SECTION 6C1-1 - GENERAL INFORMATION -

V6 SUPERCHARGED ENGINE

IMPORTANT:

Before performing any Service Operation or other procedure described in this Section, refer to Section 00

CAUTIONS AND NOTES in VX Service Information for correct workshop practices with regards to safety

and/or property damage.

1. GENERAL DESCRI PTION

The engines used in this vehicle uses a Powertrain Control Module (PCM) with both an automatic transm iss ion and

a manual transm ission to control exhaust emissions while maintaining excellent driveability and fuel economy. The

PCM maintains a desired air/fuel ratio of precisely 14.7 to 1 by monitoring electrical signals from dual oxygen

sensors mounted in the exhaust stream and optimising the amount of fuel flow from the injectors. This method of

"feed back" fuel control is called CLOSED LOOP.

In addition to fuel contr ol, the PCM als o controls ignition dwell and timing, idle s peed, EGR, electric engine cooling

fan, electric fuel pump, instrument panel "Check Powertrain" lamp and on vehicles so equipped, the A/C

com pressor clutch. The PCM also controls the automatic trans mission f unctions. The PCM also inter faces through

the serial data line with other vehicle control or information modules, such as the trip computer, Body Control

Module (BCM), ABS/ETC module, ECC module, SRS module, and theft deterrent system.

Figures 6C1-1-1 through 6C1-1-2 contain a list of the various operating conditions sensed by the PCM on the left,

and the various systems controlled on the right. Details of basic operation, diagnosis, and service are covered in

this Section.

The PCM has a built-in diagnostic system that recognises and identifies possible operational problems and alerts

the driver by illum inating the "Check Powertrain" lamp/Malf unction Indicator Lam p (MIL) on the instrum ent panel. If

the lam p com es "ON" while driving, it does not m ean that the engine should be s topped im m ediately, but the cause

of the lamp coming "ON" should be checked as soon as is reasonably possible. The PCM has built-in backup

systems that in all but the most severe failures will allow the vehicle to operate in a near normal manner until

repairs can be made.

Below the instrument panel to the left of the steering column is a Data Link Connector (DLC) which is used by the

assembly plant for a computer "c heck-out" of the s ystem . T his c onnec tor is us ed in s ervic e along with a scan tool to

help diagnose the system. Refer to Section 6C1-2, DIAGNOSIS of the VX Series Service Information for further

details.

The locations of the Engine Management System (EMS) components of the system are shown in the following

Figures 6C1-1-3 through 6C1-1-7.

For the transmission Management System components and their locations, refer to Figure 6C1-1-8 in this Section.

Figure 6C1-1-1 V6 Supercharge Engine Powertrain Control Module Systems

A/C R equest "O N or "OFF"

A/C Pressur e Transducer

Battery Voltage

Camshaft Position Sensor (CMP)

Crankshaf t Position Sensor (CKP )

Di agnostic "Test" Ter m in al

DLC Data Stream Input

Engine Coolant Temperature (ECT)

Engine Cooling Fan Response

Engine Knock (ESC)

Engine Speed (RPM)

Heated Oxygen Sensor Content (HO2S)

Inje ct or Volta ge

Intake Air Temperature (IAT)

Mass Air Flow (MAF) Sensor

Throttle Position (TP) Sensor

Tran smission G e ar Position

Theft Det er r ent Si gnal

Vehicle Speed Sensor (VSS)

Air Conditi on in g Comp ress or Clu tc h

Canister Purge Solenoid

Diagnostics

- "Check Powertrain" Lamp

- Data Link Connector (DLC)

- DLC Data Stream Output

- Field Service Mode

Electric Engine Cooling Fan

Electronic Spark Control (ESC)

Electronic Spark Timing (EST)

Fuel Control

- Fuel Injectors

- El ec t ric Fue l Pump

Idle Air Control

Boost Control Solenoid

Fuel Control Module

Battery Voltage

Engine S peed (E ngine R PM)

Engine Coolant Temperature (ECT)

Throttle Position (TP Sensor)

Power/Economy Switch

Tran sm i ssion Fl u i d Temperatu re ( TFT)

Tran smission G e ar Position

Vehicle Speed Sensor (VSS)

Tran sm i ssion Fl ui d Pres sur e (TF P)

Sw itch Assembly

TCC Enable Solenoid

TC C "PWM" Solenoid

3-2 Shif t Solenoid

1-2 Shif t Solenoid

2-3 Shif t Solenoid

OPERATING P ARAMETERS SENSED

OPERATING CONDITIONS SENSED

POWERTRAIN

CONTROL

MODULE

(PCM)

ENGINE CONTROLS

TRANSMISSION CONTROLS

V6 Supercharge Engine

NOTE: NOT ALL VEHICLES WILL CONTAIN ALL OF THE ABOVE SYSTEMS OR COMPONENTS

POWERTRAIN

CONTROL

MODULE

(PCM)

4345

SYSTEMS CONTROLLED

Figure 6C1-1-2 V6 Supercharge Engine Powertrain Control Module

Systems

Starter

Powertrain Control Module Systems

Trip

Computer

Transmission

Connector

(Solenoids)

System

Voltage B +

Canister Purge

Solenoid

Fuel Pump Relay

Fuel Pump

Control

Module

EFI

Relay

Injectors

BCM

H02S

ECT

MAF

IAT

TFT

Da t a Link Conn ect o r

(DLC)

Earth

Engine

Earth

Di agnostic Test

Power Supply

Seria l Data

Injector Voltage Monitor

Fusible

Link

4346

Idle Air

Control

Boost Control

Solenoid

Hi gh Speed

Cooling Fan

Knock

Sensor

Knock

Sensor

BCM

A/C

PCM

Co nt rol M odule

V6 Supercharge

Ignition

System Ignition

Control

VSS

Speedometer

434

21 21

789

12 18

4195

Figure 6C1-1-3 V6 Engine Compartment Component Locations

1. Fuel Pump (Inside Fuel Tank)

2. Fuel Tank

3. ECC In –Car Air Temperature Sensor

4. Fuel Pressure Regulator

5. Exhaust Gas Oxygen (O2S) Sensor (Two)

6. Engine Harness (PCM) Earth (Two

Terminals)

7. Idle Air Control (IAC) Valve

8. Throttle Position (TP) Sensor

9. Mass Air Flow (MAF) Sensor

10. Tachometer Lead

11. Powertrain Control Module (PCM) (Inside

Vehicle)

12. Intake Air Temperature (IAT) Sensor

13. Fuel Injectors

14. Ignition Coils

15. Engine Coolant Temperature (ECT) Sensor

16. DIS Module

17. Air Cleaner

18. Crankshaft Position (CKP) Sensor

19. A/C Refrigerant Pressure Sensor

20. A/C Accumulator

21. Engine Cooling Fans (Two)

22. Crankshaft Position (CKP) Sensor

23. Oil Pressure Switch

24. Camshaft Position (CMP) Sensor

25. Detonation Knock Sensors (KS) (Two)

26. Engine Harness (PCM) Earth (Two Terminals)

27. Battery

28. Battery Harness Fusible Link Housing

29. Engine Compartment Relay Housing

30. Engine Compartment Fusible Link Housing

31. Engine Compartment Fuse/Relay Center

32. ABS

33. Brake Hydraulic Failure Switch

34. EVAP Canister Purge Solenoid

35. Diagnostic Link Connector (DLC)

36. BCM

37. Check Powertrain Malfunction Indicator Lamp(MIL)

38. Fuel Pump Control Module (Rear Compartment)

39. Vehicle Speed Sensor (VSS)

Figure 6C1-1-4 Engine Compartment Fuse/Relay Locations

1. Fan 1 Fusible Link FU 15. Start Relay

2. Fan 2 Fusible Link FT 16. Headlamp High Beam Relay

3. Engine Fan Relay (Low Speed) 17. Fuel Pump Relay

4. Lighting Fusible Link FQ 18. Front Wiper Relay

5. ABS Fusible Link FR 19. Headlamp Low Beam Relay

6. Engine Fusible Link FS 20. Injectors / Ignition Fuse F35

7. Main Fusible Link FJ 21. Injectors / Ignition Fuse F34

8. Blower Fusible Link FY 22. Engine Sensors Fuse F33

9. Engine Cont. (EFI) Relay 23. Automatic Transmission Fuse F32

10. Horn Relay 24. Engine Control / BCM Fuse F31

11. A/C Relay 25. LH Headlamp Fuse F30

12. Theft Horn Relay 26. RH Headlamp Fuse F29

13. Fog Lamp Relay 27. Fuel Pump Fuse F28

14. Engine Fan Relay (High Speed) 28. Throttle Relaxer Control Module Fuse F36

Figure 6C1-1-5 V6 Supercharge Engine Component Locations

1. Throttle Position (TP) Sensor 2. Idle Air Control Valve (IAC)

3. Anti-Boost Solenoid Valve 4. Engine Coolant Temperature (ECT) Sensor

5. Injectors 6. Direct Ignition System Module

7. L.H. Knock Sensor (KS) 8. Crankshaft Position (CKP) Sensor

9. Ignition Coils (3 places) 10. Bypass Valve Actuator

910

4197

Figure 6C1-1-6 V6 Supercharge Engine Component Locations

1. Injectors

2. Canister Purge Solenoid

3. R.H. Exhaust Gas Oxygen (O2S) Sensor

4. Transmission Pass-Through Connector

5. Vehicle Speed Sensor (VSS) (Automatic Trans)

6. PCM Connectors

7. Engine Harness Earth

4199

Figure 6C1-1-7 V6 Supercharge Engine Component Locations

1. Ignition Coils (3 places)

2. Fuel Pressure Regulator

3. Direct Ignition System Module

4. Engine Harness Earth

5. Camshaft Position (CMP) Sensor

6. Oil Pressure Switch

7. R.H. Knock Sensor (KS)

8. Vehicle Speed Sensor (VSS) Automatic Trans)

9. Injectors (3 places)

4201

Figure 6C1-1-8 V6 Automatic Transmission Internal Electronic Component Locations

1. Vehicle Speed Sensor

2. Shift Solenoid B (SS) Valve

3. Shift Solenoid A (SS) Valve

4. Automatic Transmission Fluid Pressure (TFP) Manual Valve Position Switch

5. Shift Solenoid (SS) Valve Assembly

6. Torque Converter Clutch Pulse Width Modulation (TCC PWM) Solenoid Valve

7. Torque Converter Clutch (TCC) Solenoid Valve

8. Pressure Control Solenoid (PCS) Valve

1.1 POWERTRAIN CONTROL MODULE

The Powertrain Control Module (PCM), located

behind the front left hand cowl trim panel, and is

the control center of the fuel injection and

transmission management systems. It constantly

monitors information from various sensors, and

controls the systems that affect exhaust emissions

and vehicle performance. The PCM performs the

diagnostic function of the system. It can recognise

operational problems, alert the driver through a

Malfunction Indicator Lamp (MIL) "Check

Powertrain" lamp and store a diagnostic code(s)

that will identify problem areas to aid the

technician in making repairs. Refer to

Section 6C1-2 DIAGNOSIS of the VX Series

Service Information for more information on using

the diagnostic functions of the PCM.

The PCM s upplies either a buff ered 5 or 12 volts to

power various sensors or switches. This is done

through resistances in the PCM which are so high

in value that a test light will not light when

connected to the circuit. In some cases, even an

ordinary voltmeter will not give an accura te reading

because the meter's internal resistance is too low.

Figure 6C1-1-9 Powertrain Control Module Location

A 10 Megaohm input impedance digital voltmeter is

required to assure accurate voltage readings.

The PCM controls output circuits such as the

injectors, IAC, and various relays, etc. by

controlling the earth circuit through transistors or a

device c alled a "Quad-Dr iver" m odule (QDM) in the

PCM. T he two exceptions to this are the f uel pump

relay control circuit and the automatic transmission

Pressure Control Solenoid (PCS). The fuel pump

relay is the only PCM controlled circuit where the

PCM controls the +12 volts sent to the coil of the

relay. The earth side of the fuel pump relay coil is

connected to engine earth. The PCM supplies

current to the PCS and m onitors how m uch cur rent

returns to the PCM on a separate terminal.

PCM SECURITY LINK

Once the PCM and or BCM have been replaced,

the new PCM and or BCM must be security linked

to each other. If this procedure is not performed,

the vehicle will not crank.

There are two different types of procedures that

may be per form ed to acc om plish this tas k . Refer to

Section 6C1-3 of the VX Series Service

Information for this procedure.

4202

Figure 6C1-1-10 PCM Mounting

1. PCM

2. Mounting Bracket

3. Left Hand Cowl Panel

PROM

To allow one model of PCM to be used for many

diff erent vehicles, a device called a PRO M is used.

The PROM is located inside the PCM and has

information on the vehicle's weight, engine,

transmission, axle ratio and several other factors.

While one PCM part number m ay be used by many

different vehicles, a PROM is specific. For this

reason, it is ver y im portant to chec k the latest parts

catalogue and Technical Information Bulletins for

the correct part number when replacing a PROM.

A replacem ent PCM (c alled a contr oller) is supplied

without a PROM. The PROM from the old PCM

must be carefully removed and installed in

the new PCM. For details refer

Section 6C1-3 SERVICE OPERATIONS.

4204

Figure 6C1-1-11 PROM Location

1. Powertrain Control Module (PCM)

2. PROM

3. PROM Access Cover

PCM MEMORY FUNCTIONS

There are three types of memory storage within the PCM: RAM, EPROM and EEPROM.

RAM

Random Ac cess Mem ory (RAM) is the m icroproc essor "s cratch pad." T he processor can write into, or r ead from

this memory as needed. This memory is volatile and needs a constant supply of voltage to be retained. If the

voltage is lost, the memory is lost.

EPROM

Erasable Progr amm able Read Only Mem ory (EPRO M) is the portion of the PCM which means that the program

can be erased. This is also the portion of the PCM that contains software and the different engine and

transmission calibration information that is specific to year, model and emissions. This memory is erased by

exposing it to high intensity ultra violet radiation for several minutes.

The service Programmable Read Only Memory (PROM) which is used by technicians in the field to update

calibrations in the PCM is actually an EPROM. The service PROM is removable from the PCM. The PROM

should be retained with the vehicle following PCM replacement.

EEPROM

Electronically Erasable Program mable Read Only Mem ory (EEPRO M) is the portion of the PCM that m eans the

program can only be erased electronically. This type of m emor y cannot be eras ed by disconnecting the vehicle's

battery. The only way to erase this type of m emory is by a s pecial electronic tool, suc h as the Tech 2 s can tool.

This type of memory is used to store the Diagnostic Trouble Codes (DTC). DTC history data is stored in

EEPROM and will be saved even after the vehicle's battery has been disconnected. For this reason, the only

way that the DTC history data can be cleared is with the Tech 2 scan tool.

1.2 ENGINE INFORMATION SENSORS AND SIGNALS

CAMSHAFT POSITION SENSOR

The camshaft position sensor is located in the

engine front cover, behind and below the water

pump, near the camshaft sprocket.

As the cam shaf t spr ock et turns, a m agnet mounted

on it activates the Hall Ef f ec t s witch in the c amshaf t

position sensor. When the Hall Effect switch is

activated, it earth's the signal line to the DIS

module, pulling the camshaft position signal line's

applied voltage low. This is interpreted as a

camshaft position signal (Synchronisation Pulse).

Because of the way the signal is created by the

camshaft position sensor, the signal circuit is

always either at a high or low voltage (square wave

signal).

While the camshaft sprocket continues to turn, the

Hall Eff ect switch turns "OFF" as the m agnetic f ield

passes the camshaft position sensor, resulting in

one signal each time the camshaft makes one

revolution.

The camshaft position signal, which actually

represents camshaft position due to the sensor's

mounting location, is used by the PCM to properly

time its sequential fuel injection operation.

4205

Figure 6C1-1-12 Camshaft Position Sensor

1. Crankshaft Position (CKP) Sensor

Figure 6C1-1-13 Camshaft and Crankshaft Position Sensor Locations

1. Camshaft Sprocket

2. Magnetic Interrupter

3. Front Cover

4. Camshaft Position (CKP) Sensor

5. Crankshaft Position (CKP) Sensor

4206

CAMSHAFT POSITION SIGNAL

The PCM uses the camshaft position signal to determine the position of the No. 1 piston on its power stroke.

This signal is used by the PCM to c alculate sequential fuel inje ction operation. If the cam shaft pos ition signal is

lost while the engine is running, the fuel injection mode will be based on the last fuel injection pulse, and the

engine will continue to run. The engine c an be res tarted and will run in the synchronous (all s ix injec tors injec t at

once) mode as long as the fault is present.

When the camshaft position signal is not received by the PCM, DTC 48 will be set.

If the PCM sees an incorrect number of pulses on the Camshaft Position PCM input circuit, DTC 49 will set.

If either of these DTC's are set, the fuel system will not be in sequential fuel injection mode.

Figure 6C1-1-14 Camshaft Position Signal

1. DIS Module 2. Camshaft Position Signal In

3. Camshaft Position Signal Out 4. Magnetic Interrupter

5. One Camshaft Rotation 6. Camshaft Signal

7. Camshaft Gear 8. Camshaft Position (CMP) Sensor

The Camshaft signal is norm ally high signal that will go low for 60° once every 720° of crank shaft rotation. The

timing of the camshaft signal is not critical since it only provides information to the PCM for sequential fueling.

DTC 48 (Camshaft Position Sensor Circuit Low Voltage) will set if:

• The engine is running.

• The PCM detects the Camshaft Position sensor signal is low when the signal should be high for 5.0

seconds.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DTC 49 (Camshaft Position Sensor Circuit Performance) will set if:

• The engine is running.

• The incorrect number of crankshaft reference pulses have been received since the previous camshaft

position signal.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

12V

4207

DEFAULT VALUE

If either DTC is set, the PCM will determine the fuel injection sequence based on the last fuel injection pulse

received. In the calculated SFI mode, the engine continues to start and run. However, with the fault present,

only a 1 in 6 chance of the correct injection sequence exists.

RECOVERY

Recovery will occur on the next ignition cycle.

DTC 48 AND 49 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED BATTERY VOLTAGE

TIME FROM START REFERENCE VOLTAGE

TIMES OCCURRED VEHICLE SPEED

IGNITION CYCLES INJECTOR VOLTAGE

COOLANT TEMPERATURE

Figure 6C1-1-15 Camshaft Position Signal

VXSC009

PCM

D11

D12

D10

CRANKSHAFT

REFERENCE LO

CAM

SENSOR

CONNECTOR

CAMSHAFT

POSITION

SENSOR

SIGNAL

CRANKSHAFT

REFERENCE HI

CRANKSHAFT

18X SIGNAL

BYPASS CONTROL

EST OUTPUT

module power supply - in

sensor power supply - out

cam signal - in

3x crank sensor - in

18x crank sensor - in

cam signal - out

tacho signal - out

crankshaft reference - out

18X cranksignal - out

bypass control

EST signal -in

DIS

MODULE

ABCD CBA

W/B (644)

GY/R (645)

B/R (453)

CRANK

SENSOR

CONN

L BLU/W

(646) BR (633)

BLU/Y (643)

BR (121)

B (63 0)

V (43 0)

L BLU/B (647)

T/B (4 24)

IGN SW

EFI RELAY

O/Y

(479)

(482)

B/W

(152)P/B

(39)

W (423)

F35

BATTERY

LOC. E1

(1040)

LOC. E3

P (3)

R(2H)

F14

TO INSTRUMENT CLUSTER

(TERMINAL 18)

ABS/ETC (TERMINAL 30)

YB39

YE111

YE34

YB193

YE63

YE57

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

The Engine Coolant Temperature (ECT) sensor is a

thermistor (a resistor that changes value based on

temperature) mounted in the engine coolant stream

and is specifically for the PCM. A different sensor is

used for instrument panel functions. Low coolant

engine temperature produces a high sensor

resistanc e (28,939 ohm s at -20 degr ees C) while high

engine coolant temperature causes low sensor

resistance (180 ohms at 100 degrees C).

Figure 6C1-1-16 ECT Sensor

The Engine Coolant Temperature location on the V6

engine application is at the front of the engine

4208

Figure 6C1-1-17 ECT Sensor Location

1. Engine Coolant Temperature (ECT) Sensor

2. Tang

3. Wiring Harness Connector

4. Rear View Of Engine

5. Temperature Gauge Coolant Temperature Sensor

The PCM:

1. Supplies a 5 volt signal voltage to the sensor

through a resistor in the PCM, and

2. Monitors the circuit voltage, which will change

when connected to the sensor.

The circuit voltage will vary depending on the

resistance of the engine coolant temperature sensor.

The circuit voltage will be close to the 5 volt level

when the sensor is cold, and will decrease as the

sensor warms. Engine coolant temperature affects

most systems controlled by the PCM.

A failure in the engine coolant temperature sensor

circuit should set either DTC 14 or DTC 15.

An interm ittent open or a short f ailure should s et DTC

16.

The PCM supplies a 5 volt signal to the engine

coolant temperature sensor through one of two

resistor s in the PCM. When the engine coolant is c old

the PCM will operate on one resistor then switch over

to another resistor at approximately 50 degrees C.

The circuit voltage will change at this time but the

Tec h 2 scan tool will still r ead the correct tem perature

value and will not suddenly jump. A failure in one of

these two resistors should set DTC 17.

5.72

4.90

4.48

4.16

3.84

3.52

3.20

2.58

2.88

2.24

1.92

1.60

1.28

0.96

0.64

0.32

0.00 -28 -16 -4 7 19 31 49 55 79 91 115 127 139103 15167-40

4210

Figure 6C1-1-18 ECT Temperature vs Voltage

1. Engine Coolant Temperature Vs. Voltage Table

2. Sensor Voltage Above 50°C

3. Temperature °C

4. Sensor Voltage Below 50°C

5. Volts

DTC 14 (Engine Coolant Temperature (ECT) Sensor Low Voltage) will set if:

• Engine run time is longer than 10 seconds.

• The ECT sensor signal indicates an engine coolant temperature greater than 134°C (274°F).

• Above conditions present for at least 10 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DTC 15 (Engine Coolant Temperature (ECT) Sensor High Voltage) will set if:

• Engine run time is longer than 10 seconds.

• The ECT sensor signal indicates an engine coolant temperature less than -30°C (9°F).

• Above conditions present for at least 10 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DTC 16 (Engine Coolant Temperature (ECT) Signal Voltage Unstable) will set if:

• Engine run time is longer than 10 seconds.

• The ECT sensor reading changes more than 400 mV in 200 milliseconds.

• Above conditions present for at least 10 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DTC 17 (Engine Coolant Temperature (ECT) pull-up Resistor Failure) will set if:

• Engine run time is longer than 10 seconds.

• The pull-up resistor inside the PCM switches and there is less than a 60mV change in the engine coolant

temperature signal.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

When an ECT s ensor circ uit f ault is detected, and cur rent, the PCM will substitute a c oolant tem perature def ault

value. The PCM arrives at this default, or substitute value, by switching to a starting point, then counting

upwards to 95°C at a rate of 11 degrees per minute.

The starting point is the present temperature indication from the intake air temperature (IAT) Sensor.

NOTE: When a DTC 14, 15, 16 and 17 is c urrent, the PCM will turn on the elec tric engine c ooling fan(s ). T his is

a FAIL-SAFE action by the PCM to prevent a possible engine overheat c ondition, since these DTC’s indicate an

unknown actual engine coolant temperature.

If the ECT s ensor circ uit opens with the ignition off, the PCM will interpret - 30°C and deliver enough fuel to start

the engine at room temperature. If the actual ambient temperature is above 0°C, the engine may flood and not

start unless CLEAR FLOOD MODE is used by fully depressing the accelerator while cranking. In the CLEAR

FLOOD MODE the injectors pulse width is set to zero milliseconds.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 14, 15, 16 AND 17 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED ECT SENSOR

TIME FROM START IAT SENSOR

TIMES OCCURRED INTAKE AIR TEMPERATURE

IGNITION CYCLES BATTERY VOLTAGE

COOLANT TEMPERATURE REFERENCE VOLTS

Figure 6C1-1-19 ECT Sensor Circui

SUPERVX004

E16

ENGINE COOLANT

TEMPERATURE SENSOR

SENSOR EARTH

ETC SENSOR SIGNAL

348

Ω

Y (41 0)

B/Y (452)

THROTTLE POSITION

SENSOR

YB194

YE106 YB188

EXHAUST GAS OXYGEN SENSOR

The exhaust gas oxygen sensors are the key to

fuel control. The PCM uses information from the

oxygen sensors to precisely fine-tune its fuel

injector pulse width calculations, based on the

unused, "left-over" oxygen content in the exhaust.

The V6 Supercharge engine use two heated

oxygen sensors, one oxygen sensor is located in

each exhaust pipe. This is done so that the PCM

can better control the engine's fuelling

requirements. These heated oxygen sensors have

a internal heater element that is used to heat the

Zirconia element faster inside the sensors, thereby

decreasing the amount of time the fuel control

system can begin running in closed loop fuel

control.

These oxygen sensors have a zirconia element

that, when heated to temperatures above 360

degrees C, produce voltages based on the amount

of oxygen content surrounding the tip, as

compared to oxygen in the atmosphere.

The s ensor is m ounted in the exhaust pipe with the

sensing portion exposed to the exhaust gas

stream. When the sensor has reached an

operating temperature of more than 360 degrees

C, it acts as a voltage generator, producing a

rapidly changing voltage of between 10 - 1000

millivolts. This voltage output is dependent upon

the oxygen content in the exhaust gas, as

compared to the sensor's atmospheric oxygen

reference cavity. This reference cavity is exposed

to the atmosphere through the air that passes

between the wire strands and insulation.

Figure 6C1-1-20 Four Wire Heated Oxygen Sensor

When the sensor is cold, it produces either no

voltage, or an unusable, slowly changing one. Also

when cold, its internal electrical resistance is

extremely high - many million ohms. The PCM

always supplies a steady 450 millivolt, very low

current called "bias" voltage to the oxygen sensor

circuit. W hen the sensor is cold and not producing

any voltage, the PCM "detects" only this steady

bias voltage. As the sensor begins heating, its

internal resistance decreases and it begins

producing a rapidly changing voltage that will

overshadow the PCM's supplied steady bias

voltage.

When the PCM "detects" the changing voltage, it

knows the oxygen sensor is hot and its output

voltage can be used for the "fine-tuning" the fuel

injector puls e width. T he PCM monitors the ox ygen

sensor's "changing voltage" for going above and

below a mid-range voltage band (approximately

300 - 600 millivolts), to help decide when to

operate in the closed-loop mode. (refer "READY

TEST," Figure 6C1-1-23.)

When the fuel system is correctly operating in the

closed-loop mode, the oxygen sensor voltage

output is rapidly changing several times per

second, going above and below a rich/lean band.

The PCM monitors the changing voltage, and

decides the needed fuel mixture correction. (refer

"NORMAL, CLOSED-LOOP OPERATION,"

Figure 6C1-23).

An open sensor signal circuit or earth circuit, or a

defective, contaminated, or cold sensor could

cause the voltage to stay within a 350-550 millivolt

band too long, keeping the fuel control system in

open-loop and setting either DTC 13 or DTC 63.

4212

0.6 V 0.3 V

Figure 6C1-1-21 Oxygen Sensor Zirconia Element

1. Oxygen Sensor Element

2. 21% Oxygen

3. Less Conduction

4. Exhaust Gas With 2% Oxygen

5. More Conduction

6. Exhaust Gas With 0% Oxygen

If the PCM monitors a low voltage for too long (indicating a "lean" exhaust), either DTC 44 or DTC 64 will set.

If the PCM m onitors a high oxygen sensor circ uit voltage for too long ( indicating a "ric h" exhaust), either DTC 45

or DTC 65 will set.

RESPONSE TIME

Not only is it necessary for the oxygen sensor to produce a voltage signal for rich or lean exhaust, it is also

important to respond quickly to changes. T he PCM senses the response times and displays this on the Tech 2

scan tool as the "rich-lean status" and as "cross counts" If the oxygen sensor responds slowly, the customer

may complain of poor fuel economy, rough idle or lack of performance. It may also set false PCM DTCs

because the PCM uses oxygen sensor voltages for system checks.

OXYGEN SENSOR CONTAMINANTS

Carbon

Black carbon or soot deposits result f rom over-rich air/fuel m ixtures. However, carbon does not harm an oxygen

sensor. Deposits can be burned off in the vehicle by running it at least part throttle for two minutes.

Silica

Certain RTV silicone gasket materials give off vapour as they cure that may contaminate the oxygen sensor.

This contamination is usually caused by the vapours being pulled from the PCV system, into the combustion

chamber and passed on to the exhaust system. The sand like particles from the RTV silica embed in the

molecules of the oxygen sensor element and plug up the surface. With the outside of the oxygen sensor

element not able to sense all of the oxygen in the exhaust system it results in "lazy" oxygen sensor response

and engine control. The oxygen sensor will have a whitish appearance on the outside if it has been

contaminated.

There is also a possibility of silica contamination caused by silicone in the fuel. Som e oil companies have used

silicone to raise the octane rating of their fuel. Careless fuel handling practices with transport containers can

result in unacceptable concentrations of silicone in the fuel at the pump.

Ther e is also a poss ibility of s ilica contam ination caused by silicon in lubric ants used to install vacuum hoses on

fittings. Do not use silicone sealers on gaskets or exhaust joints.

Lead

Lead glazing of the sensors can be introduced when regular, or leaded fuel is burned. Fuel containing large

amounts of methanol will also result in lead contamination.

The methanol dissolves the terne coating of the fuel tank, which introduces lead into the fuel system, and into

the exhaust after combustion. It is difficult to detect lead contamination by visual inspection.

Other Substances

Oil deposits will ultimately prevent oxygen sensor operation. The sensor will have a dark brown appearance.

Causes of high oil consumption should be checked.

The additives in ethylene glycol can also affect oxygen sensor performance. This produces a whitish

appearance. If antifreeze enters the exhaus t sys tem, you will likely encounter other, m ore obvious, sym ptom s of

cooling system trouble. If for example the engine had a head gasket failure where coolant did enter the

combustion chamber it would be a good idea to check the oxygen sensor operation after the head gasket was

repaired.

Multiple Failures

Leaded fuel, silic a contamination f rom uncur ed, low- grade (unapproved) RTV s ealant, and high oil consumption

are possible.

Figure 6C1-22 Oxygen Sensor Voltage Curves

1. Rich 800 mV

2. PCM O2 Reference Signal 450 mV

3. Lean 200 mV

4. Above 780 mV Too Long. Rich Too Long in Closed Loop. DTC 45 or 65 will set.

5. Between 410-477 mV Too Long. DTC 13 or 63 Will Set.

6. Between 200 mV Too Long. Lean Too Long in Closed Loop. DTC 44 or 64 will set.

7. Normal, Closed Loop Operation

4213

Figure 6C1-1-23 Normal Oxygen Sensor Voltages, and Abnormal Trends

1. More Than 780 mV For Too Long (Plus Other Parameters), DTC 45 or 65 Will Set.

2. Rich-Lean Band at a Hot Idle.

3. Less Than 200 mV For Too Long (Plus Other Parameters), DTC 44 or 64 Will Set.

4. “Ready “ Test.

5. Code 13.

6. Millivolts.

DTC 13 (RH Oxygen Sensor Insufficient Activity) will set if:

• No TP Sensor DTC’s are set.

• The ECT sensor is more than 85°C.

• TP Sensor voltage indicates the throttle is open more than 15%.

• RH 02S voltage stays between 410-477 millivolts.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DTC 44 (RH Oxygen Sensor Lean Exhaust Indicated) will set if:

• No IAT Sensor DTC’s are set.

• The RH 02S signal voltage remains below 200 millivolts for 46 seconds.

• The system is in "Closed Loop”.

• IAT Sensor is below 75°C.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

600mV

477 mV

410 mV

300 mV

500 mV

490 mV

1000

900

800

700

600

500

400

300

200

100

4214

DTC 45 (RH Oxygen Sensor Rich Exhaust Indicated) will set if:

• No TP Sensor DTC’s are set.

• The RH 02S signal voltage remains above 780 millivolts for 40 seconds.

• The system is in "Closed Loop”.

• Throttle angle is between 9% and 30%.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

Once a 02S DTC is set, and current, the PCM will operate the fuel system in the “Open Loop” mode.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 13, 44, AND 45 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED R.H O2 SENSOR

TIME FROM START MASS AIR FLOW

TIMES OCCURRED R.H STFT

IGNITION CYCLES R.H LTFT

COOLANT TEMPERATURE THROTTLE ANGLE

DTC 63 (LH Oxygen Sensor Insufficient Activity) will set if:

• No TP Sensor DTC’s are set.

• The ECT sensor is more than 85°C.

• TP Sensor voltage indicates the throttle is open more than 15%.

• RH 02S voltage stays between 410-477 millivolts.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DTC 64 (LH Oxygen Sensor Lean Exhaust Indicated) will set if:

• No IAT Sensor DTC’s are set.

• The LH 02S signal voltage remains below 200 millivolts for 46 seconds.

• The system is in "Closed Loop”.

• IAT Sensor is below 75°C.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DTC 65 (LH Oxygen Sensor Rich Exhaust Indicated) will set if:

• No TP Sensor DTC’s are set.

• The LH 02S signal voltage remains above 780 millivolts for 40 seconds.

• The system is in "Closed Loop”.

• Throttle angle is between 9% and 30%.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

Once a 02S DTC is set, and current, the PCM will operate the fuel system in the “Open Loop” mode.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 63, 64, AND 65 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED L.H O2 SENSOR

TIME FROM START MASS AIR FLOW

TIMES OCCURRED L.H STFT

IGNITION CYCLES L.H LTFT

COOLANT TEMPERATURE THROTTLE ANGLE

Figure 6C1-1-24 V6 Supercharge Engine Four Wire Oxygen Sensor Circuit

P (439)

YE95

GY (1412)

B/R (750)

Engine

Earth

To Fuse

F33

GY/B (1413)

V (412)

V/B (413)

B/R (750)

4269

D16

D15

D14

D13

A1 450 m V

Right

Oxygen

Sensor

Signal HI

Right

Oxygen

Sensor

Signal LO

Left

Oxygen

Sensor

Signal HI

Left

Oxygen

Sensor

Signal LO

Earth

Ri ght O x ygen Sensor

Left Oxygen Sensor 450 m V

Engine

Earth

PCM

YB193

YB188

INTAKE AIR TEMPERATURE (IAT) SENSOR

The Intake Air Temperature (IAT) sensor is a

thermistor (a resistor that changes resistance with

changes in tem perature) mounted in an air cleaner

housing of the intake system. Low intake air

temperature produces high resistance in the

sensor (100,866 ohms at -40 degrees C), while

high intake air temperature causes low sensor

resistance (78 ohms at 130 degrees C).

The PCM:

1. Supplies a 5 volt signal voltage to the sensor

through a resistor in the PCM, and

2. Monitors the intake air temperature circuit

voltage, which will change when connected to

the intake air temperature sensor.

The circuit voltage will vary depending on the

resistance of the IAT sensor. The voltage will be

close to the 5 volt level when the sensor is cold,

and will decrease as the sensor warms.

The input intake air temperature signal voltage is

used by the PCM to assist in calculating the fuel

injector pulse width.

A failure in the IAT sensor circuit should set either

DTC 23 or 25.

An intermittent or unstable voltage in the IAT

sensor circuit should set DTC 26.

Figure 6C1-1-25 IAT Sensor

4215

Figure 6C1-1-26 IAT Sensor Location

1. Wiring Harness Connector

2. Air Cleaner Upper Housing

3. Mating Tang

4. Retainer

5. IAT Sensor

DTC 23 (Intake Air Temperature Sensor Signal Voltage High) will set if:

• IAT Sensor signal voltage is m ore than 4.9 volts, indicating an intake air temperature below -36°C f or more

than one second.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DTC 25 (Intake Air Temperature Sensor Signal Voltage low) will set if:

• IAT Sensor signal voltage is m ore less than 0.3 volts, indicating an intak e air temperature above 147°C for

more than one second.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DTC 26 (Intake Air Temperature Sensor Unstable Voltage) will set if:

• Engine run time is longer than 10 seconds.

• IAT Sensor reading changes more than 140 millivolts in 100 milliseconds

The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

One an IAT DTC is set, and current, the PCM will substitute an IAT value of 25°C.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

IF ANY OF THESE DTC(S) SET, THE PCM WILL DEFAULT TO A CALCULATED COOLANT TEMPERATURE

VALUE, ALLOWING THE VEHICLE TO OPERATE.

DTC 23, 25 AND 26 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED ECT SENSOR

TIME FROM START IAT SENSOR

TIMES OCCURRED BATTERY VOLTAGE

IGNITION CYCLES REFERENCE VOLTS

COOLANT TEMPERATURE

Figure 6C1-1-27 IAT Sensor Circui

SUPERVX002

F16

INTAKE AIR

TEMPERATURE SENSOR

SENSOR EARTH

IAT SEN SOR SIGNA L

PCM

BR (472)

B (46 9)

A/C PRESSURE

SENSOR AND

TFT SENSOR

YE23 YB188

YB194

MASS AIR FLOW (MA F) SENSOR

The Mass Air Flow (MAF) sensor used on these

engines utilises a heated element type of operation.

A heated element in the MAF is placed in the air

flow stream of the engine intake system. The

heating element is maintained at a constant

temperature differential above the air temperature.

The am ount of electric al power required to m aintain

the heated element at the proper temperature is a

direct function of the mass flow rate of the air past

the heated element.

Figure 6C1-1-28 Mass Air Flow Sensor

4216

Figure 6C1-1-29 MAF Sensor Location

1. MAF Sensor

Three sensing elements are used in this system.

One senses am bient air temperature and uses two

calibratable resistors to establish a voltage that is

always a function of ambient temperature. This

ambient sensor is mounted in the lower half of the

sensor housing. The other two sensing elements

are heated to a predetermined temperature that is

significantly above ambient air temperature. The

two heated elements are connected electrically in

parallel and mounted directly in the air flow stream

of the sens or housing. One sens or is in the top and

one sensor is in the bottom of the sensor housing.

This is done so that the air meter is less sensitive

to upstream ducting configurations that could skew

the flow of air through the housing.

As air passes over the heated elements during

engine operation they begin to cool. By measuring

the amount of electrical power required to maintain

the heated elements at the predetermined

temperature above ambient temperature the mass

air flow rate can be determined.

Once the mass air flow sensor has developed an

internal signal related to the mass air flow rate, it

must send this information to the PCM. In order to

preserve the accuracy and resolution of the small

voltage signal in the mass air flow sensor, it is

converted to a frequency signal by a voltage

oscillator and sent to the PCM.

4217

Figure 6C1-1-30 Sensing Elements

1. Ambient Temperature Sensor

2. Heater Sensing Elements

Figure 6C1-1-31 MAF Sensor Simplified Schematic

VXSC006A

D1A

PCM

EFI

RELAY

F33

BR/W (792)

MASS AIR FLOW

INP U T SIG NAL

EARTH

5 V

B/R (750)

LOC. E5/E15

MASS AIR F LOW SENSOR

P (43 9)

YB193

YB188

YE100

YE111

The signal that is sent from the mass air flow

sensor is sent in the form of a frequency output. A

large quantity of air passing through the sensor

(such as when accelerating) will be indicated as a

high frequency output. 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 MAF

sensor information in frequency, and in grams per

second and calculated in mg per cylinder. At idle

the readings should be low and increase with

engine RPM.

As the PCM receives this f requency signal from the

Mass Air Flow sensor, it searches its pre-

program med tables of inf ormation to determine the

pulse width of the fuel injectors required to match

the Mass Air Flow signal.

If a problem occurs in the Mass Air Flow sensor

circuit, after a period of time, the PCM will store a

DTC in its memory. The PCM will turn "ON" the

"Check Powertrain" lamp Malfunction indicator

Lamp (MIL) indicating there is a problem. If this

occurs, the PCM will calculate a "substitute" Mass

Air Flow signal based on engine speed and

Throttle Position (TP) sensor signal.

No field service adjustment is necessary or

possible with this Mass Air Flow sensor.

A failure in the Mass Air Flow sensor circuit should

set DTC 32 will set.

Remember, this DTC indicates a failure in the

circuit, so proper use of the diagnostic Table will

lead to either repairing a wiring problem or

replacing the MAF Sensor, to properly repair a

problem.

32 1

4219

Figure 6C1-1-32 Mass Air Flow Sensor Identification

1. Flow Stand Number

2. Last Four Digits Of Part Number

3. Year Julian Date

DTC 32 (Mass Air Flow System Performance) will set if:

• The engine is running.

• No MAF Signal for over two seconds.

• Above conditions present for at least 10 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

W hen a MAF sens or or circuit f ault is detected, and current, the PCM will subs titute a MAF sensor value based

on RPM, throttle angle and IAC position.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 32 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED R.H O2 SENSOR

TIME FROM START MASS AIR FLOW

TIMES OCCURRED R.H STFT

IGNITION CYCLES R.H LTFT

COOLANT TEMPERATURE THROTTLE ANGLE

Figure 6C1-1-33 MAF Sensor Circuit

THROTTLE POSITION (TP) SENSOR

The Throttle Position (TP) sensor is connected to

the throttle shaft on the throttle body unit. It is a

potentiometer with one end connected to 5 volts

from the PCM and the other end to PCM earth. A

third wire connects from a sliding contact in the T P

sensor to the PCM allowing the PCM to measure

the voltage from the TP sensor. As the throttle is

moved ( acceler ator pedal m oved), the output of the

TP sensor changes. At a closed throttle position,

the output of the TP sensor is below 1.25V. As the

throttle valve opens, the output increases so that,

at wide-open throttle (WOT), the output voltage

should be about 4 volts.

By monitoring the output voltage from the TP

sensor, the PCM c an determ ine fuel delivery based

on throttle valve angle (driver demand). A broken

or loose T P sensor c an cause intermittent bursts of

fuel from the injectors, and an unstable idle,

because the PCM interprets the throttle is moving.

Figure 6C1-1-34 TP Sensor

The TP sensor is not adjustable and there is not a

set value for voltage at closed throttle because the

actual voltage at closed throttle can vary from

vehicle to vehicle due to tolerances. The PCM has

a special progr am built into it that can adjus t for the

tolerances in the T P sensor voltage reading at idle.

The PCM uses the reading at closed throttle idle

for the zero reading (0% throttle) so no adjustment

is necessary. Even if the TP sensor voltage

reading was to be change by: tampering, throttle

body coking, sticking cable or any other reason,

the TP sensor will still be 0%. The PCM will learn

what the closed throttle value is every time the

throttle comes back to closed throttle. The new

closed throttle value will be used by the PCM and

no driveability complaint will be present because

the PCM learned a new setting.

A failure in the TP sensor circuit should set either

DTC 21 or 22.

If the internal spring in the TP sensor should fail,

the TP sensor will be stuck high. A sticking TP

sensor should set DTC 19.

4220

321

Figure 6C1-1-35 TP Sensor – Typical

1. Control Module

2. Throttle Position (TP) Sensor

3. Throttle Valve

VXSC006

MASS AIR FLOW SENSOR

PCM

CBA

AIR FLOW

FROM

AIR FILTER

AIR FLOW

THROTTLE BODY

EFI

RELAY

P (43 9)

LOC. E5/E15

BR/W (792)

MASS AIR FLOW

INPUT SIGNAL

EARTH

5 V

B/R (750)

F33

CIRCUIT

YB188

YE100

YE111 YB193

4221

Figure 6C1-1-36 TP Sensor Location

1. Idle Air Control (IAC) Valve

2. Throttle Position (TP) Sensor

3. Throttle Body

DTC 19 (Throttle Position Sensor Stuck) Sensor Low Voltage) will set if:

• The TP Sensor indicated percentage of opening is greater than the RPM that can be reached with a Mass

Air Flow of less than 301 mg/cyl.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DTC 21 (Throttle Position Sensor Signal Voltage High) will set if:

• The TP Sensor voltage between the PCM TP Sensor signal terminal and the TP Sensor earth terminal is

greater than 4.9 volts for more than two seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DTC 22 (Throttle Position Sensor Signal Voltage Low) will set if:

• The TP Sensor voltage between the PCM TP Sensor signal terminal and the TP Sensor earth terminal is

less than 0.2 volts for more than two seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

Once a T P Sens or DT C is set, and cur rent, the PCM will subs titute a T P Sensor value based on Idle Air Control

Valve position and Mass Air Flow.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 19, 21, AND 22 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED TP SIGNAL

TIME FROM START MASS AIR FLOW

TIMES OCCURRED R.H LTFT

IGNITION CYCLES BATTERY VOLTAGE

COOLANT TEMPERATURE REFERENCE VOLTS

Figure 6C1-1-37 TP Sensor Circuit

VEHICLE SPEED SENSOR (VSS)

The Vehicle Speed Sensor (VSS) is located on the

transm iss ion. Refer to F igure 6C1-1-38 f or the VSS

Location - Automatic Transmission and 6C1-1-39

for the VSS Location - Manual Transmission.

The VSS provides an indication of road speed to

the PCM. The sensor is mounted to the

transmission where it is gear driven by the

transmission output shaft. The sensor is an

electronic Hall effect switch that pulses to earth a

voltage signal c oming f rom the PCM. T hese pulses

occur 10 tim es per sens or revolution, and are used

by the speedometer for driver information.

The PCM also uses information from the VSS for

IAC valve operation and some of the engine

fuelling modes. If the PCM receives no pulses on

the vehicle speed sensor input while certain

conditions exist, DTC 24 (Automatic Transmission)

or DTC 94 (Manual Transmission) will be set.

DTC 24 or 94 will set if a fault exists in the vehicle

speed sensor circuit when the vehicle is

decelerated, and the VSS signal is constant, or not

pulsing. The DTC will set and a default value will

be substituted by the PCM. As long as the fault

remains and the diagnostic trouble code is set. If

the fault is removed, normal operation will resume

after the next ignition cycle

4222

Figure 6C1-1-38 VSS Location - Automatic Transmission

1. Vehicle Speed Sensor (VSS)

VXSC005

SENSOR EARTH

TP SENSOR SIGNAL

TP SENSOR

REFERENCE

VOLTAGE

PCM

THROTTLE

POSITION SENSOR

B11

E16

BLU (417)

B/Y (452)

GY (416)

ECT SENSOR

YB188

YB194

YE30

4223

Figure 6C1-1-39 VSS Location - Manual Transmission

1. Bolt

2. Sensor To Bracket Screw

The vehicle speed sensor contains a coil that has

continuous magnetic field. A voltage signal is

induced in the vehicle speed sensor by teeth on

the output shaft that rotate past the sensor and

break the magnetic field. Each break in the field

sends an electrical pulse to the PCM. This voltage

output will vary with transmission output shaft

speed f rom a m inim um of 0.5 volts AC at 100 RPM

to more than 100 volts AC at 8000 RPM with no

load on the c ircuit on the vehic le, with the engine at

4,000 RPM in fourth gear the voltage will be

approximately 10-12 Volts AC.

The PCM uses speed information from this sensor

to determine the following:

• Vehicle speed.

• Control shift points (Auto Trans).

• Calculate transmission slip (Auto Trans).

• Engine fuelling modes.

DTC 24 or 94 will set if a fault exists in the vehicle

speed sensor circuit indicating the vehicle is not

moving. For the automatic transmission, as the

vehicle is accelerated the PCM shifts the

transmission to second gear at approximately 50

km/h. If the vehicle speed signal is still not present

while in second gear, the DTC is set, the

transmission will have maximum line pressure, 2

ND gear only and have no TCC and a default value

will be substituted by the PCM.

DTC 72 will set if there is an intermittent failure in

the VSS c ircuit while the vehic le is moving. As long

as the fault remains and the DTC 72 is set, the

PCM will have max imum line press ure and 3rd gear

only for the automatic transmission. If the fault is

removed, normal operation will resume after the

next ignition cycle.

4224

Figure 6C1-1-40 VSS

1. “O” Ring

2. Electrical Connector

3. Magnetic Pickup

4. Rotor

DTC 24 (Vehicle Speed Sensor Circuit Low Voltage) will set if:

Automatic Transmission

• The transmission is not in Park or Neutral.

• The engine speed is greater than 3000 RPM.

• The TP Sensor angle is between 10% and 99%.

• The VSS indicates an output shaft speed of less than 3 km/h for 3 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DTC 94 (Vehicle Speed Sensor Circuit Low Voltage) will set if:

Manual Transmission

• The engine speed is between 1400 and 3000 RPM.

• The throttle is closed (throttle angle less than 1%).

• Engine load very low, MAF less than 95 mg/cyl.

• The VSS indicates no output shaft speed for more than 4 seconds.

• Vehicle in gear.

• Vehicle is decelerating from road speed.

DEFAULT VALUE

For the automatic transmission, when this DTC sets, the PCM will command second gear only, The PCM will

command maximum line pressure, The PCM will freeze shift adapts from being updated, The PCM will inhibit

TCC engagement.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 24, 94 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED THROTTL ANGLE

TIME FROM START TFT

TIMES OCCURRED MASS AIR FLOW

IGNITION CYCLES COMMANDED GEAR (AUTO)

COOLANT TEMPERATURE VEHICLE SPEED

DTC 72 (Output Speed Loss) will set if:

Automatic Transmission

• The transmission is not in Park or Neutral.

• Two successive speed readings have a difference of more than 1000 RPM in any drive range (difference

must be more than 2048 RPM in park or neutral). This test checks the vehicle speed sensor signal to the

PCM.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

W hen Diagnostic Trouble Code 72 is set, the transm ission will have maxim um line pressure and comm and 3rd

gear only. If DTC 72 is set while in 4th gear, the vehicle will stay in 4th gear. However, as the vehicle is c oasting

to stop the transm ission will downshif t normally from 4 to 3. Once the downshift into 3rd gear has occurred, the

vehicle will stay in 3rd gear.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 72 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED TRANSMISSION SLIP SPEED

TIME FROM START TFT

TIMES OCCURRED THROTTLE ANGLE

IGNITION CYCLES VEHICLE SPEED

COOLANT TEMPERATURE COMMANDED GEAR

Figure 6C1-1-41 VSS Circuit

V/W (123)

12V IGN

VEHICLE SPEED

SUPERVX016

INSTRUMENT

VEHICLE SPEED

PCM

EHICLE SPEED

SENSOR

BLU/W

(831)

(AUTO)

BLU

(831)

(MAN)

(832)

(AUTO)

(832)

(MAN)

SPEEDOMETER

YB193

YB195 (AUTO)

YB132 (MANUAL)

YE110

YB66

A/C REQUEST SIGNAL

W hen A/C is requested from the dash m aster A/C switch, the A/C request signal is sent to the BCM. The BCM

will then send a command via the serial data line to the PCM. The PCM will then supply a earth signal to the

A/C compressor relay, to energise the A/C compressor. There are no PCM DTC(s) associated with this A/C

Request Signal. Refer to Section 6C1-2A table A-11.1 or A 11.3 for A/C system diagnosis.

The PCM uses this BCM serial data command to:

1. Adjust the Idle Air Control (IAC) position to compensate for the additional load placed on the engine by the

air conditioning compressor, and then

2. Energises the A/C compressor relay, to operate the A/C compressor.

Figure 6C1-1-42 A/C Request Signal Circuit With ECC

B/Y (155)

B/G (151)

ELECTRONIC EARTH

HIGH CURRENT

EARTH

A1/A5

B10/B11

E3/D13

E9/D3

E2/D2

E20/D6

A5/A6

LOC. E3

LOC. E5/E15

LOC. E3

PCM

ECC

BCM

TO ABS/ETC

CONTROL MODULE

AND INSTRUMENTS

TO SRS

CONTROL

MODULE

DLC

SERIAL

DATA

A/C

ENABLE

SERIAL

DATA

SUPERVX018

SERIAL

DATA AUX .

R/B (1221)

G/W (1220)

SERIAL

DATA

MAIN

BATTERY

O/B (740)

(1040)

O/Y (479)

BATTERY MAIN POWER

R (2)

F14

F33

P/B

(39)

B/W

(152)

IGNITION ON

15a 15 50

30 ACC

IGN

START

IGNITION SWITCH

HIGH SERIES

BCM TERMINALS

NOM IN ATE D FIRS T

P (3)

A/C

COMPRESSOR

A/C RELAY

EFI

RELAY

F31

LG/B (366)

YB176

YB165

YB174

YB163

YB175

YB164

YB175

YB164

YB44

YB194

YB188

YB87

YE112

YE105 YE114

YE105

YE120 YE120

YB44

YE101

YE39

YE101

YB176

YB165

YB175

YB164

YE101YE101YE101

YE101

Figure 6C1-1-43 A/C Request Signal Circuit Without ECC

BATTERY VOLTAGE

The PCM continually monitors battery voltage. When the battery voltage is low, the ignition system may deliver

a weak spark and the injector mechanical m ovement takes longer to open the injector. The Powertrain Control

Module will compensate by:

1. Increasing the ignition coil dwell time if the battery voltage is less than 12 volts.

2. Increasing the engine idle RPM if battery voltage drops below 10 volts.

3. Increasing the injector pulse width if the battery voltage drops below 10 volts.

On vehicles equipped with automatic transmissions, Diagnostic Trouble Code 52 will set when the engine is

running and the voltage at PCM ter minal “ A4” is above 16 volts for 109 minutes. Diagnostic Trouble Code (DTC)

53 will set when the ignition is "ON'' and PCM terminal "A4'' voltage is more than 19.5 volts for about 2 seconds.

Diagnostic Trouble Code (DTC) 54 will set when the ignition is "ON'' and PCM terminal "A4'' voltage changed

more than 2.5 volts in 100 milliseconds.

Diagnostic T rouble Code (DT C) 75 will set when the ignition is "ON'' and PCM terminal "A4'' voltage is less than

8.6 volts for about 4 seconds . Minim um voltage allowed for Diagnos tic T rouble Code 75 to set is on a graduated

scale and will change with the tem perature. Minimum voltage at -40 degrees C is 7.3 volts, minim um voltage at

90 degrees C is 8.6 volts., minimum voltage at 152 degrees C is 11.4 volts.

SUPERVX019

D20

/C MASTER

SWITCH

HIGH SERIES

BCM TERMINALS

NOM IN ATE D FIRST

(291)

B/R

(292)

R/W

(248)

R/BR

(962)

(4)

(51)

BLOWER

MOTOR

RESISTORS

A/C

RELAY

EFI

RELAY

BLOWER

MOTOR

HEATER AND A/C

CONTROLS

BLOWER

INHIBIT

RELAY

DKG/Y (359)

LOC.E3

Y/B (52)

R/G (245)

LG/B (366)

R/Y (244) O/G

(251)

DKG/Y

(359)

BATTERY MAIN POWER

BATTERY

IGNITION SWITCH

F31

O/B

(740)

(1040)

BCM

B/G

(151) HIGH CURRENT

EARTH

IGNITION

DEMIST OUTPUT

DEMIST INPUT

A/C SWITCH INPUT

A/C LED OUTPUT

A/C BLOWER

INPUT

F14

F13

F33

E20/D6

A5/A6

E2/D2

B10/B11

A1/A5

P/B

(39)

15a 15 50

30 ACC

IGN

START

P (3)

R/B

(1221)

SERIAL DATA

A/C ENABLE

SERIAL

DATA

PCM

B/Y

(155) ELECTRONIC EARTH

R (2H)

R (2A)

P/BLU (44)

B (1 50)

YE120

YB188

YB194

YE105

YB2

YB2 YB50

YB50

YB163

YB176

YB165

YB175

YB164

YE101

YE39

YB44

YE101

YE120

YB44

YB54

YB54 YB165

YB175

YB164

YB176

YB165

YB164

YB163

DTC 52 (System Voltage Too High – Long Time) will set if:

• The engine is running and the PCM ignition voltage is greater than 16 volts for more than 109 minutes.

• The ECT sensor reading changes more than 400 mV in 200 milliseconds.

• Above conditions present for at least 10 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

During the time fault is present, the pressure control solenoid is turned "OFF", the transmission shifts

immediately to 3rd gear and TCC operation is inhibited.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 53 (System Voltage High) will set if:

• Ignition is on.

• Voltage at PCM ignition feed terminal is more than 19.5 volts for more than 2 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

During the time fault is present, the PCM will turn all transmission output devices off and freeze shift adapts

from being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 54 (System Voltage Unstable) will set if:

• Ignition is on.

• System voltage changes more than 2.5 volts in 100 millivolts.

• Above conditions present for at least 10 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

There are no default values.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 75 (System Voltage Low) will set if:

• The system voltage is less than 7.3 volts with the TFT at or above -40°C.

• The system voltage is less than 10 volts with the TFT at or below 151°C.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

When DTC 75 sets, the PCM will turn off all transmission output devices and freezes shift adapts from being

updated. The PCM will also adjust ignition timing and adjust injector pulse width to compensate for the low

voltage condition.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 52, 53, 54 AND 75 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED ECT SENSOR

TIME FROM START IAT SENSOR

TIMES OCCURRED BATTERY VOLTAGE

IGNITION CYCLES REFERENCE VOLTS

COOLANT TEMPERATURE

Figure 6C1-1-44 PCM Battery Feed

CRANKSHAFT REFERENCE SIGNAL

The Direct Ignition System (DIS) sends this signal to the PCM to tell it engine RPM and crankshaft position. This

signal is a repeating series of low voltage electrical pulses generated by the ignition module. The PCM initiates

fuel injector pulses based upon receiving these crankshaft reference signal pulses. If the PCM's MAF sensor

input detects manifold vacuum and the ignition voltage input detects less than 11 volts and there are no

distributor reference input pulses, a DTC 46 will set.

This engine also uses the c amshaf t position sensor signal to synchronise the f uel injector circ uits for sequential

fuel injection. The PCM also uses these reference pulses for Electronic Spark Timing (EST) operation.

For a full description of the ignition system operation Refer to 1.6 DIRECT IGNITION SYSTEM (DIS) of the VX

Series Service Information.

DTC 46 (No Reference Pulses While Cranking) will set if:

• MAF DTC is not set.

• Battery voltage is at or below 11 volts.

• MAF sensor input is above 2048 Hz.

• No DIS reference input pulses at PCM.

• Conditions exist for more than 2 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

SUPERVX017

# 2

# 4 # 6

# 1 # 3 # 5

PCM

B12

BATTERY FEED

(740)

BLU

(841)

(843)

(845)

INJECTOR CONTROL

IN JECTOR VOLTAGE

MONITOR LINE

IGNITION FEED

O/Y (479)

EFI R EL AY

B/W (152)

LOC. E4

P (3 )

O/B (740)

IGN SW

(481)

(39)

(846)

BR/Y

(844)

(842)

F31

F14

F34

BATTERY

R (2)

(1040)

YE112

YE114

YE111

YB194

YB188

YE39 YE39

YB188

DEFAULT VALUE

There are no default values for the Crankshaft Reference Signal. This DTC is intended to help in diagnosing a

no-start condition.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 46 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED REFERENCE VOLTS

TIME FROM START MASS AIR FLOW

TIMES OCCURRED CAM SIGNAL

IGNITION CYCLES FUELING MODE

COOLANT TEMPERATURE FUEL PUMP RELAY

BATTERY VOLTAGE

Figure 6C1-1-45 Crankshaft Reference Signal

VXSC009

PCM

D11

D12

D10

CRANKSHAFT

REFERENCE LO

CAM

SENSOR

CONNECTOR

CAMSHAFT

POSITION

SENSOR

SIGNAL

CRANKSHAFT

REFERENCE HI

CRANKSHAFT

18X SIGNAL

BYPASS CONTROL

EST OUTPUT

module power supply - in

sensor power supply - out

cam signa l - in

3x crank sensor - in

18x crank sensor - in

cam signal - out

tacho signal - out

crankshaft reference - out

18X cranksignal - out

bypass control

EST signal -in

DIS

MODULE

ABCD CBA

W/B (644)

GY/R (645)

B/R (453)

CRANK

SENSOR

CONN

L BLU/W

(646) BR (633)

BLU/Y (643)

BR (121)

B (63 0)

V (43 0)

L BLU/B (647)

T/B (4 24)

IGN SW

EFI RELAY

O/Y

(479)

(482)

B/W

(152)P/B

(39)

W (423)

F35

BATTERY

LOC. E1

(1040)

LOC. E3

P (3)

R(2H)

F14

TO INSTRUMENT CLUSTER

(TERMINAL 18)

ABS/ETC (TERMINAL 30)

YB39

YE111

YE34

YB193

YE63

YE57

ENGINE COOLI NG FAN SIGNAL

(LOW SPEED RESPONSE)

The engine c ooling low s peed fans are enabled when the low speed r elay is energized by the BCM. The PCCM

will request the BCM to turn the low speed engine cooling fan relay on or off, via the serial data bus normal

mode m essage. Af ter the PCM requests a change in the engine c ooling f an low speed relay, the BCM will send

a res ponse me ssage back to the PCM via the s erial data bus norm al mode m essage confir ming it received the

request. A failure in the response communication will set a DTC 92.

There are also four (4) suppression capacitors incorporated into the fan motor wiring circuits. These

suppress ion capacitor s help elim inate f an motor nois e through the radio speak ers. If these capacitors are open,

then noise will be present through the r adio speaker s. If shor ted to earth, the fan motor s could continuously run,

or the fuse or fusible link could fail.

DTC 92 (Low Speed Fan No BCM Response) will set if:

• Engine is idling.

• The PCM sends a request to the BCM to turn on the engine cooling fan low speed relay via the serial data

normal mode message and the BCM does not send a message back to the PCM.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

Once DTC 92 is set, the PCM will energize the engine cooling fan high speed relay.

RECOVERY

Recovery will occur on the next ignition cycle.

DTC 92 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED REFERENCE VOLTS

TIME FROM START MASS AIR FLOW

TIMES OCCURRED CAM SIGNAL

IGNITION CYCLES FUELING MODE

COOLANT TEMPERATURE FUEL PUMP RELAY

BATTERY VOLTAGE

Figure 6C1-1-46 Engine Cooling Fan Signal

VXSC032

BLU

(831)

(832)

VEHICLE SPEED

SENSOR

B/Y (452 )

B (469)

D11

C16

D10

Y (41O)

V/W (415)

G/B (259)

COOLANT TE MP

SENSOR

/C PRESSURE

SENSOR

BATTERY MAIN POWER

HIGH SERIES

BCM TERMINALS

NOMINATED FIRST

BCM

PCM

HIGH

SPEED

FAN

SERIAL DA TA

BLU/W (304)

IGNITION

15a 15 50

30 OFF/ON

LOCK

ACC

IGN

START

E20/D6

P/B

(39)

IGNITION SWITCH

87A

ENGINE

COOLING

FAN 1

ENGINE

COOLING

FAN RELAY

(LOW SPEED)

ENGINE

COOLING

FAN RELAY

(HIGH SPEED)

P/B (39)

F14

BLUE

FUSIBLE

LINK

LOC.

F31

A5/A6

O/B

(740)

ENGINE

COOLING

FAN 2

BATTERY

FT FAN 2

FU FAN 1

(1040)

O/B (740)

O/B

(208)

O/BLU

YE119

YB44

YE103

YE43

YB175

YB164

YB174

YB163

YB174

YB163

YE114

YE106

YE113

YE106

YB195

YB193

YB188

YB194

YB132

YB164

YB175

YB165

YB176

YB165

YE43

YB44

(204)

(203)

(2H)

LOW

SPEED FAN

B7/B7

R/B (1221) R/B

(1221) E2/D2 SERIAL DATA

HIGH

CURRENT EARTH

B/Y

(155) A1/A5 ELECTRONIC EARTH

B/G

(151)

LOC.

E2 LOC.

B10/B11

B/P (157)

O/B

(473)

ENGINE COOLI NG FAN

HIGH SPEED

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

Tem per ature Sensor ( ECT) . T he PCM will only turn "O N" the engine cooling fan high speed if the engine cooling

low speed fans have 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 failure is detected, such as DTC 14, 15, 16, 17 or 91.

• Coolant temperature greater than 107 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 high speed engine cooling fan relay can also be enable by the A/C Refrigerant Pressure Sensor. The

A/C Ref rigerant Press ure Sens or will enable high speed cooling f an, if the A/C system pres sur e becom es to

high.

There are also four (4) suppression capacitors incorporated into the fan motor wiring circuits. These

suppress ion capacitor s help elim inate f an motor nois e through the radio speak ers. If these capacitors are open,

then noise will be present through the r adio speak ers. Is shorted to earth, the fan motors could continuously run,

or the fuse or fusible link could fail.

DTC 91(QDSM Quad Driver Module) will set if:

• Engine run time is longer than 10 seconds.

• The ECT sensor reading changes more than 400 mV in 200 milliseconds.

• Above conditions present for at least 10 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DTC 91 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED REFERENCE VOLTS

TIME FROM START A/C RELAY

TIMES OCCURRED STARTER RELAY

IGNITION CYCLES PURGE PWM

COOLANT TEMPERATURE HIGH SPEED FAN

BATTERY VOLTAGE ACTUAL TORQUE

Figure 6C1-1-47 Engine Cooling Fan Signal

VXSC032

BLU

(831)

(832)

VEHICLE SPEED

SENSOR

B/Y (452 )

B (469)

D11

C16

D10

Y (41O)

V/W (415)

G/B (259)

COOLANT TE MP

SENSOR

/C PRESSURE

SENSOR

BATTERY MAIN POWER

HIGH SERIES

BCM TERMINALS

NOMINATED FIRST

BCM

PCM

HIGH

SPEED

FAN

SERIAL DA TA

BLU/W (304)

IGNITION

15a 15 50

30 OFF/ON

LOCK

ACC

IGN

START

E20/D6

P/B

(39)

IGNITION SWITCH

87A

ENGINE

COOLING

FAN 1

ENGINE

COOLING

FAN RELAY

(LOW SPEED)

ENGINE

COOLING

FAN RELAY

(HIGH SPEED)

P/B (39)

F14

BLUE

FUSIBLE

LINK

LOC.

F31

A5/A6

O/B

(740)

ENGINE

COOLING

FAN 2

BATTERY

FT FAN 2

FU FAN 1

(1040)

O/B (740)

O/B

(208)

O/BLU

YE119

YB44

YE103

YE43

YB175

YB164

YB174

YB163

YB174

YB163

YE114

YE106

YE113

YE106

YB195

YB193

YB188

YB194

YB132

YB164

YB175

YB165

YB176

YB165

YE43

YB44

(204)

(203)

(2H)

LOW

SPEED FAN

B7/B7

R/B (1221) R/B

(1221) E2/D2 SERIAL DATA

HIGH

CURRENT EARTH

B/Y

(155) A1/A5 ELECTRONIC EARTH

B/G

(151)

LOC.

E2 LOC.

B10/B11

B/P (157)

O/B

(473)

TRANSMISSION POWER/ECONOMY SWITCH

The Power/Economy switch is used to modify

upshifts and shift times. The driver can select

either Economy or Power mode with the switch (1)

located on the centre console. A third mode,

Cruise, is available via a switch located on the top

of the steering column.

Two green indicator lamps of 1.2 watts at 12 volts

are located in the instrument cluster and display

POWER or CRUISE when illuminated to inf orm the

driver of the mode that is enabled.

The PCM provides a voltage signal of about 12

volts, and monitors the status of this circuit. In the

Econom y pos ition, the switch is open and the PCM

voltage status signal remains high, about 12 volts.

The PCM does not allow shift point changes in the

economy mode. When the transmission switch is

pressed to the Power position the switch is

momentarily closed and the PCM voltage status

signal is mom entarily pulled low, to about 0.5 volts.

The PCM senses this voltage momentary voltage

drop and enables Power mode (alternate shift

pattern tables to be utilised).

In the Power mode, the TCC can be applied in 3rd

and 4th gears. When the TCC is applied in 3rd

gear it will stay applied until the normal 4th gear

upshift criteria is m et. W hen the 3-4 ups hift occ urs,

the TCC will be released momentarily. Also, in the

Power mode while in D gear select position, the

PCM will delay the 1-2 and 2-3 shift while under

light throttle. The shift patterns will be the same in

the Econom y and Power m odes if the TP sensor is

between 80% - 100%. The power mode should be

used when towing, as applying the TCC in 3rd and

4th gear reduces slippage in the TCC and thus

reduces heat build up.

In cr uise mode oper ation, when the driver activates

the cr uise c ontr ol, the power lamp and power m ode

will turn OFF (if vehicle was in power mode) and a

CRUISE lamp will illuminate on the instrument

panel. The transmission shift pattern will switch to

cruise shift pattern. W hen in cruise mode the PCM

will modify the transmission calibration so that

transmission shift activity is reduced.

W hen the k ey is turned O N, the PCM shift m ode is

set to the last mode that was previously selected

(Power/Econom y). The cruise control is set to OFF

at every key ON cycle.

For replacement of the Power/Economy switch,

Refer to Section 7C4 AUTOMATIC

TRANSMISSION - ON VEHICLE SERVICE in VX

Service Information..

GE N 3 0154

Figure 6C1-1-48 Transmission Power/Economy Switch

1. Automatic Transmission Power/Economy Switch

Figure 6C1-1-49 Transmission Power/Economy Switch Wiring

THEFT DETERRENT INPUT SIGNAL

When the ignition switch is turned to the “ON” position, the BCM polls the PCM and sends an encrypted

BCM / key security code. The security code is received by the BCM, via the remote k ey reader (slip ring) or via

the remote receiver in the event of no slip ring communication.

The PCM compares the received security code with its stored security code and if matched, the PCM will

continue to enable injector fuelling and engine crank.

The PCM will return a Valid Code message (OK TO START), which tells the BCM to jump to the short loop

mode to the long loop mode.

W hen the ignition s witch is turned fr om the O FF position to the ON pos ition, the BCM will com munic ate with the

PCM for antitheft purposes. If the BCM does not receive the message OK TO START from the PCM within 0.5

seconds of the ignition being switched on, the auxiliary bus is isolated via switching within the BCM.

The isolation of the auxiliary data bus during this period eliminates the possibility of a device failure other than

the BCM or PCM causing a problem on the bus and inhibiting antitheft communications.

This period is k nown as “Short Loop T im e”, and continues until the PCM responds with an ack nowledgm ent or a

maximum of 5 seconds, after which the BCM will switch to the standard poling sequence.

Following successful antitheft communications, the BCM begins sequential poling of devices on the bus and

normal system operation is established.

DTC 31 will set when the PCM at ignition ON sends 20 m essages to the BCM and does not receive a m essage

back saying it is OK to start.

SUPERVX006A1

INSTRUMENT

PCM

SERIAL

DATA

12V IGN

G/W (1 220) R/B (1221)

POWER

POWER/ECONOMY

SWITCH

12V

F12

A3 SERIAL

DATA

BLU (774)

BCM

D2 E9

YB188

YB194YE112

YE30

YB34

YB175

YB164 YB175

YB164

YB34

YB66

YB30

YE114

Figure 6C1-1-50 Theft Deterrent System

1. Remote Receiver Module

2. Remote Coded Key Reader Assembly

3. Code From Remote Coded Key

4. BCM

5. Is It OK To Start

6. OK To Start, Don’t Start

7. Theft Deterrent Alert Indicator LED

8. Enable Or Disable Fuel System Control And Starter Motor

9. Powertrain Control Module (PCM)

10. Remote Coded Key

DTC 31 (Theft Deterrent Signal Missing) will set if:

• The ignition is on.

• The PCM sends 20 messages to the BCM and does not receive a message back saying its OK to start.

• Conditions present for at least 10 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

There are no default value for DTC 31, the engine will not start if DTC 31 is current.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 31 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED REFERENCE VOLTS

TIME FROM START MASS AIR FLOW

TIMES OCCURRED CAM SIGNAL

IGNITION CYCLES FUELING MODE

COOLANT TEMPERATURE FUEL PUMP RELAY

BATTERY VOLTAGE

4225

CODE

SECURITY

Figure 6C1-1-51 Theft Deterrent Serial Data Circuit

VXSC033

PCM

BCM

SERIAL

DATA

STARTER

ENABLE

SERIAL

DATA

MAIN

BATTERY

LOC.

F31

A5/A6O/B (740)

(1040)

BATTERY MAIN POWER

R (2H)

F14

E20/D6P/B (39) IGNITION ON

15a 15 50

30 ACC

IGN

START

IGNITION SWI TCH

P (3)

LOC. G1

E2/D2

R/B (1221)

GY/BLU

(1434)

(434)

NEUTRAL START

BACK-UP SW.

( MANUAL

TRANS)

STARTER

MOTOR

START

RELAY

V (5)

V/W

(6)

36 85

HIGH SERIES

BCM TERMINALS

NOMINA TED FIRST

YE111 YB194

YB188

YB175

YB164

YB175

YB164

YB176

YB165

YE112

YB44

YE49

YB35 YB35

OIL PRESSURE SWITCH

The instruments receive oil pressure switch status

information from the PCM via the serial data bus

normal mode message. The PCM monitors the

voltage at terminal E12 to determine the status of

the oil pressure switch. When the oil pressure

switch is open the voltage at E12 will be 12 volts,

when the switch closes the voltage at term inal E12

will be pulled low, le3ss than 0.2 volts via circuit 31

(Blue wire) and the oil pressure switch.

This low voltage is seen by the PCM as an oil

pressure switch closed input signal. When the

PCM sees this low voltage at terminal E12 the

PCM will command the instruments to turn the oil

pressure warning lamp on, when the PCM sees a

high voltage at terminal E12 the PCM will

command the instruments to turn the oil pressure

warning lamp off, via the serial data bus normal

mode message.

There are no PCM trouble codes for this oil

pressure switch .

Figure 6C1-1-52 Oil Pressure Warning Lamp

Figure 6C1-1-53 Oil Pressure Warning Lamp

VXSC008

INSTRUMENT

PCM

SERIAL

DATA

12V IGN

G/W (1220) R/B (1221)

OIL PRESSURE

SWITCH

12V

E12

A3 SERIAL

DATA

BLU (31)

BCM

YB66

YE33

YB175

YB164 YB175

YB164 YB188

YB194

1.3 AUTOMATIC TRANSMISSION INFORMATION SENSORS & SIGNALS

1-2 (A) AND 2-3 (B) SHIFT SOLENOID VALVES

IMPORTANT:

The shift solenoid valve resistance should measure

19-24 ohm s minim um when m easured at 20°C (68°F ).

The shift solenoid current flow should not exceed 0.75

amps. The shift solenoid should energise at a voltage

of 7.5 volts or more (measured across the terminals).

The shift solenoid should de-energise when the

voltage is one volt or less.

If both solenoids lose power, third gear only results.

The 1-2 and 2-3 shift solenoid valves (also called A

and B solenoids) are identical devices that control the

mo vement of the 1-2 and 2- 3 shift valves (the 3-4 shift

valve is not directly controlled by a shif t solenoid). The

solenoids are normally open exhaust valves that work

in four combinations to shift the transmission into

different gears.

The PCM energises each solenoid by grounding the

solenoid through an internal quad driver. This sends

current through the coil winding in the solenoid and

moves the internal plunger out of the exhaus t position.

When ON, the solenoid redirects fluid to move a shift

valve.

IMPORTANT:

The manual valve hydraulically can override the shift

solenoids. Only in D4 do the shift solenoid states

totally determine what gear the transmission is in. In

the other manual valve positions, the transmission

shifts hydraulically and the shift solenoid states

CATCH UP when the throttle position and the vehicle

speed fall into the correct ranges. Diagnostic trouble

codes 81 and 82 indicate shift solenoid circuit voltage

faults.

The PCM-controlled shift solenoids eliminate the need

for TV and governor pressures to control shift valve

operation.

8885

Figure 6C1-1-54

DTC 81 (2-3 Shift Solenoid Circuit Electrical) will set if:

• The PCM commands the solenoid ON and the voltage input remains high (B+).

• The PCM commands the solenoid OFF and the voltage input remains low (0volts)

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

When this DTC sets, the PCM will command D2 line pressure, The PCM inhibits 3-2 downshift if the vehicle

speed is greater than 48 km/h, The PCM will freeze shift adapts from being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 81 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED TCC SOLENOID

TIME FROM START THROTTLE ANGLE

TIMES OCCURRED VEHICLE SPEED

IGNITION CYCLES COMMANDED GEAR

COOLANT TEMPERATURE

DTC 82 (1-2 Shift Solenoid Circuit Electrical) will set if:

• The PCM commands the solenoid ON and the voltage input remains high (B+).

• The PCM commands the solenoid OFF and the voltage input remains low (0volts)

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

When this DTC sets, the PCM will command 3rd gear only, The PCM commands maximum line pressure, The

PCM will inhibit TCC engagement, The PCM will freeze shift adapts from being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 82 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED 2-3 SHIFT SOLENOID

TIME FROM START THROTTLE ANGLE

TIMES OCCURRED VEHICLE SPEED

IGNITION CYCLES COMMANDED GEAR

COOLANT TEMPERATURE

Figure 6C1-1-55 Transmission Solenoid Circuits

3–2 Down shift

Control

Solenoid

1–2 Shift

Solenoid A

2–3 Shift

Solenoid B

YB 12 9 Tran s mis sion

Pass-Thru Connector

Torque

Converter

Clutch (TCC)

(PWM)

Solenoid

Torque

Converter

Clutch (TCC)

Enable

Solenoid

Pressure

Control

Solenoid A

SUPER4284-1

EF32 EFI

Relay

P/BLU

(339)

G/W (897)

LG (1222)

Y/B (1223)

GY/R (422)

BR (418)

R (1228)

GY/BLU (1229)

C13 3–2 Control

Solenoid

1–2 Shift

Solenoid

2–3 Shift

Solenoid

TCC Enable

Solenoid

TCC PWM

Solenoid

Pressure Control

Solenoid High

Pressure Control

Solenoid Low

C15

E15

E14

PCM

12V

YB194

YB110

YB193

3-2 SHIFT SOLENOID VALVE ASSEMBLY

IMPORTANT:

The 3-2 shift solenoid valve assembly resistance

should be a minimum of 20-24 ohms at 20°C (68°F).

The 3-2 shift solenoid valve assembly is an ON/OFF

solenoid that is used in order to improve the 3-2

downshift. T he s olenoid regulates the release of the 3-

4 clutch and the 2-4 band apply.

If a voltage fault is detected in the 3-2 shift solenoid

circuit, diagnostic trouble code 66 will set.

325350

Figure 6C1-1-56

DTC 66 (3-2 Shift Solenoid Circuit Electrical) will set if:

• The PCM commands the solenoid ON and the voltage input remains high (B+).

• The PCM commands the solenoid OFF and the voltage input remains low (0volts)

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

W hen this DTC sets, the PCM will comm and a soft landing to 3rd gear, The PCM will inhibit TCC engagement,

The PCM c omm ands maxim um line pr essure, The PCM inhibits 4th gear if the transm iss ion is in hot mode, T he

PCM will freeze shift adapts from being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 66 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED TFT

TIME FROM START THROTTLE ANGLE

TIMES OCCURRED VEHICLE SPEED

IGNITION CYCLES COMMANDED GEAR

COOLANT TEMPERATURE

Figure 6C1-1-57 Transmission Solenoid Circuits

TRANSMISSION PRESSURE CONTROL SOLENOID

IMPORTANT:

Transmission pressure control solenoid resistance

should measure 3-5 ohms when measured at 20°C

(68°F).

The transmission pressure control solenoid is an

electronic pressure regulator that controls pressure

based on the current flow through its coil winding. The

magnetic field produced by the coil moves the

solenoid's internal valve, which varies pressure to the

pressure regulator valve.

The PCM controls the pressure control solenoid by

commanding current between 100 and 1100

milliam ps. This c hanges the duty c ycle of the solenoid,

which can range between 5 percent and 95 percent

(typically less than 60 percent). 1100 milliamps

corresponds to minimum line pressure, and 100

milliamps corresponds to maximum line pressure (if

the solenoid loses power, the transmission defaults to

maximum line pressure).

The PCM commands the line pressure values, using

inputs such as the throttle position sensor. The

pressure control solenoid takes the place of the

throttle valve or the vacuum modulator that was used

on the past model transmissions.

If the duty cycle drops below 5 percent or rises above

95 percent, DTC 73 will set.

325352

Figure 6C1-1-58

3–2 Down shift

Control

Solenoid

1–2 Shift

Solenoid A

2–3 Shift

Solenoid B

YB 12 9 Tran s mis sion

Pass-Thru Connector

Torque

Converter

Clutch (TCC)

(PWM)

Solenoid

Torque

Converter

Clutch (TCC)

Enable

Solenoid

Pressure

Control

Solenoid A

SUPER4284-1

EF32 EFI

Relay

P/BLU

(339)

G/W (897)

LG (1222)

Y/B (1223)

GY/R (422)

BR (418)

R (1228)

GY/BLU (1229)

C13 3–2 Control

Solenoid

1–2 Shift

Solenoid

2–3 Shift

Solenoid

TCC Enable

Solenoid

TCC PWM

Solenoid

Pressure Control

Solenoid High

Pressure Control

Solenoid Low

C15

E15

E14

PCM

12V

YB194

YB110

YB193

DTC 73 (PC Solenoid Circuit Electrical) will set if:

• No DTC 75 is set.

• The system voltage is between 10 and 16 volts.

• The engine is running.

• The PC s olenoid valve duty cycle reaches its high lim it (approxim ately 95%) or low lim it (appr oximately 0%)

for 200 milliseconds.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

W hen this DTC sets , the PCM will comm and the PC solenoid valve O FF, The PCM will f reeze shift adapts f rom

being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 73 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED COMMANDED PCS

TIME FROM START ACTUAL PCS

TIMES OCCURRED THROTTLE ANGLE

IGNITION CYCLES VEHICLE SPEED

COOLANT TEMPERATURE COMMANDED GEAR

Figure 6C1-1-59 Transmission Solenoid Circuits

3–2 Down shift

Control

Solenoid

1–2 Shift

Solenoid A

2–3 Shift

Solenoid B

YB 12 9 Trans mis sion

Pass-Thru Connector

Torque

Converter

Clutch (TCC)

(PWM)

Solenoid

Torque

Converter

Clutch (TCC)

Enable

Solenoid

Pressure

Control

Solenoid A

SUPER4284-1

EF32 EFI

Relay

P/BLU

(339)

G/W (897)

LG (1222)

Y/B (1223)

GY/R (422)

BR (418)

R (1228)

GY/BLU (1229)

C13 3–2 C ontrol

Solenoid

1– 2 Shift

Solenoid

2– 3 Shift

Solenoid

TCC Enable

Solenoid

TCC PWM

Solenoid

Pressure Control

Solenoid High

Pressure Control

Solenoid Low

C15

E15

E14

PCM

12V

YB194

YB110

YB193

TORQUE CONVERTER CLUTCH SOLENOID VALVE

IMPORTANT:

The TCC solenoid resistance should be 21-26 ohms

minimum when measured at 20°C (68°F).

There are two DTCs associated with the TCC

solenoid. The first DTC is 67, TCC enable solenoid.

DTC 67 is designed to detec t a f ault in the TCC enable

solenoid electrical circuit. While DTC 67 is set, the

PCM will inhibit 4th gear if the transmission is in hot

mode, and no TCC operation. The second DTC

associated with the TCC enable solenoid is DTC 69,

TCC stuck on. DTC 69 is designed to detect TCC

enable solenoid that does not disengage. It does this

by m onitor ing engine RPM when the TCC comm anded

on. If the engine speed does not rise when the TCC

solenoid is dis engaged the DT C 69 will set. While DT C

69 is s et, the TCC will be on in all gears or 2 nd, 3rd, and

4th depending upon the failure, and the transmission

will have an early shift pattern.

The torque converter clutch solenoid valve is a

normally open exhaust valve that is used to control

torque converter clutch apply and release. When

grounded (energised) by the PCM, the TCC solenoid

valve stops converter signal oil from exhausting. This

causes converter signal oil pressure to increase and

shifts the TCC solenoid valve into the apply position.

The brak e s witch is an input to the PCM, and the PCM

directly controls the TCC apply based on the brake

switch status.

8882

Figure 6C1-1-60

TORQUE CONVERTER CLUTCH PWM SOLENOID VALVE

IMPORTANT:

TCC PW M solenoid valve resistance should be 10-11

ohms when measured at 20°C (68°F), and 13-15

ohms when measured at 100°C (212°F).

The torque converter clutch PWM solenoid valve

controls the fluid acting on the converter clutch valve,

which then controls the TCC apply and release. This

solenoid is attached to the control valve body

assembly within the transmission.

The TCC PWM solenoid valve provides smooth

engagement of the torque converter clutch by

operating on a negative duty cycle a variable percent

of ON time.

If a fault is detected in the TCC PW M circuit, code 83

will set

325355

Figure 6C1-1-61

DTC 67 (TCC Enable Solenoid Circuit Electrical) will set if:

• The engine is running.

• Battery voltage is between 10 and 16 volts.

• The PCM commands the solenoid ON and the voltage input remains high (B+).

• The PCM commands the solenoid OFF and the voltage input remains low (0volts).

• Conditions are met for 5 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

When this DTC s ets, the PCM will inhibit TCC engagem ent, T he PCM will inhibit 4th gear if the tr ans mission is in

hot mode, The PCM will freeze shift adapts from being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 69 (TCC System Stuck ON) will set if:

• No TP DTCs set.

• No VSS DTCs set.

• No TFP Valve Position Switch DTC 28 is set.

• No TCC Solenoid Valve DTC 67 is set.

• No TCC PWM Solenoid Valve DTC 83 is set.

• The TP angle is greater than 25%.

• The engine RPM is greater than 450 for 8 seconds.

• The commanded gear is not 1st.

• The gear range is D4 or D3.

• The PCM commands TCC OFF.

• The Trans slip speed is –20 to +20 RPM.

• All conditions are met for 4 seconds.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

When this DTC sets, the PCM will freeze shift adapts from being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 83 (TCC PWM Solenoid Circuit ) will set if:

• The system voltage is 8-18 volts.

• The engine speed is greater than 300 RPM for 5 seconds.

• The engine is not in fuel cutoff.

• The PCM commands first gear.

• The TCC duty cycle is less than 10% or greater than 90%.

• The PCM commands the solenoid ON and the voltage input remains high (B+).

• The PCM commands the solenoid OFF and the voltage input remains low (0volts).

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

When this DTC s ets, the PCM will inhibit TCC engagem ent, T he PCM will inhibit 4th gear if the tr ans mission is in

hot mode, The PCM will freeze shift adapts from being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 67 , 69 AND 83 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED TCC SOLENOID

TIME FROM START THROTTLE ANGLE

TIMES OCCURRED VEHICLE SPEED

IGNITION CYCLES COMMANDED GEAR

COOLANT TEMPERATURTE

Figure 6C1-1-62 Transmission Solenoid Circuits

3–2 Down shift

Control

Solenoid

1–2 Shift

Solenoid A

2–3 Shift

Solenoid B

YB 12 9 Tran s mission

Pass-Thru Connector

Torque

Converter

Clutch (TCC)

(PWM)

Solenoid

Torque

Converter

Clutch (TCC)

Enable

Solenoid

Pressure

Control

Solenoid A

SUPER4284-1

EF32 EFI

Relay

P/BLU

(339)

G/W (897)

LG (1222)

Y/B (1223)

GY/R (422)

BR (418)

R (1228)

GY/BLU (1229)

C13 3–2 Control

Solenoid

1–2 Shift

Solenoid

2–3 Shift

Solenoid

TCC Enable

Solenoid

TCC PWM

Solenoid

Pressure Control

Solenoid High

Pressure Control

Solenoid Low

C15

E15

E14

PCM

12V

YB194

YB110

YB193

TRANSMISSION FLUID PRESSURE (TFP) MANUAL VALVE POSITION SWITCH

IMPORTANT:

Seven valid combinations and two invalid

combinations are available from the TFP manual

valve position switch. Refer to the T FP Manual Valve

Position Switch Logic table below for valid/invalid

combinations for range signal circuits A, B and C.

Gear

Position Range

Signal A Range

Signal B Range

Signal C

Park Open 12 V Closed 0 V Open 12 V

Reverse Closed 0 V Closed 0 V Open 12 V

Neutral Open 12 V Closed 0 V Open 12 V

D Open 12 V Closed 0 V Closed 0 V

3 Open 12 V Open 12 V Closed 0 V

2 Open 12 V Open 12 V Open 12 V

1 Closed 0 V Open 12 V Open 12 V

Invalid Closed 0 V Open 12 V Closed 0 V

Invalid Closed 0 V Closed 0 V Closed 0 V

The transmission fluid pressure (TFP) manual valve

position switch is a set of five pressure switches on the

control valve body that sense whether fluid pressure is

present in five different valve body passages. The

combination of which switches are open and closed is

used by the PCM in order to determine actual manual

valve position. The TFP manual valve position switch,

however, cannot distinguish between PARK and

NEUTRAL because the monitored valve body

pressures are identical in both cases.

The s witches are wired to provide three signal lines that

are monitored by the PCM. These inputs are used to

help control line pressure, torque converter clutch apply

and shift solenoid valve operation. Voltage at each of

the signal lines is either zero or twelve volts.

In order to monitor the TFP manual valve position

switch operation, the PCM compares the actual voltage

com bination of the switches to a T FP com bination table

stored in its m em ory. If the PCM s ees one of two illegal

voltage combinations, a DTC 28 will result. A DTC 28

indicates a short circuit condition in either the range

signal A or the range signal C circuits.

The TFP manual valve position switch signal voltage

can be measured from each pin-to-ground and

compared to the combination table. On the automatic

transmission (A/T) wiring harness assembly, pin N is

range signal A, pin R is range signal B, and pin P is

range signal C. With the A/T wiring harness assembly

connected and the engine running, a voltage

measurement of these three lines will indicate a high

reading (near 12 volts ) when a circuit is open, and a low

reading (zero volts) when the circuit is switched to

ground.

8889

Figure 6C1-1-63

The transmission fluid temperature (TFT) sensor is

part of the TFP manual valve position switch assembly.

DTC 28 (TFP Valve Position Switch Circuit ) will set if:

Condition 1

• The PCM detects an illegal TFP manual valve position switch state for 60 seconds.

Condition 2

• The engine speed is less than 80 RPM for 0.1 second; then the engine speed is 80-550 RPM for 0.07

seconds; then the engine speed is greater than 500 RPM.

• The vehicle speed is less than 3 km/h.

• The PCM detects a gear range of D2, D4, or Reverse during an engine start.

• All conditions are met for 5 seconds.

Condition 3

• The TP angle is 8-45%.

• The PCM commands 4th gear.

• The TCC is locked ON.

• The speed ratio is 0.65-0.8 (speed ratio is engine speed divided by transmission output speed).

• The PCM detects a gear range of Park or Neutral when operating in D4.

• All conditions are met for 10 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

W hen this DTC sets, the PCM will comm and D2 line pressure, T he PCM will com mand a D4 shift pattern, The

PCM will freeze shift adapts from being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 28 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED PRNDL SWITCH

TIME FROM START TFT

TIMES OCCURRED VEHICLE SPEED

IGNITION CYCLES COMMANDED GEAR

COOLANT TEMPERATURE

Figure 6C1-1 64 TFP Switch Assembly

SUPERVX034

PCM

F10

F16

TFP SIGNAL A

TFP SIGNAL B

TRANSMISSION FLUID

TEMPERATURE (TFT)

SENSOR SIGNAL

SENSOR EARTH

TRANSMISSION FLUID

TEMPERATURE

(TF T ) SENSOR

AUTOMATIC TRANSMISSION FLUID

PRESSURE SWITCH ASSEMBLY

BR/Y (1224)

Y (1225)

GY (1226)

B/Y (1227)

B (46 9)

12V

F11 TFP SIGNAL C

12V

/C PRESSURE SENSOR

AND IAT SENSOR

YB194

YB129

YB188

YB194

VEHICLE SPEED SENSOR

IMPORTANT:

The sensor resistance is model dependent and varies

with speed from a minimum of 0.5 volts AC at 100

RPM to more than 100 volts AC at 8000 RPM.

The vehicle speed sensor (or transmission output

speed sensor) controls shift points and calculates the

TCC slip. The speed sensor contains a coil that gives

off a continuous magnetic f ield. A r otor r otates past the

sensor and the rotor teeth break the magnetic field.

Each break in the field sends a pulse to the VSSB

(Vehicle Speed Sensor Buffer). The VSSB sends two

signals to the PCM. The first is a 2002 pulse per mile

(PPM) signal that is used by the engine. The second is

the transmission/transfer case 40 pulse per revolution

(PPR) signal that is used in order to control the

transmission.

The vehicle speed sensor is located on the

transmission extension housing. Trans Output Speed

= Transfer Case Speed.

DTC 24 will set if a fault exists in the vehicle speed

sensor circuit 40 PPR line. DTC 94 will set for the

manual transmission Vehicle Speed Sensor.

62801

Figure 6C1-1-65

DTC 24 (Vehicle Speed Sensor Circuit Low Voltage) will set if:

Automatic Transmission

• The transmission is not in Park or Neutral.

• The engine speed is greater than 3000 RPM.

• The TP Sensor angle is between 10% and 99%.

• The VSS indicates an output shaft speed of less than 3 km/h for 3 seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DTC 94 (Vehicle Speed Sensor Circuit Low Voltage) will set if:

Manual Transmission

• The engine speed is between 1400 and 3000 RPM.

• The throttle is closed (throttle angle less than 1%).

• Engine load very low, MAF less than 95 mg/cyl.

• The VSS indicates no output shaft speed for more than 4 seconds.

• Vehicle in gear.

• Vehicle is decelerating from road speed.

DEFAULT VALUE

For the automatic transmission, when this DTC sets, the PCM will command second gear only, The PCM will

command maximum line pressure, The PCM will freeze shift adapts from being updated, The PCM will inhibit

TCC engagement.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 24 AND DTC 94 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED THROTTLE ANGLE

TIME FROM START TFT

TIMES OCCURRED MASS AIR FLOW

IGNITION CYCLES COMMANDED GEAR (AUTO)

COOLANT TEMPERATURE VEHICLE SPEED

Figure 6C1-1-65 VSS Circuit

V/W (123)

12V IGN

VEHICLE SPEED

SUPERVX016

INSTRUMENT

VEHICLE SPEED

PCM

EHICLE SPEED

SENSOR

BLU/W

(831)

(AUTO)

BLU

(831)

(MAN)

(832)

(AUTO)

(832)

(MAN)

SPEEDOMETER

YB193

YB195 (AUTO)

YB132 (MANUAL)

YE110

YB66

AUTOMATIC TRANSMISSION FLUID TEMPERA TURE SENSOR

The automatic transm ission fluid tem perature (TFT ) sens or is part of the automatic transm ission fluid pres sure

(T FP) m anual valve position switch as sem bly. T his sensor helps control tor que converter clutc h apply and shif t

quality. The TFT sensor is a resistor, or thermistor, which changes value based on temperature. At low

temperatures the resistance is high, and at high temperatures the resistance is low.

The PCM sends a 5 volt signal to the TFT sensor and the PCM measures the voltage drop in the circuit. You

will measure a high voltage when the transmission is cold and a low voltage when the transmission is hot.

Refer to the Temperature Vs Resistance table in Section 6C1-4.

If the TFT sensor circuit has a fault, DTC 58 or 59 is set. A DT C 58 indicates a short circuit condition, while a

DTC 59 indic ates an open circ uit condition. DT C 79 is set if the trans m ission is oper ating at a high temperatur e

for a period of time.

DTC 58 (TFT Sensor Circuit Low) will set if:

• The TFT sensor indicates a signal voltage less than 0.2 volts for 10 seconds.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

When this DT C s ets , the PCM uses a tr ansmiss ion f luid temperature def ault value bas ed on engine c oolant, engine

run time and IAT at startup, the PCM will freeze shift adapts from being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 59 (TFT Sensor Circuit High) will set if:

• The TFT sensor indicates a signal voltage greater than 4.92 volts for 6.8 minutes (409 seconds).

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

When this DT C s ets , the PCM uses a tr ansmiss ion f luid temperature def ault value bas ed on engine c oolant, engine

run time and IAT at startup, the PCM will freeze shift adapts from being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 58 AND 59 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED TFT

TIME FROM START THROTTLE ANGLE

TIMES OCCURRED VEHICLE SPEED

IGNITION CYCLES COMMANDED GEAR

COOLANT TEMPERATURE

DTC 79 (Transmission Fluid Overtemperature) will set if:

• The TFT is greater than 130° C for 10 minutes (600 seconds).

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

When this DTC sets, the PCM will freeze shift adapts from being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 79 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED TFT SENSOR

TIME FROM START TFT

TIMES OCCURRED THROTTLE ANGLE

IGNITION CYCLES COMMANDED GEAR

COOLANT TEMPERATURE

Figure 6C1-1-66 TFT Sensor

DTC 85 (Transmission Slipping) will set if:

• No Throttle Position DTCs 21 or 22.

• No VSS assembly DTCs 24 or 72.

• No TCC solenoid valve DTC 67.

• No 1-2 SS valve DTC 81.

• No 2-3 SS valve DTC 83.

• No 3-2 SS valve assembly DTC 66.

• No TCC PWM solenoid valve DTC 83.

• The engine speed is greater than 300 RPM for 5 seconds.

• The engine is not in fuel cutoff.

• The vehicle speed is 56-105 km/h.

• The speed ratio is 0.67-0.90 (the speed ratio is the engine speed divided by the transmission output speed).

• The engine speed is 1200-3500 RPM.

• The engine torque is 54-542 N.m.

• The gear range is D4.

• The commanded gear is not 1st gear.

• The Throttle Position angle is 10-50%.

• The TFT is between 20-130°C.

• DTC P1870 sets if the following conditions occur for three TCC cycles.

- The TCC is commanded ON for 5 seconds.

- The TCC is at maximum duty cycle for 1 second.

- The TCC slip speed is 80-800 RPM for 7 seconds.

SUPERVX034

PCM

F10

F16

TFP SIGNAL A

TFP SIGNAL B

TRANSMISSION FLUID

TEMPERATURE (TFT)

SENSOR SIGNAL

SENSOR EARTH

TRANSMISSION FLUID

TEMPERATURE

(TF T ) SENSOR

AUTOMATIC TRANSMISSION FLUID

PRESSURE SWITCH ASSEMBLY

BR/Y (1224)

Y (1225)

GY (1226)

B/Y (1227)

B (46 9)

12V

F11 TFP SIGNAL C

12V

/C PRESSURE SENSOR

AND IAT SENSOR

YB194

YB129

YB188

YB194

IMPORTANT:

The following actions may occur before the DTC sets:

• If the TCC is commanded ON and at maximum duty cycles for 5 seconds, the TP angle is 10-40%, and the

transm ission slip counter has incremented to either 1 or 2 (out of 3 to increm ent the fail counter for the current

ignition cycle), then the following slip conditions and actions may increment the fail counter for the current

ignition cycle:

- Condition 1: If the TCC slip speed is 80-800 RPM for 7 seconds, then the PCM will comm and maximum

line pressure and freeze shift adapts from being updated.

- Condition 2: If condition 1 is met and the T CC slip speed is 80- 800 RPM f or 7 seconds, then the PCM will

command the TCC OFF for 1.5 seconds.

- Condition 3: If condition 2 is met and the TCC slip speed is 80-800 RPM for 7 seconds, then the fail

counter on the current ignition cycle is incremented.

The above s lip conditions and ac tions m ay be disregarded if the T CC is c om m anded OF F at any time as a result of

a driving maneuver (sudden acceleration or deceleration).

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

W hen this DTC sets, the PCM inhibits TCC engagement, the PCM com mands maximum line pressure, The PCM

inhibits 4th gear if the transmission is in hot mode, the PCM will freeze shift adapts from being updated.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 85 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED TRANSMISSION SLIP SPEED

TIME FROM START TFT

TIMES OCCURRED THROTTLE ANGLE

IGNITION CYCLES VEHICLE SPEED

COOLANT TEMPERATURE COMMANDED GEAR

TRANSMISSION PASS-THRU CONNECTOR

The transmission electrical connector is an important

part of the transmission operating system. Any

interference with the electrical connection can cause

the transmission to set Diagnostic Trouble Codes

(DTCs) or affect proper operation.

The following items can affect the electrical

connection:

• Bent pins in the connector from rough handling

during connection and disconnection

• Wires backing away from the pins or coming

uncrimped (in either the internal or the external

wiring harness)

• Dirt contamination entering the connector when

disconnected

• Pins in the inter nal wiring connector back ing out of

the connector or pushed out of the connector

during reconnection

• Excessive transmission fluid leaking into the

connector, wicking up into the external wiring

harness and degrading the wire insulation

• Moisture intrusion in the connector

• Low pin retention in the external connector from

excessive connection and disconnection of the

wiring connector assembly

• Pin corrosion from contamination

• Damaged connector assembly

13265

Figure 6C1-1-67

Remember the following points:

• In order to rem ove the connector, squeeze the two

tabs toward each other and pull s traight up without

pulling by the wires.

• Limit twisting or wiggling the connector during

removal. Bent pins can occur.

• Do not pry the connector off with a screwdriver or

other tool.

• Visually inspect the seals to ensure that they are

not damaged during handling.

• In order to reinstall the external wiring connector,

first align the pins by lining up the arrows on each

half of the connector. Push the connector straight

down into the transmission without twisting or

angling the mating parts.

• The connector should click into place with a

positive feel and/or noise.

IMPORTANT:

Whenever the transmission external wiring connector

is disconnected from the internal harness and the

engine is operating, DTCs will set. Clear these DTCs

after reconnecting the external connector.

1.4 FUEL CONTROL SYSTEM

PURPOSE

The purpose of closed loop fuel control is to control tailpipe emissions consisting of hydrocarbons (HC), Carbon

Monoxide (CO), and Oxides of Nitrogen (NOx). At the same time, the system must achieve good engine

performance and good fuel economy.

The closed loop system regulates exhaust emissions by controlling the air/fuel ratio at an optimum level during

various driving c onditions. The most ef f ic ient air/f uel r atio to minimise exhaus t emiss ions is 14.7 to 1, this allows the

3-way catalytic converter to operate at maximum efficiency to control exhaust pollutants. Because of the constant

measuring of the exhaust gases by the oxygen sensors, and adjusting of the fuel injector pulse width by the PCM,

the fuel injection system is called a "closed-loop" control system.

FUNCTION

The fuel supply system delivers fuel at a regulated pressure to the fuel rail. The fuel injectors, located directly

ahead of each inlet port of the cylinder head, act as fuel flow control valves, "spraying" atomised fuel into the inlet

ports when they are electrically "pulsed" by the PCM. On this engine, all injectors ar e wired individually so they are

pulsed individually. This type of fuel injec tion is ref erred to as sequential injection because pulsation of the injector s

are individually controlled and in a specific order.

The PCM controls the am ount of fuel inj ected into the engine by controlling the length of tim e the injectors are held

open. This "length-of-time" is called PULSE WIDTH. To increase the amount of fuel injected, the pulse width is

lengthened, and vic e versa. T he pulse width is calibratable and varies between 0 - 11 m illiseconds with the engine

running at idle, and injection pulses normally occur once every crankshaft revolution.

MASS AIR FLOW SYSTEM

The Holden/Delco Fuel Injection system is a Mass Air Flow system. The system is based upon an Air Meter that

measures the mass air flow rate of the engine directly.

Advantages of Mass Air Flow:

• Base engine components can be changed.

• Automatically compensates for engine aging.

• No air measurement lag time.

• Excellent idle stability.

Two specific data sensors provide the PCM with the basic information for the fuel management portion of its

operation. That is , two specific signals; crank shaf t referenc e signal from the ignition system , and the Mass Air Flow

(MAF) s ensor signal. Both of these s ignals to the PCM establish the engine speed and mass of air ingested by the

engine. Due to the additional temper ature compens ation sensor in the MAF sens or, this sys tem does not require a

manifold absolute pressure sensor.

The engine speed signal comes from the ignition module to the PCM on the crankshaft reference signal input

circuit. The PCM uses RPM information to calculate the best fuel injector pulse width and spark timing for a given

operating RPM band.

The mass of air ingested by the engine is sent as a signal from the mass air flow sensor to the PCM.

When the engine is started, the PCM will im m ediately look at the Engine Coolant Tem per ature sens or to determ ine

how much fuel is required to start the engine. After the engine is started, the PCM will constantly monitor the MAF

sensor values to determine both the spark advance and engine fuelling requirements. The Mass Air Flow sensor

measures the mass of air ingested

into the engine. The PCM then calculates how much fuel that must be injected to maintain an air/fuel ratio of

14.7 to 1. An engine started in cold weather will require more fuel and spark advance than an engine started hot,

which requires less fuel and less spark advance.

One sensor is used to m eas ure the density factor, the Mas s Air F low (MAF) sens or. T he m ass air flow sensor used

on this engine utilises a heated element type of operation. Three sensing elements are used in this system.

As air passes over the heated elements during engine operation they begin to cool. By measuring the amount of

electrical power required to maintain the heated elements at the predetermined temperature above ambient

temperature mass air flow rate can be determined.

As the PCM receives this frequenc y s ignal from the mas s air flow sens or, it searches its pre-progr amm ed tables of

information to determine the pulse width of the fuel injectors required to match the mass air flow signals.

The s ignal that is s ent f r om the m as s air flow sensor is sent in the form of a f r equenc y output. A large quantity of air

passing through the sensor (such as when accelerating) will be indicated as a high frequency output. A small

quantity of air passing through the sensor will be indicated as a low frequency output (such as deceleration or at

idle. The T ech 2 scan tool disp lays MAF sens or inform ation in frequency, grams per second. A "norm al" reading is

approximately 4 - 9 grams per second at idle and increases with engine RPM.

The remaining sensors and switches provide electrical inputs to the PCM which are used for modification of the

air/fuel mixture as well as for other PCM control functions, such as Idle Air Control (IAC).

MODES OF OPERATION

The PCM looks at voltage signals from several sensors to determ ine how m uch fuel to give the engine, and when

to operate in the open- loop or closed-loop m odes. The fuel deliver y is contr olled in one of several possible m odes.

All the modes are controlled by the PCM, and are described in the following paragraphs.

STARTING MODE

W hen the ignition key is first turned "ON," the PCM will energise the fuel pump relay, and the fuel pump will build

up pressure to the fuel rail. The PCM then checks the engine coolant temperature sensor and determines the

proper injector pulse width for starting the engine.

When cranking begins, the PCM will operate in the Starting Mode until engine RPM is more than about 400, -or-

the "Clear Flood" mode is enabled. After the ignition is turned "ON" and the first reference signal is received, the

PCM will pulse all of the fuel inj ectors . After the firs t prim e puls e has been injec ted, the PCM will wait until the PCM

receives a good camshaft position signal. When the PCM receives a good camshaft position signal, the PCM

operates the fuel injectors in Sequential mode. Pulse width during the Starting Mode is between approxim ately 4 -

26 milliseconds, depending upon engine coolant temperature.

CLEAR FLOOD MODE

If the engine floods, it can be started by pushing the accelerator pedal down all the way to the floor while cranking

the engine. The PCM then pulses the injectors with zero millisecond pulse width, which should "clear" a flooded

engine. The PCM holds this pulse width as long as the throttle position sensor input indicates the throttle is above

80% and RPM is below 400.

If the throttle is held wide-open while attempting to make a normal start with a non-flooded engine, the

engine will not start.

NORMAL OPEN LOOP MODE

After the engine is running (RPM more than 400), the PCM will operate the fuel control system in the Open Loop

mode. In open loop, the PCM ignores the signal from the Oxygen Sensor (O2S), and calculates the air/fuel ratio

injector pulse width based on inputs from the crankshaft reference signal (RPM input) and these sensors: MAF,

IAT, ECT, and TP sensor.

The system will stay in the Open Loop m ode until all the Closed Loop mode criteria have been m et, or not at idle,

refer Open Loop Idle Mode description.

In open loop, the calculated puls e width may give an air/fuel ratio other than 14.7 to 1. An example of this would be

when the engine is cold, because a richer mixture is needed to ensure good driveability.

The normal open loop mode is not active when adverse or abnormal vehicle operating conditions are occurring

adverse conditions include engine overheating due to high vehicle speed or high ambient temperature.

OPEN LOOP IDLE MODE

The reas on for the Idle Mode is to allow a slightly richer mix ture at idle for better idle quality. Idle Mode air/fuel ratio

is about 14.0 to 1. This is an open loop mode, meaning the O2 sensor signal is ignored.

The Open Loop Idle Mode is in effect when the throttle is closed (TP Sensor), and vehicle speed is below 5 km/h

(VSS).

In the c ase where the vehicle r olls to a st op while operating in the Closed Loop m ode, Idle Mode will be delayed f or

about 20-30 seconds. During this time, the PCM will "learn" a fuel correction factor for a 14.7 to 1 air/fuel ratio

before switching to the Idle Mode.

CLOSED LOOP MODE

In Closed Loop mode, the PCM initially calculates injector pulse width based on the same sensors used in open

loop. The difference is that in closed loop, the PCM uses the Exhaust Gas Oxygen Sensor (O2S) signal to modif y

and precisely fine tune the fuel puls e width calculations in order to pr ecisely maintain the 14.7 to 1 air/fuel ratio that

allows the catalytic converter to operate at it's maximum conversion efficiency.

DELTA TPS ACCELERATION MODE

The PCM look s at rapid changes in throttle position (TP sensor) to increase engine power, and provides extra fuel

by inc reasing the injector pulse width. If the increas ed fuel requirem ents are gr eat enough, the PCM may add extra

fuel injection pulses between the injector pulses that normally occur once per crankshaft revolution.

LEAN CRUISE AIR/FUEL MODE

During steady state cruising, the air/fuel ratio is made lower in order to increase fuel economy .

The engine will operate in Lean Cruise when:

• ECT is greater than 80 degrees C.

• VSS is greater than 70 km/h.

• Engine has been running longer than 2 minutes and 30 seconds.

• Calculated A/F ratio is 14.8 to 1

• Engine is not in power enrichment mode.

If all the criteria are met, the PCM will lean out the A/F ratio by 0.1 ratio every 0.2 second until it reaches its

maximum total enleanment.

DECELERATION MODE

W hen deceleration occurs, the fuel remaining in the intake manifold can cause excessive emissions and possibly

backfiring. Again, the PCM looks at changes in throttle position (TP sensor) and engine RPM and reduces the

amount of fuel by decreasing the pulse width, but does not completely shut off the fuel.

DECEL FUEL CUTOFF MODE

Decel fuel cutoff disables fuel delivery during a deceleration to reduce emissions and to improve fuel economy.

When deceleration from road speed occurs, the PCM can cut off fuel pulses completely for short periods. The

decel fuel cutoff mode occurs when all these conditions are met:

1. Coolant temperature above 63 degrees C.

2. Engine RPM has dropped more than 200 RPM.

3. Vehicle speed above 42 km/h.

4. Throttle is less than 2 %.

When the decel fuel cutoff is in effect, any one of these can cause the injection pulses to restart.

1. Engine RPM has not dropped more than 200 RPM.

2. Vehicle speed is less than 42 km/h.

3. Throttle is open at least 2%.

PARK/NEUTRAL TO DRIVE ACCELERATION ENRICHMENT MODE

The PCM will deliver additional fuel to the engine to reduce the RPM droop associated with a transmission shift

from park/neutral to a drive shift. This mode will only add fuel based on the first 32 reference pulses after a shift

has been detected.

POWER ENRICHMENT (PE) MODE

The Power Enrichment (PE) mode delivers a rich mixture to the cylinders during a large throttle position change

command from the driver. During PE, the PCM will not make fuelling changes based on the oxygen sensor signal.

BATTERY VOLTAGE CORRECTION MODE

At low battery voltages, the ignition system m ay deliver a weak spar k, and the injector m echanical movem ent tak es

longer to "open." The PCM will compensate by:

• Increasing ignition coil dwell time if voltage is less than 12 volts.

• Increasing idle RPM if voltage drops below 10 volts.

• Increasing injector pulse width if voltage drops below 10 volts.

FUEL CUTOFF MODE

No fuel is delivered by the injectors when the ignition is (OFF). This prevents dieseling. Also, fuel pulses are not

delivered if the PCM receives no distributor reference pulses from the ignition module, which means the engine is

not running.

The Fuel Cutoff Mode is also enabled at:

• High engine RPM, as an overspeed protection for the engine. When cutoff is in effect due to high RPM,

injection pulses will resume after engine RPM drops slightly.

• High vehic le speed. When the vehic le speed ex c eeds a calibr atable value the f uel bas e puls e width is set equal

to zero. Normal fuel operation will return when the vehicle speed falls below a calibratable value.

SEQUENTIAL FUEL INJECTION MODE

When the engine is first cranked over, all injectors will be energised simultaneously. After the engine has been

started and a good camshaft signal has been processed, the PCM will energise each individual injector in the

normal firing order. This mode of operation helps to stabilize idle, reduce em issions and reduce fluctuations in fuel

pressure.

CAMSHAFT POSITION SENSOR

The Camshaft Position Sensor is located in the

engine front cover, behind and below the water

pump, near the camshaft sprocket.

As the cam shaf t spr ock et turns, a m agnet mounted

on it activates the Hall Ef f ec t s witch in the c amshaf t

position sensor. When the Hall Effect switch is

activated, it earth's the signal line to the DIS

module, pulling the camshaft position signal line's

applied voltage low. This is interpreted as a

camshaft position signal (Synchronisation Pulse).

Because of the way the signal is created by the

camshaft position sensor, the signal circuit is

always either at a high or low voltage (square wave

signal).

While the camshaft sprocket continues to turn, the

Hall Eff ect switch turns "OFF" as the m agnetic f ield

passes the camshaft position sensor, resulting in

one signal each time the camshaft makes one

revolution.

The camshaft position signal, which actually

represents camshaft position due to the sensor's

mounting location, is used by the PCM to properly

time its sequential fuel injection operation.

Refer to Figs. 6C-1-1-13 and 6C1-1-14 in this

Section for camshaft position sensor location and

camshaft position signal details.

When the camshaft position signal is not received

by the PCM, a DTC 48 will be set. An intermittent

cam shaft pos ition signal will set a DTC 49. If either

of these DTC's are set, the fuel system will not be

in sequential fuel injection mode.

4205

Figure 6C1-1-68 Camshaft Position Sensor

1. Camshaft Position (CMP) Sensor

ADAPTIVE LEARNING

Adaptive learning is the ability of the on-board computer to determine and remember its most recent operating

experience. The PCM uses this rem em bered inform ation to "learn from experience" and to m ake adjustm ents with

respect to what it learnt. If the engine were to develop a restricted fuel filter, the PCM will change the fuel injector

pulse width richer to compensate for this condition and will remember to keep this fuel injector pulse in memory

until the restriction is corrected. After the restriction has been fixed, the PCM will eventually go back to the original

pre-programmed fuel injector pulse.

Adaptive learning is an on-going process that continues throughout the life of the engine. A new engine with good

com pres sion will have good vacuum . As the engine wears and c om press ion decreas es, a slight decrease in engine

vacuum will be noticed, which translates into a slightly lower MAF grams per second at idle, which will decrease

injector pulse width to compensate for this condition.

SHORT TERM FUEL TRIM

Short T erm Fuel Trim (STFT) represents short term corrections to the fuel injector pulse width calculations, based

on the oxygen sensor input signal to the PCM.

When the engine is started cold, in "Open Loop," the PCM will control the fuel injection pulse width based upon

various sensor inputs such as RPM, ECT, MAF and TP sensor until the oxygen sensors become hot enough

(approximately 315 degrees C) to operate properly. During this "Open Loop" period, both Short Term Fuel Trim

(STFT) and Long Term Fuel Trim (LTFT) are disabled and will read 0% on a Tech 2 scan tool.

When the oxygen sensor has come up to its normal operating temperature (approximately 600 degrees C or

above), it will produce a varying voltage to the PCM and provide a good indication of what has happened in the

combustion chambers.

At this time the PCM will switch from "Open Loop" to "Closed Loop" and the STFT will start to constantly monitor

the oxygen sensor signal, so that the PCM can m odif y fuel inj ector pulse width with greater acc uracy than in "Open

Loop".

STFT monitors the oxygen sensor signal so that it can adjust the fuel injector pulse width to maintain an air/fuel

ratio of 14.7 to 1 f or maximum catalytic converter efficiency. An ST FT value of 0% is equivalent to an air/fuel ratio

of 14.7 to 1 and an average oxygen sensor signal voltage of 450 mV.

The normal pos ition f or Short Term Fuel Trim is 0%, any change from this value indic ates the Short T er m Fuel Trim

is c hanging the f uel injec tor pulse width. The am ount of pulse width change depends upon how far the ST FT value

is f r om 0%. If the STFT value is above 0%, the f uel inj ec tor puls e width is being inc reas ed, thus adding more f uel. If

the STFT value is below 0%, the fuel injector pulse width is being decreased, thus removing fuel. The normal

operating range of STFT is considered to be between -22% and +25% ; any value out of this range is usually

caused by a malfunction.

If an engine has a r est ric ted f uel f ilter , the low fuel pr es s ure will res ult in les s f uel being inj ect ed and allows more air

into the air c harge than is needed to ignite the am ount of f uel the f uel injector has injec ted, theref ore, a lean air/f uel

ratio exists in the combustion chamber. After combustion has taken place, the exhaust gases still contain more

oxygen content than nor mal and the oxygen sensor reads this as low voltage, say 200 m V. The STF T detects that

the oxygen sensor s ignal is low and will increas e the value to ric hen up the air /f uel mixtur e. On a Tech 2 s c an tool it

will display STFT as a value above 0%. This STFT change will increase the injector pulse width allowing the fuel

injectors to stay open longer and inject more fuel.

If the additional fuel was injected and the oxygen sensor signal voltage is still low, the STFT will continue to

increase its value until the oxygen sensor signal voltage goes above 450 m V. If the STFT continues to detect a low

oxygen sensor signal voltage it will continue to tr y and compensate f or the lean exhaus t condition until it runs out of

its authority in the particular Long Term Fuel Trim (LTFT) cell it's operating in. At this point, the PCM will reset

STFT to 0% and go through this procedure again until it can control the system.

If after a specif ied am ount of resets have been tr ied and failed, the PCM k nows that it cannot control f or the failure

and the STFT will remain at its maximum value.

STFT values are bas ed on the oxygen s ensor signal voltage reading, ther efore, ST FT is used by the PCM to m ake

quick changes to the fuel injector pulse width over a short period of time.

LONG TERM FUEL TRIM

Long Term Fuel Trim is used to adjust for engine to engine variation and to adjust for engine aging. LTFT is a

portion of the PCM memory used to adjust fuel delivery across all operating conditions of the engine. The PCM

monitors the STFT and will adjust the long term trend of the fuel injector pulse width if the STFT has been at a

value for a certain period of time. LTFT is used to change the long term fuel injector pulse width and is only

operational when the fuel control system is in "Closed Loop." A normal LTFT value is 0% and should follow the

STFT value.

If an engine has a restricted f uel filter, the low fuel pres sure will result in less f uel being injected and will cause the

STFT value to go higher than 0%, say 2%. If this STFT value change does not compensate for the restricted fuel

filter, the PCM will continue to increase the STFT value. The STFT may climb as high as its maximum calibrated

value if there is a severe restriction. The PCM will continue to monitor STFT as it climbs, but it will not make any

changes to the f uel injector puls e width for a specif ic period of time. Af ter a specific period of time has elapsed and

the STFT value has remained above say +8%, the LTFT will move up to say 4% and wait again to detect if the

STFT has dr opped bac k down to 0%. If not, the ST F T will gradually move toward its m a ximum calibr ated value limit

until it gains control of the fuel injection system. If STFT and LTFT are both set at their maximum value limit, the

fuel control system is "out of the limits of control" and will set either a Diagnostic Trouble Code (DTC) 44, or DTC

64 (lean exhaust) or DT C 45, or DTC 65 (rich exhaust) and go into "open loop" operation. Under the conditions of

power enrichment, (Wide Open Throttle, WOT), the PCM sets the STFT to 0% and freezes it there until power

enrichment is no longer in effect. This is done so that LTFT will not try to correct for the commanded richness of

power enrichment.

The PCM will keep the latest LT FT values stored in its LT FT mem ory cells. MAF sens or readings and engine RPM

are used by the LTFT to determ ine what cell to read. LTFT values are stored in the PCM's long term m emory, for

use each time the engine's RPM and load matches one of the LTFT cells. All LTFT values are reset to 0% when

the PCM's "long term memory power supply" is disconnected, as when diagnostic trouble codes are cleared. The

Tech 2 scan tool also has the ability to reset LTFT to 0% with a special command.

+ 1% 0%

–

-2%

–

-1%

+ 2%

–

-1%

+ 1%

+ 2%

–

-1%

–

-2%

+ 1%

1314

22 23

+ 1%

4227

Figure 6C1-1-69 Long Term Fuel Trim Values

1. Light % Canister Purge

2. Heavy % Canister Purge

3. Hysteresis

4. 4 km/h

5. High

6. 1000 RPM

7. Vehicle Speed

8. Low

9. RPM

10. 0 RPM

11. 4000 RPM

12. 2000 RPM

13. 975 RPM

14. 17 G/S

15. AirFlow

16. 25 G/S

17. 45 G/S

18. 0G/S

19. Throttle Position

20. 9 G/S

21. 0%

22. 0 km/h

LONG TERM FUEL TRIM CELLS

The Long Term Fuel Trim function of the PCM is divided up into cells arranged by a Mass Air Flow (MAF) and

Engine Speed (RPM). Each cell corresponds to a region on a MAF vs RPM table. Each region is calibrated to a

LTFT value of 0%. A value of 0% in a given block indicates no fuel adjustment is needed for that engine load

condition. A higher number, say + 4%, indicates that the PCM has detected a lean exhaust indication under those

conditions, and is adding fuel (increasing fuel injector pulse width) to compensate. Conversely, a lower number,

say -6%, indicates that the PCM has detected a rich exhaust indication under those load conditions, and is

subtracting fuel (decreasing fuel injector pulse width) to compensate.

As the vehicle is driven from a standing start and accelerated or decelerated from various engine speeds, the

engine's LTFT calibration will change from one cell to another cell. As the LTFT changes cell so does STFT,

however, STFT will only make short term corrections in whatever LTFT cell the engine is operating in. When the

engine is idling, it can be in one of two cells. On a vehicle with automatic transmission, depending upon canister

purge, the engine will idle in cell 0 or 17. If the engine was running at idle and the canister purge was "ON", we

would be in cell number 0 on an automatic transmission equipped vehicle. Cells 16 and 33 are used for idle on

vehicles with manual transmission only. Whatever cell the engine is operating in, the PCM will read that cell's

particular LTFT value and electronically adjust the fuel injector base pulse width to compensate for a rich or lean

condition in the engine. If an engine has a restricted fuel f ilter and the customer has driven the vehicle like this f or

quite some time, the STFT value would be high, and the PCM would be compensating for this condition by adding

more fuel. Because the STFT value is above 0%, LTFT will also be greater than 0% in most of the cells to

compensate for the lean exhaust. If you suspect a driveability problem associated with an over rich or over lean

condition, then use the STFT value to detect what the fuel control system is doing at the present time. Use the

LTFT to identify what the system has "learned" over a greater period of time to compensate for the condition.

Use the LTFT cells to determine if the fuel control system is commanding rich or lean throughout the operating

range. If it is only rich or lean at idle or part throttle, look for components that would cause problems in these areas.

All LT FT c ell values are rese t to 0% when long term mem or y power to the PCM is rem oved, s uch as when clearing

DTC's.

The Tech 2 scan tool has the ability to reset all LTFT cells to 0% with a special command.

A system malf unction that causes too great a dif ference between the right and lef t Short Term Fuel Trim values or

too great a difference between the right and left Long Term Fuel Trim values will set either a DTC 78 or DTC 76.

CELL

15 CELL

CELL

1314

22 23

CELL

4228

21 18

Figure 6C1-1-70 Long Term Fuel Trim Cell Matrix

1. Light % Canister Purge

2. Heavy % Canister Purge

3. Hysteresis

4. 4 km/h

5. High

6. 1000 RPM

7. Vehicle Speed

8. Low

9. RPM

10. 0 RPM

11. 4000 RPM

12. 2000 RPM

13. 975 RPM

14. 17 G/S

15. AirFlow

16. 25 G/S

17. 45 G/S

18. 0G/S

19. Throttle Position

20. 9 G/S

21. 0%

22. 0 km/h

DTC 76 (Short Term Fuel Trim (STFT) Delta High) will set if:

• The lef t hand short term fuel trim value varies from the right hand short term fuel trim value by m ore than 63%

for more than 32 seconds

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DTC 78 (Long Term Fuel Trim (LTFT) Delta High) will set if:

• The lef t hand long ter m f uel trim value varies f rom the r ight hand long term f uel trim value by mo re than 59% for

more than 32 seconds

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

Once DTC 76 or 78 are set, and current, the PCM will operate the fuel system in the open loop mode.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 76 AND 78 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED L.H STFT

TIME FROM START R.H LTFT

TIMES OCCURRED L.H LTFT

IGNITION CYCLES R.H O2 SENSOR

R.H STFT L.H O2 SENSOR

BASIC FUEL SYSTEM OPERATION

The f uel control system starts with the fuel in the f uel tank. A single in- tank high pressure fuel pum p (located inside

a m odular s ender unit) is used. From the high pressur e pump, f uel flows through a f uel filter, then on to the engine

fuel rail through the fuel pressure supply line.

The high pressure in-tank single pump is capable of providing fuel at more than 414 kPa. A pressure regulator

connects between the fuel rail and the return fuel line, and keeps fuel available to the injectors at a regulated

pressur e between 270 and 350 k Pa. The regulated pres sure will vary, depending on intake manif old pres sure. The

pressur e regulator senses manif old pressur e through a sm all hose connecting it to the thr ottle body adapter. When

throttle body adapter pressure is low (closed-throttle), the regulated pressure is at its lowest. W hen the throttle is

wide open, intake manifold pressure is high and the fuel pressure also is at its highest.

Fuel in ex ces s of inj ec tor needs is r eturned to the f uel tank by the separate return line connec ted to the outlet of the

pressure regulator.

The injectors, located in each runner of the intake manifold just ahead of the inlet ports to the cylinder head, are

controlled by the PCM. They deliver fuel in one of several modes, as described previously.

The fuel pum p is energised by the PCM via the fuel pum p relay. Refer to Diagnosis TABLE A 4.1 of the VX Ser ies

Service Information for further diagnosis of the fuel pump electrical system.

SYSTEM COMPONENTS

The Fuel Control System is made up of the following components:

• PCM

• Fuel pressure supply line

• Fuel pump relay

• Fuel rail

• Injectors

• Modular Fuel Sender Assembly

• Fuel Pump

• Fuel pressure regulator

• Fuel filter

• Fuel return line

• Swirl pot

Prior To Starting Engine, Check Fuel System For Leaks As Follows:

1. Turn Ignition “ON”.

2. Check Fuel System For Leaks, Particularly At Points Marked In Figure 6C1-1-71, With Fuel Pump Running.

3. Repair Leaks If Present.

4229

Figure 6C1-1-71 Fuel Delivery System

1. V6 Supercharge Engine

2. Fuel Pump

3. Fuel Pump Harness Connector

4. V6 Non-Supercharge Engine

5. Fuel Tank

6. Vent Tube

7. Vapour Tube

8. Fuel Filter

MODULAR FUEL SENDER ASSEMBLY

The modular fuel sender assembly is attached to

the top of the f uel tank, and extends f rom the top of

the fuel tank to the bottom.

The modular fuel sender assembly consists of the

following major components:

• A Fuel Sender Cover

• Fuel Pipes (above cover)

• A Fuel Pump

• A Fuel Pump Strainer

• A Fuel Pump Reservoir

• A Fuel Sender Strainer

• A Ceramic Fuel Level Sensor Assembly

The fuel level sender assembly consists of the

following:

• A Float

• The Wire Float Arm

• A Rheostat

The fuel level is sensed by the position of the float

and float arm, position changes, the amount of

current passing through the rheostat varies, thus

changing the fuel gauge reading on the instrument

panel.

The V6 Supercharged Engine application uses a

ROLLERVANE f uel pump. T his fuel pum p can only

be serviced as a complete unit with the sender unit

assembly.

Figure 6C1-1-72 Modular Sender Assembly

Figure 6C1-1-73 Fuel Pump/Sender Assembly

1. Fuel Feed 2. Fuel Return

3. Flex Pipe (Convoluted Fuel Tube) 4. External Strainer

5. External Filter 6. Umbrella Valve

7. Fuel Entering Umbrella Valve 8. Fuel Pump Strainer

9. Fuel Pump

4230

Figure 6C1-1-74 V6 Supercharge Engine Rollervane Fuel Pump Assembly

1. Aluminum Shell 2. Inlet

3. Impeller 4. Pump Housing

5. Rivets 6. Plate Face

7. Bearing 8. Rotor & Sleeve

9. Outlet Plate 10. Roller

11. Ring (Eccentric) 12. Fuel Pump Flex Pipe Attaches Here

13. End Cap Assembly 14. Crossover Pipe Attached Here

15. Armature 16. Flux Carrier & Magnets

THROTTLE BODY UNIT

The throttle body unit is made up of one casting

assembly, with two electrical components

connected to it. They are:

1. An Idle Air Control ( IAC) valve to control air flow

bypassing around the throttle blade. This

"bypass" airflow provides the air requirements

for the engine when the throttle is closed. More

"bypass" air gives the engine the ability of a

higher idle speed, while lower flow rates of this

"bypass" air give lower idle speeds. The IAC

acts as an PCM-controlled bypass air valve,

allowing the PCM to control idle speed.

2. A Throttle Position Sensor, which gives the

PCM information about current throttle position,

and if the throttle is m oving (opening or closing) .

The PCM can also determine how quickly the

throttle is opening or closing with this signal.

The throttle body contains 2 vacuum ports. The

small port provides manifold vacuum to the

evaporative em ission's canister purge solenoid. T he

larger port is for the positive crankcase ventilation

system.

4221

Figure 6C1-1-75 Throttle Body with TPS and IAC

1. Idle Air Control (IAC) Valve

2. Throttle Position (TP) Sensor

3. Throttle Body

4231

There are specific throttle body assemblies for

vehicles with automatic and manual transmission.

Identification is by a drill point marking on the

throttle used for vehicles with manual transmission.

4233

Figure 6C1-1-76 Throttle Body Identification

1. Drill Point

IDLE INSPECTION

For this V6 application, the engine idle must be

checked every 80,000km. If the Idle Air Control

(IAC) Valve steps displayed on the Tech 2 are

greater than 25 at idle, the throttle body will need to

be removed and cleaned. For throttle

body cleaning procedure, Refer to

Section 6C1-3 SERVICE OPERATIONS of the VX

Series Service Information.

Ther e is a specific thro ttle body assem bly for this V6

application. Although the throttle body for this

application looks very similar to previous V6

application, the main distinctive difference is the

addition of a small air flow hole in the throttle blade

above the throttle blade shaft. Also, the Idle Air

Control (IAC) valve air passage has been

redesigned to allow more air flow. The redesign of

this throttle body assembly is to help improve idle

quality and help prevent engine stalling.

4348

Figure 6C1-1-77 Throttle Body Identification

1. Air Flow Hole

2. IAC valve

3. Throttle Stop Screw

4. TP Sensor

FUEL INJECTORS

The fuel injectors are electrically operated fuel flow

control valves. They are supplied with +12 volts

through a Fuse and EFI relay, both located in the

engine compartment fuse and relay housing. The

injectors are controlled by the PCM providing the

earth circuit. The PCM energises the injectors to

"open" the flow of f uel. The injector s are never f ully

energised "ON," as that would flood the engine

with too much fuel. The PCM supplies the earth

circuit in short pulses. The longer the duration of

the pulse (pulse width), the more fuel is injected

into the engine. Inside, the injectors have a coil of

electrical wire that becomes an electromagnet

when energised. The resistance of these windings

is important for the PCM to operate correctly.

The injector electrical resistance is

approximately 12.2 ohms at 20 C. If

measurement with an accurate ohmmeter

shows less than 11.8 ohms or more than 12.8

ohms, replace the injector.

(Acceptable: 11.8-12.8 ohms)

A fuel injector that does not open causes a misfire

condition. An injector which is stuck partly open

could c ause dieseling becaus e some f uel would be

delivered to the engine after the ignition key is

turned "OFF." If there is an electrical fault with any

of the injector circuits, DTC 57 will set.

4234

Figure 6C1-1-78 Fuel Injector

1. Supercharge Injector

2. Non-Supercharge Injector

DTC 57 (Injector Voltage Monitor Fault) will set if:

• The engine is running.

• DTC 54 is not set.

• Injector voltage monitor line voltage is 2.2 volts different than system voltage for 3 seconds.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

There are no default values.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 57 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED BATTERY VOLTAGE

TIME FROM START REFERENCE VOLTS

TIMES OCCURRED VEHICLE SPEED

IGNITION CYCLES INJECTOR VOLTAGE

COOLANT TEMPERATURE

Figure 6C1-1-79 Injector Circuit

FUEL PRESSURE REGULATOR

The fuel pressure regulator is a diaphragm-

operated relief valve with fuel pump pressure on

one side and intake manifold pressure (engine

vacuum) combined with mechanical spring

pressur e on the other. The f unction of the regulator

is to maintain a regulated pressure at the injectors

at all times by controlling the flow into the return

line.

The fuel pressure regulator is mounted on the fuel

rail and may be serviced separately.

If the fuel pressure is too low, poor performance

and a DTC 44, or 64 could set. If the pressure is

too high, excessive odour and a DTC 45, or 65

may result. Refer to Table A-4.1-1 for information

on diagnosing fuel pressure conditions.

4235

Figure 6C1-1-80 Typical Fuel Pressure Regulator

1. Fuel Inlet

2. Fuel Return Outlet

3. Valve

4. Valve Holder

5. Diaphragm

6. Compression Spring

7. Vacuum Connection

SUPERVX017

# 2

# 4 # 6

# 1 # 3 # 5

PCM

B12

BATTERY FEED

(740)

BLU

(841)

(843)

(845)

INJECTOR CONTROL

IN JE C TOR VOLTAGE

MONITOR LINE

IGNITION FEED

O/Y (479)

EFI R EL AY

B/W (152)

LOC. E4

P (3 )

O/B (740)

IGN SW

(481)

(39)

(846)

BR/Y

(844)

(842)

F31

F14

F34

BATTERY

R (2)

(1040)

YE112

YE114

YE111

YB194

YB188

YE39 YE39

YB188

4236

Figure 6C1-1-81 Fuel Pressure Regulator Location

V6 Supercharge Engine

1. Fuel Pressure Regulator

FUEL FILTER

The fuel filter is located under the vehicle by the

left hand rear side frame, forward of the fuel tank.

The fuel filter is mounted in place by a plastic

retaining s trap attac hed to the r ear fr am e. Both fuel

pressure hoses at the filter are quick connects to

the filter. T hese quick connections can be rem oved

by squeezing the oval shaped connections at the

filter.

For removal of the fuel filter, Refer to

Section 6C1-3 SERVICE OPERATIONS of the VX

Series Service Information.

765

4238

Figure 6C1-1-82 Fuel Filter Location

1. Fuel Vapour Canister To Engine

2. Fuel Vapour Line

3. Fuel Feed Line

4. Fuel Tank

5. Flow Arrow

6. Fuel Filter

7. Fuel Return Line

8. EVAP Canister

FUEL PUMP ELECTRICAL CIRCUITS SUPERCHARGED ENGINE

When the ignition switch is turned to "ON" or 'crank' after

having been "O FF" for at least 10 s econds, the PCM will imm ediately energis e the fuel pump r elay, which will then

activate the Fuel Pum p Control Module (f igure 6C1-1-85) to operate the f uel pum p. T his builds up the f uel pres sure

quick ly. If the engine is not c ranked within two seconds, the PCM will shut the f uel pum p relay "OFF" and wait until

the engine is cranked. As soon as the engine begins cranking, the PCM will sense the engine turning from the

crankshaft reference input, and turn the relay "ON" again to run the fuel pump.

A failed fuel pump relay circuit will cause a no start condition. Refer to Figure 6C1-1-84 for fuel pump relay location.

Figure 6C1-1-83 Fuel Pump Electrical Circuits V6 Supercharge Engine

4239

Figure 6C1-1-84 Fuel Pump Relay Location

1. Fuel Pump Relay

Battery

Fuel Pump

Relay

PCM

12V

8V (120)

V/W ( 1120)

B/W (489)

LOC.E7

G/W

(465)

LBLU (411)

O (240)

F28

(1040)

B/W (152)

4268

Fuel Pump

Rela y Control

In-Tank

Fuel Pump Fuel Pump

Co nt rol Module

Fuel Pump

Co ntrol M odule

YB96

YB39

YR44

YE112YB74

YR45

YR44

YR32

YB110 YB188

YB194

FUEL PUMP CONTROL MODULE

The V6 Supercharged engine utilises a two speed

Fuel Pump and a Fuel Pump Control module. The

Fuel Pump Control Module is located in the boot.

The Fuel Pump Control Module can vary the fuel

pump output depending on the required engine

load. When the ignition is first turned "ON", the

PCM energises the fuel pump relay, which applies

power to the Fuel Pump Control Module. The fuel

pump will then pressurise the fuel system.

The purpose for the Fuel Pump Control Module is

that this Supercharged system requires more fuel

volume under heavy engine load conditions then

the non-superc harged system. T he fuel pum p used

in the non-superc harged system m ay be capable of

supplying the required fuel volume for the

supercharged system, but with the increased fuel

volume required, the non-supercharged fuel pump

would eventually f ail from running at the higher f uel

volume.

The PCM controls the current flow through the fuel

pump with a Pulsed Width Modulation (PWM)

signal at 128 Hertz (Hz) to the fuel pump control

module. T he fuel pum p control module controls the

current flow through the fuel pump depending on

the PWM signal received from the PCM.

Under normal driving conditions the required fuel

volume is less, s o the fuel pum p operates at a duty

cycle of 67% "ON", that is the PCM controls the

fuel pump circuit, via the fuel pump control module

at 67% "ON" and 33% "OFF", at a frequency of

128 Hz.

When the engine load is increased, as measured

by the Mas s Air Flow sensor, the f uel pump control

module will switch from the normal duty cycle

(67%) to a higher duty cycle (100%) based on the

com m and f rom the PCM. T his higher duty cycle will

increase the current supply through the fuel pump,

increasing the fuel volume delivered by the fuel

pump.

Another feature of this Fuel Pump Control Module

is that when the fuel pump is running at the lower

duty cycle, (normal driving conditions), and the

returned fuel to the fuel tank (from the fuel

pressure regulator) is less. This lower volume of

returned fuel to the fuel tank will result in lower

emissions (fuel tank vapours).

Also with the fuel pump running at a lower duty

cycle (normal driving conditions), the voltage

output required to run the pump is lower. This will

require less generator output and will decrease

overall vehicle fuel usage.

Refer to Table A-4.1-1 for diagnosis of the fuel

pump electrical circuit.

Figure 6C1-1-85 Fuel Pump Control Module Location

1.5 IDLE AIR CONTROL (IAC) VALVE

The purpose of the Idle Air Control (IAC) valve is to

control engine idle speed, and pr event s talls due to

changes in engine load at idle.

The IAC valve, mounted in the throttle body,

controls bypass air around the throttle valve. By

extending the pintle (to decrease airflow) or

retracting the pintle (to increase airflow), a

controlled amount of air can move around the

throttle valve. If RPM is too low, more air is

bypassed around the throttle valve to increase

RPM. If RPM is too high, less air is bypassed

around the throttle valve to decrease RPM.

The IAC valve moves in small steps numbered

from 0 (extended pintle, bypass air passage fully

shut) to 255 (retracted pintle, maximum bypass

airflow) as commanded by the PCM.

At idle, the desired position of the IAC valve is

calculated by the PCM based on coolant

temperature, actual engine RPM, engine load, and

battery voltage.

If the IAC valve is disconnected or reconnected

with the engine running, the PCM can "lose track"

of the actual pos ition of the IAC. T his also happens

when PCM's keep alive memory voltage, i.e., PCM

connectors, ENGINE fuse F31, or battery cables,

are disconnected. If this happens, the PCM will

"reset" the IAC. After the engine has been run for

at least 5 seconds, then upon ignition "OFF" the

IAC will be reset.

4240

{

Figure 6C1-1-86 IAC Valve

1. IAC Valve Pintle

2. Idle Air Housing

3. Throttle Valve

4. Air Inlet

5. Throttle Body Assembly

6. Idle Air Control (IAC) Valve Assembly

7. Electrical Input Signal

The "reset" procedure is as follows:

The PCM commands the IAC to shut the idle air

passageway in the throttle body. It does so by

issuing enough "extend" pulses to move the IAC

pintle fully shut in the bore, regardless of where the

actual position was. Then, the PCM calculates the

IAC is at a fully shut position, and calls that position

"0 steps." Next, the PCM issues "retract" steps to

properly position the pintle.

The IAC can also be reset with the engine running

by a special command on the Tech 2 scan tool.

The IAC valve affects only the idle RPM of the

engine. If it is open fully, too much air will be

allowed into the manif old and idle speed will be too

high. If it is s tuck clos ed, too little air will be allowed

into the intake manifold, and idle speed will be too

low.

A system malfunction that causes too great a

difference between desired idle and the actual idle

speed will set a DTC 35 or DTC 36.

4221

Figure 6C1-1-87 IAC Valve Location

1. Idle Air Control (IAC) Valve

2. Throttle Position (TP) Sensor

3. Throttle Body

DTC 35 (Idle Speed Low)

DTC 36 (Vacuum Leak/ Idle Speed High) Either DTC will set if:

• No TP Sensor, IAT Sensor or VSS DTCs are set.

• The engine has been running for at least 15 seconds.

• The IAT is less than 73°C.

• The engine speed is 200 RPM below the desir ed idle s peed for 5 sec onds and the IAC has been opened to its

maximum position (255 steps), then a DTC P0506 will set. If the PCM detects a condition where a high idle

speed is present and the IAC has been closed (0 steps); the PCM will command the IAC motor to open 50

steps. If the RPM increase more than 50 RPM it is accepted that the IAC motor is moving and therefore the

fault is a vac uum leak, and DTC 35 will set. If the RPM does not c hange when the PCM comm ands the IAC to

open, the PCM will set DTC 36.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

There ARE no default values.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 35 AND 36 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED BATTERY VOLTAGE

TIME FROM START REFERENCE VOLTS

TIMES OCCURRED MASS AIR FLOW

IGNITION CYCLES CAM SIGNAL

COOLANT TEMPERATURE FUEL PUMP RELAY

STALL DATA

If an engine stall occurs the PCM will capture nine data values. The PCM will store the first stall condition data

values, then count the number of stalls after the first.

Note: Stall data will be erased from the PCM memory whenever DTC HISTORY DATA is cleared.

STALL DATE

PARAMETER PARAMETER

ENGINE SPEED VEHICLE SPEED

TIME FROM START BATTERY VOLTAGE

TIMES OCCURRED THROTTLE ANGLE

IGNITION CYCLES A/C REQUEST

IDLE AIR CONTROL

Figure 6C1-1-88 IAC Valve Circuit

SUPERVX025

PCM

C10

LG/W

(443)

IAC VALVE

IAC

COIL B LO

IAC

COIL A LO

IAC

COIL B HI

IAC

COIL A HI

12V

LG/B

(444)

LBLU

(441)

LBLU/B

(442)

YE36

YB193

1.6 DIRECT IGNITION SYSTEM (DIS)

PURPOSE

The Direct Ignition System (DIS) system controls

fuel combustion by providing a spark to ignite the

compressed air/fuel mixture at the correct time. To

provide optimum engine performance, fuel

economy, and control of exhaust emissions, the

PCM controls spark advance with the DIS system.

DIS has several advantages over a mechanical

distributor system:

• No moving parts

• Less maintenance

• Remote mounting capability

• No mechanical load on the engine

• More coil cool down time between firing events

• Elimination of mechanical timing adjustments

• Increased available ignition coil saturation time

4241

Figure 6C1-1-89 Crankshaft Sensor & Crankshaft Balancer

1. Crankshaft Position (CKP) Sensor

2. Front Cover Stud (Three Places)

3. Crankshaft Balancer Assembly

4. Crankshaft Position Sensor Shield

OPERATION

The Direct Ignition System (DIS) is an ignition

system that does not use a conventional distributor

and ignition coil. The DIS ignition system consists

of; 3 ignition coils, a DIS module, a dual Hall-effect

crankshaft position sensor, an engine crankshaft

balancer with crankshaft sensor interrupter rings

attached to the rear, related connecting wires, and

the EST (electronic spark timing) portion of the

PCM. The PCM controls only the ignition timing

and dwell only. The DIS coils do the actual fir ing of

the spark plugs.

Conventional ignition coils have one end of the

secondary winding connected to earth. In the

Direct Ignition System, neither end of the

secondary winding is earthed. Instead, eac h end of

a coil's secondary winding is attached to a spark

plug. These two plugs are on "companion"

cylinders, i.e., on top dead centre at the same time.

When the coil discharges, both plugs fire at the

same time to complete the series circuit. The

cylinder on compression is said to be the `event'

cylinder and the one on exhaust is the `waste'

cylinder. The cylinder on the exhaust stroke

requires very little of the available energy to fire the

spark plug at idle. The remaining energy will be

used as required by the cylinder on the

compression stroke. This method of ignition is

called "waste spark" ignition.

Since the polarity of the ignition coil primary and

secondary windings is fixed, one s park plug always

fires with a forward current flow and it's

`companion' plug fires with a reverse current flow.

This is dif fer ent fr om a conventional ignition system

that fires all the plugs with the same direction of

current flow.

4242

Figure 6C1-1-90 DIS Module And Coils

1. Direct Ignition System Coil And Module Assembly

2. Bolt

3. Wiring

4. Powertrain Harness Retainer

Since it requires approximately 30% more voltage

to fire a spark plug with reverse current flow, the

ignition coil design is im proved, with saturation tim e

and primary current flow increased. This redesign

of the system allows higher secondary voltage to

be available from the ignition c oils - gr eater than 40

kilovolts (40,000 volts) at any engine RPM. The

voltage required by each spark plug is determined

by the polarity and the cylinder pressure. The

cylinder on compression requires more voltage to

fire the spark plug (approximately 8 kilovolts) than

the one on exhaust (approximately 3 kilovolts).

It is possible for one spark plug to f ire even though

a plug wire fed by the same coil may be

disconnected from its 'companion' spark plug. The

disconnected plug wire acts as one plate of a

capacitor, with the engine being the other plate.

These two 'capacitor plates' are charged as a

spark jumps across the gap of the still-connected

spark plug. The `plates' ar e then discharged as the

secondary energy is dissipated in an oscillating

current across the gap of the still-connected spark

plug. Secondary voltage requirements are very

high with an 'open' spark plug or wire. The ignition

coil has enough reserve energy to fire the still-

connected plug at idle, but possibly not under high

engine load. A more noticeable misfire may be

evident under load; both spark plugs may be

misfiring.

4243

Figure 6C1-1-91 Waste Spark Ignition, Companion

Cylinders

1. Primary Coil

2. Secondary Coil

3. Companion Cylinders: 1&4, 5&2, 3&6

4. Compression Stroke, TDC

5. Companion Cylinders Have Pistons At TDC At The

Same Time

6. Exhaust Stroke TDC

7. Ignition Coil (One Of Three)

SYSTEM COMPONENTS

CRANKSHAFT SENSOR CRANKSHAFT BALANCER INTERRUPTER RINGS

The dual crankshaft sensor, secured in aluminum

mounting br acket and bolted to the f ront left s ide of

the engine timing chain cover, is partially behind

the cr anks haft balancer . A 4-wire electric al harness

connector plugs into the sensor, connecting it to

the DIS module.

The DIS dual crankshaft sensor contains two Hall-

effect switches with one shared magnet mounted

between them. The magnet and each Hall switch

are separated by an air gap.

A Hall switch reacts like a solid-state switch,

earthing a low-current signal voltage when a

magnetic field is present. When the magnetic field

is shielded from the switch by a piece of steel

placed in the air gap between the magnet and the

switch, the signal voltage is not earthed. If the

piece of steel (called an interrupter) is repeatedly

moved in and out of the air gap, the signal voltage

will appear to go "ON-OFF-ON-OFF-ON-OFF."

Compared to a conventional mechanical

distributor, this "ON-OFF" signal is similar to the

signal that a set of breaker points in the distributor

would generate as the distributor shaft turned and

the points opened & closed.

567

4244

Figure 6C1-1-92 Crankshaft Sensor

1. Aluminum Mounting Bracket

2. CKP Sensor

3. Towards Crankshaft

4. 3X Sensor

5. 3X Air Gap

6. Magnet

7. 18X Air Gap

8. 18X Sensor

In the case of the DIS system, the piece of steel is

two concentric interrupter r ings m ounted to the rear

of the crankshaft balancer. Each interrupter ring

has blades and windows that, with crankshaft

rotation, either block the magnetic f ield or allow it to

reach one of the Hall switches. The outer Hall

switch is called the 18X-crankshaft sensor,

because the outer interrupter ring has 18 evenly

spaced same-width blades and windows. The 18X -

crankshaft sensor produces 18 "ON-OFF" earth

pulses per crankshaft revolution. The Hall switch

closest to the crankshaft, the 3X-crankshaft

sensor, is so called because the inside interrupter

ring has 3 unevenly spaced, different-width blades

and windows. The 3X-crankshaft sensor produces

3 different length "ON-OFF" earth pulses per

crankshaft revolution.

W hen a 3X interrupter ring 'window' is between the

magnet and inner switch, the magnetic field will

cause the 3X Hall switch to earth the 3X c rank shaf t

signal voltage supplied from the DIS module. The

18X-interrupter ring and Hall switch react similarly.

The DIS module interprets the 18X and 3X "ON-

OFF" signals as an indication of crankshaft

position, and must have both signals to "fire" the

correct ignition coil. The DIS module determines

crankshaft position for correct ignition coil

sequencing by counting how many 18X-signal

transitions occur, i.e. "ON-OFF" or "OFF-ON,"

during a 3X pulse.

A failure in the crankshaft reference signal input

circuit will set a DTC 46. A failure in the 18X

reference signal circuit will set DTC 47.

Figure 6C1-1-93 Crankshaft Balancer with Interrupter Rings

Figure 6C1-1-94 18X and 3X Crankshaft Sensor Pulses for One Crankshaft Revolution

1. One 18 X Transition

2. Two 18 X Transition

3. Three 18 X Transition

4. 18 X Crankshaft Sensor

5. 3 X Crankshaft Sensor

6. One Crankshaft Rotation - 360°

º10

75 TDC

1 & 4

10 20

75 TDC

6 & 3

75 5 & 2

TDC

ºº

4245

Figure 6C1-1-95 18X & 3X Crankshaft Sensor Pulses and - Crankshaft Reference Signal sent to the PCM

1. One 18X Transition

2. Two 18 X Transition

3. Three 18 X Transition

4. 18 X Crankshaft Sensor

5. 3 X Crankshaft Sensor

6. Crankshaft Reference Signal (Sent to PCM)

7. One Crankshaft Rotation - 360°

DTC 46 (No Reference Pulses While Cranking) DTC will set if:

• No MAF sensor DTC is set.

• Battery voltage is at or below 11 volts.

• The MAF sensor input signal is greater than 2048 Hz.

• No crank shaft r eference input puls es are received at the PCM c ranks haft refe rence input term inal for at least 2

seconds.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

There are no default values for the crankshaft reference signal as the PCM uses this signal to determine if the

engine is running and initiate injection pulses. The engine will not run if the PCM does not receive a crankshaft

reference signal. With no crankshaft reference signal the PCM will not issue any injection pulses.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 46 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED BATTERY VOLTAGE

TIME FROM START REFERENCE VOLTS

TIMES OCCURRED MASS AIR FLOW

IGNITION CYCLES CAM SIGNAL

COOLANT TEMPERATURE FUEL PUMP RELAY

º10

75 TDC

1 & 4

100 20

75 TDC

6 & 3

90 30

110

5 & 2

TDC

ºº

4246

DTC 47 (18X Reference Signal Missing) DTC will set if:

• The engine is running.

• The MAF sensor input signal is greater than 2048 Hz.

• The PCMM detects 253 crankshaft reference pulses and no 18X pulses.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUE

When DTC 47 is set and current (no 18X reference signal), the PCM uses the crankshaft reference signal to

determine engine speed. This condition will cause the EST to be degraded; no high resolution spark.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 47 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED COOLANT TEMPERATURE

TIME FROM START BATTERY VOLTAGE

TIMES OCCURRED REFERENCE VOLTS

IGNITION CYCLES INJECTOR VOLTAGE

IGNITION COILS

Three twin-tower ignition coils are individually

mounted to the DIS module, with six screw type

fasteners. Each coil provides the spark for two

spark plugs simultaneously (waste spark

distribution), and all three coils can be replaced

individually. Spade type electrical terminals

connect each coil to the DIS module. Three of the

six terminals are connected together by a circuit in

the DIS module, supplying +12 volts to the primary

windings of all three coils. The other three

terminals are individually connected to the DIS

module, so that the DIS module can control only

one coil firing at a time, in the correct order, by

removing the primary circuit earth path at the

proper time.

4247

Figure 6C1-1-96 Ignition Coils & Ignition Module

1. Bolt

2. Direct Ignition System Coil and Module Assembly.

DIS IGNITION MODULE

The DIS module serves several functions:

• It powers the dual crankshaft sensor internal circuits.

• It supplies the 3X and 18X voltage signals that each respective Hall switch pulses to earth to generate the 3X

and 18X crankshaft sensor pulses.

• It determines the correct ignition coil firing sequence, based on how many 18X transitions occur during a 3X

pulse. This coil sequencing occurs at start-up. After the engine is running, the module remembers the

sequence, and triggers the proper ignition coil.

• It s ends a "crank shaft r eference" s ignal to the PCM. The PCM interprets engine RPM from this signal. It is also

used by the PCM to determine crankshaft position for EST spark advance calculations. (The falling edge of

each crankshaft reference signal pulse occurs 75 degrees before TDC of any cylinder.) The crankshaft

reference signal sent to the PCM by the DIS module is an "on-off" pulse occurring 3 times per crankshaft

revolution. This is neither the 3X nor the 18X -c r ank s haf t s ens or puls e, but both of thes e are r equir ed by the DIS

module to generate the crankshaft reference signal.

The DIS module generates the crankshaft reference signal by an internal "divide-by-6" circuit. This divider

circuit divides the 18X crank shaft sensor pulses by 6. The divider circuit is enabled, or ready to begin dividing,

only after it receives 3X crankshaft sensor pulses. After it receives the first 3X-crankshaft sensor signal, the

divider c irc uit does not need the 3X pulses to c ontinue operating. If either the 18X or 3X puls es ar e miss ing, the

divider cannot generate any crankshaft reference signal pulses (sent to the PCM), and no fuel injector pulses

will occur.

• Below 450 engine RPM (or anytime the PCM does not apply 5 volts to the DIS module 'bypass' cir cuit), the DIS

module controls ignition by triggering each of the three coils in the proper sequence at a predetermined dwell,

with spark advance fixed at 10 degrees BTDC. This is called bypass mode ignition. The DIS module provides

proper ignition coil sequencing during both the module and EST modes.

• Above 450 RPM, the PCM applies 5 volts to the DIS module 'bypass' circ uit, signalling the module to allow the

PCM to control the dwell and spark timing. This is EST mode ignition. During EST mode, the PCM adjusts

spark dwell and timing advance for all driving conditions. Again, the DIS module is responsible for proper

ignition coil sequencing during both the module and EST modes.

Figure 6C1-1-97 Computer Controlled Coil Ignition

1. Powertrain Control Module (PCM)

2. Coil Options

3. 1st Spark Plug Pair Firing

4. 2nd Spark Plug Pair Firing

5. 3rd Spark Plug Pair Firing

6. Ignition Coil

7. Camshaft Reference

8. Reference Crank Signal

9. EST

10. Bypass

11. Input/Output Buffers

12. Camshaft Sensor

13. Control Logic

14. Crankshaft Sensor

4248

10 9

DIRECT IGNITION SYSTEM (DIS) NOTEWORTHY INFORMATION

There are important considerations to point out when servicing the Direct Ignition System. This "Noteworthy

Information" will list some of these, to help the technician in servicing the DIS system.

A. The ignition coils secondary voltage output capabilities are very high - more than 40,000 volts. Avoid body

contact with DIS high voltage secondary components when the engine is running, or personal injury

may result!

B. T he dual Hall-effect 18X - 3X crank shaft sens or is the mos t c ritical part of the DIS system. If the crank shaft

sensor is damaged so that the 18X or 3X crankshaft sensor pulses are not generated, the engine will not

start!

C. There are 4 c ircuit wires connec ting the dual crank s haft sens or to the DIS m odule. If there is a pr oblem with

any of the four, the engine will not start (No spark and no injector pulses). The circuits are:

• +10-to-12 volt operating power supply for the Hall switches from the DIS module.

• 18X sensor pulse signal to the DIS module.

• 3X sensor pulse signal to the DIS module.

• Earth circuit for both Hall switches.

• Equally important (for the engine to run) is the crankshaft reference signal generated by the DIS

module, sent to the PCM. If the PCM does not receive this signal, it will not pulse the fuel injectors.

D. If the 3X crankshaft sensor pulses cease while the engine is running; the engine will stop running and will

not restart.

E. If the 18X crank shaft sensor pulses cease while the engine is running; the engine will stop running and will

not restart.

F. The crankshaft sensor is not adjustable in its aluminium mounting bracket.

G. Ignition timing is not adjustable. Clearance of the crankshaft sensor is only for proper clearance of the

rotating interrupter rings in the sens or air gap, and does not aff ect ignition timing. Ther e are no tim ing m ark s

on the crankshaft balancer or timing chain cover.

H If crankshaft sensor replacement is necessary, the crankshaft balancer must be removed first. The

balancer is a pr ess f it onto the crank s haft and m us t be rem oved with a special tool; r em oving the serpentine

accessory drive belt, balancer and crankshaft sensor shield will allow access to replacing the crankshaft

sensor. When reinstalled, the proper torquing of the balancer attachment bolt is critical to ensure the

balancer stays attached to the crankshaft.

I If a crankshaft sensor assembly is replaced, 2 items are very important:

1. Check the crankshaft balancer interrupter rings for any blades being bent (runout and concentricity). If

this is not checked closely and a bent blade exists, a new crankshaft sensor can be destroyed by the

bent blade with only one revolution of the crankshaft!

2. The proper crankshaft sensor replacement procedure must be followed. Refer to

Section 6C1-3 SERVICE OPERATIONS of the VX Series Service Information for proper replacement

procedure. This procedure will position the interrupter rings in the centre of the sensor air gaps.

J. Neither side of the ignition coil primary or secondary windings is connected to engine earth.

K. Be careful not to damage the high tension leads or boots (dust caps) when servicing the ignition system.

Rotate each boot to dislodge it from the plug or coil tower before pulling it from either a spark plug or the

ignition coil. Never pierce a high tension lead or boot for any testing purposes! Future problems are

guaranteed if pinpoints or test lights are pushed through the insulation for testing.

L The DIS module is earthed to the engine block through 2 mounting studs used to secure the module to it's

mounting bracket. If servicing is required, ensure that good electrical contact is made between the module

and its mounting bracket, including proper hardware & torque.

M A conventional tachometer used to check RPM on a primary ignition 'tacho lead' will not work on DIS. To

check RPM, use one of the following methods:

• A tachometer designed with an inductive pickup, used on the secondary side of an ignition system.

• These tachometers are identified by a 'clamp' that goes around a spark plug wire. Set the tacho to '2-

cycle' operation. The reason f or 2- cycle? Spark plugs on this engine fire every time the piston is at the

top of its stroke. If a '2 cycle' selection is not available, divide the indicated 4 cycle reading by 2.

• Tech 2 scan tool. Use "Engine Speed" display to read actual RPM.

1.7 ELECTRONIC SPARK TIMING (EST)

The V6 Direc t Ignition System uses the sam e four ignition m odule to PCM circuits, as do all other Delco engine

management systems. They are:

• Crankshaft Reference PCM Input

• Crankshaft Reference Earth

• Bypass Control

• EST Output

Electronic Spark Tim ing is the PCM's m ethod of c ontrolling spark advance and ignitions dwell, when the ignition

system is operating in the EST mode.

There are two "modes" of ignition system operation:

• Bypass mode

• EST mode

In the bypass mode, the ignition system operates independently of the PCM, with bypass mode spark advance

always at 10 degrees BTDC. T he bypass m ode is in effect when cranking the engine. T he PCM has no control

of the ignition system when in this m ode. In fac t, the PCM could be disc onnected and rem oved f rom the car and

the ignition system would still fire the spark plugs while cranking, as long as the other ignition system

components were functioning! (This would provide spark but no fuel injector pulses, and a no-start.)

After the engine starts (RPM greater than 450), the PCM will cause the ignition system to change over to the

EST mode. Once the change is made to EST mode, it will stay in effect until either:

1. The ignition key is turned "OFF,"

2. The engine quits running, or

3. An EST fault is detected.

If an EST fault is detected while the engine is running, the ignition system will switch back to the bypass mode.

The engine may quit running, but will restart and stay in the bypass mode.

Figure 6C1-1-98 Cranking Below 450 RPM

1. Engine Cranking Below 450 RPM 2. DIS Module

3. Coil Sequencing Control Logic 4. Spark Plugs

5. Ignition Coils 6. Signal Converter

7. 0 Volts 8. Crankshaft Reference Earth Low

9. Bypass Control 10. 0.1 0.2 Volts

11. EST Output 12. Crankshaft Reference Input

13. 2-3 Volts 14. Powertrain Control Module

15. From EFI Relay 12+ Volts 16. Sensor Power Supply

17. Sensor Earth 18. 18 X Crankshaft Sensor

19. 3 X Crankshaft Signal 20. Crankshaft Position Sensor (CKP)

18X

15 6

4249

Figure 6C1-1-99 Engine Running Above 450 RPM

1. Engine Running Above 450 RPM

2. DIS Module

3. Coil Sequencing Control Logic

4. Spark Plugs

5. Ignition Coils

6. Signal Converter

7. 0 Volts

8. Crankshaft Reference Earth Low

9. Bypass Control

10. 4-5 Volts

11. EST Output

12. 1-4 Volts RPM Variable

13. Crankshaft Reference Input

14. 2-3 Volts Steady

15. Powertrain Control Module

16. From EFI Relay 12+ Volts

17. Sensor Power Supply

18. Sensor Earth

19. 18 X Crankshaft Sensor

20. 3 X Crankshaft Signal

21. Crankshaft Position Sensor (CKP)

In the EST mode, the ignition spark timing and ignition dwell time is fully controlled by the PCM. EST spark

advance and ignition dwell is calculated by the PCM using the following inputs:

• Engine speed (crankshaft reference)

• Crankshaft position (crankshaft reference)

• Engine load (MAF)

• Engine coolant temperature (ECT)

• Throttle position (TP sensor)

• Park/neutral (TFP)

• Detonation (Knock sensor)

• Vehicle speed (VSS)

• Diagnostic request input - (DLC diagnostic test" terminal)

• PCM supply voltage

The following describes the four PCM-to-ignition module circuits.

18X

16 6

4250

Figure 6C1-1-100 Engine Running with EST Inputs

1. Engine Running With EST Inputs

2. DIS Module

3. Coil Sequencing Control Logic

4. Spark Plugs

5. Ignition Coils

6. Signal Converter

7. 0 Volts

8. 4-5 Volts

9. DTC Monitor

10. RPM Counter

11. Bypass Control

12. Knock

13. ECT

14. BARO

15. MAF

16. RPM

17. 1-4 Volts

18. 2-3 Volts

19. EST Modifier

20. Powertrain Control Module

21. From EFI Relay 12+ Volts

22. Sensor Power Supply

23. Sensor Earth

24. 18 X Crankshaft Sensor

25. 3 X Crankshaft Signal

26. Crankshaft Position Sensor (CKP)

18X

21 6

10 11

4251

CRANKSHAFT REFERENCE PCM INPUT.

From the ignition module, the PCM uses this signal to calculate engine RPM and crankshaft position. The PCM

compares pulses on this circuit to any that are on earth crankshaft reference low circuit. The PCM also uses the

pulses on this circuit to initiate injec tor pulses. If the PCM receives no pulses on this c ircuit, no fuel inj ection pulses

will occur, the engine will not run, and DTC 46 will set when attempting to start the engine.

CRANKSHAFT REFERENCE EARTH.

This is an earth circuit for the digital RPM counter inside the PCM, but the wire is connected to engine earth only

through the ignition m odule. Although this c ircuit is elec trically connected to the PCM, it is not connec ted to earth at

or through the PCM. The PCM compares voltage pulses on the reference input circuit to any on this circuit. If the

circuit is open, or connected to earth at the PCM, it may cause poor engine performance and possibly a "Check

Powertrain" Lamp with no DTC.

BYPASS CONTROL.

The PCM either allows the ignition m odule to keep the spark advance at "bypass mode" 10 degrees BTDC, or the

PCM signals the ignition module that the PCM is going to control the spark advance (EST mode). The ignition

module switches between the two m odes by the level of voltage that the PCM sends to the ignition m odule on the

bypass control circuit. The PCM provides 5 volts to the ignition module if the PCM is going to control spark timing

(EST m ode). If the PCM does not turn "ON" the 5 volts , or if the ignition m odule doesn't rec eive it, then the module

will keep c ontr ol of s park timing (bypass mode). An open or ear thed bypass control c irc uit will set a DT C 42 and the

ignition system will stay in 'bypass mode'. If the bypass control circuit is shorted to voltage then DTC 41 will set.

EST OUTPUT

The EST output circuitry of the PCM sends out timing pulses to the ignition module on this circuit. When in the

"bypass mode," the ignition module earths these pulses. When in the EST mode, these pulses are the ignition

timing pulses used by the ignition module to energise the ignition coil. If the EST output circuit is open when the

engine is started, a DTC 41 will set and the ignition system will stay in the bypass mode. If this circuit becomes

shorted to voltage or earthed during EST mode operation above 1600 RPM, then DTC 42 will set.

HOW DTC 41 AND DTC 42 ARE DETERMINED

The EST output circ uitry in the PCM issues EST output pulses anytime cr ankshaf t reference s ignal input pulses ar e

being received. When the ignition system is operating in the bypass mode (no voltage on the bypass control

circuit), the ignition module earths the EST pulses sent from the PCM. The ignition module will remove the earth

path for the EST pulses only after switching to the EST m ode. (T he PCM com m ands the s witching between bypass

& EST modes, via applying 5 volts on the bypass control circuit to the ignition module.)

The PCM has voltage monitors on the EST output line and the bypass control line. The PCM monitors it's EST

output, and expects to detect no EST pulses on the EST circuit when it has not supplied the 5 volts on the bypass

control circuit. W hen the RPM for EST operation is reached (approxim ately 450 RPM), the PCM applies 5 volts to

the bypass control circuit, and the EST pulses should no longer be earthed by the ignition module. The PCM

constantly monitors it's EST output, and should 'detect' the high EST pulses only when in the 'EST mode.'

If EST output circuit is open, the PCM will detect EST output pulses while attempting to start the engine (in the

bypass mode) due to the ignition module not being able to earth the EST pulses. The PCM will check for this

condition during engine cr anking. Thr ee things will occur: 1. A DT C 41 will s et, 2. The PCM will not apply 5 volts to

the bypass control circuit, and 3. The engine will start and run in the bypass mode.

If EST output circuit is earthed or shorted to voltage, the PCM would not detect a problem until the change to

EST mode happens. W hen the PCM applies 5 volts to the bypass control circuit, the ignition module will switch to

the EST mode. With EST circuit earthed or shorted to voltage, there would be no EST pulses for the ignition

module to trigger the ignition coil with, and the engine may falter. The PCM will quickly revert back to the bypass

mode (turn "OFF" the 5 volts on the bypass control circuit), DTC 42 will set, after the engine speed exceeds 1600

RPM. The ignition s ystem will operate in the bypass mode until the fault is corr ected and the engine is stopped and

restarted.

If bypass control circuit is open OR earthed, the ignition module can not switch to the EST mode. In this case,

the EST pulses will stay earthed by the ignition module, and DTC 42 will be set after the

engine speed exceeds 1600 RPM. The engine will start and run in the bypass mode.

If bypass contro l circuit is shorted t o voltag e, the ignition m odule will be switched to the EST m ode all the tim e.

In this c as e, the PCM would detec t voltage on the bypass circuit only with the engine cranking and set DTC 41. T he

engine would start and run in the EST mode.

RESULTS OF INCORRECT OPERATION

An open or ear th in the EST or bypass c irc uit will set a DT C 41 or DT C 42. If a fault oc cur s in the EST output c irc uit

when the engine is running, the engine m ay falter or quit running but will restart and run in the bypass mode. A fault

in either circ uit will force the ignition s ystem to operate on bypass m ode tim ing (10 degrees BTDC), which will res ult

in reduced performance and fuel economy.

The PCM us es information fr om the MAF and c oolant temperature s ens ors in addition to RPM to c alc ulate the main

spark advance values as follows:

High RPM = more advance

Low MAF frequency

(Low engine load) = more advance

Cold engine = more advance

Low RPM = less advance

High MAF frequency

(High engine load) = less advance

Hot engine = less advance

Therefore, detonation could be caused by incorrect low MAF output frequency or incorrect high resistance in the

coolant temperature sensor circuit. Poor performance could be caused by incorrect high MAF output frequency or

incorrect low resistance in the coolant temperature sensor circuit.

DTC 41 (Ignition Electronic Spark Timing Output Circuit Fault) will set if:

• The ignition is ON.

• The PCM has detected at least 2 EST output pulses during the first 3 crankshaft reference pulses received

from the ignition module.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DTC 42 (Ignition Bypass Circuit Fault) will set if:

• The engine is cranking or running.

• The PCM has commanded EST.

• The PCM has detected no EST output pulses for 400 ms.

• The engine RPM is greater than 1600 RPM.

• The PCM will illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

When either DTC 41 or 42 are set, the PCM will operate in the Bypass spark mode.

RECOVERY

Recovery will occur on the next ignition cycle.

DTC 41 AND 42 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED COOLANT TEMPERATURE

TIME FROM START REFERENCE VOLTS

TIMES OCCURRED VEHICLE SPEED

IGNITION CYCLES SPARK MODE

Figure 6C1-1-101 Ignition System

VXSC009

PCM

D11

D12

D10

CRANKSHAFT

REFERENCE LO

CAM

SENSOR

CONNECTOR

CAMSHAFT

POSITION

SENSOR

SIGNAL

CRANKSHAFT

REFERENCE HI

CRANKSHAFT

18X SIGNAL

BYPASS CONTROL

EST OUTPUT

module power supply - in

sensor power supply - out

cam signal - in

3x crank sensor - in

18x crank sensor - in

cam signal - out

tacho signal - out

crankshaft reference - out

18X cranksignal - out

bypass control

EST signal -in

DIS

MODULE

ABCD CBA

W/B (644)

GY/R (645)

B/R (453)

CRANK

SENSOR

CONN

L BLU/W

(646) BR (633)

BLU/Y (643)

BR (121)

B (63 0)

V (43 0)

L BLU/B (647)

T/B (4 24)

IGN SW

EFI RELAY

O/Y

(479)

(482)

B/W

(152)P/B

(39)

W (423)

F35

BATTERY

LOC. E1

(1040)

LOC. E3

P (3)

R(2H)

F14

TO INSTRUMENT CLUSTER

(TERMINAL 18)

ABS/ETC (TERMINAL 30)

YB39

YE111

YE34

YB193

YE63

YE57

1.8 ELECTRONIC SPARK CONTROL (ESC) SYSTEM

PURPOSE

Varying octane levels in today's petrol may cause

detonation in some engines. Detonation is caused

by an uncontrolled pressure in the combustion

chamber. This uncontrolled pressure could

produce a flame front opposite that of the normal

flame front produced by the spark plug.

The "rattling" sound normally associated with

detonation is the result of two or more opposing

pressures (flame fronts) colliding within the

combustion chamber. Though "light" detonation is

sometimes considered normal, "heavy" detonation

could result in engine damage. Light detonation

occurs when the point of maximum pressure has

been exceeded.

To control spark knock, a Knock Sensor (KS) is

used. This system is designed to retard spark

timing up to 15 degrees to reduce spark knock in

the engine. T his allows the engine to use max imum

spark advance to improve driveability and fuel

economy .

4252

Figure 6C1-1-102 Knock Sensor

1. Knock Sensor (KS)

OPERATION

The ESC system has two major components:

• Knock Sensor Module (part of PCM)

• Knock Sensors (2)

The knock sensor detects abnormal mechanical vibration (spark knocking) in the engine. There are several

calibrations of k nock sensor s bec ause each engine produc es a dif ferent f requenc y of mechanic al noise. T he k nock

sensor is specifically chosen for this engine to best detect engine knock, over all the other noises in the engine.

This engine has two knock sensors. Each sensor is mounted in the engine block near each bank of cylinders to

better detect detonation.

Figure 6C1-1-103 Knock Sensor Locations

1. Attaching Bolt. 7. Attaching Bolt.

2. Knock Sensor Shield. 8. Wiring Harness Connector.

3. R.H Knock Sensor. 9. L.H Side of Engine View.

4. Wiring Harness Connector. 10. L.H Knock Sensor.

5. Attaching Bolt. 11. Knock Sensor Shield.

6. R.H Side of Engine View. 12. Attaching Bolt.

10 11

12 23

4253

Under a no knock condition, each circuit should

measure about 32 mV AC. The knock sensors

produce an AC output voltage that increases with

the sever ity of the knoc k. T his signal voltage inputs

to the PCM. This AC signal voltage to the PCM is

processed by an analog signal to a Signal Noise

Enhancement Filter (SNEF) module. This SNEF

module is used to determine if the AC signal

com ing in is noise or actual detonation. T his SNEF

module is part of the PCM and cannot be replaced.

The processed knock sensor signal is then

supplied to the PCM. The PCM then adjusts the

ignition control system to reduce the spark

advance. How muc h the tim ing is retar ded is based

upon the amount of time knock is detected and is

limited to a maximum value of 15 degrees. After

the detonation stops, the timing will gradually

return to it's calibrated value of spar k advance. T he

Knock Sensor system will only retard timing after

the following conditions are met:

• Engine running longer than 5 seconds

• Battery voltage higher than 9.3 volts

• Engine speed above 550 RPM

• ECT greater than 45 degrees C

4254

Figure 6C1-1-104 Knock Sensor Sectioned View

1. Piezo Crystal

2. Shunt Resistor

The T ech 2 scan tool has two data displays to check for diagnosing this k nock sensor circ uit. "KNOCK SIGNAL" is

used to monitor the input signal from the knock sensors. This position will display "YES" when knock is being

detected. "KNOCK RETARD" is the indication of how much the PCM is retarding the spark advance.

The T ech 2 scan tool has two data displays to check for diagnosing this k nock sensor circ uit. "KNOCK SIGNAL" is

used to monitor the input signal from the knock sensor. This position will display "YES" when knock is being

detected. "KNOCK RETARD" is the indication of how much the PCM is retarding the spark advance.

The Knock Sensor System has two DTC's to detect a failure in its system. DTC 43 is designed to diagnose the

knock sensor and wiring, so that problems encountered with this circuit should set the DTC. The PCM learns a

minimum noise level from the knock sensors.

• The actual noise level is determined as: Noise level = Filtered noise - minimum noise

If the noise level is too low or too high then DTC 43 will be set.

The second DTC associated with the Knock Sensor is DTC 93. DTC 93 indicates that the engine has been

detonating longer than norm al. The PCM monitors the output of the SNEF circuit. W hen the SNEF output signal is

significantly longer than the longest expected "norm al": output it is assum ed that the SNEF circuitry has failed and

DTC 93 is set.

DTC 43 (Knock Sensor Circuit) will set if:

• No DTC 14,15,16,17,19 ,21, 22, or 93 are set.

• Engine has been running longer than 10 seconds.

• Engine Coolant Temperature is greater than 65

degrees C.

• TP sensor signal is greater than 22%.

• Engine RPM is between 2000 and 6375 RPM.

• There is no knock sensor signal or too high a knock sensor signal detected by the PCM for 3 seconds

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DTC 93 (Knock Sensor System) will set if:

• The engine has been running for more than 10 seconds

• The PCM’s SNEF circuit indicates knocking for more than 10 seconds

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

Once DTC 43 OR 93 is set, and current, the PCM uses a default spark advance table.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 43 AND 93 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED MASS AIR FLOW

TIME FROM START KNOCK DETECTION

TIMES OCCURRED INTAKE AIR TEMPERATURE

IGNITION CYCLES SPARK ADVANCE

COOLANT TEMPERATURE THROTTLE ANGLE

Figure 6C1-1-105 Knock Sensor Wiring

VXSC007

PCM

SNEF

KNOCK SENSOR

SIGNAL INPUT

C12

RH KNOCK

SENSOR

LH KNOCK

SENSOR

PIEZO CRYSTAL

SHUNT

RESISTOR

PIEZO CRYSTAL

SHUNT

RESISTOR

W/R (815)

YE3 YE3

YB193

1.9 EVAPORATIVE EMISSION

The Evaporative Emission Control System (EECS)

used on this vehicle is the charcoal canister

storage method. This method transfers fuel vapour

from the fuel tank to an activated carbon (charcoal)

storage device (canister located under the rear of

the vehicle) to hold the vapours when the vehicle is

not operating. W hen the engine is running, the fuel

vapour is purged from the carbon element by

intake air flow and consumed in the normal

combustion process.

The EECS purge solenoid valve allows manifold

vacuum to purge the canister. The Powertrain

Control Module (PCM) supplies an earth signal to

energise the EECS purge solenoid valve (purge

“ON”). The EECS purge solenoid control is Pulse

W idth Modulated (PWM) or turned “ON” and “OFF ”

several times a second. The PCM controlled PW M

output is commanded when the appropriate

conditions have been met:

• Engine coolant temperature above 80°C.

• Engine has been running longer than 3

minutes.

• Engine is not in Decel Fuel Cutoff Mode.

• Throttle opening is less than 92%.

• Engine is in Closed Loop mode.

4255

Figure 6C1-1-106 Fuel Vapour Canister

1. Canister Purge Port

2. Vapour From Fuel Tank Port

3. Air Vent Port

EECS purge PWM duty cycle varies according to

operating conditions determined by mass air flow,

fuel trim and intake air temperature. The EECS

purge will be re-enabled when TP angle decreases

below 92%.

The canister (located under the rear of the vehicle)

cannot be repaired, and is serviced only as an

assembly. Periodically check the canister at the

time or distance intervals specified in the vehicle

Series Owners Handbook. If there is a fault with

the Canister Purge Solenoid elec trical c ircuits , DTC

97 will set.

4256

Figure 6C1-1-107 Canister Purge Solenoid Location

1. To Throttle Body

2. To Canister

3. Solenoid Valve

4. Solenoid Mounting Bracket Screw

5. Solenoid Mounting Bracket

The fuel vapour canister is mounted in a bracket

underneath the vehicle, located by the fuel filter.

This canister is a three port design. The fuel

vapour is absorbed by the charcoal within the

canister. When the engine is running at idle speed

and above idle, air is drawn into the canister

through the atmospheric port at the top of the

canister assembly. The air mixes with the fuel

vapour and the mixture is drawn into the intake

manifold via the canister purge line. Uppermost

port on the canister is controlled by a PCM

controlled canister purge solenoid. The canister

purge solenoid contr ols the m anif old vacuum signal

from the throttle body. The port below the canister

purge port is the vapour inlet from the fuel tank.

The single off centre port is open to the

atmosphere.

RESULTS OF INCORRECT OPERATION

• Poor idle, stalling and poor driveability can be

caused by:

-Inoperative canister purge solenoid

-Damaged canister.

-Hoses split, cracked and/or not connected to

the proper tubes.

• Evidence of fuel loss or fuel vapour odour can

be caused by:

4257

Figure 6C1-1-108 Canister Location

1. Canister

-Liquid fuel leaking from fuel lines.

-Cracked or damaged canister.

-Disconnected, misrouted, kinked, deteriorated

or damaged vapour hoses, or control hoses.

If the solenoid is stuc k open, or the control c ircuit is

shorted to earth the c anister will purge to the intak e

manifold all the time. This can allow extra fuel at

idle or during warm-up, which can cause rough or

unstable idle or a rich fuel operation.

If the canister purge solenoid is always closed, the

canister can become over loaded, with fuel

resulting in fuel odour.

A failure in the canister purge solenoid or circuit

may result in DTC 97.

GEN 03 0042

123

Figure 6C1-1-109 Sectioned View of Canister

1. Air Vent Port

2. Canister Purge Port

3. Vapour From Fuel Tank Port

4. Evaporative Canister

5. Volume Compensator

6. Charcoal Bed

DTC 97 (Canister Purge Circuit Fault) will set if:

• The ignition is ON

• The PCM detects the incorrect voltage on the canister purge solenoid driver

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

There are no default values for DTC 97.

RECOVERY

Recovery will occur when the PCM sees a valid condition.

DTC 97 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED COOLANT TEMPERATURE

TIME FROM START PURGE PWM

TIMES OCCURRED MASS AIR FLOW

IGNITION CYCLES

Figure 6C1-1-110 Typical Evaporative Emission Control Schematic

SUPERVX026

THROTTLE BODY

CANISTER PURGE

SOL EN OID VALVE

CARBON CANISTER

FUEL TANK

PCM

CANISTER PURGE

F33

F14

IGN SW

EFI

RELAY

BATTERY

P (3 ) P/B

(39)

R (2H)

(1040)

P (439)

O/Y

(479)

YE99

YE39

YB111

YB193

1.10 ELECTRIC COOLING FAN

This V6 engine has two, two speed electric engine

cooling fan assembly that provides the primary

means of moving air through the engine radiator.

The two, two speed elec tric cooling f an are used to

cool engine coolant flowing through the radiator.

The two, two speed electric cooling fans are also

used to cool the ref rigerant f lowing through the A/C

condenser (if fitted).

Each engine cooling fan motor has four terminals,

two negative and two positive terminals. The two

negative terminals are the relay controlled circuits

for fan operation. The two positive terminals are

the direct power feed from a fusible link to the fan

motors. When a earth signal is applied to one of

the negative term inals , the fan m otor will operate at

low speed. When a earth signal is applied to both

negative terminals, both fan will operate at high

speed.

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 a s pecial Data Comm unication to

the BCM. The BCM controls the earth path for the

engine cooling fan low speed relay. The engine

cooling fan high speed relay and the engine

cooling fan low speed relay are used to control the

earth s ignal to the elec tric motor that drives the f ive

bladed fan.

The PCM determines operation of the two, two

speed engine cooling fan based on A/C request,

engine coolant temperature, A/C Refrigerant

Pressure Sensor, and vehicle speed signal inputs.

There are also four (4) suppression capacitors

incorporated into the fan motor wiring circuits.

These suppression capacitors help eliminate fan

motor noise through the radio speakers. If these

capacitors are open, then noise will be present

through the radio s peakers. Is shorted to earth, the

fan motors could continuously run, or the fuse or

fusible link could fail.

4259

Figure 6C1-1-111 Engine Cooling Fan Assembly

1. Engine Cooling Fan Motor Connector

2. Main Wiring Harness

3. Engine Cooling Fan Assembly

ENGINE COOLING FA N LOW SPEED

The engine cooling fan low speed relay is

energised by the BCM. The PCM determ ines when

to enable the low speed fan based on inputs from

the BCM serial data, Engine Coolant Temperature

(ECT) sensor and the Vehicle Speed Sensor

(VSS). The cooling fan low speed relay will be

turned "ON'' when:

• The A/C request indicated (YES) and either

• the vehicle speed is less than 30 km/h.

• A/C pressure is greater than 1500 kPa

• The coolant temperature is greater than 104

degrees C.

• If the coolant temperature is greater than 117

degrees C when the ignition is switched off , the

relay is energised for up to approximately 4

minutes.

4260

Figure 6C1-1-112 Cooling Fan Low Speed Relay Location

1. Radiator Fan Low Speed Relay

2. Radiator Fan High Speed Relay

• If an engine coolant tem per ature sens or f ault is

detected, such as DTC 14, 15, 16, or 17.

The cooling fan low speed relay will be turned

"OFF'' when any of the following conditions have

been met :

• The A/C request is not indicated (NO)

• Engine coolant temperature is less than 99

degrees C.

• The A/C request is indicated (YES) and the

vehicle speed is greater than 50 km /h and A/C

pressure is less than 1170 kPa.

LOW SPEED RESPONSE

The engine cooling low speed fans are enabled when the low speed relay is energized by the BCM. The PCM will

request the BCM to turn the low speed engine cooling fan relay on or off, via the serial data bus normal mode

message. After the PCM requests a change in the engine cooling fan low speed relay, the BCM will send a

response message back to the PCM via the serial data bus normal mode message confirming it received the

request. A failure in the response communication will set a DTC 92.

DTC 92 (Low Speed Fan – No BCM Response) will set if:

• Engine is idling

• The PCM sends a request to the BCM to turn ON the engine cooling fan low speed relay via the serial data

normal mode message and the BCM does not send a message back to the PCM.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

Once DTC 92 is set, the PCM will energise the engine cooling fan high-speed relay

RECOVERY

Recovery will occur on the next ignition cycle.

DTC 92 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED REFERENCE VOLTS

TIME FROM START MASS AIR FLOW

TIMES OCCURRED CAM SIGNAL

IGNITION CYCLES FUELING MODE

COOLANT TEMPERATURE FUEL PUMP RELAY

BATTERY VOLTAGE

Figure 6C1-1-113 Engine Cooling Fan Circuit

VXSC032

BLU

(831)

(832)

VEHICLE SPEED

SENSOR

B/Y (452 )

B (469)

D11

C16

D10

Y (41O)

V/W (415)

G/B (259)

COOLANT TE MP

SENSOR

/C PRESSURE

SENSOR

BATTERY MAIN POWER

HIGH SERIES

BCM TERMINALS

NOMINATED FIRST

BCM

PCM

HIGH

SPEED

FAN

SERIAL DA TA

BLU/W (304)

IGNITION

15a 15 50

30 OFF/ON

LOCK

ACC

IGN

START

E20/D6

P/B

(39)

IGNITION SWITCH

87A

ENGINE

COOLING

FAN 1

ENGINE

COOLING

FAN RELAY

(LOW SPEED)

ENGINE

COOLING

FAN RELAY

(HIGH SPEED)

P/B (39)

F14

BLUE

FUSIBLE

LINK

LOC.

F31

A5/A6

O/B

(740)

ENGINE

COOLING

FAN 2

BATTERY

FT FAN 2

FU FAN 1

(1040)

O/B (740)

O/B

(208)

O/BLU

YE119

YB44

YE103

YE43

YB175

YB164

YB174

YB163

YB174

YB163

YE114

YE106

YE113

YE106

YB195

YB193

YB188

YB194

YB132

YB164

YB175

YB165

YB176

YB165

YE43

YB44

(204)

(203)

(2H)

LOW

SPEED FAN

B7/B7

R/B (1221) R/B

(1221) E2/D2 SERIAL DATA

HIGH

CURRENT EARTH

B/Y

(155) A1/A5 ELECTRONIC EARTH

B/G

(151)

LOC.

E2 LOC.

B10/B11

B/P (157)

O/B

(473)

ENGINE COOLING FAN HIGH SPEED

The engine cooling fan high speed relay is

controlled by the PCM based on input from the

Engine Coolant Temperature (ECT) sensor. The

PCM will only turn “ON’’ the engine cooling fan

high speed relay fan if the engine cooling fan low

speed relay has been “ON” for 2 seconds and the

following conditions are satisfied.

• There is a BCM mess age r es ponse fault, which

will cause a DTC 92.

• An engine coolant temperature sensor fault is

detected such as DTC 14, 15, 16, or 17.

• Coolant temperature greater than 104

degrees C.

• The engine cooling fan high speed relay can

also be enabled by the A/C Refrigerant

Pressure Sensor. When the A/C Refrigerant

Pressure Sensor determines the A/C system

pressur e is to high, greater than 2600 kPa, and

this will instruct the PCM to enable the high

speed fan.

Notice:If the low speed fan was "OFF" when the

criteria was met to turn the high speed fan "ON",

the high speed fan will com e "ON" 5 seconds after

the low speed fan is turned "ON". "

If both the engine cooling fan relays are "ON", the

PCM will turn "OFF" the high speed relay when:

• The engine coolant temperature is less than

103 degrees C.

• A/C request not indicated (NO)

• A/C request indicated (YES) and A/C pressure

is less than 1500 kPa.

There are no DTC’s associated with the high speed

cooling fan relay.

4260

Figure 6C1-1-114 Cooling Fan High Speed Relay Location

1. Radiator Fan Low Speed Relay

2. Radiator Fan High Speed Relay

1.11 A/C CLUTCH CONTROL

This vehicle uses two types of A/C clutch controls.

One type is standard A/C (Figure 6C1-1-117) and

the other uses an Elec tronic Clim ate Control (ECC)

module (Figure 6C1- 1-118).

With the ECC system, when the A/C is requested,

the Electronic Clim ate Control Module will supply a

signal to the BCM. T he BCM will then send a serial

data request to the PCM. W hen 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 be

inoperative.

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. The A/C Refrigerant

Pressure Sensor signal indicates high side

refrigerant pressure to the PCM. The PCM uses

this inf or mation to adj ust the idle air c ontrol valve to

compensate for the higher engine loads present

with high A/C refrigerant pressures. A fault in the

A/C Refrigerant Pressure Sensor signal will cause

DTC 96 to set.

4262

Figure 6C1-1-115 A/C Relay Location Location

1. A/C Relay

The PCM will NOT energise the A/C control

relay if any of the following conditions are

present:

• Coolant temperature is above 119°C. Once

coolant temperature is below 116°C, A/C is

reactivated.

• RPM more than 5,800. If de-energised

because of RPM, it can re-energised when

RPM falls below 5,400.

• Throttle is more than 96% open. When de-

energised during wide-open throttle, it will be

re-energis ed when the throttle is less than 92%

open.

On vehicles equipped with non-ECC systems the

power flow is different. With the blower fan

switched "ON", and the air conditioning switched

"ON," switched ignition voltage is supplied from

fuse F13 through the A/C master switch, and then

to the BCM. T he BCM will then supply a serial data

signal to the PCM requesting A/C. If the BCM does

not rec eive a earth signal from the blower switch to

BCM terminal "3", the BCM will not supply the

serial data r eques t f or A/C. O nc e the PCM rec eives

this serial data signal, the PCM will energise the

A/C compressor relay. The BCM also supplies the

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 like on the ECC system also

incorporates a A/C Refrigerant Pressure Sensor.

The A/C Refrigerant Pressure Sensor signal

indicates 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 Refrigerant Pressure

Sensor signal will cause DTC P0530 to set.

There are no DTC’s associated with A/C system

except for the A/C Refrigerant Pressure Sensor

DTC 96.

4261

Figure 6C1-1-116 A/C Refrigerant Pressure Sensor Location

1. A/C Refrigerant Pressure Sensor Connector

Figure 6C1-1-117 A/C Clutch Control Without ECC

SUPERVX019

D20

/C MASTER

SWITCH

HIGH SERIES

BCM TERMINALS

NOM IN ATE D FIRST

(291)

B/R

(292)

R/W

(248)

R/BR

(962)

(4)

(51)

BLOWER

MOTOR

RESISTORS

A/C

RELAY

EFI

RELAY

BLOWER

MOTOR

HEATER AND A/C

CONTROLS

BLOWER

INHIBIT

RELAY

DKG/Y (359)

LOC.E3

Y/B (52)

R/G (245)

LG/B (366)

R/Y (244) O/G

(251)

DKG/Y

(359)

BATTERY MAIN POWER

BATTERY

IGNITION SWITCH

F31

O/B

(740)

(1040)

BCM

B/G

(151) HIGH CURRENT

EARTH

IGNITION

DEMIST OUTPUT

DEMIST INPUT

A/C SWITCH INPUT

A/C LED OUTPUT

A/C BLOWER

INPUT

F14

F13

F33

E20/D6

A5/A6

E2/D2

B10/B11

A1/A5

P/B

(39)

15a 15 50

30 ACC

IGN

START

P (3)

R/B

(1221)

SERIAL DATA

A/C ENABLE

SERIAL

DATA

PCM

B/Y

(155) ELECTRONIC EARTH

R (2H)

R (2A)

P/BLU (44)

B (1 50)

YE120

YB188

YB194

YE105

YB2

YB2 YB50

YB50

YB163

YB176

YB165

YB175

YB164

YE101

YE39

YB44

YE101

YE120

YB44

YB54

YB54 YB165

YB175

YB164

YB176

YB165

YB164

YB163

Figure 6C1-1-118 A/C Clutch Control With ECC

B/Y (155)

B/G (151)

ELECTRONIC EARTH

HIGH CURRENT

EARTH

A1/A5

B10/B11

E3/D13

E9/D3

E2/D2

E20/D6

A5/A6

LOC. E3

LOC. E5/E15

LOC. E3

PCM

ECC

BCM

TO ABS/ETC

CONTROL MODULE

AND INSTRUMENTS

TO SRS

CONTROL

MODULE

DLC

SERIAL

DATA

A/C

ENABLE

SERIAL

DATA

SUPERVX018

SERIAL

DATA AUX .

R/B (1221)

G/W (1220)

SERIAL

DATA

MAIN

BATTERY

O/B (740)

(1040)

O/Y (479)

BATTERY MAIN POWER

R (2)

F14

F33

P/B

(39)

B/W

(152)

IGNITION ON

15a 15 50

30 ACC

IGN

START

IGNITION SWITCH

HIGH SERIES

BCM TERMINALS

NOM IN ATE D FIRS T

P (3)

A/C

COMPRESSOR

A/C RELAY

EFI

RELAY

F31

LG/B (366)

YB176

YB165

YB174

YB163

YB175

YB164

YB175

YB164

YB44

YB194

YB188

YB87

YE112

YE105 YE114

YE105

YE120 YE120

YB44

YE101

YE39

YE101

YB176

YB165

YB175

YB164

YE101YE101YE101

YE101

1.12 A/C REFRIGERANT PRESSURE SENSOR

The A/C Refrigerant Pressure Sensor is a sealed

gauge reference capacitive pressure sensor with

on board signal conditioning. It provides a 0 to five

volt output and requires a five volt regulated power

supply.

In operation the Sensor senses applied pressure

via the deflection of a two piece ceramic diaphragm

with one half being a parrel plate capacitor.

Changes in capacitance influenced by the

refrigerant pressure under the ceramic diaphragm

are converted to an analogue output by the

Sensors integral signal electronics.

The pressure Sensor’s electronics are on a flexible

circuit board contained in the upper section of the

Sensor. They provide linear calibration of the

capacitance signal from the ceramic sensing

diaphragm.

Benefits of using the pressure Sensor over a

normal type pressure switch is that the Sensor is

constantly monitoring pressures and sending

signals to the Powertrain Control Module (PCM).

The normal type pressure switch only has an upper

and lower cut-out point. The PCM will disengage

the A/C compressor at Low or High refrigerant

pressures and control the operation of the engine

cooling fans.

If there is a failure in the A/C Pressure Sensor

circuit DTC 96 will set.

4261

Figure 6C1-1-119 A/C Refrigerant Pressure Sensor Location

1. A/C Refrigerant Pressure Sensor Connector

4347

Figure 6C1-1-120 A/C Refrigerant Pressure Sensor

Cut-Away View

1. Signal Electronics.

2. Pressure Port.

3. Ceramic Diaphragm.

4. Pressure Sensor.

5. High Side Charge Port.

Low Pressure Compressor Cut OFF at 180kPa

ON at 240 kPa

High Pressure Compressor Cut OFF at 2900 kPa

ON at 2400 kPa

Engine Cooling Fan Low ON at 1500 kPa

Speed OFF at 1250 kPa

Engine Cooling Fan High ON at 2600 kPa

Speed OFF at 2300 kPa

DTC 96 (A/C Pressure Sensor Circuit) will set if:

• Engine Coolant Temperature is below 119°C

• Intake Air Temperature is below 90°C

• Engine RPM is below 2000

• Engine has been running for less than 10 minutes

• A/C Refrigerant Pressure Sensor signal voltage is greater than 4.9 volts

• All of the above conditions are present for longer than 10 seconds.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

W hen DTC 96 is set, the low speed cooling fan will operate for five seconds, then the high speed fan will turn ON

and remain on until the fault is removed.

RECOVERY

Recovery will occur on the next ignition cycle.

DTC 96 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED ECT SENSOR

TIME FROM START IAT SENSOR

TIMES OCCURRED INTAKE AIR TEMPERATURE

IGNITION CYCLES BATTERY VOLTAGE

COOLANT TEMPERATURE REFERENCE VOLTS

REFERENCE VOLTS

Figure 6C1-1-121 A/C Refrigerant Pressure Sensor Circuit

SUPERVX001

PCM

F16

A/C

PRESSURE

SENSOR

SENSOR EARTH

A/C PRESSURE

SENSOR SIGNAL

REFERENCE

VOLTAGE

5V 5V

V/W (415)

B (46 9)

G/B (259)

TFT AND

IAT SENSORS

YB188

YB194

YE113

1.13 S UP ERCHARGER SYSTEM

DESCRIPTION

The supercharger is a positive displacement pump that consists of two counter-rotating rotors in housing with an

inlet port and an outlet port. The rotors are designed with three lobes and a helical twist. An air bypass circuit is

built into the housing. T he rotors in the s uperchar ger are des igned to run at a m inim al clearance, not in contact with

each other or the hous ing. The r otors ate tim ed to eac h other by a pair of precision spur gears , which are pressed

onto the r otor shafts . T he forward end of the rotors are held in position by deep groove ball bearings. T he back end

of the rotors are supported by sealed roller bearings.

The gears and ball bearings are lubricated by synthetic oil. The oil reservoir is self-contained in the supercharger

and does not rely on engine oil for lubrication.

The c over on the superc harger c ontains the input shaf t, which is s upported by two deep groove ball bear ings and is

coupled to the rotor drive gears. The pulley is pressed and keyed onto the input shaft. These bearings are

lubricated by the synthetic oil contained in the same reservoir as the gears and rotor bearings.

SUPERCHARGER OPERATION

The supercharger is designed to pump more air than the engine would normally use. This excess air creates a

boost pressure in the intake manifold. Maximum boost can range from 50 to 80 kPa (7 to 11 P.S.I.). Since the

superchar ger is a positive displacem ent pum p and is directly driven from the engine access ory drive system , boost

pressure is available at all driving conditions.

When boost is not desired, such as during idle and light throttle cruising, the excess air that the supercharger is

producing is routed through the bypass passage between the intake manifold and the supercharger inlet. This

bypass circuits regulated by a bypass valve which is similar to a throttle plate. The bypass valve is controlled by a

vacuum actuator, which is connected to the vacuum signal between the throttle and the supercharger inlet. Spring

force from the actuator holds the valve closed to create boost and vacuum pulls the valve open when the throttle

closes to decrease boost. The open bypass valve reduces pumping loss thereby increasing fuel efficiency.

The Boost Control Solenoid valve is an electronically controlled valve. This valve, controlled by the PCM,

determines whether pressure from the manifold is routed to the bypass actuator or closed off. The solenoid allows

pressure from the manifold to open the bypass valve and regulate boost pressure during specific driving conditions.

BOOST CONTROL

The boost control system regulates induction boost pr essur e during rapid deceler ation, under very high engine load

situations and anytime reverse gear is selected.

Figure 6C1-1-122 Supercharger Components

1. Lobes 2. Inlet Manifold

3. Boost Control Actuator and Valve 4. Throttle

5. Rotors 6. Timing Gears

4263

OPERATION

Under most conditions, the PCM commands the

Boost Control Solenoid to operate at 100% duty

cycle ("ON"), keeping the solenoid valve closed

and allowing only inlet vacuum to control the

position of the Bypass valve. At idle, full inlet

vacuum is applied to one side of the Bypass Valve

Actuator diaphragm counteracts spring tension to

hold the bypass valve open. As the engine load

increases, reduced vacuum acts upon the spring

tension in the Bypass Valve Actuator, causing the

bypass valve to close and increasing boost

pressur e. When reduced boost press ure is desired,

the PCM commands the Boost Control Solenoid to

operate at 0% duty cycle ("OFF"). This opens the

solenoid valve and allows boost pressure from the

intake manifold to counteract the spring tension in

the Bypass Valve Actuator, opening the bypass

valve and recirc ulation excess boost pressur e back

into the supercharger inlet. With reverse gear

selected, the PCM commands the Boost Control

Solenoid to operate at 0% duty cycle ("OFF") at all

times.

4264

Figure 6C1-1-123 Bypass Valve Actuator

1. Bypass Valve Actuator

2. Throttle Body

RESULTS OF INCORRECT OPERATION

An open Boost Control Solenoid driver circuit, ignition feed circuit, or Boost Control Solenoid valve stuck open

will cause reduced engine power, especially during wide open throttle operation.

The Boost Control Solenoid driver circuit shorted to earth, Boost Control Solenoid valve stuck closed or a

restric tion in the boost s ource or signal hoses will caus e full boost to be c omm anded at all tim es and a possible

overboost condition during high engine load situations.

A res triction in the vacuum signal hoses to the Bypass Valve Actuator or a stuck closed bypass valve will cause

a rough idle and reduced fuel economy.

DIAGNOSIS

The boost control system diagnosis is covered in Table 2-6. For further information on the Supercharger and

boost control system, and on vehicle service, refer to Supercharger Service Operation 3.24 of the VX Series

Service Information.

Figure 6C1-1-124 Boost Control Solenoid Location

1. Boost Control Solenoid 2. Rear View of Engine Assembly

3. Expanded ViewFigure 6C1-1-125 Boost Control

System (Bypass Closed)

4265

Figure 6C1-1-125 Boost Control System (Bypass Closed)

1. Boost Control Solenoid ON With Full Boost Commanded 2. PCM

3. Bypass Closed For Full Boost Condition 4. Bypass Valve Actuator

5. Boost Source Hose 6. Throttle Butterfly

7. Bypass Valve (Closed) 8. Intake Manifold

9. Boost Signal Hose 10. Supercharger

11. B+ Power Supply 12. Inlet Vacuum Signal

4266

Figure 6C1-1-126 Boost Control System (Bypass Open)

1. Boost Control Solenoid OFF (Open) With Reduced Boost

Commanded, ON (Closed) At Idle 2. PCM

3. Bypass Open For Reduced Boost Condition 4. Bypass Valve Actuator

5. Boost Source Hose 6. Throttle Butterfly

7. Bypass Valve (Open) 8. Intake Manifold

9. Boost Signal Hose 10. Supercharger

11. B+ Power Supply 12. Inlet Vacuum Signal

Figure 6C1-1-127 Boost Control Solenoid Circuit

4267

BOOST CONTROL

SOLENOID

PCM

BOOST CONTROL

SOLENOID DRIVE

VXSC036

F33

F14

IGN SW

EFI

RELAY

BATTERY

LOC. E1

P (3 ) P/B

(39)

YE111

YB194

YE115

YE39

1.14 ELECTRONIC TRACTION CONTROL

PURPOSE

The Electronic Traction Control (ETC) system is

designed to maintain traction and reduce wheel

over spin at the drive wheels on slippery surfaces

during acceleration. This system is designed to

operate at all vehicle speeds and reduces wheel

slip by use of the engine torque management

system and Anti-Lock Brake (ABS) system.

The ABS/ETC m odule monitors both front and rear

wheel speeds through the wheel speed sensors. If

at any time during acceleration the ABS/ETC

module detects drive wheel slip, it will request (on

the Torque Request circuit) the Powertrain Control

Module (PCM) to bring ex cess engine torque into a

specific range. This is accomplished via two high

speed Pulse Width Modulated (PWM) circuits

between the ABS/ETC module and the PCM. This

is displayed on the scan tool as a N.m number.

The PCM will then adjust spark firing and air/fuel

ratio, and shutting "OFF" up to five (5) injectors (if

necessary), and report the modified torque value

(on the Torque Achieved circuit) back to the

ABS/ETC module in the form of a N.m number.

These N.m numbers should match closely when

traction control is being requested. Simultaneous

with engine torque management, the ABS/ETC

module will activate the ABS isolation valves, turn

on the ABS pump motor and s upply brake pres s ure

to the over spinning wheel(s).

The isolation valves isolate the front brake

hydraulic circuits from the master cylinder and rear

brake hydraulic circuits. Once the rear brake

hydraulic circuits are isolated, pressure can be

applied to the rear wheels without affecting any

other brake hydraulic circuits. The ABS/ETC

module turns on the ABS pump motor to apply

pressure, and begins cycling the ABS assembly's

inlet and outlet valves.

The inlet and outlet valve cycling aids in obtaining

maximum road surface traction in the same

manner as the Anti-Lock Brake mode. The

difference between Electronic Traction Control and

Anti-Lock Brake mode is that brake fluid pressure

is increased to lesson wheel spin (Traction Control

mode), rather then reduced to allow greater wheel

spin (Anti-Lock Brake mode).

If at any time during Traction Control mode, the

brakes are manually applied, the brake switch

signals the ABS/ETC module to disable Traction

Control mode and allow manual braking.

If there is a malfunction with the Torque Request

PWM circuit between the ABS/ETC module and

the PCM, DTC 95 will set. If there is a malfunction

with the Torque Achieved circuit between the

ABS/ETC module and the PCM, a ABS/ECT DTC

will set.

For further description on the Anti-Lock Brake

(ABS) system, and Electronic Traction

Control (ETC) system, Refer to

Section 12L ABS & ABS/ETC in VX Service

Information for information on ABS/ETC operation

and DTC diagnosis.

Figure 6C1-1-128 ABS/ETC Module Location

1. ABS/ETC Hydraulic Modulator

2. Nut (2 Places) 5.0 - 12.0 N.m

DTC 95 (Request Torque Out of Range) will set if:

• The engine is running.

• The PCM detects the incorrect voltage on the Requested Torque circuit.

• The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

DEFAULT VALUES

When DTC 95 is set, traction control will be disabled and a corresponding DTC will be set in the ABS/ETS module.

RECOVERY

Recovery will occur when the DTC has been cleared and the ignition cycled OFF and ON.

DTC 95 HISTORY DATA

PARAMETER PARAMETER

ENGINE SPEED TFT

TIME FROM START THROTTLE ANGLE

TIMES OCCURRED VEHICLE SPEED

IGNITION CYCLES COMMANDED GEAR

COOLANT TEMPERATURE

Figure 6C1-1-129 Traction Control Circuit

12V

BR/R(121)

BR (121)

ENGINE SPEED

DIS

12V

C11

REQUESTED

TORQUE (M MR)

MMI ACTUAL

TORQUE (M MI)

O/W (1426)

B/W (1247)

BATTERY POWER

BATTERY

ABS/ETC

IGNITION

SWITCH

15a 15 50

30 ACC

IGN

START

F27

P (3)

SUPERVX024

PCM

R (855)

MMR

YE57

YB194

YB193

YB44

YB98

YE110

YE112

1.15 ABBREVIATIONS AND GLOSSARY OF TERMS

Abbreviations used in this Service Information are listed below in alphabetical order with an explanation of the

abbreviation.

AC - A LTERNATING CURRENT - A current with varying magnitude.

A/C - AIR CONDITIONING

A/F - AIR/FUEL (A/F RATIO)

ANALOG SIGNAL - An electrical signal that varies in voltage within a given parameter.

BAROMETRIC PRESSURE- Atmospheric pressure. May be called BARO, or barometric absolute pressure.

BATTERY - Stores chemical energy and converts it into electrical energy. Provide DC current for the vehicles

electrical systems.

CAMSHAFT POSITION SENSOR - The PCM uses this signal to determine the position of the No.1 piston in its

power stroke. This signal is used by the PCM to calculate sequential fuel injection mode of operation.

CAT. CONV. - CATALYTIC CONVERTER - A muffler-shaped device fitted in the exhaust system, between the

engine and the muffler. It is the primary "workhorse" of the emission control system, and the PCM's control of the

air/fuel ratio allows it to operate efficiently. It contains platinum, palladium and rhodium. It receives pollutants (HC,

CO, and NOx) emitted by the engine, and through a chemical reaction, converts these harmful pollutants into

harmless water vapour, carbon dioxide, and nitrogen. Maximum conversion efficiency of exhaust emissions is

achieved with precise control of the air/fuel ratio at 14.7-to-1.

CCP - CONVERTER CANISTER PURGE - A PCM controlled solenoid to purge the charcoal canister.

"CHECK POWERTRAIN" LAMP - W arning indicator with the outline of an engine. The "check powertrain lamp" is

located on the instrument panel, and is controlled by the PCM. "Check powertrain lam p" is illuminated by the PCM

when it detects a malfunction in the engine or transmission management system. "Check powertrain lamp" is on

and when the ignition is "ON" with the engine not running (bulb check).

CKT - CIRCUIT

CLOSED LOOP - A fuel contr ol sys tem m ode of oper ation that uses the signal f rom the ex haust oxygen sensor, in

order to control the air/fuel ratio precisely at a 14.7 to 1 ratio, allowing maximum efficiency of the catalytic

converter.

CO - CARBON MONOXIDE - One of the pollutants found in engine exhaust.

DC - DIRECT CURRENT - A current with a constant direction.

DTC - DIAGNOSTIC TROUBLE CODE - The PCM can detect malfunctions in the engine or transmission

management system. If a malfunction occurs, the PCM may turn on the "Check Powertrain" lamp, and a two-digit

code number will set in the PCM's memory. A diagnostic trouble code can be obtained from the PCM through the

"Check Powertrain" lamp, or with the Tech 2 scan tool. This DTC will indicate the area of the malfunction, and

properly following the service manual diagnostic procedures for the engine management system will locate the

source of the problem. NOTE: DTC 12 is used to verify that the PCM's diagnostic ability is operational.

DIAGNOSTIC "TEST" ENABLE TERMINAL - A terminal of the Data Link Connector (DLC) earthed to obtain a

Diagnostic Trouble Code by flashing out the MIL "Check Powertrain Lamp".

DIGITAL SIGNAL - An electrical signal that is either one of two states, "ON" or "OFF" with no in between.

DLC - DATA LINK CONNECTOR - The 16 pin connector used at the assembly plant to evaluate the control

module sy stem.

The c onnector is also us ed in service to f lash the Malfunction Indic ator Lam p (MIL) "Check Powertrain Lamp". T his

connector is also used by the Tech 2 scan tool to make system checks.

DLC DATA STREAM - An output of the PCM, initiated by the Tech 2 scan tool sending a command to the PCM.

This output is a digital c om puter language s ignal, used by assembly plant test equipm ent and the Te ch 2 sc an tool.

This signal is transmitted to the data link connector.

DRIVER - An electronic device, usually a power transistor, that operates like a switch; that is, it turns something

"ON" or "OFF."

DUTY CYCLE - The measurement of the length of time, in percentage, that a circuit is "ON" versus "OFF" when

compared with a 100% full ON/OFF time factor.

DVM (10 Meg.) - Digital voltmeter with 10 million ohms per volt impedance - used for voltage and resistance

measurement in electrical/electronic systems.

EECS - EVAPORATIVE EMISSIONS CONTROL SYSTEM - Used to prevent petrol vapours in the fuel tank from

entering the atmosphere. Stores the vapours in a storage canister, located in the engine compartment. Canister

contains activated charcoal, and the vapours are "purged" by engine vacuum during certain operating conditions.

EEPROM - ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY - Type of read only

memory (ROM) that can be electrically programmed, erased and reprogrammed.

EMI OR ELECTRICAL NOISE - An unwanted signal interfering with another needed signal; like an electric razor

upsets a television picture, or driving under high voltage power lines upsets the AM radio in a vehicle.

EGR - EXHAUST GAS RECIRCULATION VALVE - A device that is used to lower Oxides of Nitrogen (NOx)

emission levels by recalculating exhaust gases back into the combustion chamber.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR - Device that senses the engine coolant temperature, and

passes that information to the powertrain control module.

EPROM - ERASABLE PROGRAMMABLE READ ONLY MEMORY - Type of read only memory (ROM) that can

be erased with ultraviolet light and reprogrammed.

ESD - ELECTROSTATIC DISCHARGE - The discharge of static electricity, which has built up on an insulative

material.

FIELD SERVICE MODE - A PCM mode of operation that is used during service. It is operational when the engine

is running and the DLC diagnostic "test" enable terminal is earthed.

FUSE - A thin m etal strip that m elts through when excessive c urrent flows through it, thereby stopping current f low

and protecting a circuit from damage.

HC - HYDROCARBONS - One of the pollutants found in engine exhaust.

HIGH - A voltage more than a specific threshold such as earth or 0. In digital signals, high is "ON" and low is

"OFF".

HYSTERESIS - Movement that does not follow the same path as it entered an area as it exits.

IAC - IDLE AIR CONTROL - Installed in the throttle body unit and controlled by the PCM to regulate idle air flow,

and thus idle RPM.

IAT - INTAKE AIR TEM PERAT URE SENSOR - Senses intake m anifold inc oming air temper ature, and pas ses that

information to the PCM.

IDEAL M IXT URE - The air/f uel ratio that provides the bes t perfor mance, while m aintaining max imum conversion of

exhaust emissions, typically 14.7 to 1 on petrol engines.

IGN - IGNITION

INPUTS - Information from sensors (MAF, TPS, etc.) and switches (A/C request, etc.) used by the PCM to

determine how to control it's outputs.

INTERMITTENT - Oc curs now and then; not continuously. In electrical circuits , refers to oc casional open, short, or

earth.

I.C. - INSTRUMENT CLUSTER

LOW - A voltage less than a specif ic thres hold. Operates the sam e as an earth and m ay, or may not, be connected

to chassis earth.

M AF - M ASS AIR FLO W SENSOR - A devic e that monitors the amount of air f low coming in the engine intak e. The

MAF sensor sends a signal to the PCM.

MODE - A particular state of operation.

N.C. - NORMALLY CLOSED - Switch contacts that are connected, or together, when no outside forces

(temperature, pressure, position) are applied.

N.O. - NORMALLY OPEN - Switch contacts that are not connected, or not together, when no outside forces

(temperature, pressure, position) are applied.

NOx - NITROGEN OXIDES - One of the pollutants found in engine exhaust.

O2 - OXYGEN

OXYGEN SENSOR - Exhaust gas oxygen sensor, fitted in the exhaust manifold. Senses leftover oxygen after the

combustion process, and produces a very small electrical signal based on the amount of oxygen in the exhaust

gas, as compared to oxygen in the atmosphere.

OPEN LOOP - Describes PCM control of the fuel control system without use of oxygen sensor information.

OUTPUT - Functions, typically solenoids and relays that are controlled by the PCM.

PCM - POWERTRAIN CONTROL MODULE. A metal cased box (located in passenger compartment) containing

electronic circuitry that electrically monitors and controls the transmission system and emission systems of the

engine management system. It also turns "ON" the "Check Powertrain" lamp when a malfunction occurs in the

system.

PCV - POSITIVE CRANKCASE VENT ILAT ION - Method of reburning crankcase fumes, rather than passing them

directly into the atmosphere.

PFI - PORT FUEL INJECTIO N - Method of injecting f uel into the engine. Places a fuel inj ector at eac h inlet port of

a cylinder head, directly in front of the intake valve, mounted in the intake manifold.

PROM - PROGRAMMABLE READ ONLY MEMORY - an electronic term used to describe the engine calibration

unit. A plug-in memory unit that instructs the PCM how to operate for a particular vehicle.

PULSE WIDTH MODULATED (PWM)- a digital signal turned "ON" and "OFF'" for a percentage of available on-

plus-off cycle time, such as 30% "on" and 70% "off" would be called a 30% "ON" PWM signal.

QUAD DRIVER - A "chip" device in the PCM, capable of operating four separate outputs. Outputs can be either

"ON-OFF" or pulse width modulated.

RAM - RANDOM ACCESS MEMORY - Is the m ic roproces sors "scr atch pad". T he proces sor c an write into, or read

from this mem ory as needed. T his mem ory is volatile and needs a constant supply of voltage to be retained. If the

voltage is lost or removed, this memory is lost.

SERIAL DATA - Serial date is a series of rapidly changing voltage signals pulsed from high to low voltage. These

voltage signals are typically 5 volts (high) and 0 volts (low) and are transmitted through a wire often referred to as

the serial data line.

SEQUENTIAL FUEL INJECTION - A mode of injecting fuel into the engine on the intake stroke of each cylinder.

SOLENOID - An electromagnetic coil that creates a magnetic field when current flows through it and causes a

plunger or ball to move.

SUPPRESSION CAPACITORS - These capacitors are connected between the power and earth circuits of the

cooling fan motors. These capacitors are for controlling fan motor noise in the radio.

SWITCH - Opens and closes circuits, thereby stopping or allowing current flow.

TCC - TORQUE CONVERTER CLUTCH - PCM controlled solenoid in automatic transmission that positively

couples the transmission input shaft to the engine.

TECH 2 SCAN TOOL - A hand-held diagnostic tool, containing a microprocessor to interpret the PCM's DLC data

stream. A display panel displays the PCM input signals and output commands.

TP SENSOR - T HROT TL E POSIT ION SENSO R - Device that tells the PCM the c urr ent thr ottle position, and, when

it is moving, the rate of throttle opening / closing.

VACUUM, MANIFOLD - Vacuum source in the engine.

VACUUM , PORTED - Vac uum soured f rom a sm all "port" in the throttle body. W ith the throttle closed, there would

be no vacuum meas ured, because the port is on the air cleaner side of the throttle blade, and is exposed to engine

vacuum only after the throttle is open.

VSS - VEHICLE SPEED SENDER (Vehicles with Manual Transmission) - Pulse generator mounted in the

transm ission. T he speedom eter circuitr y contains an electronic divider c ircuit that sends a s ignal to the PCM and, if

so equipped, the body control module or trip computer.

VSS - VEHICLE SPEED SENSOR (Vehicles with Automatic Transmission) - A permanent magnet type sensor

which produces AC voltage which is sent to the PCM to determine vehicle speed.

UART - UNIVERSAL ASYNCHRONOUS RECEIVE AND TRANSMIT - A method of communicating between two

electronic devices.

WOT - WIDE OPEN TH ROTTLE