a low frequency output (such as

when decelerating or at idle). The Tech 2 "Scan" tool displays this information both as air flow in grams per second,

grams per cylinder and frequency. A normal reading is approximately 6-10 grams per second at idle and increases

with RPM.

TEST DESCRIPTION:

Number(s) below refer to Step number(s) on the Diagnostic Chart.

3. This checks for the proper Mass Air Flow in grams per second at idle.

4. This checks for the proper Mass Air Flow in grams per second at 2500 RPM.

5. This checks the Mass Air Flow sensor for a steady decrease in grams per second as the RPM changes from

2500 to idle.

DIAGNOSTIC AIDS:

• Check the air intake ducts for any restrictions.

• Check the air intake ducts for leaks between the MAF sensor and the intake manifold.

• Check for a partially restricted exhaust system.

• Check for any other source that would allow air into the engine after the MAF sensor.

• This would include:

 inlet manifold gasket

 inlet manifold

 throttle body and or gasket

 PCV system, this includes the oil dipstick for proper seating

 injector o-rings

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check in

this Section

2Is a DTC 32 present? Go to DTC 32 Go to Step 3

31. Ignition ON, the engine

running at the normal

operating temperature

(90°C).

2. Install a Tech 2 scan

tool.

3. Using the Tech 2;

select "Mass Air Flow

G/S".

Is the reading between

the specified value at

idle?

6-10

Grams

Per

Second

(G/S)

at Idle

Go to Step 4 Go to Step 6

41. Increase the engine

speed to 2500 RPM

and hold the speed

steady.

2. Monitor the Tech 2

MAF sensor reading.

Is the reading between

the specified value?

20-30

Grams

Per

Second

(G/S) at

2500

RPM

Go to Step 5 Go to Step 6

5Release the throttle, and

watch the MAF sensor

readings on the scan tool.

Does the Mass Air Flow

G/S decrease at a steady

rate between the specified

value at idle?

6-10

Grams

Per

Second

(G/S)

at idle

No trouble found

with Mass Air

Flow sensor

Go to Step 6

6Check for a restriction in

the Mass Air Flow

induction system. Also

check for air leaks after

the MAF sensor or a

possible restricted

exhaust system.

Refer to Diagnostic Aids

above.

If all checks OK, replace

the Mass Air Flow sensor.

Is the action complete ?

Verify Repair

CHART A-6.2 - TP SENSOR OUTPUT CHECK

CIRCUIT DESCRIPTION:

The TP sensor is a potentiometer which is mounted to the throttle body. The TP sensor is rotated by the throttle

body shaft. The PCM supplies a 5 volt reference and an earth circuit to the TP sensor. The TP sensor will send a

voltage signal back to the PCM based on the throttle angle position.

At a closed throttle position, the output voltage is usually less than 1.0 volt. As the throttle valve opens, the output

increases so that, at wide-open throttle, the output should be greater than 4.0 volts. By monitoring the output voltage

from the TP sensor, the PCM can determine the fuel needs based on throttle opening (driver demand).

If the PCM receives a high voltage when the engine is running at less than 400 RPM, a hard start may result (clear-

flood mode). Once a Diagnostic Trouble Code is set, the PCM will use a default value for TP sensor based on

engine RPM to enable the vehicle to be driven, although performance could be less than normal.

The TP sensor is not adjustable. The PCM uses the reading at idle as 0% throttle, so no adjustment is necessary.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. This checks the voltage in the idle position. The voltage is usually less than 1.0 volt.

3. The voltage should increase at the same steady rate in which the throttle is opened.

6. With the throttle valve wide open, the TP sensor output should be greater than 4 volts.

7. If the throttle stop screw has been inadvertently reset, the TP sensor output at idle could be out of limit.

9. If the closed-throttle voltage is over 2.5 volts, hard starting may be encountered (worse cold) due to "clear-

flood" mode. This mode occurs when engine RPM is less than 400, and TP sensor input indicates the throttle

is more than 80% open. Possible causes: short to voltage on input signal circuit 417, open earth circuit 452, or

a faulty sensor.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check

21. Ignition ON, engine

OFF, throttle plate

closed.

2. Install a Tech 2 scan

tool.

3. Monitor the TP sensor

Voltage.

Is the voltage on Tech 2

Scan tool between the

specified values?

0.25 to

1.25

volts

Go to Step 3 Go to Step 4

31. Ignition ON engine

OFF.

2. While monitoring the

Tech 2 Scan tool,

slowly and steadily

depress the

accelerator pedal to a

wide open position.

Did the voltage increase

at a steady rate w ith the

throttle movement?

Go to Step 6 Go to Step 8

41. Ignition ON, engine

OFF.

2. With a Tech 2 Scan

monitor the TP sensor

voltage.

Is the TP sensor voltage

within the specified value?

1.25 to

2.5 volts Go to Step 7 Go to Step 5

5Is the TP sensor voltage

greater than the specified

value?

2.5 volts Go to Step 9 Go to Step 12

61. Ignition ON engine

OFF.

2. With the Tech 2 Scan

tool still connected,

monitor the voltage as

the throttle valve is

opened to a wide open

position.

Have a helper ensure that

the throttle valve is fully

open when accelerator

pedal is fully depressed.

If throttle valve does not

fully open when pedal is

depressed, check for

extra floor mats or carpet

under accelerator pedal.

Then refer SERVICE

OPERATIONS, Section

6C2-2 - "Throttle Cable -

Adjust".

Is the TP sensor voltage

greater than the specified

value?

4 volts TP sensor is

working properly

Go to OBD

System Check in

this Section.

Go to Step 8

STEP ACTION VALUE YES NO

71. Check the throttle stop

screw, refer to Section

6C2-3 SERVICE

OPERATIONS. Reset

if incorrect.

2. Ignition ON engine

OFF.

3. Recheck the TP

sensor voltage.

Is the TP sensor voltage

within the specified value?

0.25 to

1.25

volts

Go to Step 6 Go to Step 8

8Replace the TP sensor.

Is the action complete? Verify Repair

91. Ignition OFF.

2. Disconnect the TP

sensor.

3. Ignition ON engine

OFF.

4. Monitor the TP sensor

voltage with the Tech 2

scan tool.

Is the TP sensor voltage

below the specified value?

1.25 volt Go to Step 10 Go to Step 11

10 Check for an open in the

TP sensor earth circuit.

Was problem found?

Verify Repair Go to Step 8

11 Repair the short to voltage

in the TP sensor signal

circuit.

Is the action complete?

Verify Repair

12 The voltage is below 0.25

volts

Repair the short to earth

in the TP sensor signal

circuit.

Is the action complete?

Verify Repair

CHART A-6.3 - OXYGEN SENSOR CHECK

CIRCUIT DESCRIPTION:

The O2 sensor is located in the exhaust stream near the engine. The O2 sensor monitors the oxygen content of the

exhaust gases in the exhaust stream then sends an output voltage to the PCM relative to the oxygen content. This

voltage ranges from less than 100 mV (high O2 exhaust content-lean mixture) to greater than 900 mV(low O2

exhaust content-rich mixture).

The PCM should always supply the O2 sensor with a constant 450 mV bias voltage. As the O2 sensor begins

heating up its internal resistance begins to decrease. The O2 sensor then begins to produce a rapidly changing

voltage that differs from the PCM supplied bias voltage. When the PCM recognises the changing voltage of the O2

sensor the PCM knows the O2 sensor’s output voltage is ready to be used for fuel control.

When the ignition is turned ON, B+ is applied to the O2 sensor’s heater element. Approximately 30 seconds after

the B+ is applied to the heater portion of the O2 sensor, the O2 sensor should reach a temperature greater than

500°C. The heated O2 sensor becomes active much quicker than a non-heated O2 sensor. This allows the PCM to

control the air/fuel ratio more consistent over a wider range of operating conditions.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the Diagnostic Chart.

2. Never perform this test on a cold engine. The oxygen sensor must be near normal operating temperature for

this chart to work. It is important to see a low voltage because this means the oxygen sensor is only monitoring

oxygen in the exhaust pipe.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Start the engine.

2. Run the engine

between 1600 and

1800 RPM for 2

minutes or until the

engine coolant

temperature is above

85° C, then let the

engine idle.

3. Install a Tech 2 scan

tool.

4. Monitor the O2 sensor

voltages.

5. With the engine idling,

Press the Down arrow

button on the Tech 2

"Scan" tool until 11.7

A/F ratio is displayed,

at the same time note

the response of the O2

Sensor.

6. The O2 Sensor should

display above the

specified value.

7. Then press the button

on the Tech 2 "Scan"

tool until 17.7 A/F ratio

is displayed, at the

same time note the

response of the O2

Sensor.

Did the O2 Sensor display

above and below the

specified value?

Above

700 mV

Below

100 mV

No trouble found Go to Step 3

3Replace the O2 Sensor.

Is the action complete? Verify Repair

CHART A-6.3A - OXYGEN SENSOR HEATER CHECK

CIRCUIT DESCRIPTION

The O2 sensor is located in the exhaust stream near the engine. The O2 sensor monitors the oxygen content of the

exhaust gases in the exhaust stream then sends an output voltage to the PCM relative to the oxygen content. This

voltage ranges from less than 100 mV (high O2 exhaust content-lean mixture) to greater than 900 mV(low O2

exhaust content-rich mixture).

The PCM should always supply the O2 sensor with a constant 450 mV bias voltage. As the O2 sensor begins

heating up its internal resistance begins to decrease . The O2 sensor then begins to produce a rapidly changing

voltage that differs from the PCM supplied bias voltage. When the PCM recognises the changing voltage of the O2

sensor the PCM knows the O2 sensor’s output voltage is ready to be used for fuel control.

When the ignition is turned ON, B+ is applied to the O2 sensor’s heater element. Approximately 30 seconds after

the B+ is applied to the heater portion of the O2 sensor, the O2 sensor should reach a temperature greater than

500°C. The heated O2 sensor becomes active much quicker than a non-heated O2 sensor. This allows the PCM to

control the air/fuel ratio more consistent over a wider range of operating conditions.

TEST DESCRIPTION

Number(s) below refer to step number(s) on the Diagnostic Chart.

2. Never perform this test on a cold engine. The oxygen sensor must be near normal operating temperature for

this chart to work.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check in

this section

21. Ignition ON.

2. Install a Tech 2 scan

tool and monitor the

LH and RH O2

sensors.

3. Ignition ON, engine

OFF.

Did LH and RH O2 Sensor

voltages drop to specified

value within 40 seconds?

450 mV

to less

than 100

No problem

found.

Oxygen Sensor

Heater is OK

If both dropped

to the specified

value, Go to

Step 8

---------------------

If only one

dropped to the

specified value,

Go to Step 3

31. Ignition OFF.

2. Disconnect the oxygen

sensor harness

connector from the

sensor that did not

drop.

3. Connect a test light

between the oxygen

sensor connector on

the powertrain

harness, circuit 439,

and circuit 750.

4. Ignition ON.

Did the Test light

illuminate?

Go to Step 4 Go to Step 7

41. Ignition OFF.

2. Using a DVM, measure

the resistance of the

oxygen sensor heater

between circuits 439

and circuit 750.

Is the resistance within

the specified value?

3.5 -

13.2

ohms

Go to Step 6 Go to Step 5

5Replace the heated

oxygen sensor.

Is the action complete?

Verify Repair

STEP ACTION VALUE YES NO

6Repair the poor

connection at oxygen

sensor.

Is the action complete?

Verify Repair

71. Ignition OFF.

2. Connect a test light to

B+.

3. Probe the oxygen

sensor connector on

the powertrain harness

connector, circuit 750.

Is the test light ON?

Go to Step 8 Go to Step 9

8Repair the open or the

short to earth in circuit

439 between fuse F9 and

the oxygen sensor.

Replace the fuse if the

fuse is open.

Is the action complete?

Verify Repair

9Repair the open in circuit

750.

Is the action complete?

Verify Repair

CHART A-7.1 - IDLE AIR CONTROL (IAC) SYSTEM

CIRCUIT DESCRIPTION:

The IAC valve contains a bi-directional motor driven by two coils. The PCM controls the IAC valve by sending

voltage pulses (called counts or steps to the IAC motor windings. The PCM controls the air entering the engine by

adjusting a pintle inside the IAC valve inward or outward from the valves seat. The pintle valve moves a given

distance for each pulse received.

TO INCREASE THE IDLE SPEED: The PCM sends pulses to retract the pintle valve, this allows more air to bypass

the throttle plate through an idle air passage, until the PCM commanded idle speed reaches the PCM-desired idle

speed.

TO DECREASE THE IDLE SPEED: The PCM sends pulses to extend the pintle valve , this reduces the airflow

bypassing the throttle plate through an idle air passage, until The PCM commanded idle speed reaches the PCM-

desired speed.

The PCM desired idle speed, and the PCM commanded IAC position, is based on the following conditions.

• The Engine Coolant Temperature.

• The actual engine RPM (crankshaft reference input).

• The engine load (A/C request input, engine fan command).

• The battery voltage.

• The vehicle speed (VSS).

• The throttle position (TP) sensor angle.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. This tests the PCM's ability to control IAC valve.

DIAGNOSTIC AIDS:

Remove the IAC valve and check for a frozen or a sticking IAC valve. Check that the TP sensor is within an

acceptable range.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Install a TECH 2 scan

tool.

2. Start the engine and

allow the engine to

idle.

3. With the up/down

arrows, vary the

engine speed from 600

RPMs to 1675 RPMs.

Does the engine speed

increase and decrease

when

Commanded?

Go to Step 3 Go to Chart A-7.2

in this Section

3No trouble found with IAC

system.

Check For:

• Vacuum leaks (causes

fast idle speeds).

• Sticking or binding

throttle shaft, cables,

or linkages.

• Engine Coolant

Temperature Sensor

resistance.

• Refer to DTC 14 in this

Section.

• The TP sensor

operation, refer to

CHART A-6.2 in this

Section.

• System earth circuit

terminals at the engine

for being clean and

tight.

• Spark plugs that are

excessively worn, mis-

gapped, or cracked.

• Initial base ignition

timing , refer to Section

6C2-3 SERVICE

OPERATIONS.

• Inspect all the

accessory drive

pulleys. They should

spin freely.

• For high or low fuel

pressure, or leaking

injectors - refer

CHART A-4.2 in this

Section

• A/C clutch control

circuit fault, refer to

CHART A 11.1 or

CHART A 11.3 in this

Section

• Generator output - if

less than 9 volts or

greater than 17 volts,

the PCM will not

command the IAC.

• Throttle body -

remove the IAC and

inspect the bore for

foreign material or

evidence of IAC valve

"dragging" in the bore.

• Throttle stop screw,

refer. SERVICE

OPERATIONS,

SECTION 6C2-3.

Refer to "rough, unstable,

or incorrect idle" in

Section 6C2-2B

SYMPTOMS.

Verify Repair

CHART A-7.2 - IDLE AIR CONTROL (IAC) SYSTEM

CIRCUIT DESCRIPTION:

The PCM controls engine idle speed by moving the IAC valve to control closed-throttle air flow around the throttle

plate. It does this by sending voltage pulses (called "counts" or "steps") to the IAC motor windings. The motor shaft

and conical valve move a given distance for each pulse received.

TO INCREASE IDLE SPEED: The PCM sends enough pulses to retract the IAC valve and allow more air to bypass

the throttle plate through the idle air passage, until idle speed reaches the PCM - desired idle RPM.

TO DECREASE IDLE SPEED: The PCM sends enough pulses to extend the IAC valve and reduce the air flow

bypassing the throttle plate through the idle air passage, until idle speed reaches the PCM-desired RPM.

The PCM desired idle RPM, and the commanded IAC position, is based on:

• Engine Coolant Temperature (ECT)

• Actual engine RPM (crankshaft reference input)

• Engine load (A/C request input, engine fan command

• Battery voltage (voltage at PCM terminal A4

• Vehicle Speed (VSS)

• Throttle Position (TPS

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. The Tech 2 IAC reset, the PCM should issue electrical "extend/retract" signals to the IAC valve. With the IAC

disconnected, each connector terminal should have a "pulsing" voltage, noted by a flashing or flickering test

light. The rate of flashing or flickering is not important.

8. There are 2 separate windings in the IAC motor. Each winding (A - to - B, and C - to- D) should have between

40 and 80 ohms resistance. Also, there should be no continuity between the two windings.

NOTE:

When performing this test, ensure that a standard low power test light is used.

Do not use a "High-Wattage" test light, as the PCM could be damaged. A high wattage test light will either give

inaccurate test results, damage the PCM, or both.

A low-power test light must be used for any circuit testing. While a particular brand of test light is not suggested, a

simple test on any test light will ensure it to be OK for PCM circuit testing. Connect an accurate ammeter (such as

the digital multimeter) in series with the test light being tested, and power the test light-ammeter circuit with the

vehicle battery (See above). If the ammeter indicates less than 3/10 amp current flow (0.3 A or 300 ma), the test

light is OK to use. If more than 0.3A (300 ma), do not use.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

2From Chart A-7.1

1. Disconnect the IAC

valve electrical

connector.

2. Ignition ON, engine

OFF.

3. Using the TECH 2;

Reset the IAC valve.

4. Probe each IAC

harness connector

terminal for five

seconds with the test

light connected to

earth.

• See note above for

proper test light usage.

Does the test light flash

on all the terminals while

the IAC valve is being

reset?

Go to Step 3 If No light one or

more terminals,

go to Step 6

-----------------------

If steady light one

or more terminals,

go to Step 13

3Check for faulty IAC valve

terminals.

Were any faulty terminals

found?

Go to Step 4 Go to Step 5

4Repair the faulty

terminals.

Is the action complete?

Verify Repair

5Replace the IAC valve.

Is the action complete? Verify Repair

6Check for an open or a

short to earth in the

circuit(s) that did not light

the test light.

Were any opens or shorts

found?

Go to Step 7 Go to Step 8

7Repair any opens or

shorts found.

Is the action complete?

Verify Repair

81. Remove the throttle

body, refer to Section

6C2-3 SERVICE

OPERATIONS.

2. Check the resistance

across the IAC coils.

3. Check all of the IAC

terminals opposite of

the harness connector

terminals "A" to "B"

and "C" to "D".

Are all of the IAC coils

within the specified value?

40 to 80

ohms Go to Step 9 Go to Step 5

STEP ACTION VALUE YES NO

9Using a DVM measure the

resistance between the

IAC valve terminals "A"

and "D".

Is the reading at the

specified value?

Infinite Go to Step 10 Go to Step 5

10 Check for faulty PCM

terminals.

Were any faulty terminals

found?

Go to Step 17 Go to Step 11

11 Check for faulty IAC

terminals.

Were any faulty terminals

found?

Go to Step 16 Go to Step 12

12 Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for Security

Link procedure.

Is the action complete?

Verify Repair

13 1. Ignition OFF.

2. Disconnect the PCM

electrical connector.

3. Ignition ON engine

OFF.

4. Check for a short to

voltage on the circuit

that the light was on

steady.

Was a short to voltage

found?

Go to Step 15 Go to Step 14

14 Check for faulty IAC valve

connections.

Were any faulty

connections found?

Go to Step 16 Go to Step 5

15 Repair the short to

voltage.

Is the action complete?

Verify Repair

16 Repair the faulty IAC

valve connections.

Is the action complete?

Verify Repair

17 Repair the faulty PCM

terminals.

Is the action complete?

Verify Repair

CHART A-8.1 - IGNITION SYSTEM CHECK

CIRCUIT DESCRIPTION:

The ignition system controls the fuel combustion by providing a spark to ignite the air/fuel mixture in the cylinder at

the correct time. This provides good engine performance, fuel economy, and control exhaust emissions. The PCM

controls the spark advance and the ignition dwell when the ignition system is operating in the EST mode.

The main components that make up the ignition system for the V8 engine are:

• The Distributor Assembly

• The Ignition Coil

• The Ignition Module

• The PCM

• The Spark Plugs

• The Spark Plug Wires

• The Cam sensor

• The Crankshaft Sensor

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. Do not use this chart unless sent here from chart A-3.1

3. The tachometer lead is only intended for service use. If the tachometer lead is connected, the lead most likely

connects to equipment not installed at the factory. A factory-installed tachometer is connected to circuit 121 at

a different location.

NOTE:

When performing this test, ensure that a standard low-power test light is used. Do not use a high wattage test light,

as the distributor hall switch could be damaged. A high wattage test light will either give inaccurate test results or

damage the hall switch.

5. Thoroughly inspect the distributor cap for any carbon build up or contamination that could effect the current

flow. Also, inspect the cap and the rotor for any cracks or signs of water intrusion.

DIAGNOSTIC AIDS:

Remove the spark plugs and inspect for the following conditions.

• Fuel fouling

• Contamination

• Cracks

• Excessive wear

• Improper gap

• Carbon tracking

• Improper heat range

Replace any plugs that are in question. Refer to Diagnosis in Section 6D2-3 for additional checks.

Spray a fine coat of water on the distributor and the wires while listening for a change in engine speed. This could

help find a crack in the component.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check

2From Chart A-3.1

Was spark found on any

of the cylinders?

Go to Step 5 Go to Step 3

31. Locate the tachometer

lead behind the left

front shock tower.

2. Connect a test light to

B+, and probe the tach

terminal lead.

Does the test light

illuminate?

Go to Step 8 Go to Step 4

41. Ignition OFF.

2. Disconnect the ignition

coil wire at the

distributor cap.

3. Connect an ST-125

tester to the ignition

coil wire lead .

4. Crank the engine and

look for spark.

CAUTION:

Do not touch the ignition

coil wire while cranking

the engine.

Was there a crisp blue

spark observed?

Go to Step 5 Go to Step 7

51. Check for

contamination or

cracks in the distributor

cap and rotor.

2. Replace or repair any

component that was

found at fault.

Was a problem found?

Verify Repair Go to Step 6

6Check the resistance in all

the spark plug wires.

Replace any wires that

show more than the

specified value of

resistance.

Is the action complete?

30,000

ohms Verify Repair

7Replace the ignition coil.

Is the action complete? Verify Repair

8Repair the short in the

tacho lead circuit.

Is the action complete?

Verify Repair

CHART A-11.1 - A/C CLUTCH CONTROL (NON ECC SYSTEM)

CIRCUIT DESCRIPTION:

With the blower fan ON, and the air conditioning ON, the switched ignition voltage is supplied from fuse F13 through

the A/C master switch, and then to the BCM. The BCM will then supply a serial data signal to the PCM requesting

A/C. If the BCM does not receive a earth signal from the blower switch to BCM terminal "3", the BCM will not supply

the serial data request for the A/C. Once the PCM receives the serial data signal, the PCM will energise the A/C

compressor relay by supplying a earth signal (A/C Relay Control ). The BCM also supplies a earth signal from BCM

terminal "7" to the low speed cooling fan relay .

This serial data signal to the PCM is also used to adjust the idle speed before turning ON the A/C compressor relay.

If this signal is not available to the PCM, the A/C compressor will be inoperative.

This system also incorporates a A/C Pressure Transducer. The A/C Pressure Transducer signal indicates low side

and high side refrigerant pressure to the PCM. The PCM uses this information to adjust the idle air control valve to

compensate for the higher engine loads present with high A/C refrigerant pressures. A fault in the A/C Pressure

Transducer signal will cause DTC 96 to set.

The purpose of the A/C Pressure Transducer is to protect the system from damage due to either the refrigerant

pressure being too low (which could damage the compressor due to insufficient lubrication), or too high (which

could result in a leak in the sealed refrigerant R134a system).

The PCM will NOT energise the A/C control relay if any of the following conditions are present:

• A DTC 91, or 96 is set.

• The engine speed is greater than 4,800 RPM. If de-energised because of RPM,

• the A/C will re-energise when the engine speed falls below 4,000 RPM for at least seconds.

• The Throttle Position angle is greater than 90%.

• The A/C Refrigerant Pressure Sensor voltage is too Low or too High

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

1. The PCM's diagnostic circuits must be proven before any further testing is performed.

2. The PCM does not normally energise the A/C control relay unless the engine is running.

4. This checks for operation of the condenser fan.

20, 21, 22, 23, 24, 26, 28.

There are no terminal identification on the relay connector (although the relay has terminal numbers). Make

certain the correct relay connector terminal (not the relay) is being probed.

39. The most likely cause of an automotive air conditioner not working is a discharged refrigerant R134a system,

due to a refrigerant leak.

CHECK FOR:

If fuse F13 is open, check for short to earth on all the circuits associated with this fuse.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check in

this Section.

21. Ignition ON, engine

stopped.

2. Disconnect the A/C

compressor clutch

electrical connector

and reconnect, and

note the compressor

clutch.

Did the compressor clutch

cycle OFF then ON with

the electrical connector

disconnected and

reconnected?

If the A/C clutch

cycled OFF then

ON or will not

disengage

Go to Step 6

Go to Step 3

31. Ignition ON, engine

idling.

2. Blower Switch turned

ON.

3. Cycle the A/C switch

ON and OFF, waiting a

few seconds between

positions.

Listen to the A/C

compressor clutch. Does

the A/C compressor

clut ch cycle ON and

"OFF?

Go to Step 4 Go to Step 14

41. Ignition ON, engine

idling.

2. The A/C switch in the

ON position.

Does the A/C condenser

fan operate when the A/C

switch is turned ON?

Go to Step 5 Go to Chart A-12

in this Section

51. A/C clutch control

circuits OK.

2. If the complaint is

insufficient cooling,

review the symptoms.

Is the action complete?

Verify Repair

61. Ignition OFF.

2. Disconnect the A/C

compressor electrical

connector.

2. Observe the A/C

clutch.

Is the A/C clutch engaged

to the A/C compressor?

Go to Step 7 Go to Step 8

7Replace the A/C

compressor clutch. Refer

to Section 2B AIR

CONDITIONING -

REMOVAL AND

INSTALLATION for

details.

Is the action complete?

Verify Repair

STEP ACTION VALUE YES NO

81. Ignition ON, engine

OFF.

2. Using a test light

connected to B+,

backprobe PCM

terminal for A/C Relay

Control.

Does the test light

illuminate?

Go to Step 9 Go to Step 11

9Check for a short to earth

in circuit for A/C Relay

Control from the PCM to

A/C Compressor Relay.

Was a problem found?

Verify Repair Go to Step 10

10 Replace the PCM.

Refer to Section 6C2-3

Service Operations, for

PCM Security Link

procedure.

Is the action complete?

Verify Repair

11 1. Ignition ON.

2. Disconnect the A/C

compressor electrical

connector.

3. Using a test light

connected to earth,

probe the A/C

compressor electrical

connector power

circuit.

4. With the test light ON,

remove the A/C

Compressor Relay and

note the test light.

Did the test light turn

OFF?

Go to Step 12 Go to Step 13

12 Replace the A/C

Compressor Relay.

Is the action complete?

Verify Repair

13 Repair the short to voltage

on the A/C compressor

power feed circuit from

the A/C Compressor

Relay to the A/C

compressor.

Is the action complete?

Verify Repair

14 1. Ignition ON, engine

idling.

2. Install a scan tool.

3. Observe the A/C

Refrigerant Pressure

Sensor voltage display

on the scan tool.

Is the indicated A/C

Refrigerant Pressure

Sensor voltage at or

between the specified

value?

0.35V -

4.2V Go to Step 15 Go to Step 39

STEP ACTION VALUE YES NO

15 Check the power supply

fuse to the A/C master

switch.

Is the fuse open?

Go to Step 16 Go to Step 17

16 Repair the short to earth

in the fuse circuit, and

replace the fuse.

Is the action complete?

Verify Repair

17 1. Ignition ON, engine

OFF.

2. Turn the A/C Master

Switch to the ON

position.

2. Using a test light

connected to earth,

backprobe the BCM

terminal to the A/C

Select Input circuit.

Does the test light

illuminate??

Go to Step 20 Go to Step 18

18 Check for an open or a

poor connection in the

circuit from the A/C

Master Switch to the BCM

A/C Select Input, or an

open in power feed circuit

to the A/C Master Switch.

Was a problem found?

Verify Repair Go to Step 19

19 Replace the A/C Master

Switch.

Is the action complete?

Verify Repair

20 1. Ignition ON, engine

idling.

2. Remove the Blower

Inhibit Relay from

Relay center, leave

harness connector

connected to the relay.

3. Using a test light

connected to B+,

backprobe the relay

harness connector

terminal 30.

4. Turn the A/C Master

Switch to the ON

position.

Does the test light

illuminate?

Go to Step 21 Go to Step 26

STEP ACTION VALUE YES NO

21 1. Ignition ON, engine

idling.

2. Using a test light

connected to B+,

backprobe the BCM

terminal for the Blower

Switch Input Signal.

3. Turn the A/C Master

Switch to the ON

position.

4. Turn the Blower Switch

to the ON position.

Does the test light

illuminate?

Go to Step 22 Go to Step 33

22 1. Ignition OFF.

2. Remove the A/C

Compressor Relay

from the relay center.

3. Ignition ON, engine

idling.

4. Turn the A/C Master

Switch to the ON

position.

5. Turn the Blower Switch

to the ON position.

6. Using a test light

connected to B+,

probe terminal "2" of

the A/C Compressor

Relay harness

connector.

Does the test light

illuminate?

Go to Step 23 Go to Step 35

23 1. Ignition ON, engine

OFF.

2. Using test light

connected to earth ,

probe A/C Compressor

Relay harness

terminals 1 and 3.

Does test light illuminate

on both circuits?

Go to Step 24 Go to Step 36

STEP ACTION VALUE YES NO

24 1. Ignition OFF.

2. Reinstall Blower Inhibit

Relay and A/C

Compressor Relay.

3. Disconnect electrical

connector at A/C

compressor.

4. Ignition ON, engine

idling.

5. Turn A/C Master

Switch to the ON

position.

6. Turn Blower Switch to

the ON position.

7. Using test light

connected to earth,

probe A/C compressor

harness power feed

circuit from A/C

Compressor Relay to

compressor.

Dose test light illuminate?

Go to Step 25 Go to Step 37

25 Check A/C compressor

earth circuit for an open, if

open repair. If earth circuit

is OK, Replace A/C

compressor. Refer to

Section 2B AIR

CONDITIONING -

REMOVAL AND

INSTALLATION.

Is the action complete?

Verify Repair

26 1. Ignition ON, engine

idling.

2. Using a test light

connected to B+,

backprobe the Blower

Inhibit Relay terminal

85 for Blower Inhibit

Relay Earth Output

Signal from BCM.

3. Turn the A/C master

switch ON.

Does the test light

illuminate?

Go to Step 28 Go to Step 27

27 Check for open in circuit

from BCM to Blower

Inhibit Relay or poor

connection at BCM. If OK,

replace BCM.

Is action complete?

Verify Repair

28 1. Ignition ON, engine

OFF.

2. Disconnect the Blower

Inhibit Relay from the

harness connector.

3. Using a test light

connected to earth,

probe the relay

harness terminal 86.

Does the test light

illuminate?

Go to Step 30 Go to Step 29

STEP ACTION VALUE YES NO

29 Repair the open in the

circuit from the Blower

Inhibit Relay terminal 86

to the Ignition Switch.

Is the action complete?

Verify Repair

30 1. Ignition ON, engine

OFF.

2. With the Blower Inhibit

Relay still

disconnected, probe

the relay harness

terminal 87 with a test

light connected to B+.

Does the test light

illuminate?

Go to Step 31 Go to Step 32

31 Replace the Blower Inhibit

Relay.

Is the action complete?

Verify Repair

32 Repair the open in the

earth circuit to the Blower

Inhibit Relay.

Is the action complete?

Verify Repair

33 Check for open circuit

from the Blower Switch to

the BCM Blower Switch

Input terminal.

Was a problem found?

Verify Repair Go to Step 34

34 Check for an open in the

circuit from the Blower

Inhibit Relay terminal 30

to the Blower Switch.

Was a problem found?

Verify Repair Go to Step 38

35 Check for an open in the

circuit from the A/C

Compressor Relay to the

PCM terminal for the A/C

Relay Control.

Was a problem found?

Verify Repair Go to Step 10

36 Repair the open in the

circuit that did not light.

Is the action complete?

Verify Repair

37 Check for an open in the

circuit from the A/C

Compressor to the A/C

Compressor Relay.

Was a problem found?

Verify Repair Go to Step 12

38 Replace the Blower

Switch.

Is the action complete?

Verify Repair

39 Check the A/C Pressure

Sensor signal circuit for

short to earth.

Was a problem found?

Verify Repair Go to Step 40

40 Check the A/C refrigerant

(R-134a) system for being

undercharged, or

overcharged.

Is the action complete.

Verify Repair

CHART A-11.3 - A/C CLUTCH CONTROL WITH ELECTRONI C CLIM ATE

CONTROL (ECC)

CIRCUIT DESCRIPTION:

When the A/C is requested, the Electronic Climate Control Module will supply a signal to the BCM. The BCM will

then send a serial data request to the PCM. When the PCM receives the serial data request on PCM terminal B12,

it indicates that air conditioning has been requested and approximately 1/2 second after the PCM receives this

signal, it will energise the A/C control relay . This serial data signal to the PCM is also used to adjust the idle speed

before turning ON the A/C compressor relay. If this signal is not available to the PCM, the A/C compressor will not

operate. If there is a problem with the A/C Relay Control circuit, QDSM DTC 91 will set. The BCM also supplies the

earth signal from BCM terminal "7" to the low speed cooling fan relay.

This A/C system also incorporates an A/C Refrigerant Pressure Sensor (A/C Pressure Transducer). The A/C

Refrigerant Pressure Sensor signal indicates low and high side refrigerant pressures to the PCM. The PCM uses

this information to adjust the idle air control valve to compensate for the higher engine loads present with high A/C

refrigerant pressures., and not allow A/C operation if pressure is to low A fault in the A/C Refrigerant Pressure

Sensor signal will cause DTC 96 to set.

The PCM will NOT energise the A/C control relay if any of the following conditions are present.

• A DTC 91, or a DTC 96 is set.

• The engine speed is greater than 4,800 RPM. If disabled because of RPM, the fan will re-enable when the

engine speed falls below 4000 RPM for at least 10 seconds.

• The throttle angle is greater than 90%.

• The A/C Refrigerant Pressure Sensor is less than.2V or greater than 4.9V.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

1. The PCM's diagnostic circuits must be proven before any further testing is performed.

3. The PCM does not normally energise the A/C control relay unless the engine is running.

4. When the Tech 2 scan tool is installed, and the A/C switch is turned ON, the scan tool should display "A/C

Requested".

6. This checks for operation of the condenser fan.

7. The most likely cause of an automotive air conditioner not cooling properly is a discharged or overcharged

refrigerant R134a system.

18, 19, 20 There are no terminal identification on the relay connector (although the relay itself has terminal

numbers). Make certain the correct relay connector terminal (not the relay) is being probed.

CHECK FOR:

If fuse F13 is open, check for short to earth on all circuit associated with this fuse.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check in

this Section

2Check the Electronic

Climate Control module

fuse.

Is the fuse OK?

Go to Step 3 Go to Step 18

31. Ignition ON, engine

OFF.

2. Cycle the A/C master

switch ON and OFF,

waiting a few seconds

between positions.

3. Observe the A/C

compressor clutch.

Did the compressor clutch

cycle ON and OFF?

If either engages

or will not

disengage Go to

Step 15

Go to Step 4

41. Ignition ON engine

OFF.

2. Install a Tech 2 scan

tool.

3. Turn the A/C switch

ON.

Does the Tech 2 scan

tool display "A/C

Requested"?

Go to Step 5 Go to Step 10

51. Ignition ON, engine

idling.

2. Cycle the A/C switch

ON and OFF, waiting a

few seconds between

positions.

3. Listen to the A/C

compressor clutch.

Does the A/C compressor

clutch cycle ON and OFF?

Go to Step 6 Go to Step 19

61. Ignition ON, engine

idling.

2. Turn the A/C switch

ON for 5 to 10

seconds.

3. The A/C clutch should

stay engaged ON for

the same time.

Does the compressor

clutch stay engaged ON?

Go to Step 7 Go to Step 9

7Ignition ON, engine idling.

Does the A/C condenser

fan operate when the A/C

is turned ON?

Go to Step 8 Go to Chart A-12

in this Section

8The A/C clutch control

circuits OK. If complaint is

insufficient A/C cooling,

review sympto m section.

Is the action complete?

Verify Repair

STEP ACTION VALUE YES NO

9Check the A/C refrigerant

(R 134a) system for being

undercharged. Recharge

as necessary.

Is the action complete?

Verify Repair

10 Check for a poor

connection or an open

circuit between the BCM

and the Electronic Climate

Control Module.

Was a problem found?

Verify Repair Go to Step 11

11 1. Ignition OFF.

2. Disconnect the BCM

connectors.

3. Ignition ON, engine

OFF.

4. With a DVM connected

to earth, probe the

BCM harness

connector terminal for

the A/C Select Input

from the Electronic

Climate Control

module.

5. Turn ON the A/C

switch.

Is the voltage between the

specified value?

2 - 4

volts Go to Step 13 Go to Step 12

12 Check for an open or a

short to earth in the A/C

Select circuit between the

BCM and the Electronic

Climate Control module.

Was a problem found?

Verify Repair Go to Step 14

13 Replace the BCM.

Is the action complete? Verify Repair

14 Check for poor connection

at the Electronic Climate

Control module, if the

connection is OK, replace

the Electronic Climate

Control Module.

Is the action complete?

Verify Repair

15 Check for a short to earth

from the A/C Relay

Control circuit to the A/C

Compressor Relay.

Was a problem found?

Verify Repair Go to Step 16

16 Check for a short to

voltage in the power feed

circuit to the A/C

compressor.

Was a problem found?

Verify Repair Go to Step 17

STEP ACTION VALUE YES NO

17 Replace the defective A/C

compressor relay.

NOTE:

If the compressor clutch

still will not disengage,

replace the A/C

compressor clutch. Refer

to Section 2B AIR

CONDITIONING -

REMOVAL AND

OPERATION for details.

Is the action complete?

Verify Repair

18 1. Repair the short to

earth in the fuse

circuit.

2. Replace the fuse.

Is the action complete?

Verify Repair

19 1. Ignition ON, engine

idling.

2. Disconnect the A/C

compressor relay.

3. Probe both relay

terminals "3" and "1" of

the harness connector,

with a test light

connected to earth.

Is the test light ON at both

terminals?

Go to Step 20 Go to Step 26

20 1. Ignition ON, engine

idling.

2. Probe the A/C

compressor relay

socket circuit for the

A/C Relay Control with

a test light connected

to B+.

3. Turn the A/C switch

ON.

Is the test light ON when

the A/C switch is ON?

Go to Step 21 Go to Step 24

21 1. Ignition ON, engine

idling.

2. Reconnect the A/C

compressor relay.

3. Backprobe relay

harness terminal "5"

circuit with a test light

connected to earth.

4. Turn the A/C switch

ON.

Is test light ON when A/C

switch is turned ON?

Go to Step 22 Go to Step 28

STEP ACTION VALUE YES NO

22 1. Ignition OFF.

2. Disconnect the A/C

compressor electrical

connector.

3. Ignition ON, engine

idling.

4. Probe the compressor

harness connector

terminal power feed

circuit with a test light

connected to earth.

5. Turn the A/C switch

ON.

Is the test light ON when

the A/C switch is turned

ON?

Go to Step 23 Go to Step 29

23 1. Check for a defective

"Discharge Gas

temperature" switch in

the compresso r, or a

defective A/C clutch.

2. Repair or replace as

necessary.

Is the action complete ?

Verify Repair

24 Check for a faulty

connection at the A/C

compressor relay.

Was a poor connection

found ?

Verify Repair Go to Step 25

25 Check for an open in the

PCM A/C Relay Control

circuit, from the PCM to

the A/C compressor relay.

Was a problem found ?

Verify Repair Go to Step 27

26 Repair the open in the

circuit that did not light the

test light.

Is the action complete?

Verify Repair

27 Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for Security

Link procedure.

Is the action complete?

Verify Repair

28 Replace the A/C

compressor.

Is the action complete?

Verify Repair

29 Repair the open in circuit

59 to the A/C compressor

clutch.

Is the action complete?

Verify Repair

CHART A-12.1 - ELECTRIC FAN CONTROL

CIRCUIT DESCRIPTION:

The V8 engine has two duel speed electric fan which provides the primary means of moving air through the engine

radiator. The engine cooling fan high speed relay is controlled by the PCM. The PCM controls the earth path for the

engine cooling fan high speed relay.

The low speed of the electric fan is controlled by the PCM through special Data Communication to the BCM. The

BCM controls the earth path for the engine cooling fan low speed relay.

Both relays are used to control the earth paths to the electric motor that drives the five blade fan.

The engine cooling fan low speed relay is energised by the BCM. The PCM determines when to enable the engine

cooling fan low speed based on inputs from the A/C request signal, vehicle speed and engine coolant temperature.

The engine cooling low speed fan will be turned ON when.

• The A/C request indicated (YES).

• The Vehicle speed is less than 54 Km/h.

- OR -

• The engine coolant temperature is greater than 104 degrees C. The fan will remain on until the coolant

temperature goes below 99 degrees C.

ENGINE COOLING FAN HIGH SPEED

The engine cooling fan high speed is controlled by the PCM based on input from the Engine Coolant Temperature

Sensor (ECT). The PCM will only turn ON the engine cooling fan high speed if the engine cooling low speed fan has

been ON for 2 seconds and the following conditions are satisfied.

• There is a BCM message response fault which will cause a DTC 92.

• An engine coolant temperature sensor fault is detected, such as DTC 14,15,16,17, or 91.

• An engine coolant temperature greater than 109 degrees C.

If the fan low speed was OFF when the criteria was met to turn the fan high speed ON, the fan high speed will come

ON 5 seconds after the fan low speed is turned ON. The engine cooling fan High speed relay can also be enable by

the A/C Refrigerant Pressure Sensor. The A/C Refrigerant Pressure Sensor will provide a signal to the PCM when

A/C pressure becomes to high approximately 1770 kPa.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. This entire diagnostic procedure must begin with a "cold" engine - at ambient air temperature. If the coolant is

hot when diagnosis is performed, replacement of good parts will result. Fan should not be running if engine

coolant temperature is less than 99 degrees C and air conditioning is not ON.

10. On A/C equipped vehicles, the engine cooling fan High speed relay should energise by the PCM, as soon as

the PCM energises the A/C clutch.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check

21. Ignition ON, engine

OFF.

2. Engine coolant

temperature below 99

degrees C.

Is the electric fan

running ?

Go to Step 3 Go to Step 9

31. Ignition OFF.

2. Remove the Radiator

Fan High Speed Relay.

3. Ignition ON.

Does the fan continue to

run ?

Go to Step 4 Go to Step 5

41. Ignition ON, Engine

OFF.

2. Remove the Fan Low

Speed Relay.

Does the fan continue to

run ?

Go to Step 13 Go to Step 16

51. Ignition ON.

2. Probe the Radiator

Fan High Speed Relay

harness connector

circuit 304 with a test

light to B+.

Is the test light ON?

Go to Step 6 Go to Step 8

61. Ignition OFF.

2. Disconnect the PCM

connectors.

3. Ignition ON.

4. Probe the Fan High

Speed Relay harness

connector circuit 304

with a test light

connected to B+.

Is the test light ON?

Go to Step 14 Go to Step 7

STEP ACTION VALUE YES NO

7Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for the

Security Link procedure.

Is the action complete?

Verify Repair

8Replace the Radiator Fan

High Speed Relay. Verify Repair

91. Ignition ON.

2. Using the scan tool,

Select HIGH FAN

relay control.

3. Turn ON the HIGH

FAN with up/down

arrow keys.

Does the cooling fan

operate in high fan mode?

Go to Step 20 Go to

Chart A-12.2 in

this Section

10 Is the vehicle equipped

with A/C? Go to Step 11 Go to Step 12

11 1. Start engine, allow to

idle.

2. Turn A/C ON.

3. Electric fan should run

when the A/C clutch

engages.

NOTE:

If A/C clutch will not

engage, refer Chart A-

11.1 or Chart A-11.3 in

this Section.

Does the fan run when the

A/C clutch is engaged?

Go to Step 12 Go to Step 9

12 The electric fan circuit is

OK. Verify Operation

13 1. Connect a test light to

B+.

2. Probe circuit 533 of

Radiator Fan Low

Speed Relay.

Is the test light ON ?

Go to Step 15 Go to Step 18

14 Repair the short to earth

in circuit 304. Verify Repair

15 Repair the short to earth

in circuit 533. Verify Repair

16 1. Ignition ON.

2. Probe the Fan Low

Speed Relay harness

connector circuit 473

with a test light

connected to B+.

Is the test light ON?

Go to Step 17 Go to Step 21

17 Check for short to earth

on circuit 473.

Was a short to earth

found ?

Verify Repair Go to Step 18

18 Replace the BCM.

Is the action complete? Verify Repair

STEP ACTION VALUE YES NO

19 1. Reinstall the Radiator

Fan High Speed Relay.

2. Ignition ON.

3. Use the scan tool to

turn on the "LOW FAN

" with the up/down

arrow keys.

Does the radiator fan

motor run?

Go to Step 10 Go to

Chart A-12.3 in

this Section

20 1. Ignition ON.

2. Use the scan tool in

order to turn on the

high fan with the

up/down arrow keys.

3. While the fan is

running, remove the

Radiator Fan High

Speed Relay.

Did the cooling fan motor

go to a lower running

speed ?

Go to Step 19 If the radiator fan

motor is turned

OFF,

Go to Chart

A-12.2 in this

Section

21 Check for short to earth in

circuit 250.

Was a problem found?

Verify Repair Go to Step 22

22 Replace the Radiator Fan

Low Speed Relay.

Is the action complete?

Verify Repair

CHART A-12.2 - ELECTRIC FAN CONTROL

CIRCUIT DESCRIPTION:

The engine has a water pump driven radiator fan incorporating a semi-fluid hydraulic fan clutch. This engine-driven

fan provides the primary means of moving air through the engine radiator. On vehicles equipped with air

conditioning, an additional electric motor driven fan is placed in front of the A/C condenser.

• The electric fan(s) will turn ON when the engine cooling fan relay is energised by the PCM.

• The electric fan(s) will turn ON, if any of the following conditions are present;

• The engine coolant temperature exceeds 110 degrees C. (After the PCM turns the fan ON, it will run until the

coolant temperature is below 105 degrees C.).

• An engine coolant temperature sensor DTC is detected (refer DTC 14 or 15 Chart in this Section).

• An A/C request signal is received and the vehicle speed (VSS input) is less than 64 km/h.

• The Field service mode is active. (Ignition ON, engine OFF, and the DLC diagnostic test enable terminal

earthed.)

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

3. This checks for B+ to the fan relay on both supply circuits.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check.

2From Chart A-12.1

Check fusible links FS,

FT, FU, and White fusible

link for open. Was a

problem found?

Go to Step 8 Go to Step 3

31. Ignition OFF.

2. Remove Radiator Fan

High Speed Relay.

3. Ignition ON.

4. Probe relay socket,

circuit 39 with test light

connected to earth.

Is test light ON?

Go to Step 4 Go to Step 10

41. Ignition ON.

2. Probe Radiator Fan

High Speed Relay

socket circuit 304 with

a test light connected

to B+.

3. Using scan tool,

Select HIGH FAN,

enable fan ON with

up/down arrows.

Is test light ON?

Go to Step 5 Go to Step 9

51. Ignition ON.

2. Reinstall Radiator Fan

High Speed Relay.

3. Back-probe Radiator

Fan High Speed Relay

harness connector

circuit 250 with test

light connected to B+.

4. Using scan tool, Select

HIGH FAN, enable fan

ON with the up/down

arrow keys.

Is the test light ON.

Go to Step 6 Go to Step 11

61. Ignition ON.

2. Disconnect both

electric cooling fan

wiring harness

connector.

3. Probe both fan

harness connector,

circuits 533 and 250

with a test light to B+.

4. Using scan tool, Select

HIGH FAN, enable fan

ON by pressing the

up/down arrow keys.

Is the test light ON for

both circuits ?

Go to Step 7 Go to Step 13

STEP ACTION VALUE YES NO

7Probe both fan harness

connector power feed

circuits, with a test light

connected to earth.

Is the test light ON for all

circuits ?

Go to Step 12 Go to Step 15

81. Check for short to

earth that caused

fusible link to blow.

2. Check the engine

cooling fan motor for

drawing to much

current. Is the action

complete ?

Verify Repair

91. Ignition ON.

2. Using scan tool,

Select HIGH FAN,

enable output by

pressing the up/down

arrow keys.

3. Backprobe PCM

terminal "F6" with a

test light connected to

B+.

Is the test light ON?

Go to Step 14 Go to Step 16

10 Repair the open or the

short to earth in circuit 39.

Replace the fuse if blown.

Verify Repair

11 With test light connected

to B+, backprobe Radiator

Fan High Speed Relay

harness connector circuit

157.

Does test light illuminate?

Go to Step 17 Go to Step 18

12 Check for poor a

connection at both fan

motors. If OK, replace the

electric fan motor that did

not operate.

Is the action complete?

Verify Repair

13 Check for open in circuits

533 or 250.

Was a problem found?

Verify Repair Go to Step 18

14 Repair open in circuit 304. Verify Repair

15 Repair open in fan motor

power circuit that did not

light test light.

Verify Repair

16 Check for short to voltage

in circuit 304, or faulty

connection at PCM, if OK

replace PCM.

Verify Repair

17 Replace Radiator Fan

High Speed Relay. Verify Repair

18 Check for open in earth

circuit 157.

Was a problem found?

Verify Repair Go to Step 19

19 Replace the Radiator Fan

Low Speed Relay. Verify Repair

CHART A-12.3 - ELECTRIC FAN CONTROL

CIRCUIT DESCRIPTION:

The V8 engine has two (2) two speed electric fan which provides the primary means of moving air through the

engine radiator. The two speed electric cooling fan are used to cool engine coolant flowing through the radiator. It is

also used to cool the refrigerant flowing through the A/C condenser.

The engine cooling fan high speed relay is controlled by the PCM. The PCM controls the earth path for the engine

cooling fan high speed relay.

The low speed of the electric fan is controlled by the PCM through special Data Communication to the BCM. The

BCM controls the earth path for the engine cooling fan low speed relay.

Both relays are used to control the earth paths to the electric motor's that drives both five bladed fan's.

ENGINE COOLING FA N LOW SPEED:

The engine cooling fan low speed relay is energised by the BCM. The PCM determines when to enable the engine

cooling fan low speed based on inputs from the A/C request signal, vehicle speed and engine coolant temperature.

The engine cooling low speed fan will be turned ON when:

• The A/C request indicates (YES).

• The vehicle speed is less than 54 Km/h.

- OR -

• The coolant temperature is greater than 104 degrees C and will remain on until the coolant temperature goes

below 99 degrees C

ENGINE COOLING FAN HIGH SPEED

The engine cooling fan high speed is controlled by the PCM based on input from the Engine Coolant Temperature

Sensor (ECT). The PCM will only turn ON the engine cooling fan high speed if the engine cooling low speed fan has

been ON for 2 seconds and the following conditions are satisfied:

• There is a BCM message response fault which will cause a DTC 92.

• An engine coolant temperature sensor fault is detected, such as DTC 14,15,16,17, or 91.

• The engine coolant temperature is greater than 109 degrees C.

If the fan low speed was off when the criteria was met to turn the fan high speed on the fan high speed will come on

5 seconds after the fan low speed is turned on. The engine cooling fan High speed relay can also be enable by the

A/C Refrigerant Pressure Sensor. The A/C Refrigerant Pressure Sensor will provide a signal to the PCM when A/C

pressure becomes to high approximately 1770 kPa.

TEST DESCRIPTION

Number(s) below refer to step number(s) on the diagnostic chart.

3. This checks the FS fusible link power supply to the Radiator Fan Low Speed Relay.

4. This step checks for proper BCM operation for the Radiator Fan Low Speed Relay.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2. Go to OBD

System Check.

21. Ignition OFF.

2. Remove Radiator Fan

Low Speed Relay.

3. Probe the relay socket,

circuit 250 with a test

light connected to B+.

Is the test light ON?

Go to Step 7 Go to Step 3

31. Ignition OFF.

2. Remove Radiator Fan

Low Speed Relay.

3. Ignition ON.

4. Probe relay socket,

circuit 1040 with test

light connected to

earth

Is the test light ON?

Go to Step 4 Go to Step 9

41. Ignition ON.

2. Probe the radiator Fan

Low Speed Relay

socket, circuit 473 with

a test light connected

to B+.

3. Using a scan tool,

Select LOW FAN,

enable the fan ON with

the up/down arrow

keys.

Is the test light ON?

Go to Step 5 Go to Step 8

51. Ignition ON.

2. Reinstall Radiator Fan

Low Speed Relay.

3. Back-probe the low

speed relay wiring

harness connector,

circuit 533 with test

light connected to B+.

4. Using a scan tool,

Select LOW FAN,

enable the fan ON with

the up/down arrow

keys.

Is the test light ON?

Go to Step 10 Go to Step 6

STEP ACTION VALUE YES NO

61. Ignition OFF.

2. Disconnect both the

electric cooling fan

wiring harness

connectors.

3. Probe both wiring

harness connector

circuit's 533 with a test

light connected to B+.

4. Using a scan tool,

Select LOW FAN,

enable the fan ON with

the up/down arrow

keys.

Is the test light ON?

Go to Step 14 Go to Step 12

7Repair the short to earth

in circuit 250.

Is the action complete?

Verify Repair

81. Ignition ON.

2. Using a scan tool,

Select LOW FAN,

enable fan ON.

3. Backprobe BCM

terminal "7" with a test

light connected to B+.

Is the test light ON?

Go to Step 13 Go to Step 15

9Repair the open in the

circuit which causes the

test light not to come ON.

Is the action complete?

Verify Repair

10 Replace the Radiator Fan

Low Speed Relay.

Is the action complete?

Verify Repair

11 Repair the short to earth.

Is the action complete? Verify Repair

12 Repair the open in circuits

533 or 250.

Is the action complete?

Verify Repair

13 Repair the open in circuit

473 between the BCM

and the Radiator Fan Low

Speed Relay.

Is the action complete?

Verify Repair

14 Replace the Radiator fan

motor that did not operate.

Is the action complete?

Verify Repair

15 Check for a faulty

connection at the BCM, if

OK replace the BCM.

Is the action complete?

Verify Repair

CHART A-13 - RESTRICTED EXHAUST CHECK

A restricted exhaust can cause a variety of symptoms. Below is a list of some of these symptoms.

• No power, sluggish

• Hesitation on acceleration

• Surges while driving

• Poor fuel economy

• Stalling

• Hard starting

Conditions that could cause a restricted exhaust;

• A collapsed exhaust pipe.

• Loose baffles in the muffler can cause an internal restriction.

• Catalytic converter.

Things that can cause a catalytic converter to become restricted are; 1. The use of LEADED FUEL (2) A very

rich-running engine. This rich-running condition could be caused by fuel pressure to high, or by a malfunction in the

engine control system (3) Engine in a bad state of tune. Worn parts in the ignition system can cause an engine

misfire, which sends unburned fuel into the exhaust system. The catalytic converter sees this unburned fuel as a

rich-running condition. (4) Push-starting the engine can send a tremendous amount of unburned fuel into the

exhaust system.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

2Carefully remove the O2

sensor.

Could the O2 sensor be

removed from the exhaust

system?

Go to Step 3 Go to Step 6

31. Install an exhaust back

pressure gauge in

place of the removed

O2 sensor.

2. Start the engine and

allow to idle.

3. Observe the exhaust

system back pressure

reading on the gauge.

Is the reading less than

the specified value?

8.6 kPa Go to Step 4 Go to Step 7

4Rev the engine to 2000

RPM and observe the

reading on the gauge.

Is the reading on the

gauge less than the

specified value?

20.7

kPa Go to Step 5 Go to Step 7

5No problem found with the

exhaust system.

Is the action complete?

Go to the OBD

System Check in

this Section

6If the O2 sensor will not

remove from the exhaust

system, run the engine

until the exhaust system

temperature is greater

than 60°C.

Was the removal of the

O2 sensor successful?

Go to Step 3 Verify Repair

7NOTE:

If there are no obvious

reasons for the excessive

back pressure, a

restricted catalytic

converter should be

suspected and replaced

using the current

recommended

procedures.

Refer above, for things

that could cause a

restricted exhaust: for

possible causes.

Is the action complete?

Verify the Repair

and Go to the

OBD System

Check in this

Section

DTC 13 - RIGHT HAND (RH) NO OXYGEN SENSOR SIGNAL

CIRCUIT DESCRIPTION:

The right side O2 sensor is located in the exhaust stream forward of the catalytic converter. The O2 sensor monitors

the oxygen content of the exhaust gas in the exhaust stream then sends a voltage to the PCM relative to the oxygen

content. This voltage ranges from less than 100 mV (high O2 exhaust content-lean mixture) to greater than 900 mV

(low O2 exhaust content-rich mixture).

The PCM provides the O2 sensor with a constant 450 mV bias voltage. As the O2 sensor begins heating up its

internal resistance begins to decrease . The O2 sensor then begins to produce a rapidly changing voltage that

differs from the PCM supplied bias voltage. When the PCM recognises the changing voltage of the O2 sensor the

PCM knows the O2 sensor’s output voltage is ready to be used for fuel control.

When the ignition is turned ON, B+ is applied to the O2 sensor’s heater element. Approximately 30 seconds after

the B+ is applied to the heater portion of the O2 sensor, the O2 sensor should reach a temperature greater than

500°C. The heated O2 sensor becomes active much quicker than a non-heated O2 sensor. This allows the PCM to

control the air/fuel ratio more consistent over a wider range of operating conditions.

DTC 13 WILL SET IF:

• One or more of the following DTCs are not set. DTC 19, 21, or DTC 22 is not set.

• The engine run time is greater than 2 minutes.

• The engine coolant temperature is greater than 85°C.

• The Throttle Position (TP) sensor angle is greater than 6.25%.

• The O2 sensor voltage stays between 347 and 551 mV.

• The above conditions have been present for 20 seconds.

When a DTC 13 is active, the PCM will operate the fuel system in the open-loop mode.

TEST DESCRIPTION:

Number(s) below refer to number(s) on the diagnostic chart.

2. The Tech 2 Scan tool allows you to read the same oxygen sensor voltage the PCM is using for its calculations.

3. This step simulates a lean exhaust indication to the PCM. If the PCM and wiring are OK, the PCM will see the

lean indication and the Tech 2 Scan tool should display the O2 sensor voltage below 200 mV.

8. In doing this test, use only a high impedance digital volt-ohm meter. This test checks the continuity of circuits

412 and 150. If circuit 150 is open, the PCM voltage on circuit 412 will be over 0.6 volts.

9. The earth circuit is a separate wire from the PCM to the engine. The PCM uses this circuit to compare it with

the voltage on circuit 412. It completes the earth path for the PCM's oxygen sensor circuitry. This circuit must

be complete, clean, and tight connection to the engine.

DIAGNOSTIC AIDS:

Normal Tech 2 Scan tool voltage varies between 100 mV and 999 mV when in Closed Loop.

Carbon deposits caused by a rich running of the engine can cause a temporary poisoning of the sensor. This will

result in a slow or sluggish O2 sensor. The sensor can be cleaned by running the vehicle for several minutes at

operating temperature while not in the rich condition. If a rich condition is present find the problem causing the rich

condition before attempting to clean the O2 sensor.

Check for other forms of contamination.

• Silica from gasket forming material.

• Lead from the use of leaded gasoline.

• Metallic compounds from the use of inferior or low grades of petrol or engine oil.

Some of these contaminants will clean themselves from continuous running of the engine. Do not attempt to clean

the O2 sensor with any form of cleaner solvent this may cause permanent damage.

Check the O2 sensor pigtail wire for proper routing. If the O2 sensor pigtail wire contacts the exhaust manifold the

wire insulation can burn and short itself to the exhaust manifold.

Also, check the O2 sensor for any leaks around its sealing surface or any exhaust leaks. Refer to "Intermittents" in

Section 6C2-2B SYMPTOMS. To diagnose the oxygen sensor, refer to CHART A-6.3 in this Section.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Run the engine until

the engine coolant

temperature reaches

85°C.

2. Install a Tech 2 scan

tool.

3. Monitor the RH O2

sensor voltage on the

scan tool.

Is the Right Hand O2

sensor voltage between

the specified values?

347-

551 mV Go to Step 3 If no additional

DTCs were

stored, refer to

"Intermittents" in

Section 6C2-2B

SYMPTOMS

31. Turn the engine OFF.

2. Disconnect the Right

Hand O2 sensor

electrical connector.

3. Jumper the harness

circuit (PCM side) to

earth.

4. Start the engine and

allow the engine to

idle.

5. Monitor the RH O2

sensor voltage on the

scan tool.

Is the RH O2 sensor

voltage below the

specified value?

0.2 Volt

(200

mV)

Go to Step 4 Go to Step 5

4Check for a faulty

connection at the oxygen

sensor pigtail wire

connector.

Was a poor connection

found?

Go to Step 11 Go to Step 9

STEP ACTION VALUE YES NO

51. Turn the engine OFF.

2. Remove the jumper.

2. Ignition ON, engine

OFF.

3. Using a DVM check

the voltage in the RH

O2 sensor signal circuit

(PCM side) at the RH

O2 sensor harness

connector.

Is the RH O2 sensor

voltage between the

specified values?

0.3 - 0.6

Volts

(300-

600 mV)

Go to Step 10 Go to Step 6

61. Turn the engine OFF.

2. Remove the jumper

wire.

3. Ignition ON, engine

OFF.

4. Use a DVM to check

the voltage in the RH

O2 sensor signal circuit

(PCM side) at the RH

O2 sensor harness

connector.

Is the RH O2 sensor

voltage greater than the

specified value?

0.6 Volts

(600

mV)

Go to Step 7 Go to Step 8

7Check for an open or a

faulty connection in the

RH O2 sensor ground

circuit (3 total).

Was a problem found?

Verify Repair Go to Step 10

8Check for an open or a

faulty connection in the

RH O2 sensor signal

circuit.

Was a problem found?

Verify Repair Go to Step 10

9Replace the RH O2

sensor.

Is the action complete?

Verify Repair

10 Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for Security

Link procedure.

Is the action complete?

Verify Repair

11 Repair the fault in the RH

O2 sensor pigtail

connector.

Is the action complete?

Verify Repair

DTC 14 - ENGINE COOLANT TEMPERATURE (ECT) SENSOR - SIGNAL

VOLTAGE LOW

CIRCUIT DESCRIPTION:

The PCM supplies a 5 volt reference and a earth circuit to the ECT sensor. The ECT sensor in turn will send an

output voltage to the PCM based on engine coolant temperature. When the engine coolant temperature is cold, the

ECT sensor (thermistor) resistance will be high, therefore the PCM voltage signal will be high. As the engine coolant

temperature warms up, the sensor resistance decreases, and the PCM will see a lower signal voltage. At engine

operating temperature (85 °C to 95 °C), the voltage should be between .9 and 1.5 volts.

DTC 14 WILL SET IF:

The engine coolant temperature voltage is less than 0.3V (140°C) for one second.

• The engine run time is greater than 10 seconds.

• The PCM will use a default value of 90°C whenever a DTC 14 is set.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

3. This test will determine if circuit 410 is shorted to earth which will cause the conditions for DTC 14.

4. If checking the resistance at the engine coolant temperature sensor is difficult because of sensor location,

disconnect the PCM connectors and check the resistance between the engine coolant temperature signal

circuit and the sensor earth circuit.

Whenever replacing the PCM perform the security link procedure found in Section 6C2-3 SERVICE

OPERATIONS.

DIAGNOSTIC AIDS:

Check the harness routing for a potential short to earth in circuit 410.

Check the terminals at the ECT sensor for a good connection.

After the engine is started, the temperature should rise steadily to about 90°C then stabilise when the thermostat

opens.

The "Temperature vs Resistance Value" chart may be used to compare the engine coolant temperature sensor at

various temperatures to evaluate the possibility of a shifted sensor. A shifted ECT sensor could result in a

driveability problem. Refer to "Intermittents" in Section 6C2-2B SYMPTOMS.

ENGINE COOLANT TEMPERATURE SENSOR TEMPERATURE VS. RESISTANCE VALUES(APPROXIMATE)

COHMS

110 110

100 190

90 250

70 450

40 1,200

30 1,800

20 2,500

0 6,000

-10 8,750

-20 15,000

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Install a Tech 2 scan

tool.

2. Start the engine and

monitor the Engine

Coolant Temperature

until the coolant

temperature reaches

the specified

temperature.

Does the engine coolant

temperature reach the

specified temperature?

140°C Go to Step 3 If no additional

DTCs were

stored, refer to

"Intermittents" in

Section 6C2-2B

SYMPTOMS.

31. Ignition Off.

2. Disconnect the engine

coolant temperature

sensor electrical

connector.

3. Ignition ON engine

OFF.

4. Monitor the engine

coolant temperature.

Is the engine coolant

temperature less than the

specified value?

-30°C Go to Step 4 Go to Step 6

4Check the resistance

across the engine coolant

temperature sensor

terminals.

Does the resistance

values match the

specified values for the

ECT sensor vs resistance,

refer above ?

See

table

above

Go to Step 5 Go to Step 8

STEP ACTION VALUE YES NO

5Check for an intermittent

or loose terminal in the

sensor harness

connector.

Was a faulty connection

found?

Go to Step 9 Go to Step 7

6Check the ECT sensor

signal circuit for a short to

earth.

Was a short found?

Go to Step 10 Go to Step 7

7Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for Security

Link procedure.

Is the action complete?

Verify Repair

8Replace the ECT sensor.

Is the action complete? Verify Repair

9Repair the ECT sensor

connector terminals.

Is the action complete?

Verify Repair

10 Repair the short to earth

in the ECT sensor signal

circuit.

Is the action complete?

Verify Repair

DTC 15 - ENGINE COOLANT TEMPERATURE (ECT) SENSOR - SIGNAL

VOLTAGE HIGH

CIRCUIT DESCRIPTION

The PCM supplies a 5 volt reference and a earth circuit to the ECT sensor. The ECT sensor in turn will send an

output voltage to the PCM based on engine coolant temperature. When the engine coolant temperature is cold, the

ECT sensor resistance will be high, therefore the PCM voltage will be high. As the engine coolant temperature rises,

the sensor resistance decreases, and the PCM sees a lower signal voltage. At normal engine operating

temperature (85 °C to 95 °C), the voltage should be between .9 and 1.5 volts.

DTC 15 WILL SET IF:

• The engine run time is greater than 10 seconds.

• The ECT input signal voltage is greater than 4.7 volts, indicating an engine coolant temperature less than about

-35 degrees C for one second.

The PCM will use a default value of 90°C whenever a DTC 14 is set.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

3. This test simulates a Diagnostic Trouble Code 14. If the PCM recognises the low signal voltage, (high

temperature) and the Tech 2 "Scan" tool reads 130 degrees C or above, then the PCM and wiring are OK.

4. This test will determine if circuit 410 is open. There should be an open circuit voltage of 5 volts at the Engine

Coolant Temperature (ECT) sensor harness connector. By jumping the 5 volt signal to earth, the PCM should

recognise this change.

9. Whenever the PCM is replaced, perform the Security Link procedure found in Section 6C2-3 SERVICE

OPERATIONS.

DIAGNOSTIC AIDS:

A Tech 2 scan tool reads engine coolant temperature in degrees Celsius. After the engine is started, the

temperature should rise steadily to about 90 degrees C then stabilise when the thermostat opens.

A faulty connection, an open in circuit 410 or an open in circuit 452 will result in a Diagnostic Trouble Code (DTC)

15 to set.

If a DTC 21 or a DTC 59 are also set, check circuit 452 for faulty wiring or connections. Check terminals at the

sensor for a good connection.

The "Temperature vs Resistance Value" scale may be used to test the engine coolant temperature sensor at

various temperature to evaluate the possibility of a shifted sensor. A shifted sensor could result in poor driveability.

Refer to "Intermittents" in Section 6C2-2B SYMPTOMS.

ENGINE COOLANT TEMPERATURE SENSOR TEMPERATURE VS. RESISTANCE VALUES (APPROXIMATE)

COHMS

110 110

100 190

90 250

70 450

40 1,200

30 1,800

20 2,500

0 6,000

-10 8,750

-20 15,000

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Install a Tech 2 scan

tool.

2. Ignition ON engine

OFF.

Is the ECT sensor

temperature at or between

the specified value?

-35°C to

-40°C Go to Step 3 If no additional

DTCs were

stored, refer to

"Intermittents" in

Section 6C2-2B

SYMPTOMS

31. Ignition OFF.

2. Disconnect the ECT

sensor electrical

connector.

3. Jumper the harness

terminals together.

4. Ignition ON engine

OFF.

Is the ECT sensor

temperature greater than

the specified value?

130°C Go to Step 8 Go to Step 4

41. Engine OFF.

2. Jumper the ECT

sensor signal circuit to

earth.

Does the Scan tool

display ECT sensor

temperature greater than

the specified value?

130°C Go to Step 5 Go to Step 7

5Check the resistance

across the engine coolant

temperature sensor

terminals.

Does the DVM reading

match the specified

values for the

temperatures vs sensor

resistance table, refer

above ?

Go to Step 6 Go to Step 10

STEP ACTION VALUE YES NO

6Check for a faulty

connection in the sensor

harness connector.

Was a faulty connection

found?

Go to Step 11 Go to Step 9

7Check the ECT sensor

signal circuit for an open

or a faulty connection at

the PCM.

Was a fault connection

found?

Go to Step 11 Go to Step 9

8Check for a faulty ECT

sensor connection.

Was a faulty connection

found?

Go to Step 11 Go to Step 10

9Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for Security

Link procedure.

Is the action complete?

Verify Repair

10 Replace the ECT sensor.

Is the action complete? Verify Repair

11 Repair the faulty

connection or circuit.

Is the action complete?

Verify Repair

DTC 16 - ENGINE COOLANT TEMPERATURE (ECT) SENSOR - SIGNAL

VOLTAGE UNSTABLE

CIRCUIT DESCRIPTION:

The PCM supplies a 5 volt reference and a earth circuit for the ECT sensor. The ECT sensor in turn will send an

output voltage to the PCM based on engine coolant temperature. When the engine coolant temperature is cold, the

ECT sensor (thermistor) resistance will be high, therefore the PCM voltage signal will be high. As the engine coolant

temperature warms up, the sensor resistance decreases, and the PCM will see a lower signal voltage. At normal

engine operating temperature (85 °C to 95 °C), the voltage should be between 0.9 and 1.5 volts.

DTC 16 WILL SET IF:

• The engine run time is greater than 10 seconds.

• A DTC 14, 15 or 17 is not set.

• The ECT temperature changes more than 20 in 400 milliseconds.

TEST DESCRIPTION:

Numbers below refer to step(s) on the diagnostic chart.

2. The cause of an unstable ECT sensor is most likely caused from a bad connection causing intermittent voltage

spikes. By moving the wires and watching for a change in voltage on the scan tool can help identify the

problem area.

7. Whenever the PCM is replaced, perform the Security Link Procedure found in Section 6C2-3 SERVICE

OPERATIONS.

DIAGNOSTIC AIDS:

When attempting to diagnose an intermittent problem, use the snapshot mode of the Tech 2 scan tool, to review

diagnostic information.

This DTC is most likely to set on a cold engine than on a hot engine because of the pull up resistors in the PCM.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Install a Tech 2 Scan

tool.

2. Set up the snapshot

mode to trigger on

DTC 16.

3. Ignition ON engine

OFF.

4. Monitor the Scan tool

while wiggling the

ECT sensor connector.

Does the “Eng Coolant

Temp” reading change

sharply while wiggling the

wires?

Go to Step 8 Go to Step 3

3Wiggle and tug the ECT

sensor harness.

Does the "Eng Coolant

Temp" reading change

sharply while wiggling the

harness?

Go to Step 9 Go to Step 4

4Wiggle and tug the

harness at the PCM.

Does the "Eng Coolant

Temp" reading change

sharply while wiggling the

wires at the PCM

harness?

Go to Step 10 Go to Step 5

5Lightly tap on the PCM.

Does the "Eng Coolant

Temp" reading change

sharply when tapping on

the PCM?

Go to Step 6 DTC 16 is

intermittent.

Refer to

diagnostic Aids

above.

6Make sure the PCM is

mounted securely to the

vehicle.

Was a mounting fault

found?

Verify Repair Go to Step 7

STEP ACTION VALUE YES NO

7Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for Security

Link procedure.

Is the action complete?

Verify Repair

81. Check the ECT sensor

connector.

2. Check the tension of

the female terminal

grip with a spare male

terminal.

3. Inspect the connectors

for corrosion. If the

connectors are

corroded, clean the

connectors with

electronic part cleaner

and retest.

4. If these repairs do not

resolve the problem,

replace the terminals.

Is the action complete?

Verify Repair

91. Check for broken

strands of wire in the

ECT sensor harness.

2. Check for cuts and

pinches in the ECT

sensor harness.

3. Repair as necessary.

Is the action complete?

Verify Repair

10 1. Check the ECT sensor

connection at the

PCM.

2. Check the tightness of

the female terminal

grip with a spare male

terminal.

3. Inspect the connectors

for corrosion. If the

connectors are

corroded, clean them

with electronic parts

cleaner and retest.

Is the action complete?

Verify Repair

DTC 17 - PCM ERROR - ECT CIRCUIT

CIRCUIT DESCRIPTION:

The PCM uses two different internal pull-up resistors to increase the resolution throughout the entire range of

engine operating temperatures. When the engine coolant temperature is less than 50 degrees C, the 4K ohm

resistor is used. When temperature is above 50 degrees C, the PCM switches to the 348 ohm resistor. If the pull-up

resistor does not switch, a DTC 17 will set.

DTC 17 WILL SET IF:

• The engine run time is greater than 10 seconds.

• The pull-up resistor inside the PCM switches and the ECT voltage changes less than 60 mV.

TEST DESCRIPTION:

Number(s) below refer to step(s) on the diagnostic chart

2. Whenever the PCM is replaced perform the Security Link procedure in Section 6C2-3 SERVICE

OPERATIONS.

DIAGNOSTIC AIDS:

DTC 17 is an internal fault within the PCM. Replace the PCM.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

2Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for Security

Link procedure.

Is the action complete?

Verify Repair

DTC 19 - THROTTLE POSITION (TP) SENSOR - STUCK

CIRCUIT DESCRIPTION:

The Throttle Position (TP) sensor provides a voltage signal to the PCM that changes relative to the throttle blade

angle. The PCM supplies a 5 volt reference voltage and an earth circuit to the TP sensor. The TP sensor in return

sends a voltage to the PCM based on throttle blade angle (driver demand).The TP signal voltage will vary between

0.25 and 1.25 volts at idle to greater than 4 volts at Wide Open Throttle (WOT).

DTC 19 WILL SET IF:

• The throttle position (TP) sensor angle changes less than 2% during 100ms of airflow below 300mg/cyl.

The PCM will use a default value of 35% during the time the fault is present.

DIAGNOSTIC AIDS:

The scan tool reads throttle position in volts. The TP sensor signal voltage should be between 0.25 to 1.25 volts

when the throttle is closed. The TP sensor voltage should increase at a steady rate as the throttle is opened.

The Tech 2 scan tool will also read throttle angle. 0%=closed throttle; 100%=WOT.

If the voltage is steady above the DTC 22 voltage criteria and below the DTC 21 voltage criteria, look for a short to

voltage on the TP signal circuit.

Refer to "Intermittents" in Section 6C2-2B SYMPTOMS.

DTC 19 CRITERIA TABLE (APPROXIMATE)

TPS% RPM

13 800

16 1,200

19 1,600

23 2,000

26 2,400

29 2,800

32 3,200

34 3,600

39 4,000

43 4,400

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

2Inspect the movement of

the throttle cable, the

throttle linkage, and the

throttle blade.

Are any of the

components binding or

sticking?

Go to Step 3 Go to Step 4

3Is the Throttle Position

(TP) sensor binding or

sticking during its

movement from closed

throttle too wide open

throttle and back to closed

throttle position?

Go to Step 5

4Repair or replace the

binding or the sticking

component as necessary.

Is the action complete?

Verify Repair Go to Step 5

5Replace the Throttle

Position (TP) sensor.

Is the action complete?

Verify Repair

DTC 21 - THROTTLE POSITION (TP) SENSOR - SI GNAL VOLTAGE HIGH

CIRCUIT DESCRIPTION:

The Throttle Position (TP) sensor provides a voltage signal to the PCM that changes relative to the throttle blade

angle. The PCM supplies a 5 volt reference voltage and an earth circuit to the TP sensor. The TP sensor in return

sends a voltage to the PCM based on throttle blade angle (driver demand). The TP signal voltage will vary between

0.25 and 1.25 volts at idle to greater than 4 volts at Wide Open Throttle (WOT).

DTC 21 WILL SET IF:

• The TP sensor throttle angle is greater than 4.8V for 2 seconds.

When a DTC 21 is set the PCM will default to a 35% throttle angle for engine operation.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

3. With the TP sensor disconnected, the TP sensor signal voltage should go low if the PCM and wiring are OK.

4. Probing circuit 452 with a test light connected to B+ checks the sensor’s earth circuit. A faulty TP sensor earth

circuit will set a DTC 21.

8. Whenever replacing the PCM perform the Security Link procedure found in Section 6C2-3 SERVICE

OPERATIONS.

DIAGNOSTIC AIDS:

The scan tool reads throttle position in volts. The TP sensor signal voltage should be between 0.25 to 1.25 volts

when the throttle is closed. The TP sensor voltage should increase at a steady rate as the throttle is opened.

The Tech 2 scan tool will also read throttle angle. 0%=closed throttle; 100%=WOT.

When a DTC 21 is set, the PCM does not receive the proper signal from the TP sensor. The PCM can still

determine the TP sensor value with a default value based on MAF and engine RPM. If DTC 21 is set, the

transmission will have; no TCC, high line pressure, harsh shifts and no 4th gear (if in hot mode).

Refer to "Intermittents" in Section 6C2-2B SYMPTOMS.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Install a Tech 2 scan

tool.

2. Throttle closed.

3. Ignition ON engine

OFF.

Does the Tech 2 scan

tool display Throttle

Position voltage over the

specified value?

2.5 volts Go to Step 3 If no additional

DTCs were

stored, refer to

"Intermittents" in

Section 6C2-2B

SYMPTOMS.

31. Ignition OFF.

2. Disconnect the TP

sensor electrical

connector.

Does the scan tool display

throttle position voltage

less than specified value?

0.2 volts

(200 mV) Go to Step 4 Go to Step 6

4Probe the TP sensor earth

circuit with a test light

connected to battery

voltage.

Is the test light ON?

Go to Step 5 Go to Step 7

5Check for a faulty

connection.

Was faulty connection

found?

Go to Step 9 Go to Step 10

6Check for a short to

voltage in the TP sensor

signal circuit.

Was a fault found?

Go to Step 9 Go to Step 8

7Check for an open in the

TP sensor earth circuit.

Is the TP sensor earth

circuit open?

Go to Step 9 Go to Step 8

8Replace the PCM. Refer

to Section 6C2-3 Service

Operation, for Security

Link procedure.

Is the action complete?

Verify Repair

9Repair the faulty

connection or the faulty

circuit.

Is the action complete?

Verify Repair

10 Replace the Throttle

Position Sensor.

Is the action complete?

Verify Repair

DTC 22 - THROTTLE POSITION (TP) SENSOR - SI GNAL VOLTAGE LOW

CIRCUIT DESCRIPTION:

The Throttle Position (TP) sensor provides a voltage signal to the PCM that changes relative to the throttle blade

angle. The PCM supplies a 5 volt reference and an earth circuit to the TP sensor. The TP sensor in return sends a

voltage to the PCM based on throttle blade angle(driver demand).The TP signal voltage will vary between 0.25 and

1.25 volts at idle to greater than 4 volts at Wide Open Throttle (WOT).

DTC 22 WILL SET IF:

• The TP sensor angle is less than 120 mV for 2 seconds.

The PCM will use a default value of 35% for the TP sensor whenever a DTC 22 sets.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

3. This test simulates a Diagnostic Trouble Code 21 (high voltage). If the PCM recognises the high signal voltage

and the Scan tool reads over 4 volts, then the PCM and wiring are OK.

4. This simulates a high signal voltage to check for an open in circuit 417. The Tech 2 Scan tool will not read 12

volts, but what is important is that the PCM recognises the signal.

8. Whenever replacing the PCM perform the Security Link procedure found in Section 6C2-3 SERVICE

OPERATIONS.

DIAGNOSTIC AIDS:

A Tech 2 scan tool reads throttle position in volts. With the ignition ON or at an idle, the TP sensor voltage should

read between 0.25 and 1.25 volts with the throttle closed. The voltage should increase at a steady rate as the

throttle is moved toward Wide Open Throttle (WOT).

The Tech 2 Scan tool will read throttle angle. 0%=closed throttle; 100%=WOT.

When a DTC 22 is set, the PCM does not receive the proper signal from the TP sensor. The PCM can still

determine the TP sensor value with a default value based on MAF and engine RPM. If DTC 22 is set, the

transmission will have no TCC high line pressure, harsh shifts and no 4th gear (if in hot mode).

Refer to "Intermittents" in Section 6C2-2B SYMPTOMS.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Install a Tech 2 scan

tool.

2. Throttle closed.

3. Ignition ON engine

OFF.

Does the Tech 2 scan tool

display TP sensor voltage

below the specified value?

0.12 volt

(120 mV) Go to Step 3 DTC 22 is

intermittent. If no

additional DTCs

were stored, refer

to "Intermittents"

in Section 6C2-

2B SYMPTOMS.

31. Ignition OFF.

2. Disconnect the TP

sensor electrical

connector.

3. Jumper circuits 416

and 417 together.

4. Ignition ON engine

OFF.

Does the scan tool display

throttle position voltage

greater than the specified

value?

4.0 volts

(4000

mV)

Go to Step 7 Go to Step 4

41. Ignition OFF.

2. Remove the jumper

wire.

3. Probe the TP sensor

signal circuit with a test

light connected to B+.

4. Ignition ON engine

OFF.

Does the scan tool display

TP sensor voltage greater

than the specified value?

4.0 volts

(4000

mV)

Go to Step 5 Go to Step 6

5Check for an open or a

short in the TP sensor’s

5V reference circuit or a

faulty connection.

Was a fault found?

Go to Step 9 Go to Step 8

6Check for an open or a

short in the TP sensor

signal circuit or a faulty

connection.

Was a short, open or

faulty connection found?

Go to Step 9 Go to Step 8

7Replace the Throttle

Position Sensor.

Is the action complete?

Verify Repair

8Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for Security

Link procedure.

Is the action complete?

Verify Repair

9Repair the fault in the

circuit or the connection.

Is the action complete?

Verify Repair

DTC 23 - INTAKE AIR TEM PERATURE (IAT)

SENSOR - SIGNAL VOLTAGE HIGH

CIRCUIT DESCRIPTION:

The Intake Air Temperature (IAT) sensor is a thermistor used to control the signal voltage to the PCM. The PCM

supplies a 5 volt reference voltage and a earth circuit to the IAT sensor. The IAT sensor in turn will send a signal

voltage back to the PCM based on intake air temperature. When the intake air is cold, the IAT sensor output voltage

and resistance will be high. If the intake air is warm, the IAT sensor output voltage and resistance will be low.

DTC 23 WILL SET IF:

• The IAT sensor signal voltage is greater than 4.9 volts,(indicating an intake air temperature below -38 degrees

C) for one second.

The PCM will use a default value of 25°C during the time the fault is present.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

3. A Diagnostic Trouble Code 23 will set, due to an open sensor, wire or connection. This test will determine if the

wiring and the PCM are OK.

6. This will determine if the IAT sensor signal circuit or the IAT sensor earth circuit is open.

11. Whenever replacing the PCM perform the Security Link procedure found in Section 6C2-3 SERVICE

OPERATIONS.

DIAGNOSTIC AIDS

A Tech 2 scan tool indicates the temperature of the air in the intake. When the PCM detects a fault in the IAT

sensor circuit, a default value of 46 degrees C will be used by the PCM.

Carefully check the harness and the connections for possible open circuit 472 or circuit 469.

An open circuit 469 will set DTC 23 and DTC 33, if the engine has been allowed to sit overnight, then the intake air

temperature and engine coolant temperature values should be within a few degrees of each other. After the engine

is started, the IAT sensor will increase due to engine compartment temperatures.

Refer to "Intermittents" in Section 6C2-2B SYMPTOMS.

IAT SENSOR TABLE TEMPERATURE VS RESISTANCE VALUES (APPROXIMATE)

°C OHMS

100 185

70 450

38 1,800

20 3,400

4 7,500

-7 13,500

-18 25,500

-40 100,700

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Install a Tech 2 scan

tool.

2. Ignition ON engine

OFF.

3. Monitor the IAT sensor

temperature.

Does the scan tool display

the IAT sensor

temperature at or between

the specified value?

-35°C to

-40°C Go to Step 3 If no additional

DTCs were

stored, refer to

"Intermittents" in

Section 6C2-2B

SYMPTOMS.

31. Ignition OFF.

2. Disconnect the IAT

sensor electrical

connector.

3. Jumper the harness

terminals together

(PCM side).

4. Ignition ON engine

OFF.

Does the Scan tool

display the IAT sensor

temperature greater than

the specified value?

130°C Go to Step 4 Go to Step 6

4Measure the resistance

across the IAT sensor

terminals.

Is the value within the

specified range?

See IAT

table

above

Go to Step 5 Go to Step 10

5Check for an intermittent

or a loose terminal in the

IAT sensor harness

connector.

Is a problem found?

Go to Step 12 Go to Step 9

61. Ignition OFF engine

ON.

2. Jumper the IAT sensor

5V reference/signal

circuit to earth.

3. Ignition ON engine

OFF.

Is the IAT sensor

temperature greater than

the specified value?

130°C Go to Step 7 Go to Step 8

STEP ACTION VALUE YES NO

7Check for an open in the

IAT sensor earth circuit or

for faulty connection.

Was an open or faulty

connection found?

Go to Step 12 Go to Step 11

8Check for an open in the

IAT sensor circuit 5V

reference/signal circuit or

for a faulty connection.

Wan an open or faulty

connection found?

Go to Step 12 Go to Step 11

91. Remove the jumper

from the IAT sensor

harness.

2. Ignition OFF.

3. Disconnect the PCM

connectors.

4. Ignition ON engine

OFF.

5. Check for short to

voltage in the IAT

sensor 5V

reference/signal circuit.

Was a fault found?

Go to Step 12 Go to Step 11

10 Replace the intake air

temperature sensor.

Is the action complete?

Verify Repair

11 Replace the PCM. Refer

to Section 6c2-3 Service

Operations, for the

Security Link procedure.

Is the action complete?

Verify Repair

12 Repair the faulty circuit or

the faulty connection.

Is the action complete?

Verify Repair

DTC 24 - NO VEHICLE SPEED SENSOR SIGNAL

CIRCUIT DESCRIPTION:

The Vehicle Speed Sensor (VSS) Assembly provides vehicle speed information to the PCM. The VSS Assembly is

a Permanent Magnet (PM) generator. The PM generator produces a pulsing AC voltage. The AC voltage level and

the number of pulses increase with the speed of the vehicle. The PCM then converts the pulsing voltage to vehicle

speed. The PCM uses this information for calculations. A scan tool can display the vehicle speed.

When the PCM detects a low or no vehicle speed, when there is high engine speed in a drive range and a low

throttle position voltage, then a DTC 24 sets.

DTC 24 WILL SET IF:

• One of the following DTC's are set. DTC 19, 21, 22, or DTC 32.

• Circuit 123 voltage is constant - that is, NOT pulsing.

• The engine RPM is between 1400 and 3000 RPM.

• The throttle position sensor angle is less than 1%.

• The engine load is low (MAF sensor) 95 mg/cyl.

DTC 24 will set if the VSS circuit is open from a standing stop. As the vehicle is accelerated the transmission will

shift from 1st to 2nd gear at approximately 54 km/h. If a VSS signal is not present, a DTC 24 will set.

TEST DESCRIPTION:

The numbers below refer to the step numbers on the diagnostic chart.

3. This tests the integrity of the VSS Assembly.

4. This tests the VSS Assembly circuit.

DIAGNOSTIC AIDS:

• Inspect the wiring for poor electrical connections at the PCM. Look for the following conditions:

A bent terminal

A backed out terminal

Poor terminal tension

A chafed wire

A broken wire inside the insulation

Moisture intrusion

Corrosion

• When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test

equipment for a change.

• Check circuits 831 and 832 for the proper connections to be sure they are clean and tight and the harness is

routed correctly.

• The scan tool should indicate vehicle speed whenever the drive wheels are turning greater than 3 km/h.

• The vehicle speed sensor resistance should be between 1470-2140 Ohms at 20°C, and 2270-2820 Ohms at

100° C.

• Refer to 'intermittents' in Section 6C2-2B SYMPTOMS.

When a DTC 24 sets, the PCM will command second gear only, commands maximum line pressure, freeze shift

adapts from being updated and inhibit TCC engagement.

STEP ACTION VALUE YES NO

1Was the On-Board

Diagnostic (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check.

21. Install the scan tool.

2. With the engine OFF,

turn the ignition switch

to the RUN position.

IMPORTANT:

Before clearing the DTCs,

use the scan tool in order

to record the DTC history

for reference. The Clear

Info function will erase the

data.

3. Record the DTC

history.

4. Clear the DTC.

5. Raise the drive wheels.

NOTE:

Do not perform this test

without supporting the

rear axle assembly or the

lower control arms on

vehicles with independent

rear suspension so that

the drive shafts are in a

normal horizontal position.

6. Start the engine.

7. Place the transmission

in any drive gear.

With the rear wheels

rotating, does the scan

tool Vehicle Speed

increase with the drive

wheel speed?

Go to “Diagnostic

Aids” above Go to Step 3

31. Turn the ignition switch

to the OFF position.

2. Disconnect the VSS

connector from the

VSS assembly.

3. Using the J 35616

Connector Test

Adapter Kit, connect

the J 39200 DVM to

the VSS terminals.

4. Select AC volts.

5. Place the transmission

selector in the neutral

position.

6. Rotate the drive

wheels by hand,

ensuring that the

driveshaft is turning.

With rear wheels rotating,

is the DVM voltage

greater than the specified

value?

0.5 volts

AC Go to Step 4 Go to Step 11

STEP ACTION VALUE YES NO

41. Turn the ignition switch

to the OFF position.

2. Reconnect the VSS

connector to the VSS

Assembly.

3. Disconnect the PCM

connector 1 (Pink-32

pin) from the PCM.

4. Connect the DVM test

leads to the connector

terminals D5 (T) and

C6 (Blu/W).

5. Place the transmission

selector in the neutral

position.

6. Rotate the drive

wheels by hand,

ensuring that the

driveshaft is turning.

With rear wheels rotating,

is the DVM voltage

greater than the specified

value?

0.5 volts

AC Go to Step 13 Go to Step 5

51. Select W (Ohms), on

the DVM.

2. Measure the

resistance between the

connector terminals D5

(T) and C6 (Blu/W).

Is the circuit resistance

within the specified

range?

1470-

2820 ohm Go to Step 6 Go to Step 8

6Connect the DVM

between the connector

terminal C6 and earth.

Is the circuit resistance

less than the specified

value?

250k ohm Go to Step 7 Go to Diagnostic

Aids above

71. Check circuit 831 and

circuit 832 for a short

to earth.

2. Repair the circuit if

necessary.

Was the short to earth

condition found and

corrected?

Go to Step 14 Go to Diagnostic

Aids above

8Is the resistance reading

in step 6 greater than the

specified value?

2820 ohm Go to Step 10 Go to Step 9

91. Check circuit 831 and

circuit 832 for a

shorted together

condition.

2. Repair the circuit if

necessary.

Was a shorted together

condition found and

corrected ?

Go to Step 14 Go to Diagnostic

Aids above

STEP ACTION VALUE YES NO

10 1. Check circuit 831 and

circuit 832 for an open

condition.

2. Repair the circuit if

necessary.

Was an open condition

found and corrected ?

Go to Step 14 Go to Diagnostic

Aids above

11 1. Remove the VSS

Assembly.

2. Inspect the VSS

Output Sensor Rotor

for damage or

misalignment.

Did you find a condition?

Refer to

Section 7B-2

MANUAL

TRANSMISSION

- V8 or

Section 7C-4

AUTOMATIC

TRANSMISSION

Go to Step 12

12 Replace the VSS

Assembly. Refer to

Service Operations.

Is the action complete?

Go to Step 14

13 Replace the PCM. Refer

to Section 6C2-3 Service

Operations. For the

Security Link procedure

Is the action complete?

Go to Step 14

14 In order to verify your

repair, perform the

following procedure:

1. Select DTC.

2. Select Clear Info.

3. Operate the vehicle

ensuring that the

vehicle speed is

greater than 10 km/h

and observe the scan

tool Vehicle Speed.

Is the scan tool Vehicle

Speed greater than the

specified value?

10 km/h System OK Begin the

Diagnosis Again

Go to Step 1

DTC 25 - INTAKE AIR TEM PERATURE (IAT) SENSOR - SIGNAL VOLTAGE

LOW

CIRCUIT DESCRIPTION:

The Intake Air Temperature (IAT) sensor is a thermistor that is used to control the signal voltage to the PCM. The

PCM supplies a 5 volt reference voltage and a earth circuit to the IAT sensor. The IAT sensor in turn will send a

signal voltage back to the PCM based on intake air temperature. When the intake air is cold, the IAT sensor output

voltage and resistance will be high, therefore, the PCM will sense a high signal voltage. If the intake air is warm, the

IAT sensor output voltage and resistance will be low, therefore, the PCM will sense a low signal voltage.

DTC 25 WILL SET IF:

• The engine run time is greater than 60 seconds.

• The Intake Air Temperature (IAT) signal voltage is less than 0.1 volts, for one second.

• The PCM will use a default value of 25°C for IAT during the time the fault is present.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. This will verify the if the DTC still is present.

3. The range should be between -30 degrees C and - 40 degrees C if the fault condition exists.

4. The values listed are approximates and should be close.

8. Whenever replacing the PCM perform the Security Link procedure found in Section 6C2-3 SERVICE

OPERATIONS.

DIAGNOSTIC AIDS:

The Intake Air Temperature (IAT) on a Tech 2 scan tool indicates the temperature of the air entering into the

engine. If the engine has been allowed to sit overnight, the IAT sensor and engine coolant temperature sensor

values should be within a few degrees of each other. After the engine is started, the IAT will increase due to engine

compartment temperatures, however, the IAT sensor will rarely exceed 80 degrees C.

When the PCM detects a fault in the IAT circuit, a default value of 25° C will be used.

Check harness routing for possible short to earth in circuit 469.

Refer to "Intermittents" in Section 6C2-2B SYMPTOMS.

IAT SENSOR TABLE TEMPERATURE VS RESISTANCE VALUES (APPROXIMATE)

deg. C OHMS

100 185

70 450

38 1,800

20 3,400

4 7,500

-7 13,500

-18 25,500

-40 100,700

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Install a Tech 2 scan

tool.

2. Ignition ON engine

OFF.

Does the scan tool display

IAT sensor temperature

greater than the specified

temperature?

134°C Go to Step 3 DTC 25 is

intermittent. If no

additional DTCs

were stored, refer

to "Diagnostic

Aids" above

31. Ignition OFF.

2. Disconnect the IAT

sensor electrical

connector.

3. Ignition ON engine

OFF.

Does the scan tool

display IAT sensor

temperature below the

specified value?

-30°C to

-40°C Go to Step 4 Go to Step 6

41. Ignition OFF.

2. Measure the

resistance across the

IAT sensor terminals.

Does the value

correspond to the

specified value?

See IAT

table

above

Go to Step 5 Go to Step 7

5Check for a loose terminal

in the harness connector,

or terminals being shorted

together.

Was a problem found?

Go to Step 9 Go to Step 8

STEP ACTION VALUE YES NO

6Check for a short in the

IAT sensor 5V reference/

signal circuit.

Was a problem found?

Go to Step 9 Go to Step 8

7Replace the IAT sensor.

Is the action complete? Verify Repair

8Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for the

Security Link procedure.

Is the action complete?

Verify Repair

9Repair the circuit as

necessary.

Is the action complete?

Verify Repair

DTC 26 - INTAKE AIR TEM PERATURE (IAT) SENSOR - SIGNAL VOLTAGE

UNSTABLE

CIRCUIT DESCRIPTION:

The Intake Air Temperature (IAT) sensor is a thermistor used to control the signal voltage to the PCM. The PCM

supplies a 5 volt reference voltage and a earth circuit to the IAT sensor. The IAT sensor in turn will send a signal

voltage back to the PCM based on intake air temperature. When the intake air is cold, the IAT sensor output voltage

and resistance will be high. If the intake air is warm, the IAT sensor output voltage and resistance will be low .

DTC 26 WILL SET IF:

• The IAT sensor reading changes more than .14V (140 mV) in 100 milliseconds.

• The engine run time is greater than 10 seconds.

The PCM will use a default value of 25°C for IAT during the time the fault is present.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. By gently moving the wires while watching the Tech 2 for a voltage change can help identify the location of the

problem.

7. Whenever replacing the PCM perform the Security Link procedure found in Section 6C2-3 SERVICE

OPERATIONS.

DIAGNOSTIC AIDS:

When attempting to diagnose an intermittent problem, use the snapshot mode on the Tech 2 "Scan" tool to review

the diagnostic information.

IAT SENSOR TABLE TEMP. TO RESISTANCE VALUES (APPROXIMATE)

COHMS

100 185

70 450

38 1,800

20 3,400

4 7,500

-7 13,500

-18 25,500

-40 100,700

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Install a Scan tool.

2. Ignition ON, engine

OFF.

3. Monitor the Tech 2

Scan tool while

wiggling the IAT

sensor connector.

Does the IAT sensor

reading change sharply?

Go to Step 8 Go to Step 3

3Wiggle and tug the IAT

sensor harness.

Does the IAT sensor

reading change sharply?

Go to Step 9 Go to Step 4

4Wiggle and tug the

harness at the PCM.

Does the IAT sensor

value change sharply?

Go to Step 10 Go to Step 5

5Lightly tap on the PCM.

Does the IAT sensor

value change sharply?

Go to Step 6 DTC 26 is

intermittent.

Refer Diagnostic

Aids above.

6Check that the PCM is

mounted securely to the

vehicle.

Was a mounting fault

found?

Verify Repair Go to Step 7

7Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for the

Security Link procedure.

Is the action complete?

Verify Repair

STEP ACTION VALUE YES NO

81. Inspect the IAT sensor

connector.

2. Check the tension of

the female terminal

with a spare male

terminal.

3. Inspect connectors for

corrosion. If the

connectors are

corroded clean them

with electronic part

cleaner and retest.

4. If these repairs do not

resolve the problem,

replace the terminals.

Is the action complete?

Verify Repair

91. Check for an open in

the IAT harness.

2. Check for broken

strands of wire in the

IAT sensor harness.

3. Check for cuts or

pinches in the IAT

sensor harness.

4. Make any repairs as

necessary.

Is the action complete?

Verify Repairs

10 1. Check the IAT sensor

connection at the

PCM.

2. Check the tension of

the female terminal

grip with a spare male

terminal.

3. Inspect the connectors

for corrosion. If

connectors are

corroded, try cleaning

with them electronic

parts cleaner and

retest.

Is the action complete?

Verify Repairs

DTC 28 - TRANSMISSION FLUID PRESSURE (TFP)

MANUAL VALVE POSITION SWITCH ASSEMBLY CIRCUIT

CIRCUIT DESCRIPTION:

The Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Valve Position Switch) consists of

five pressure switches (two normally-closed and three normally-open) and a Transmission Fluid Temperature (TFT)

sensor combined into one unit. The combined unit mounts on the valve body. The PCM supplies the battery voltage

for each range signal. By earthing one or more of the circuits through various combinations of the pressure

switches, the PCM detects which manual valve position you select. The PCM compares the actual voltage

combination of the switches to a TFP Valve Position Switch combination chart stored in memory. The TFP Valve

Position Switch. cannot distinguish between Park and Neutral because the monitored valve body pressures are

identical. With the engine OFF and the ignition switch in the RUN position, the TFP Valve Position Switch indicates

Park/Neutral. Disconnecting the transmission pass-through connector removes the earthing potential for the three

range signals to the PCM. In this case, with the engine OFF, and the ignition switch in the RUN position, D2 will be

indicated.

When the PCM detects an invalid state of the TFP Valve Position Switch or the TFP Valve Position Switch circuit by

deciphering the TFP Valve Position Switch inputs, then DTC 28 set.

DTC 28 WILL SET IF:

DTC 28 sets when the PCM detects an illegal switch combination for 6 seconds.

TEST DESCRIPTION:

The numbers below refer to the step numbers on the diagnostic chart.

3. This step compares the indicated range signal to the manual valve position that is actually selected.

4. This step tests for correct voltage from the PCM to the transmission pass-through connector terminals.

DIAGNOSTIC AIDS:

Refer to the TFP Valve Position Switch Logic Table for the normal range signals and the illegal combination signals.

Inspect the wiring for poor electrical connections at the PCM. Inspect the wiring for poor electrical connections at the

transmission pass-through connector. Look for the following conditions.

• A bent terminal

• A backed out terminal

• Poor terminal tension

• A chafed wire

• A broken wire inside the insulation

• Moisture intrusion

When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test

equipment for a change.

Refer to Automatic Transmission Fluid Pressure Manual Valve Position Switch Resistance Check or

Functional Test Procedure for further information.

TFP VALVE POSITION SWITCH LOGIC

Gear

Position Range

Signal A Range

Signal B Range

Signal C

-P-OPEN 12V CLOSED

0V OPEN 12V

-R-CLOSED

0V CLOSED

0V OPEN 12V

-N-OPEN 12V CLOSED

0V OPEN 12V

-D-OPEN 12V CLOSED

0V CLOSED

-3-OPEN 12V OPEN 12V CLOSED

-2-OPEN 12V OPEN 12V OPEN 12V

-1-CLOSED

0V OPEN 12V OPEN 12V

Illegal CLOSED

0V OPEN 12V CLOSED

Illegal CLOSED

0V CLOSED

When DTC 28 is set, the PCM will inhibit TCC engagement, command D2 line pressure, and freeze shift adapts

from being updated

STEP ACTION VALUE YES NO

1Was the On-Board

Diagnostic (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check

2Perform the following

inspections.

Ensure that the

transmission linkage from

the select lever to the

manual valve is adjusted

properly.

Perform the fluid checking

procedure/inspection.

Did you perform the

inspections?

Go to Step 3 Perform the

Inspections

31. Install the scan tool.

2. With the engine OFF,

turn the ignition switch

to the RUN position.

IMPORTANT:

Before clearing the DTCs,

use the scan tool in order

to record the DTC history

for reference. The Clear

Info function will erase the

data.

3. Record the DTC

history.

4. While the engine is

idling at normal

operating temperature,

apply the parking

brake.

5. Select each

transmission range: P,

R, N, D, 3, 2, and 1.

Does each selected

transmission range match

the scan tool TFP Switch

A/B/C display?

Refer to the TFP Valve.

Position Switch. Logic

Table.

Go to “Diagnostic

Aids” above Go to Step 4

STEP ACTION VALUE YES NO

4Turn the ignition OFF.

Disconnect the

transmission pass-

through connector

(additional DTCs may

set).

Install the J 39775 Jumper

Harness on the engine

side of the transmission

pass-through connector.

With the engine OFF, turn

the ignition switch to the

RUN position.

Using the J 39200 DVM

and J 35616 Connector

Test Adapter Kit, check

for voltage at connector

terminals N, R, and P.

Is B+ displayed on all

three circuits?

Go to Step 6 Go to Step 5

5Check the circuits that did

not indicate B+ for an

open or a short to earth.

Repair the circuits if

necessary.

Did you find and correct

the problem?

Go to Step 13 Go to Step 7

6In order to verify that

circuit 1224, circuit 1225,

and circuit 1226 are not

shorted together, use a

fused jumper to earth, on

each circuit while

monitoring the scan tool

TFP Switch A/B/C display.

When a range signal

circuit is earthed, are any

other range signal circuits

affected?

Go to Step 8 Go to Step 9

7Replace the PCM.

Refer to Section 6C2-3

Service Operations, for

the Security Link

procedure.

Is the action complete?

Go to Step 13

8Repair the affected wiring

as necessary.

Is the action complete?

Go to Step 13

STEP ACTION VALUE YES NO

91. Turn the ignition switch

to the OFF position.

2. Reconnect the pass-

through connector.

3. Select the PARK

position.

4. Start the engine.

5. Apply the brakes.

6. Move the shift selector

through all gear

ranges, while

observing the A and

the C range signals on

the scan tool.

Does either range signal

always indicate 0

volts/ON?

Go to Step 10 Intermittent

Problem Go to

“Diagnostic Aids”

above

10 1. Turn the ignition switch

to the OFF position.

2. Disconnect the

transmission pass-

through connector.

3. Remove the

transmission pan.

4. Remove the internal

wiring harness

connector from the

TFP Valve Position

Switch.

5. Check the internal

wiring harness circuits

1224 and 1226 for a

short to earth.

Did you find a short to

earth condition on either

circuit?

Go to Step 12 Go to Step 11

11 Replace the TFP Valve

Position Switch. Refer to

Section 6C2-3 Service

Operations.

Is the action complete?

Go to Step 13

12 Replace the internal A/T

Wiring Harness

Assembly. Refer to

Service Operations in

Section 7C-5

AUTOMATIC

TRANSMISSION.

Is the replacement

complete?

Go to Step 13

STEP ACTION VALUE YES NO

13 In order to verify your

repair, perform the

following procedure:

1. Select DTC.

2. Select Clear Info.

3. Operate the vehicle

under the following

conditions:

• With the engine OFF,

turn the ignition switch

to the RUN position for

at least 2 seconds.

• Start the vehicle and

idle for 5 seconds.

• Select each

transmission range: P,

R, N, D4, D3, D2 and

D1.

• Compare the scan tool

TFP Switch A/B/C/

display, to the TFP

Valve Position Switch

Logic Table.

Does each shifter position

range signal match the

scan tool TFP Switch

A/B/C display?

System OK Begin the

diagnosis again.

Go to Step 1

DTC 31 - THEFT DETERRENT SIGNAL MISSING

CIRCUIT DESCRIPTION:

When the ignition is turned ON, the PCM will send a message over the Fuel Enable Input circuit to the BCM. When

the BCM receives this message, it instantly enables the starter and sends a message back to the PCM. The

message says that the proper ignition key has been used and that it is OK for the PCM to enable the fuel injectors

to start the vehicle. If the BCM does not receive communications from the PCM when the ignition is switched ON,

the starter motor will enable after a one second delay.

DTC 31 WILL SET IF:

The PCM sends 10 messages to the BCM and does not receive a message saying it is OK to start.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. If the engine cranks after a one second delay it means the BCM did not see a message from the PCM when

the ignition was turned ON.

3. An open or short to earth on circuit 1221 will disable any serial data communication.

5. Whenever replacing the PCM perform the Security Link procedure found in Section 6C2-3 SERVICE

OPERATIONS.

DIAGNOSTIC AIDS:

Check for any damage to the harness which could cause an intermittent open or short to earth or backed out

terminals at the PCM connectors, broken locks, improperly formed or damaged terminals.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this section

2Attempt to start the

vehicle.

Does the engine crank

after a one second delay

when the ignition is turned

ON?

Go to Step 3 DTC 31 is

intermittent.

Refer "Diagnostic

Aids" above

3Ignition ON engine OFF.

Is the voltage between

DLC terminal "9" and

earth between the

specified value?

4 - 6

volts Refer to Section

12F THEFT

DETERRENT

SYSTEM for

further diagnosis

Go to Step 4

41. Check for an open, a

short or a poor

connection at the PCM

terminal in the fuel

enable circuit 1221.

2. Repair as necessary.

Was a problem found?

Verify Repair Go to Step 5

5Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for the

Security Link procedure.

Is the action complete?

Verify Repair

DTC 32 - MASS AIR FLOW (MAF) SENSOR OUT OF RANGE

CIRCUIT DESCRIPTION:

The Mass Air Flow (MAF) sensor measures the flow of air which passes through in a given time. The PCM uses

this information to monitor the operating condition of the engine for fuel delivery calculations. A large quantity of air

movement indicates acceleration, while a small quantity indicates deceleration or idle. The MAF sensor produces a

frequency signal which cannot be easily measured. The MAF sensor can be diagnosed using the procedures on this

chart. With DTC 32 set, the PCM will use a default value for air flow based on throttle position, and engine speed

and some vehicle performance will return. When DTC 32 is set the MIL "Check Powertrain Lamp" will be

illuminated.

DTC 32 WILL SET IF:

• The engine is running.

• No MAF signal for over two seconds.

TEST DESCRIPTION:

Number(s) below refer to step(s) on the diagnostic chart.

5. Verifies that both ignition feed voltage and a good earth circuit are available.

6. The normal reading at idle should be between 5-10 grams per second.

7. A voltage reading at sensor harness connector terminal "A" of less than 4 or over 6 volts indicates a fault in

circuit 792 or poor connection.

13. Perform the Security Link procedure whenever replacing the PCM. Refer to Section 6C2-3 SERVICE

OPERATIONS for linking procedure.

DIAGNOSTIC AIDS:

An intermittent may be caused by a poor connection, a mis-routed harness, a rubbed through wire insulation, or a

wire broken inside the insulation.

Check the following conditions:

• A Poor Connection at PCM Pin - Inspect harness connectors for backed out terminals, improper mating, broken

locks, improperly formed or damaged terminals, and poor terminal to wire connection.

• A Mis-Routed Harness - Inspect MAF sensor harness to ensure that it is not too close to high voltage wires,

such as spark plug leads.

• A Damaged Harness - Inspect the harness for damage. If the harness is OK, observe the Tech 2 scan tool while

moving the related connectors and wiring harness. A change in the display would indicate the intermittent fault

location.

• A Plugged Air Filter - A wide open throttle acceleration from a stop should cause the MAF reading on the Tech 2

scan tool to range from about 5-10 g/s at idle to 100 or greater at the time of the 1-2 shift on an automatic

transmission. If not, check for restriction.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2. Go to OBD

System Check in

this Section.

21. Ignition ON.

2. Using Tech 2 scan

tool, select MAF

frequency.

Is the "MAF frequency"

reading at the specified

value ?

0 Hz Go to Step 4 Go to Step 3

3Replace the MAF sensor.

Is action complete ? Verify Repair

41. Ignition OFF.

2. Disconnect the MAF

sensor.

3. Ignition ON.

4. Connect a test light to

earth, and probe the

MAF sensor harness

connector terminal "C".

Is the test light ON?

Go to Step 5 Go to Step 11

51. Ignition OFF.

2. Disconnect the MAF

sensor.

3. Ignition ON.

4. Measure the voltage

between MAF sensor

harness connector

terminals "B" and "C" .

Is the voltage greater then

the specified value?

10 volts Go to Step 7 Go to Step 10

61. Ignition OFF.

2. Reconnect the MAF

sensor.

3. Ignition ON engine

idling.

Is the MAF sensor "MASS

AIR FLOW" reading

between specified value?

5 - 10

grams/

sec

DTC 32 is

intermittent. If no

additional DTC's

were stored, refer

to "Diagnostic

Aids" above.

Go to Step 3

STEP ACTION VALUE YES NO

71. Ignition OFF.

2. Disconnect the wiring

harness connector

from the MAF sensor.

3. Ignition ON.

4. Measure the voltage at

MAF sensor harness

connector terminal "A"

with a voltmeter to

earth.

Is the measured voltage

between the specified

values?

4 - 6

Volts Go to Step 6 Go to Step 8

8Is the voltage on MAF

sensor harness connector

terminal "A" less than

specified value?

4 volts Go to Step 9 Go to Step 12

9Check for an open or

short to earth on circuit

792.

Was a problem found?

Verify Repair Go to Step 13

10 Repair the open in circuit

750.

Is the action complete?

Verify Repair

11 Repair the open or the

short to earth in circuit

439.

Replace the fuse F33 if

open.

Is the action complete?

Verify Repair

12 Repair the short to voltage

on circuit 792.

Is the action complete?

Verify Repair

13 Replace the PCM.

Refer to Section 6C2-3

Service Operations, for

PCM Security Link

procedure.

Is the action complete?

Verify Repair

DTC 35 - IDLE SPEED ERROR

CIRCUIT DESCRIPTION:

The IAC valve is a stepper motor. Stepper motors have coils that the PCM turns ON and OFF several times per

second. This allows for an incremental clockwise and counter clockwise rotation of a pintle valve. The pintle valve

has a threaded shaft that either extends or retracts with each pulse of the PCM. The controlled pulses are called

steps or counts. The PCM controls the air entering into the engine at idle through the IAC valve. To increase the

idle speed, the PCM will command the pintle valve away from the throttle body. This allows more air to bypass the

throttle blade and thus increase engine RPM. To decrease the engine RPM at idle, the PCM will command the

pintle valve toward the throttle body seat to restrict air from entering into the engine and thus reduce engine RPM.

DTC 35 WILL SET IF:

• One or more of the following DTC's are not set. DTC 19, 21, 22, 23, 25, 26, 35, 36, 72, 94.

• The IAT sensor reading is less than 73°C.

• The engine idle speed varies more than ± 75 RPM from desired idle speed for greater than 5 seconds.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. The Tech 2 Scan tool RPM control mode is used to extend and retract the IAC valve. The valve should move

smoothly within the specified range. If the idle speed is commanded (IAC extended) too low (below 600 RPM),

the engine may stall. This may be normal and would not indicate a problem. Retracting the IAC beyond its

controlled range (above 1675 RPM) will cause a delay before the RPM's start dropping, this too is normal.

8. The test lights each should flash, to indicated a good circuit. While the sequence is not important, if either light

is OFF or does not flash, check the circuits for faults, beginning with poor terminal contacts.

14. The engine is idling at less than 75 RPM from desired idle speed for greater than 5 seconds.

DIAGNOSTIC AIDS:

A slow, unstable, or fast idle may be caused by a non-IAC system problem that cannot be compensated by the IAC

valve. Out of control range IAC Tech 2 "Scan" tool 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:

• Vacuum Leak (High Idle).

• If the idle speed is above 800 RPM, locate and correct the vacuum leak. Including the PCV system. Also, check

for binding of the throttle blade or linkage.

• System too lean (High Air/Fuel Ratio).

• The idle speed may be too high or too low. Engine speed may be too high or too low. Engine speed may vary up

and down and disconnecting the IAC valve does not help. DTC 44 may be set. Tech 2 Scan tool O2 voltage will

be less than 300 mV. Check for low regulated fuel pressure, water in the fuel or a restricted injector.

• System too rich (Low Air/Fuel Ratio).

• The idle speed will be too low. The Tech 2 "Scan" tool IAC counts will usually be above 80. The system is

obviously rich and may exhibit black smoke in the exhaust. The Tech 2 "Scan" tool O2 voltage will be fixed

above 800 mV. Check for high fuel pressure, a leaking or a sticking fuel injector. A silicon contaminated O2

sensor voltage will be slow to respond.

• Throttle Body.

• Remove the IAC valve and inspect the bore for foreign material.

• IAC valve Electrical Connections.

• The IAC valve connections should be carefully checked for proper contact tension.

• PCV Valve.

• An incorrect or faulty PCV valve may result in an incorrect idle speed.

• Refer to "Rough, Unstable, Incorrect Idle or Stalling" in Section 6C2-2B SYMPTOMS

• If the intermittent poor driveability or the idle symptoms are resolved by disconnecting the IAC valve, carefully

recheck the connections, the IAC valve terminal resistance, or replace the IAC valve.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check in

this Section

21. Install a Tech 2 scan

tool.

2. Start the engine and

allow the engine to idle

until the specified

temperature is

reached.

3. Transmission in park

or neutral.

4. Set the park brake.

5. Turn the A/C OFF.

6. Use the Tech 2 scan

tool to cycle the IAC

valve from 600 RPM to

1675 RPM.

Does the engine speed

change smoothly when

commanded?

80°C Go to Step 3 Go to Step 5

31. Ignition OFF.

2. Disconnect the IAC

valve electrical

connector.

3. Measure the

resistance across the

IAC valve terminals A

and B.

4. Measure the

resistance across the

IAC valve terminals C

and D.

Are the resistance

readings across terminals

A and B, and terminals C

and D between the

specified values?

40-80

ohms Go to Step 4 Go to Step 13

41. Measure the

resistance across the

IAC valve terminals B

and C.

2. Measure the

resistance across the

IAC valve terminals A

and D.

Are the resistance

readings across terminals

B and C, and terminals A

and D within the specified

values?

Infinite IAC valve control

circuits are OK.

Refer to

Diagnostic Aids

above.

Go to Step 13

STEP ACTION VALUE YES NO

51. Disconnect the IAC

valve electrical

connector

2. Ignition ON engine

OFF.

3. With a test light

connected to earth,.

Probe the IAC valve

electrical connectors.

Does the test light

illuminate on two

terminals?

Go to Step 6 Go to Step 7

6With a test light

connected to B+, probe

the IAC valve electrical

connector terminals.

Does the test light

illuminate on two

terminals?

Go to Step 8 Go to Step 7

7Check for an open or a

short in the IAC valve HI

and Lo circuits.

Was a problem found?

Go to Step 12 Go to Step 14

81. Start the engine and

allow to idle.

2. With a test light

connected to earth,

probe the IAC valve

electrical terminals?

Does the test light flash

ON and OFF on all the

terminals?

Go to Step 10 Go to Step 9

9Did the test light remain

ON steady for the

terminals

that did not flash?

Go to Step 7 Go to Step 11

10 Check the IAC passages

for a restriction.

Was a fault found?

Go to Step 15 Go to Step 7

11 Check the PCM electrical

connector for proper

tension at the terminals.

Was a problem found?

Go to Step 12 Go to Step 14

12 Repair the circuit or the

connector as necessary.

Is the action complete?

Verify Repair

13 Replace the IAC valve.

Is the action complete? Verify Repair

14 Replace the PCM. Refer

to Section 6C2-3 Service

Operations, for the

Security Link procedure.

Is the action complete?

Verify Repair

15 Clean the passages as

necessary.

Is the action complete?

Verify Repair

DTC 36 - VACUUM LEAK

CIRCUIT DESCRIPTION:

The PCM controls the engine idle speed by adjusting the position of the Idle Air Control (IAC) motor pintle. The IAC

is a bi-directional motor driven by two coils. The PCM sends pulses (steps) to the IAC to extend or retract the IAC

pintle into a passage in the throttle body to decrease or increase air flow. The commanded IAC position (displayed

in counts) can be monitored on the scan tool; a lower number of counts indicates less commanded airflow (pintle

extended). This method allows highly accurate control of the idle speed and quick response to changes in engine

load. If the PCM detects a high idle speed, the PCM will send 50 counts (steps) to the IAC motor. If the RPM

increases more than 50 RPM it is accepted that the IAC motor is moving and therefore the fault is a vacuum leak,

and DTC 36 will set. If the RPM does not change when the PCM commands the IAC to respond to a commanded

count (steps), the PCM will set a DTC 35.

DTC 36 WILL SET IF:

• A DTC 35 is not set

• The actual engine idle speed varies by more than 75 RPM from desired the PCM will command the IAC valve

out 50 steps. If the idle speed increases by more than 75 RPM when command out than a DTC 36 will set.

TEST DESCRIPTION:

Number(s) below refer to step number(s) on the diagnostic chart.

2. The importance of this step cannot be stressed too strongly. It can lead to correcting a problem without further

checks and save valuable time.

4. By restricting the vacuum supply hoses, you are isolating which vacuum circuit may have a vacuum leak.

When the leak is stopped, the engine should respond immediately.

DIAGNOSTIC AIDS:

Check the IAC air passage for possible foreign material.

Code 36 may also be set by other system faults. Refer to 'Symptom Charts" for diagnostic by symptoms.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check in

this Section

21. Ignition Off.

2. Perform a

visual/physical check

of all the vacuum

hoses and air duct

between the Mass Air

Flow Sensor and the

throttle body for:

Cracks, Splits, Kinks,

Connections and in

their proper location.

Was a problem found?

Verify Repair Go to Step 3

31. Ignition "ON", engine

running.

2. Listen for a hissing

sound as evidence of a

vacuum leak.

Was a problem found?

Verify Repair Go to Step 4

41. Ignition "ON", engine

running.

2. Using pliers, restrict

each vacuum hose

near the intake

manifold and listen for

the engine RPM to

change when hoses

are restricted.

Did RPM change when

with vacuum hoses

restricted?

Repair vacuum

leak in hose or

vacuum circuit.

Verify Repair

Go to Step 5

5Inspect suspect areas of

the intake system such

as:

• The intake manifold

gaskets

• PCV system

• Throttle body vacuum

hose connections

• Throttle body gasket

• Oil dipstick seal and oil

fill cap for sources of

un-metered air.

• IACV O-ring

Was a problem found?

Verify Repair Go to Step 6

6Clear DTC and drive

vehicle.

Does DTC reset?

Go to Step 7 Repair Complete

7Replace PCM.

Refer to Section 6C2-3

Service Operations, for

PCM Security Link

procedure.

Is action complete?

Verify Repair

DTC 41 - IGNITION ELECTRONIC SPARK TIMING (EST) CI RCUI T

CIRCUIT DESCRIPTION:

There are two modes of ignition system operation. The BYPASS timing mode, and the ELECTRONIC SPARK

TIMING mode. The bypass mode is normally used while cranking the engine.

The Electronic Spark Timing mode is used to allow the PCM to control the ignition system after the engine is

running. The PCM controls a "Bypass control circuit", used to control the ignition module between the different

ignition system modes.

The PCM's Electronic Spark Timing (EST) output circuitry generates EST output pulses anytime crankshaft

reference input pulses are received. The PCM also monitors it's EST output terminal, to monitor if and when EST

pulses are present.

When the ignition system is operating in the Bypass mode (such as when the engine is cranking), the ignition

module earths the EST pulses coming from the PCM. Because the EST pulses should be earthed through the

ignition module during Bypass mode operation., the PCM should not detect EST pulses on it's EST output terminal.

If the EST output circuit between the PCM and the ignition module has an "open circuit", then the ignition module

can not earth the PCM's EST output pulses. If the PCM detects three EST pulses during the first 3 crankshaft

reference input pulses, a DTC 41will set.

A DTC 41 will also set if the Bypass control circuit is shorted to voltage. If this where to happen, the PCM's EST

monitor would not sense the EST signal being earthed in the ignition module while cranking, and a DTC 41 would

set.

If CKT 423 is open, the ignition module will switch to the EST mode. If CKT 423 circuit is open, no EST pulses will

reach the ignition module, and the engine may stall. A DTC 41 may set. The engine can be restarted, but the

ignition system will operate in the bypass mode until the fault is corrected. When operating in the bypass mode, the

ignition spark timing is set to 10 ° advance, which will cause a loss of engine performance.

DTC 41 WILL SET IF:

• The ignition switch is in the ON position.

• The PCM has detected at least 3 EST output pulses, during the first 3 crankshaft reference signal pulses

received from the ignition module.

TEST DESCRIPTION:

Number(s) below refer to the step(s) on the diagnostic chart.

2. This will verify if the fault is intermittent.

3. The typical voltage on this circuit with the ignition OFF should be less than .5V.

7. The actual voltage may go as high as 2.5V. The important fact is that the voltage is at least two volts.

10. Perform the Security Link procedure whenever the PCM is replaced. Refer to Section 6C2-3 SERVICE

OPERATIONS.

DIAGNOSTIC AIDS:

Check all the ignition wiring and connectors to and from the PCM and the ignition module.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to OBD

System Check in

this Section

21. Clear DTC 41.

2. Start the engine.

3. Observe the DTC(s).

Did a DTC 41 set?

Go to Step 3 DTC 41 is

intermittent. If no

additional DTC's

were stored, refer

to "Diagnostic

Aids" above.

31. Ignition OFF.

2. Disconnect the ignition

module 4 pin

connector.

3. Probe the ignition

module harness

connector terminal for

circuit 424 (T/B) with a

voltmeter connected to

earth.

4. Ignition ON.

Is the voltage greater than

the specified value?

0.5V Go to Step 4 Go to Step 7

41. Ignition OFF.

2. Disconnect the PCM

C-D connector.

3. Ignition ON.

4. robe the ignition

module harness

connector terminal for

circuit 424 (T/B) with a

voltmeter connected to

earth.

Is the voltage greater than

the specified value?

0.5V Go to Step 5 Go to Step 10

5Repair the short to voltage

in the Bypass circuit 424

Is the action complete?

Verify Repair

STEP ACTION VALUE YES NO

6Replace the ignition

module.

Is the action complete?

Verify Repair

71. Ignition OFF.

2. Reconnect the 4 pin

connector to the

ignition module.

3. Backprobe the PCM

connector D10 with a

voltmeter connected to

earth.

4. Start or crank the

engine.

Is the voltage

approximately at the

specified value while

cranking or with engine

running?

2 volts Go to Step 8 Go to Step 9

8Check for a faulty

connection, or an open in

the EST circuit 423.

Was a problem found?

Verify Repair Go to Step 6

9Check the PCM for a

faulty connection.

Was a faulty connection

found?

Verify Repair Go to Step 10

10 Replace the PCM. Refer

to Section 3 for the

Security Link procedure.

Is the action complete?

Verify Repair

DTC 42 - IGNITION BYPASS CIRCUIT

CIRCUIT DESCRIPTION:

There are two modes of ignition system operation. The BYPASS timing mode, and the ELECTRONIC SPARK

TIMING mode. The bypass mode is normally used while starting the engine. The Electronic Spark Timing mode is

used to allow the PCM to control the ignition system after the engine is running. The PCM controls a "Bypass

control circuit", used to control the ignition module between the two different ignition system modes.

The PCM's Electronic Spark Timing (EST) output circuitry generates EST output pulses anytime crankshaft

reference input pulses are received. The PCM also monitors it's EST output terminal, to monitor if and when EST

pulses are present.

When the ignition system is operating in the By pass mode (such as when the engine is cranking), the ignition

module earths the EST pulses coming from the PCM. Because the EST pulses should be earthed through the

ignition module during Bypass mode operation, the PCM should not detect EST pulses on the EST output terminal.

DTC 42 WILL SET IF:

• The engine speed is greater than 1600 RPM.

• The PCM does not receive any EST pulses within 400 ms.

When a DTC 42 is set, the ignition will run in the bypass mode.

TEST DESCRIPTION:

Number(s) below refer to step(s) on the diagnostic chart.

2. Confirms that the DTC 42 is present.

13. Checks whether the DTC 42 is a faulty PCM or an intermittent in circuits 423 or 424.

14. Whenever the PCM is replaced perform the Security Link procedure in Section 6C2-3 SERVICE

OPERATIONS.

DIAGNOSTIC AIDS:

• Refer to "Intermittents" in Section 6C2-2B SYMPTOMS.

• Check all the circuit wiring and the connections to the PCM, and the ignition module.

STEP ACTION VALUE YES NO

1Was the "On-Board

Diagnostic" (OBD) System

Check performed?

Go to Step 2 Go to the OBD

System Check.

21. Clear the DTC 42.

2. Start the engine.

3. Observe the DTC(s).

Did the DTC 42 set?

Go to Step 3 Refer to

Diagnostic Aids

above

31. Ignition OFF.

2. Disconnect the ignition

module 4 pin

connector.

3. Probe the ignition

module harness

connector terminal for

circuit 423(W) with a

voltmeter connected to

earth.

4. Ignition ON.

Is the voltage greater than

the specified value?

0.5V Go to Step 4 Go to Step 6

41. Ignition OFF.

2. Disconnect the PCM

C-D connector.

3. Ignition ON.

Is there voltage present at

the ignition module

harness connector for

circuit 423(W)?

Go to Step 5 Go to Step 15

5Repair the short to voltage

in circuit 423.

Is the action complete?

Verify Repair

61. Ignition ON.

2. Probe the ignition

module harness

connector for circuit

423 with a test light

connected to battery

voltage.

Is the test light ON?

Go to Step 7 Go to Step 9

71. Ignition OFF.

2. Disconnect the PCM

C-D connector.

3. Probe the ignition

module connector

harness terminal for

circuit 423 with a test

light connected to B+.

Is the test light ON?

Go to Step 8 Go to Step 14

STEP ACTION VALUE YES NO

8Repair the short to earth

in circuit 423. Is the action

complete?

Verify Repair

91. Ignition ON.

2. Disconnect the ignition

module 4 pin

connector.

3. With a test light

connected to B+,

probe the ignition

module harness

connector for circuit

424.

Is the test light ON?

Go to Step 10 Go to Step 12

10 1. Ignition OFF.

2. Disconnect the PCM

C-D connector.

3 Ignition ON.

4 Disconnect the ignition

module 4 pin

connector.

5 With a test light

connected to B+,

probe the ignition

module harness

connector for circuit

424.

Is the test light ON?

Go to Step 11 Go to Step 14

11 Repair the short to earth

in circuit 424.

Is the action complete?

Verify Repair

12 1. Ignition OFF.

2. Disconnect the PCM

C-D connector.

3. Check for a faulty

connection or an open

in circuit 424.

Was a problem found?

Verify Repair Go to Step 13

STEP ACTION VALUE YES NO

13 1. Ignition OFF.

2. Reconnect the ignition

control module 4 pin

connector.

3. Disconnect PCM C-D

connector.

3. Ignition ON.

4. Probe the PCM

harness connector for

circuit 423 with an

ohmmeter connected

to earth.

5. Probe the PCM

harness connector for

circuit 424 with a test

light connected to B+.

NOTE:

As the test light contacts

circuit 424, does the

resistance switch from

less than the specified

value to greater than the

specified value?

40 ohms

Infinity

Go to Step 14 Go to Step 15

14 Replace the PCM. Refer

to Section 6c2-3 Service

Operations, for the

Security Link procedure

Is the action complete?

Verify Repair

15 Replace the ignition

control module.

Is the action complete?

Verify Repair

DTC 43 - KNOCK SENSOR CIRCUIT

CIRCUIT DESCRIPTION:

The Electronic Spark Control (ESC) system detects engine detonation. The PCM will retard the Electronic Spark

Tim ing (EST ) based on the signal being received f rom the k nock s ensor. T his input allows the EST spar k advanc e

to be optimised under all conditions. This allows the knock sensor input to reduce the total advance when

detonation is detected. T otal EST advance can be retarded by as much as 12 degrees by the knock sensor input.

This could be described as a "closed-loop" spark advance system.

A loss of this s ignal would caus e the EST advanc e to r emain at a "no detonation" level. However, if detonation were

occurring, the advance would not be retarded, and detonation could become severe enough under heavy engine

load conditions to result in pre-ignition and potential engine damage.

The knock sensor produces a small AC voltage, which goes above and below the DC voltage supplied from the

PCM. The sensor’s AC voltage output is dependent upon the level of detonation or knock. This portion of the sensor

reacts like a microphone, producing a small signal voltage based on vibration.

DTC 43 WILL SET IF

• One or more of the following DTC's are not set. DTC 14, 15, 16, 17, 19, 21, 22, or 93.

• The TP sensor angle is greater than or equal to 10%.

• The ECT is greater than 65°C.

• The engine speed is greater than 2500 RPM.

• The engine run time is greater than 10 seconds.

• The PCM does not receive a knock signal.

• The above conditions are present for 3 seconds.

TEST DESCRIPTION:

Number(s) below refer to step(s) on the diagnostic chart.

2. This step determines if conditions for DTC 43 still exist (voltage on circuit 815 above 4.4 volts or below

0.2 volt)

4. If the knock sensor is generating a knock signal, then DTC 43 is intermittent.

5. This Step determines if the knock sensor circuit is shorted to voltage.

6. This confirms that the knock sensor’s resistance is OK.

DIAGNOSTIC AIDS:

If circuit 815 is not open or not shorted to earth the most likely cause is an open circuit in the PCM and a

replacement should be fitted. If a replacement PCM did not correct the problem, then Refer to "Intermittents" in

Section 6C2-2B SYMPTOMS in this Service Information.

STEP ACTION VALUE YES NO

1 Was the "On-Board Diagnostic" (OBD)

System Check performed? Go to Step 2 Go to the OBD

System Check in

this Section

2 1. Install Tech 2 scan tool.

2. Record then clear DTC(s).

1. Ignition “ON”, engine idling.

2. Using Tech 2 scan tool, select

“Knock Signal” and “Knock

Retard”.

Is “Knock Retard” above the specified

value?

Go to Step 3 Go to Step 4

3 Repair short to voltage on circuit 815.

Is action complete? Verify Repair

4 1. Ignition “ON”, engine idling.

2. Lightly tap on alternator bracket

with hammer.

Is the Tech 2 scan tool indicating

“Knock Retard” above the specified

value?

0 degrees DTC 43 is

intermittent. If no

additional DTC’s

were stored, refer

to “Diagnostic

Aids” above.

Go to Step 5

5 1. Ignition “ON”, engine stopped.

2. Backprobe PCM connector

terminal for circuit 815, with DVM

connected to earth.

3. Set DVM to read DC voltage

Is voltage reading on DVM above the

specified value?

0 volts Go to Step 3 Go to Step 6

6 1. Ignition “OFF”.

2. Disconnect PCM connectors.

3. Back probe PCM connector

terminal for circuit 815, with DVM

connected to earth

4. Set DVM to read resistance.

Is resistance on DVM at the specified

value?

80 kOhms

(80,000

Ohms)

Go to Step 7 Go to Step 10

7 1. Ignition “OFF”.

2. Reconnect PCM connectors.

3. Back probe PCM connector

terminal for circuit 815, with DVM

connected to earth

4. Set DVM to read AC voltage.

Is DVM indicating above specified

value?

50 mV AC Go to Step 8 Go to Step 11

8 Check for poor connection at PCM.

Was a poor connection found? Verify Repair Go to Step 9

9 Replace PCM.

Refer to Section 6C2-3 Service

Operations for PCM Security Link

procedure

Is the action complete?

Verify Repair

10 Check for open or short to earth in

circuit 815.

Was a fault found?

Verify Repair Go to Step 11

11 Replace knock sensor(s)

Is the action complete? Verify Repair

DTC 44 - RIGHT HAND (RH) LEAN EXHAUST INDICATED

CIRCUIT DESCRIPTION:

The O2 sensor monitors the oxygen content of the exhaust gas in the exhaust stream then sends a voltage to the

PCM relative to the oxygen content. This voltage ranges from less than 100 mV (high O2 exhaust content-lean

mixture) to greater than 900 mV(low O2 exhaust content-rich mixture).