SECTION 12L - ANTI-LOCK BRAKING &

ELECTRONIC TRACTION CONTROL - GEN III V8

ENGINE

CAUTION:

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

seat belt pre-tensioners and a driver's air bag, seat belt pre-tensioners and a driver's and front

passenger's air bag s or seat belt pre- tensio ners, d riv er’s and fron t p asseng er’s air bag and lef t and rig ht

hand side air bags. Refer to SAFETY PRECAUTIONS, Section 12M Supplemental Restraint System of the

VT Series I Service Information before performing any service operation on, or around any SRS

components, the steering mechanism or wiring. Failure to follow the SAFETY PRECAUTIONS could

result in SRS deployment, resulting in possible personal injury or unnecessary SRS system repairs.

CAUTION:

This vehicle may be equipped with LPG (Liquefied Petroleum Gas). In the interests of safety, the LPG

fuel system should be isolated by turning 'OFF' the manual service valve and then draining the LPG

service lines, before any service work is carried out on the vehicle. Refer to the LPG leaflet included with

the Owner's Handbook for details or the appropriate Section of this Service Information CD for more

specific servicing information.

CAUTION:

Whenever any component that forms part of the ABS or ABS/ETC (if fitted), is disturbed during Service

Operations, it is vital that the complete ABS or ABS/ETC system is checked, using the procedure as

detailed in 4 DIAGNOSIS, ABS or ABS/ETC FUNCTION CHECK, in Section 12L ABS & ABS/ETC, in either

of the VT Series I Service Information 7 (V6) or the VT Series II Service Information (GEN III V8) of this

Service Information CD.

1. GENERAL INFORMATION

NOTE: ABS is an Anti-locking Braking System only while the ABS/ETC system is an Anti-locking Braking System

(ABS) and an Electronic Traction Control system (ETC). Depending on the Model variant, both of these systems are

available as either an option or standard equipment to VT Series Models.

ABS for VT Series II Models (including vehicles f itted with GEN III V8 engines) carries over from earlier VT Series

Models, with all information detailed in Section 12L ABS & ABS/ETC of the VT Series I Service Information.

ABS/ETC for VT Series II Models carries over from earlier VT Series Models for vehicles fitted with V6 and V6

Supercharged engines only, with all information detailed in Section 12L ABS & ABS/ETC of the VT Series I

Service Information.

On VT Series II Models with GEN III V8 engines, the ABS element of the ABS/ETC system is functionally and

systematically the same as what has been published for VT Series Models with V6 engines of the VT Series I

Service Information.

Additionally with the ETC elem ent of the ABS/ET C system, VT Series II Models with GEN III V8 engines use brak e

intervention, however, this is where the similarity ends. As a result of this, this Section details only the ABS/ETC

system used on VT Series Models with GEN III V8 engines, and in certain situation, only what varies from

previously published inform ation. For General Inf ormation c overing the basic func tion and purpose of an Elec tronic

Traction Control system, refer to Section 12L ABS & ABS/ETC of the VT Series I Service Information.

The ABS/ETC system on VT Series II Models with GEN III V8 engine uses a throttle relaxer to control the throttle

position of the throttle body. The throttle relaxer is controlled by its own control module; throttle relaxer control

module, which receives inf ormation from the ABS/ETC control m odule. As with the V6 system, engine intervention

is also used and will retard the ignition timing to reduce the amount of torque.

The throttle relaxer is positioned part way along the accelerator cable in the engine c om partm ent. T he request f rom

the accelerator pedal (pedal depressed) is transmitted via the cable to the throttle relaxer. The request then

continues on to the throttle body under normal driving conditions.

In a situation where a rear wheel is about to lose traction, under heavy acceleration for the road condition, the

throttle relaxer will interrupt the request from the accelerator pedal and control the throttle position of the throttle

body. This will bring the wheels back to a controlled condition.

2. GENERAL DESCRIPTI ON

On all VT Series Models, the conventional portion (non-ABS) of the braking system comprises the conventional

heavy duty braking system, specific brake pipe harness and lines and a common master cylinder with the

conventional non-ABS braking system, but has a screw-in blanking plug installed into the lower of the two front

brak e outlets. Each front wheel hub also includes the wheel speed sens or as part of the ass embly. The rear wheel

speed sensors are toothed pulse rings attached to each of the inner axle flanges.

At road speeds above approximately 3 km /h, the ABS is designed to c ontrol brak e f luid press ure so that the wheels

are prevented fr om lock ing-up dur ing brak ing, irrespec tive of the r oad conditions and tyre grip. The s ystem s tarts to

regulate when one wheel is detected to be decelerating faster than the other wheels, tending to lock. The vehicle

remains steerable, even in the event of panic braking, for instance on bends or when swerving to avoid an obstacle.

The ABS/ETC fitted to VT Series Models with GEN III V8 engines modulates braking pressure separately at each

front and rear wheel. The ABS/ETC is referred to as a four channel system as each of the four wheels have a

separate hydraulic brake circuits which are used to achieve anti-lock braking and traction control functions. The

term modulated refer s to the ABS ability to 'Maintain', 'Reduc e' or 'Incr ease' (Build-up) the hydraulic press ure in the

various brake circuits based on various inputs.

The TECH 2 diagnostic scan tool is programmed to assist with VT electrical diagnosis and problem solving,

including ABS and ABS/ETC.

TECH 2 connects to the ABS/ETC serial data communication information via the Data Link Connector (DLC),

attached to the instrum ent panel lower r ight hand trim , to the right of the s teering colum n. F or additional infor m ation

on DLC location and system diagnosis, refer to 4. ABS DIAGNOSIS in this Section. For additional and more

comprehensive information regarding TECH 2, refer to Section 0C TECH 2 of the VT Series I Service Information.

T212L001

Figure 12L-1 Typical location of components for ABS/ETC on vehicles with GEN III V8 engines

1. Hydraulic modulator and control module assembly 10. Left rear wheel speed sensor

2. Master cylinder 11. Powertrain Interface Module (PIM)

3. Stop lamp switch 12. Throttle relaxer (actuator) control module

4. Body Control Module (BCM) 13. Throttle relaxer (actuator) assembly

5. TRAC OFF warning lamp 14. Left front wheel speed sensor

6. TRAC LOW warning lamp 15. Powertrain Control Module (PCM)

7. ABS OFF warning lamp 16. Throttle Position Sensor (TPS)

8. Traction control on/off switch 17. Right front wheel speed sensor

9. Right rear wheel speed sensor

2.1 ABS/ETC SYSTEM OVERVIEW

BASIC OPERA TING PRINCIPLE

The rotational speed of each wheel is measured by inductive wheel speed sensors. W hen the brak es are applied,

the change in rotational speed is used by the processor in the ABS/ETC control module to determine the

deceleration, acceleration and slip of the wheels.

On vehicles with ABS/ETC, the front and rear wheels are individually controlled (four channel system).

Fig 12L-2 provides an overview of a four channel ABS/ETC system. The braking force for each wheel (front and

back) is regulated using individual inlet and outlet solenoid valves within the hydraulic modulator. Four sensors

measure the individual speed of each wheel.

T212L007

3b 3b

3a 3a

Figure 12L-2 Four Channel ABS/ETC

1. Wheel speed sensors 3a.Solenoid valve 5. Electronic control module

2. Brake callipers 3b.Return pump 6. Switching valve

3. Hydraulic modulator 4. Brake master cylinder 7. Priming valve

2.2 NORMAL CONDITIONS DURING ABS AND ETC INTERVENTION

During anti-lock braking, a series of rapid pulsations are felt through the brake pedal. These pulsations occur as

solenoid valves within the under hood hydraulic modulator assembly change position to modulate brake hydraulic

pressure. Brake pedal pulsation continues until the vehicle is stopped or the ABS mode disengages.

The operation of the pump, also within the hydraulic modulator assembly, is characterised by rapid brake pedal

pulsations that is accom panied by some electric m otor and pump noise. Pump operation m ay be perceived during

regular vehicle oper ation or during initial ABS/ETC contr ol module self -test. W hile these f unctions som etime caus e

driver concern, they are normal functions of ABS/ETC operation.

Traction control intervention operates in three stages; engine spark retard, throttle angle reduction, and rear brake

application.

The first is less noticeable; with only a power sag from the engine being felt as the ABS/ETC control module

requests the PCM to retard the engine spark as appropriate.

If the ABS/ETC control module continues to detect the rear wheels are rotating faster than the front, it will request

the throttle relaxer control module to reduce the throttle angle.

The final step taken to control the rear wheel is for the ABS/ETC control module to apply the rear brakes, thus

reducing the torque to the rear wheels.

W hen the vehicle reaches approxim ately 6 km /h and provided the ABS/ET C control module does not sense a stop

lamp switch input, after initial engine start-up and driving away, the ABS/ETC control module tests the solenoid

valves and pump. This self test can be heard by the driver and is a normal oper ating f unc tion of the ABS/ETC. If the

ABS/ETC control module does sense a stop lamp switch input, the self test will not occur until the vehicle is

travelling at approximately 18 km/h.

Normal function of the ABS, TRAC OFF and LOW TRAC warning lamps in the instrument cluster are as follows:

ABS lamp: should illuminate when the ignition is switched on and will go out approximately two seconds later.

Should the lamp not go out, the ABS/ETC control module has detected a system fault.

TRAC O FF lamp: s hould illuminate when the ignition is switched on and will go out appr ox imately five s ec onds later

(or two seconds later with engine running). If the lamp does not go out, either the ABS/ETC control module has

detected a system fault, or the system has been manually switched off.

LOW TRAC lamp: should illuminate when the ignition is switched on and will go out approximately two seconds

later. This lamp will flash whenever the ETC system is engaged.

2.3 ABS/ETC SYSTEM COMPONENTS

WHEEL SPEED SENSORS AND PULSE RINGS

Inductive wheel speed sensors are used to detect

the rotational speed of each wheel. There are

specific wheel sensor assemblies for front and rear

wheels.

Introduced as a running change (approximately

April, 1999), the design of the front wheel

hub/bearing/sensor changed. As a consequence of

this change, the wheel speed sensor wiring

harness connector (2) changed to a ‘push-on’ type

with a locking tang, in lieu of the screw retained

connector used previously.

Front Wheel Speed Sensors

The front wheel speed sensors (1) are incorporated

as part of the front suspension front wheel hub

assembly.Figure 12L-3

There are three specific front wheel hub

assemblies available. For vehicles with ABS or

ABS/ETC, there is a right and left, which

incorporates the wheel speed sensor and a 48

tooth magnet impulse ring. For non ABS vehicles, a

common hub is used for both sides.

Identification of the front wheel hub assemblies is

by the assembly part number etched on the outer

surface (1) of the hub wheel flange or by simply

noting whether a wheel speed sensor cap is fitted

to the hub (2).

CAUTION: During any service operation that

requires the replacement of the front hub

assembly on a vehicle equipped with ABS/ETC,

ensure that the correct replacement hub

assembly is installed, otherwise malfunctioning

of the ABS or ABS/ETC will occur.

NOTE 1: Always refer to the latest Holden spare

parts information (PartFinderTM) for the correct front

wheel hub assembly part numbers.

NOTE 2: Apart f rom wheel stud replacem ent, there

are no serviceable items in the front wheel hub

assembly. With the unit being a ‘sealed for life’

assembly, there are no requirements for wheel

speed sensor and/or bearing adjustments. Should

a non-standard condition develop, then the hub

assembly must be replaced as complete unit.

T212L004

Figure 12L-4

Fig. 12L-5 illustrates a sectioned view of the front

wheel sensor in the front hub assembly.

The components of the sensor are:

• magnetic impulse ring (1)

• coil (3)

• flux concentrator (4)

• coaxial connector (6)

The magnetic impuls e ring ( 1), attached to the fr ont

hub rotating member (2), is magnetised and

contains 48 individual magnets evenly spaced

around the ring.

On the flux concentrator (4) there are a

corresponding 48 evenly spaced teeth (5).

Magnetic flux (7), generated from the impulse ring

(1), is induced into the coil (3) via the flux

concentrator (4).

As the road wheel is rotated, the front hub inner

member and magnetic impulse ring rotate as one,

causing a variation of the magnetic flux generated

in the flux concentrator. This change in the

magnetic flux causes an alternating voltage to be

induced in the coil of the sensor.

Figure 12L-5

The frequency and amplitude of the induced

voltage are dependent on wheel RPM, the number

of turns of the coil, the magnetisation level of the

impulse ring and the number teeth of the flux

concentrator. Of all these factors, the only variable

is the wheel RPM, so the frequency and amplitude

of the output signal depend on the speed of wheel

rotation.

The dotted line (1) in Fig 12L-6 represents the

voltage generated by the wheel speed sensor

versus time (T) at low wheel speed.

The continues line (2) in Fig 12L-6 represents the

voltage generated by the wheel speed sensor

versus time (T) at high wheel speed.

T212L005

Figure 12L-6

Rear Wheel Speed Sensors

The rear wheel speed sensor (1) basically consists

of a magnetic core and a coil. The pole tip (2) is

surrounded by a m agnetic f ield. As the wheel turns,

the teeth of the pulse ring (3) cause c hanges in this

magnetic field. The magnetic flux thereby changes

and an alternating voltage is induced in the coil of

the wheel speed sensor.

The pole piece on the outer surface of the sensor is

of a plastic construction and therefore there is no

requirement to coat the outer surface with high

temperature grease when reinstalling sensor

assemblies (as on previous models).

The rear wheel speed sensors have a high voltage

output and therefore, there is no need to install

shim s between the sens or and its mating m ounting

bracket.

1. Wheel speed sensor

2. Pole tip

3. Pulse ring

4. Sensor output

T212L006

Figure 12L-7

The rear wheel speed sensors (1) are located in a

bracket which is part of the final drive rear cover.

Each pulse ring (2) is a toothed ring made of a

ferrous metal that rotates to allow the wheel speed

sensor to read the rotational speed of each rear

wheel.

The rear wheel pulse rings are part of the final drive

inner axle flanges and are not serviced separately.

As the road wheels rotate, the wheel speed

sensors generate an AC electrical signal

proportional (in frequency and amplitude) to the

wheel speed. The ABS or ABS/ETC c ontrol m odule

uses wheel speed signals to determine when anti-

lock control or traction control is required.

Specifically, the module uses wheel speed sensor

signals to find out whether any of the wheels are

decelerating rapidly (lock ing) or ac celerating rapidly

(slipping).

The ABS/ET C s ystem is calibr ated to us e tyres of a

known rolling radius and pulse rings with a specif ic

number of teeth. The num ber of teeth on the pulse

rings correspond directly to tyre size. If one of the

tyres f itted to the vehicle is larger or s maller (not to

original equipment size) than the remainder of the

tyres on the vehicle, the ABS/ETC control module

will not modulate brake system hydraulic pressure

properly. Improper system operation occurs

because the wheel speed signal from the off-size

tyre makes the module think that one wheel is

accelerating or decelerating faster than the others.

T212L008

Figure 12L-8

NOTE: IT IS IMPORTANT THAT THE VEHICLE

ONLY BE EQUIPPED WITH THE ORIGINAL

EQUIPMENT TYRE SIZE AS NOMINATED ON

THE VEHICLES TYRE PLACARD. CHANGING

TYRE SIZE COULD AFFECT SYSTEM

FUNCTION.

ABS/ETC CONTROL MODULE

The ABS/ETC control module (1) evaluates the

signals from the wheel speed sensors and

computes the permissible wheel slip for optimum

braking and traction.

During ABS, it regulates the necessary braking

pressure in the brake callipers by means of

solenoid valves within the hydraulic modulator

assembly (2). The ABS/ETC control module tests

the system in accordance with a defined program

and monitors it during driving.

The ABS/ETC control module also monitors both

front and rear wheel speeds through the wheel

speed sensors for wheel slip. If at any time during

acceleration the ABS/ETC control module detects

drive wheel slip, it will act to bring excess engine

torque into a specific range by:

• Requesting the PCM to retard the amount of

spark advance, via the spark retard circuit,

circuit 1687 (Grey/Black wire).

• Throttle angle reduction: sending a message

to the throttle relaxer control module, via the

requested throttle position line (DKR), circuit

1426 (Orange/White wire), to reduce the

throttle angle. The throttle relaxer control

module achieves this by driving the throttle

relaxer motor, which in turn pulls back the

throttle cable, reducing the throttle body

opening.

The throttle relaxer control module sends a

signal back to the ABS/ETC control module

via the actual throttle position line ( DKI), circ uit

1427 (Black/White), reporting on the actual

throttle position.

• Brake application: the ABS/ETC control

module will activate the ABS isolator valves,

turn on the ABS pum p m otor and supply brake

pressure to the spinning wheel/s.

The ABS/ETC contr ol module is integrated with the

hydraulic modulator and is located in the engine

compartment, forward of the master cy linder (3).

There are different control modules used in VT

Series Model vehicles for ABS and ABS/ETC

systems. It is physically impossible to fit an ABS

control m odule to an ABS/ETC hydraulic m odulator

or an ABS/ETC control module to a ABS hydraulic

modulator. However, if replacing either an ABS or

ABS/ETC control m odule, always refer to the latest

VT Series Model Parts Information for the correct

ABS and ABS/ETC control module part numbers.

Figure 12L-9

HYDRAULIC MODULATOR

The hydraulic modulator (2) for the ABS/ETC

system consists of ten solenoid valves (four inlet,

four outlet and two ETC solenoid valves), two

accumulators, one for the front brake circuits and

the other for the rear brak e circuit and a brak e f luid

return pump.

The solenoid valves are actuated by the ABS/ETC

control module (1). Depending on the switching

stage, they connect the wheel brake calliper s either

with the brake m aster cylinder (3) or with the pump

assembly, or disconnect the wheel brake calliper

from both the circuit and pump. When pressure is

reduced, the return pump conveys the brake fluid

flowing out of the wheel brake cylinders back into

the brake master cylinder via the corresponding

accumulator. The accumulators serve to

temporarily accommodate the brake fluid 'surplus'

which suddenly occurs following a drop in pressure.

The hydraulic modulator is mounted in the engine

compartment, forward of the brake master cylinder. Figure 12L-10

THROTTLE RELAXER

Mounted to the cockpit module, in the engine

compartment, the throttle relaxer consists of: three

pulleys (2), a dust cover (1) and a motor (3).

The accelerator pedal cable is connected to the

centre (B) of the three pulleys. The throttle cable

(throttle relaxer to throttle body cable) attaches to

the bottom (A) of the three pulleys. If the vehicle is

fitted with cruise control, the cruise control cable

attaches to the top pulley (C).

Via a raised lug on pulley B, through an elongated

slot in pulley C, pulleys B and C are connected to

each other. This allows for the operation of the

cruise control, and interruption free movement of

pulley B (accelerator pedal position) when the

cruise control is not in operation.

Pulleys A and B are connected to each other via an

internal spring. Under normal operating conditions,

the load applied to pulleys B and C (accelerator

pedal and cruise control actuator load) is

transferred through the internal spring to pulley A

and onto the throttle body.

During ETC intervention, the throttle relaxer motor

controls pulley A regardless of the accelerator

pedal position. The internal spring between pulley A

and B is compres s ed and theref or e, the ac celer ator

pedal is overridden. A slight sensation on the

accelerator pedal can be felt during this stage.

If the cruise control is engaged and the ETC

intervenes, the cruise control will automatically be

disengaged.

T212L009

ABC1

Figure 12L-11

THROTTLE RELAXER CONTROL MODULE

The throttle relaxer control module is located

behind the passenger side shroud lower trim

assembly, next to the Powertrain Interface Module

(PIM).

The throttle relaxer control module operates using

information received from both the throttle position

sensor and the ABS/ETC control module.

The ABS/ETC control module communicates with

the throttle relaxer control module via Pulse Width

Modulated (PWM) signals sent and received on two

circuits; DKR circuit 1426 (Orange/W hite wire) and

DKI circuit 1427 (Blac k /White wire). DKR translates

to the requested throttle position, DKI translates to

actual throttle position.

Diagnostic Trouble Codes DTCs for the throttle

relaxer are incorporated into the ABS/ETC control

module.

Figure 12L-12

ABS WARNING LAMP

Located in the instrument cluster, the ABS warning

lamp is part of the driver warning system.

The ABS warning lamp is controlled by the

ABS/ETC control module. It is illuminated to warn

the driver that autom atic anti- lock brak ing capability

is totally inhibited. This does not affect the

operation of the vehicle's conventional braking

system.

The ABS warning lamp will illuminate when:

1. The ignition is turned on. The lamp will go out

after a stationary 'Self Check' is completed

(two to five seconds).

2. The ABS or ABS/ETC control module detects

an ABS electrical wiring or component

problem.

3. The ABS or ABS/ETC control module detects

a problem within itself.

These conditions are part of the ABS self-check.

4. When using TECH 2 in certain diagnostic

modes for ABS/ETC diagnosis, the ABS/ETC

system is disabled by the ABS/ETC control

module while it is communicating with

TECH 2.

Should the ABS warning lamp lose power (from

fuse F13 ignition fuse) or the ABS control module

lose earth (terminals 19, 20 and 21), the ABS

warning lamp will not illuminate at any time.

TRAC

OFF LOW

TRAC

ABS

T212L011

Figure 12L-13

ELECTRONIC TRACTION CONTROL (ETC) WARNING LAMPS

There are two electronic traction control warning

lamps located in the instrument panel cluster;

TRAC OFF and LOW TRAC.

The TRAC OFF warning lamp is controlled by the

ABS/ETC control module, via the serial data bus

circuit, and will illuminate to warn the dr iver that the

ETC system has been disabled.

The TRAC OFF warning lamp will illuminate when:

1. The ignition is turned on. The lamp will go out

after a stationary 'Self Check' is completed

(two to five seconds).

2. When the ETC system is manually switched

off, via the TRAC CTRL button.

3. The ABS/ETC control module detects an ETC

electrical wiring or component problem.

4. The ABS/ETC control module detects a

problem within itself.

5. When using TECH 2 in certain diagnostic

modes for ABS/ETC diagnosis, the ABS/ETC

system is disabled by the ABS/ETC control

module while it is communicating with the

TECH 2.

Should the TRAC OFF or LOW TRAC warning

lamps lose power (from fuse F13 ignition fuse)

neither of these lamps will illuminate. Also, if the

ABS/ETC c ontrol module los es earth (ter minals 19,

20 and 21), the LOW TRAC warning lamp will not

illuminate.

The LOW T RAC warning lamp is also controlled by

the ABS/ETC control module and will illum inate for

two seconds when the ignition is switched on and

then go out, or when the ABS/ETC control module

is controlling wheel spin, indicating that the vehicle

is in a critical situation.

TRAC

OFF LOW

TRAC

ABS

T212L012

Figure 12L-14

ELECTRONIC TRACTION CONTROL ( ETC) SWITCH

In certain circumstances (i.e. if the vehicle became

bogged and could be ‘rocked out’) it may be

necessary to disable the electronic traction control

system (ETC). This is achieved by pressing the

TRAC CTRL button, located near the transmission

selector, refer to

Fig. 12L-15. If the traction control system is

switched off, the TRAC OFF lamp will illuminate.

The system can be switched on again by either

pressing the TRAC CTRL button again or when the

ignition is next cycled (off to on).

NOTE 1: If the electronic traction control system is

commanded off, the ABS will still function normally.

NOTE 2: If the TRAC CTRL button is depressed

and held for 10 or more seconds, the ABS/ETC

control module will see this as a short circuit and

the ETC will be permanently enabled (for that

ignition cycle) until the ignition is switched off and

the engine restarted. Additionally, the TRAC OFF

warning lamp (if illuminated) will be turned off until

the ignition is switched off and the engine restarted.

T212L013

Figure 12L-15

BRAKE MASTER CYLINDER

On VT Series Models, regardless of the engine

configuration, a common brake master cylinder is

used on vehicles with standar d, ABS and ABS/ET C

brake systems. The only difference being that the

master cylinder used with ABS and ABS/ETC

systems has a screw-in blanking plug installed and

tightened into the lower of two front brak e outlets in

the master cylinder.

1. Rear brake outlet pipe.

2. Front brake outlet pipe.

3. Blanking plug.

T212L014

Figure 12L-16

ABS & ETC FUSES

An ABS 60 amp fusible link, marked FR, is

incorporated in the engine c ompar tment f usible link

housing.

The throttle relaxer and throttle relaxer control

module are supplied voltage via fuse F36, also

located in the engine compartment fusible link

housing.

An additional 10 am p fuse, F27 is used f or the ABS

and is located in the passenger compartment fuse

panel at fuse location No. 27.

The ABS, TRAC OFF & LOW TRAC warning

lamps are supplied voltage via fuse F13 located in

the passenger compartment fuse panel.

Figure 12L-17

STOP LAMP SWITCH

The stop lamp switch, located in the brake pedal

support, provides a BRAKES APPLIED 12 volt

input signal to terminal 14 of the ABS/ETC control

module. Whenever the ABS/ETC control module

receives this signal the ABS control cycle will begin.

If the driver pum ps the brake pedal during the ABS

operation, the control cycle will be reset.

The stop lamp switch is a nor mally open switch that

supplies battery voltage to the stop lamps and

terminal 14 of the ABS/ETC control module, when

closed. When the switch is open (brakes not

applied), terminal 14 of the ABS/ETC control

module is earthed through the stop lam ps, causing

the voltage at terminal 14 to be pulled low (less

than 0.2 volts)

Also, if the ABS/ET C control module senses a stop

lamp switch input, the self test will not occur until

the vehicle is travelling at approximately 18 km/h.

For all service operations on the stop lamp switch,

refer to Section 12B LIGHTING SYSTEM of the

VT Series I Service Information.

Figure 12L-18

2.4 INSTALLATION POSITION OF ABS AND ABS/ETC COMPONENTS

The following figures illustrate the installed positions of the various ABS/ETC components for VT Series Models with

GEN III V8 engines.

Figure 12L-19 Installation and location of Hydraulic modulator and control modules

1. ABS/ETC Hydraulic modulator and

control module assembly 2. Throttle relaxer control module 3. Powertrain Control Module (PCM)

Figure 12L-20 Installation and location of throttle relaxer and cables, powertrain harness to PCM and throttle relaxer,

and main wiring harness to ABS/ETC control module

1. ABS/ETC control module connector 5. PCM 9. Cruise control cable

2. Main wiring harness 6. Throttle relaxer 10. Accelerator cable

3. Power steering harness 7. Powertrain harness to throttle relaxer 11. Throttle cable

4. Powertrain harness to PCM 8. Throttle relaxer cover

Figure 12L-21 Engine compartment and front brake line routing

1. Modulator to LH rear brake hose 5. Modulator to LH front brake hose 9. Front brake calliper

2. Master cylinder to modulator rear pipe 6. Modulator to RH front brake hose 10. Front brake hose

3. Modulator to RH rear brake hose 7. Master cylinder and brake booster 11. Front brake hose to calliper

4. Master cylinder to modulator front

pipe 8. Brake line retaining clip bolt and washer

Figure 12L-22 Front wheel speed sensor lead routing

1. Front wheel s

eed sensor and lead

assembly 2. Main wiring harness 3. Retaining clip

NOTE: View A shows left hand side wheel speed sensor assembly, Views B and C are from inside the engine compartment.

Figure 12L-23 Rear wheel speed sensor lead and body wiring harness routing

1. Body wiring harness 2. Rear wheel speed sensor and lead assembly 3. Retaining clip

2.5 GEN III V8 ENGINE ABS/ETC PRINCIPLES OF OPERATION

NON-ANTI-LOCK BRAKING / NON-TRACTION CONTROL

Under normal braking and driving conditions, the anti-lock braking system functions much like a conventional

braking system. Brake fluid pressure is provided by the brake master cylinder and the power booster.

For non-anti- lock braking, hydraulic press ur e is applied to the br ake calliper s without any intervention from the ABS.

At this time, the hydraulic modulator establishes an open two-way fluid path from the master cylinder to the brake

callipers. Non-anti-lock braking occurs when the wheel sensors do not detect wheel lock-up tendencies. However,

even though the ABS is passive during normal braking, the ABS/ETC module is constantly monitoring for rapid

acceleration (wheel slip) and deceleration (wheel lock) of any of the wheels and a signal from the brake switch

(brakes applied input).

ANTI-LOCK BRA KING

When the ABS senses any tendency for wheel lock-up, it enters the anti-lock mode. During anti-lock braking, the

ABS modulates hydraulic pressure in the brake circuits to control wheel slip to approximately 10 - 20%. For anti-lock

braking, the ABS control module controls current flow to the hydraulic modulator solenoid valves to control (by

maintaining, decreasing or increasing) hydraulic pressure in the brake circuits.

NOTE: The hydraulic modulator cannot increase brake circuit hydraulic pressure above the pressure supplied by

the brake master cylinder during anti-lock braking.

ELECTRONIC TRACTION CONTROL

W hen the ABS/ET C control module s enses spin fr om the drive wheels due to too m uch engine torque for the road

conditions, it enters the traction control mode.

The ABS/ET C module 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:

• The PCM, via the spark retard circuit, to retard the amount of spark advance.

• The throttle relaxer control module to reduce the engine throttle opening by a certain percentage to bring

engine torque into a specific range.

The throttle relaxer control module accomplishes this by commanding the throttle relaxer to override the

accelerator pedal cable and physically reduce the throttle body butterfly opening by winding the throttle cable

back.

This is ac hieved via two high speed Puls e Width Modulated ( PWM) c irc uits between the ABS/ETC module and

the throttle relaxer control module. The ABS/ETC control module sends a message to the throttle relaxer

control m odule on the requested throttle pos ition (DKR) c ircuit. T he throttle r elaxer c ontrol m odule then repor ts

the modif ied throttle pos ition opening back to the ABS/ET C control m odule via the ac tual throttle position (DKI)

circuit.

Simu ltaneously with engine spark retard and throttle position intervention, the ABS/ET C control m odule will activate

the ABS isolation valves, turn on the ABS pump motor and supply brake pressure 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 opens the priming valve, allowing fluid to be

drawn from the m aster cylinder to the pump m otor, tur ns on the ABS pump m otor to apply pressure, begins cycling

the ABS assembly's inlet and outlet valves, and closes the switching valve, ensuring fluid is directed to the wheel

not back into the master cylinder.

The inlet and outlet valve cycling aids in obtaining m aximum road surf ace traction in the sam e manner as the Anti-

Lock Brake m ode. The diff erence between Traction Contr ol and Anti-Lock Brake mode is that brak e fluid pres sure

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 dur ing Traction Contr ol mode, the brakes are manually applied, the brake s witch signals the ABS/ET C

module to inhibit brake intervention and allow for manual braking (throttle reduction and spark retard intervention

can still occur if necessary).

Figure 12L-24

ABS/ETC CONTROL MODULE OPERATION

Inputs

The following ABS/ETC components send signals to the ABS/ETC control module where they are evaluated in

order for the module to maintain and control wheel slip/spin.

• Ignition on input, (via fusible link FJ, ignition switch, fuse F27) - ABS/ETC control module terminal No. 15.

• Wheel speed sensor inputs - ABS/ETC control m odule terminal No’s. LHF 6 and 7, RHF 4 and 5, LHR 8 and 9,

and RHR 1 and 2.

• Brakes applied input (from brake lamp switch) - ABS/ETC control module terminal No. 14.

• Battery voltage - ABS/ETC control module terminals 17 and 18.

• Actual throttle position (DKI) - ABS/ETC control module terminal 27.

• Engine speed signal - ABS/ETC control module terminal 30.

• ETC disable switch (TRAC CTRL) - ABS/ETC control module terminal 31.

• Serial data (input and output) - ABS/ETC control module terminal No. 11.

T212L022

.....

RIGHT REAR

R IGHT FR ONT

LEFT F RONT

LEFT REAR

BRAKE LAMP SWITCH

SER IAL DATA

IG NIT ION " ON"

12 VOLT

ACTUAL THROTTLE POSITION (D KI)

ETC DISABLE SWITCH

ENGIN E SPEED SIG NAL

WHEEL SPEED

SENSORS

INPUTS OUTPUTS

16 19

.....

20 R EQUESTED THR OTTLE POSITION (DKR)

SER IAL DAT A

DIAGNOSTIC TER MINAL

E.T.C. WARNING LAMPS

A.B.S. WARNING LAM PS

R EQUESTED SPARK R ET AR D

PUMP RELAY/

PU MP MOT OR

INT ERNAL CONTROL

VALVE RELAY/

SOLENOI D VALVES

INT ERNAL CONTROL

ABS/ETC

CONTROL

MODULE

Outputs

To control the anti-lock braking system and traction control system, the ABS/ETC control m odule sends command

signals to the following components.

• Valve relay/solenoid valves - internal control.

• Pump relay/pump motor - internal control.

• Serial data (input and output) - ABS/ETC control module terminal No. 11.

• Self diagnostic 'Flash Code Actuation' - ABS/ETC control module terminal No. 12.

• Requested throttle position - ABS/ETC control module terminal No. 13.

• ETC warning lamp (TRAC OFF, LOW TRAC) - ABS/ETC control module terminal 20.

• ABS warning lamp - ABS/ETC control module terminal No. 21.

• Requested spark retard – ABS/ETC control module terminal No. 28.

With the ignition switch in the on position, batter y voltage is applied to the ABS/ETC control m odule ter m inal No. 15

via fuse F27. Battery voltage is also applied to the pum p motor relay and valve relay via fusible link FR. Neither of

the relays operate until they receive an earth from the ABS/ETC control module.

Also, battery voltage is supplied to the ABS and ETC warning lamps via fuse F13. The LOW TRAC and ABS

warning lamp s will not illum inate until they are earthed by ABS/ETC control m odule. If the ABS/ET C c ontrol module

wiring harness connector YE98, is not connected to the control module, terminals 19, 20 and 21 are shorted

together by a shorting bar, and the LOW TRAC and ABS warning lamps will be illuminated. The TRAC OFF warning

lamp is defaulted to the on position and is turned off via a serial data message from the ABS/ETC control module

when the ignition is turned on (provided the system is OK).

Wheel speed sensors are located at each front wheel and at each final drive inner axle flange. When the vehicle

starts m oving, all of the speed sensors create signals that are input to the ABS/ET C control module at terminals 1

and 2, 4 and 5, 6 and 7, 8 and 9. These signals are AC electrical pulses that are proportional (in frequency and

amplitude) to wheel rotational speed.

Once the vehicle has been started and dr iven over approx imately 6 km /h, the c ontro l module perf or ms an ABS/ETC

self test. The control module test cycles each solenoid valve and the return pump in the hydraulic modulator to

check component operation. The control module checks its own logic section and circuitry. If errors are detected

during this test, the control module earths terminal 20, illuminates the ABS warning lamp and also sends a

message, via the serial data circuit, commanding the TRAC OFF warning lamp to be illum inated. The ABS and/or

ETC warning lamp/s are illuminated to warn the driver of a problem with the system/s. The ABS/ETC control module

remains deactivated until the next ignition switch OFF to ON cycle when the process is repeated and the ABS

and/or TRAC OFF warning lamp/s will be illuminated.

The ABS self test occurs once each ignition cy cle as follows:

1. After receiving an ignition ON input, the control module earths and activates the valve relay.

2. As soon as the ABS/ETC control module receives a signal from any of the wheel speed sensors, it checks

wheel speed sensor output. If any of the wheel speed sensor signals are not detected, or are incorrect, the

ABS/ETC system will be disabled and the warning lamps will be illuminated.

3. When the vehicle reaches approximately 6 km/h, the control module tests the solenoid valves and the return

pump in the modulator. If the control lamp switch receives a brake lamp switch input before the vehicle has

reach 6 km/h, the self test will not occur until the vehicle reaches a road speed of approximately18 km/h.

4. If the pum p or s olenoid valves f ail to operate, the ABS/ET C s ystem will be dis abled and the warning lam ps will

be illuminated.

Once the vehicle is moving, the control module continuously monitors itself and the following components:

1. Solenoid valves.

2. Wheel speed sensors.

3. Wiring harness and relays.

4. Battery voltage.

If battery voltage drops below approximately 9 volts, the ABS/ETC will be disabled and the ABS and TRAC OFF

warning lamps will be illuminated, while the voltage remains below 9 volts.

During braking applications, if one or more wheels start to decelerate too quickly, the ABS is engaged and the

modulation process begins. Wheel speed information sent to the ABS/ETC control module is processed and the

module deter mines pr oper solenoid valve oper ation in the modulator. The modulator c ontains ten s olenoid valves ; a

priming and switching relay, plus one inlet and one outlet valve for each wheel.

When wheel spin is detected and traction control mode begins, the ABS/ETC control module also engages ABS

through the modulation process. Additionally, the ABS/ETC control module simultaneously changes the engine

output conditions by reducing the amount of spark advance and reducing the throttle opening.

HYDRAULIC MODULATOR OPERATION

The hydraulic modulator executes ABS control

module commands using 10 solenoid valves.

These solenoid valves, located in the hydraulic

modulator assembly, are in series with the brake

master cylinder and the brake circuits. The

hydraulic modulator solenoid valves are activated

separately by the ABS/ETC control module

corresponding to various ABS or ETC control

phases:

1. Non-ABS Braking (ABS and ETC phases)

2. Maintaining Pressure (ABS phase)

3. Reducing Pressure (ABS phase)

4. Increasing (Building-up) Pressure (ABS phase)

5. Normal condition (ABS and ETC phases -

brakes off)

6. Applying (ETC phase)

The hydraulic modulator assembly contains 10

solenoid valves and a brake fluid return pump;

however, for explanation of the operation, only one

accumulator and four solenoid valves will be

described ( rear brak es). T he operation is the s ame

for all four circuits.

Non-ABS Braking (ABS and ETC phases)

During this condition, the inlet and outlet valves are

not activated. The inlet valve (pressure holding

solenoid valve) is open. This allows brake fluid to

flow in either direction between the brake master

cylinder and the brake calliper, providing for

conventional non-ABS braking. The outlet valve

(pressure release outlet solenoid valve) is closed,

blocking off the passage to the accumulator and

the return pump.

The brake master cylinder hydraulic pressure is

applied to the brake circuits (calliper). If the

ABS/ETC control module (not shown) does not

detect any rapid wheel deceleration, the ABS will

remain passive at this time.

Hydraulic modulator status:

LH inlet valve... Open LH outlet valve.Closed

RH inlet valve .. Open RH outlet valve Closed

Priming valve... Closed Switching valve Open

Motor ............... OFF

Figure 12L-25

Figure 12L-26

Maintaining Pressure (ABS phase)

NOTE: The following diagram and explanation

assumes the right hand rear wheel is having a

tendency to lock.

When the ABS/ETC control module detects

excessive wheel deceleration (based on the wheel

speed sensor (not shown) s ignal), it com m ands the

right hand inlet valve (pressure holding solenoid

valve) to maintain brake circuit pressure. It does

this by earthing the respective circuit (RH in this

case), ther efore allowing a current f low through the

coil of inlet valve solenoid. This causes the

armature and valve to move downward, isolating

the brake circuit (calliper) from the master cylinder.

NOTE: W ith the brak e circuit isolated, brake circuit

pressure between the modulator and the brake

calliper circuit remains constant despite increased

master cylinder hydraulic pressure.

Hydraulic modulator status:

LH inlet valve... Open LH outlet valve.Closed

RH inlet valve .. Closed RH outlet valve Closed

Priming valve... Closed Switching valve Open

Motor ............... OFF

Figure 12L-27

Figure 12L-28

Reducing Pressure (ABS phase)

NOTE: The following diagram and explanation

assumes the right hand rear wheel is having a

tendency to lock.

If isolation of a brake circuit between the brake

master cylinder and the brake calliper does not

reduce the excessive wheel deceleration, the

ABS/ETC control module commands the outlet

valve (pressure release solenoid valve) open to

reduce hydraulic brak e press ure in the brak e circ uit

(RH outlet valve in this case). During this phase,

the ABS/ETC control module earth’s the coil of the

RH outlet valve, allowing a current flow through the

coil windings. This causes the armature and valve

to move downward, opening a passage from the

brake circuit to the accumulator and the pump

assem bly inlet. At this stage, both the RH inlet and

RH outlet valves are activated simultaneously.

NOTE: At this time, the brake circuit is isolated

from the mas ter c ylinder by the return pump valving

and the energised return pump.

This action sends brake fluid from the brake

circuits back to the master cylinder. The return

pump continues to operate during the remainder of

the anti-lock cycle. This will increase the r eturn f low

pressure from the calliper, thus allowing the fluid

released from the calliper to be returned back to

the master cylinder. The pump will continue to

operate during the rest of the anti-lock brake cy cle.

Hydraulic modulator status:

LH inlet valve... Open LH outlet valve.Closed

RH inlet valve .. Closed RH outlet valve Open

Priming valve... Closed Switching valve Open

Motor ............... ON

NOTE: Motor will remain operational until ABS

mode is exited.

Accumulators

During the 'Reducing Pressure' phase of ABS

modulation, the acc umulators ( 2c) temporar ily store

fluid from the brake circuits. Some road conditions

require the relief of a large volum e of fluid f rom the

brak e callipers . In such c onditions, the accum ulator

guarantees pressure reduction. As soon as the

solenoid valve (2b) moves to the 'Reduction

Pressur e' pos ition, brake f luid f rom the br ak e c irc uit

flows into the accum ulator. Thus, before the return

pump (2d) starts operation, the accum ulator allows

an immediate pressure reduction in the brake

circuit. The front brake circuits share a common

accumulator. The rear brake circuit uses a

separate accumulator. The accumulators are

spring-loaded and designed to operate at less than

1000 kPa.

Figure 12L-29

Figure 12L-30

Increasing (Building-up) Pressure (ABS phase)

NOTE: The following diagram and explanation

assumes the right hand rear wheel is having a

tendency to lock.

The wheel accelerates again as a result of the

reduced braking pressure. Upon reaching a

specific limit, the ABS/ETC control module

registers the fact that the wheel is now not being

braked sufficiently.

The ABS/ETC control module then de-energises

both the RH inlet and RH outlet valves and the

formerly reduced pressure is then incr eas ed so that

the wheel is again decelerated. The ABS/ETC

control cycle begins again. There is approximately

4 - 6 control cycles per second, depending on the

state of the road surface.

Hydraulic modulator status:

LH inlet valve .....Open LH outlet valve ......Closed

RH inlet valve.....Open RH outlet valve......Closed

Priming valve .....Closed Switching valve......Open

Motor.................. ON

Figure 12L-31

Figure 12L-32

ETC Normal condition (ABS and ETC phases)

In the normal condition, there is no brake

intervention. All the valves in the hydraulic

modulator are in their normal rest positions,

allowing for uninterrupted flow for normal braking

condition. The schematic below depicts no

pressure in the system, therefore no application of

brakes.

Hydraulic modulator status:

LH inlet valve... Open LH outlet valve.Closed

RH inlet valve .. Open RH outlet valve Closed

Priming valve... Closed Switching valve Open

Motor ............... OFF

Figure 12L-33

ETC in operation (ETC phase)

NOTE: The following diagram and explanation assumes the right hand rear wheel is having a tendency to spin.

BRAKE INTERVENTION

In the following schematic, the ABS/ETC control module has detected that the wheel is about to enter into a

situation where wheel slippage is about to occur from excess engine torque for the road condition.

The ABS/ETC control module commands the priming valve open, allowing fluid to be drawn from the master

cylinder by the pum p assem bly. T he switching valve is clos ed, ensuring fluid is dir ected to the wheels and not back

to the master cylinder.

With the right wheel tending to spin, the left inlet valve closes, allowing the brakes to be applied only to the right

wheel. This will transfer the torque to the left wheel. This operation can be applied approximately 4 - 6 times a

second and can function on either of the driven wheels, or both.

Hydraulic modulator status:

LH inlet valve... Closed LH outlet v alve....Closed

RH inlet valve..Open RH outlet valve ...Closed

Priming valve... Open Switching valve...Closed

Motor ............... On

Engine spark and throttle position inter vention

Simultaneously to brake intervention, the ABS/ETC control module communicates with the Powertrain Control

Module (PCM) and the throttle relaxer control m odule requesting the PCM to retard the spark advance and for the

throttle relaxer control module to reduce the throttle opening.

W ith the engine running, the PCMs continually supplies and monitors a 12 volt pull-up voltage to the spark retard

circuit. The ABS/ETC control module requests spark retard by pulling this voltage low. The PCM then responds by

reducing the spark advance of the engine.

The ABS/ET C control m odule constantly sends a Pulse Width Modulated ( PW M) s ignal at 90% with a frequency of

100Hz to the throttle relaxer control m odule on the reques ted throttle pos ition line (DKR) T his s ignal is to indicate to

the throttle relaxer control module that the traction control system (ETC) is in a state of readiness.

With the engine running, the ABS/ETC control module constantly sends a Pulse Width Modulated (PMW) signal

with a duty cycle of 90% to the throttle relaxer control module via the requested throttle position line (DKR). The

throttle relaxer control module responds on the actual throttle position line (DKI) with a PWM signal with a duty cycle

of 9%.

When the ABS/ETC c ontr ol module determines that a r educ tion in throttle is r equired, it r educ es the PWM signal on

the requested throttle position line (DKR), from 90% (no throttle reduction) to as low as approximately 14%

(maximum throttle reduction). The throttle relaxer control module then drives the throttle relaxer motor, overriding

the accelerator pedal command (drivers foot), pulling the throttle cable back, and thus, closing the amount of throttle

opening.

Figure 12L-34

MASTER CYLINDER OPERATION

The operation of the master cylinder assembly used on vehicles with ABS/ETC is the sam e as the assem bly used

on vehicles without ABS/ETC, r efer to Section 5A STANDARD BRAKES of the VT Series I Ser vice Inform ation for

details.

OPERATION AND TESTING OF THE ABS AND ‘TRAC OFF’ WARNING LAMPS

Should a vehicle equipped with ABS/ETC come into the workshop with one of the following customer complaints,

make sure of the circumstances before checking the complete ABS/ETC with the TECH 2 diagnostic scan tool.

1. Warning lamp(s) does not illuminate after switching the ignition on.

2. Warning lamp(s) does not go out after engine has started.

3. Warning lamp(s) illuminates again while driving or illuminates occasionally.

The following gives information about the functioning and malfunctioning of the ABS and TRAC OFF warning lamps.

ABS and TRAC OFF Warning Lamps

W hen the ignition is switched on, the ABS warning

lamp illuminates for approximately two seconds

and the TRAC OFF warning lamp f or appr ox imately

five seconds (with engine running, TRAC OFF lamp

will illuminate for only two seconds also). During

this period of time, the ABS/ETC control module

performs a check of the ABS/ETC system wiring.

On all vehicles with ABS/ETC, as soon as all four

wheels of the vehicle exceed a speed of

approximately 6 km/h for the first time after starting,

the ABS/ETC system tests itself automatically

(ABS/ETC 'Self-Test'). The ABS/ETC control

module cycles each solenoid valve and the return

pump motor in the hydraulic modulator to check

component operation. The ABS/ETC control

module also checks its own circuitry.

This procedure is repeated every time the ignition is

switched OFF and the engine is started again. In

addition, the ABS/ETC system constantly tests

itself while the vehicle is travelling.

The warning lamp is also used for self diagnosis

purposes.

NOTE: The TRAC OFF warning lamp will also

illuminate if the TRAC CTRL button has been

pressed. The TRAC OFF light will then stay

illuminated until either the ignition is switched off or

the TRAC CTRL button is pressed again.

Figure 12L-35

Incorrect Warning Lamp Indications (ABS and TRAC OFF)

1. Warning lamp(s) does not illuminate after switching ignition ON.

2. Warning lamp(s) does not go out after approximately 2 seconds.

3. Warning lamp(s) illuminates when driving or illuminates occasionally.

NOTE: The T RAC O FF warning lam p will illum inate if the ETC system is m anually switched of f by the T RAC CT RL

switch located in the console and the LOW TRAC warning lamp will flash if the ETC system is functioning (in a

wheel spin situation). If either of these lights illuminate under these conditions, the system is functioning correctly.

Illumination of the ABS warning lamp indicates to the driver that the ABS is defective.

Illumination of the TRAC OFF warning lamp indicates to the dr iver that the ETC system is either manually disabled

or defective.

When the ABS warning lamp is activated, the vehicle reverts to normal braking as in vehicles without ABS fitted

(e.g. under emergency braking, wheel/s may lock).

When the TRAC OFF warning lamp is activated, the ABS still functions correctly.

Occasional illumination of the warning lamps may be brought about through the battery being insufficiently charged.

The lamp lights up only as long as there is a low voltage, e.g. after switching on electrical components at idle.

The causes of trouble can be determined with the assistance of the TECH 2 diagnostic scan tool.

LOW TRAC warning lamp

The LOW TRAC lam p is used to inform the driver that the vehicle is in a critical driving situation and that the ETC

system has been engaged to control wheel spin.

3. SERVICE OPERATIONS

NOTE: With exception to the following Service Operations, all Service Operations for VT Series II ABS and

ABS/ETC carry over from those described in Section 12L ABS & ABS/ETC of the VT Series I Service Information.

3.1 THROTTLE RELAXER CONTROL MODULE

REMOVE

1. Disconnect battery earth lead.

2. Remove left hand front shroud panel lower

trim assembly (kick panel trim), refer to

Section 1A2 UNDERBODY of the VT Ser ies I

Service Information.

3. Using a flat bladed screw driver, push the

lower retaining tab (between the shroud lower

panel and the back of the throttle relaxer

control module mounting bracket) forward

while lifting the base of the mounting bracket

outwards, approximately two centimetres.

With the lower retaining tab disengaged, pull

the mounting bracket assembly downwards to

disengage the top retaining tab.

Figure 12L- 36

4. Disconnect the throttle relaxer control module

connector by:

1. Lift the locking lever on the control

module connector.

2. Pull the top of connector away from

control module.

3. Lift connector upwards, disengaging the

base of the connector from the control

module.

Figure 12L-37

Techline

5. Lift the two retaining tabs (1) on the mounting

bracket and slide the throttle relaxer control

module (2) out of mounting bracket.

Figure 12L-38

REINSTALL

Reinstallation of the throttle relaxer control module

is the revers e of the rem oval procedur e, noting the

following:

1. To reconnect the throttle relaxer control

module wiring harness connector, use the

following procedure:

1. Hook base of connector into throttle

relaxer control module.

2. Push top edge of connector into throttle

relaxer control module using the base as

a pivot.

3. Push locking lever down and towards the

throttle relaxer control module.

4. Ensure lever seats flush with top of

connector housing.

2. Turn ignition ON and observe the ABS and

TRAC OFF warning lamps. Lamps should

illuminate for approxim ately 2 - 5 se conds and

then turn off. If warning lamps remain

illuminated, refer to 4.4 ABS OR ABS/ETC

FUNCTIONAL CHECK in this Section.

3.2 THROTTLE RELAXER

Refer to Section 6C3-3 POWERTRAIN MANAGEMENT - GEN III V8 ENGINE of the VT Series II Service

Information for the correct procedure of how to remove, reinstall and adjust the throttle relaxer assembly and

accelerator and throttle cables.

4. ABS/ETC DIAGNOSIS

CAUTION: Certain components in the Anti-lock Brake System and Electronic Traction Control system are

not intended to be serviced individually. Attempting to remove or disconnect certain system components,

such as the solenoid valves or pump motor from the hydraulic modulator, may result in personal injury

and/or improper system operation. Only those components with approved removal and reinstallation

procedures describ ed in 3. SERVICE OPERAT IONS in this Section and Section 12L ABS & ABS/ETC of the

VT Series I Service Information should be serviced.

Before attempting any diagnostic work on the ABS, refer to and read the 'SAFETY AND PRECAUTIONARY

MEASURES' as described in 3. SERVICE OPERATIONS, Section 12L ABS & ABS/ETC of the VT Series I

Service Information.

4.1 GENERAL DESCRIPTION

Diagnostic information in this Section relates only to ABS/ETC systems on vehicles with GEN III V8 engines.

Additionally, only diagnostic information that differs from the ABS/ETC system used on VT Series Models with V6

engines is detailed. For diagnostic information that is not detailed in this Section, refer to

Section 12L ABS & ABS/ETC of the VT Series I Service Information.

The following information is necessary when diagnosing any Anti-lock Braking System problem or failure,

specifically it should be used to diagnose conditions that may cause the illumination of the ABS or TRAC OFF

warning lamps in the instrument cluster.

Should conditions exist with the conventional (non ABS) portion of the braking system which cause the BRAKE

FAILURE warning lamp to illuminate (also in the instrument cluster), or there is some other obvious brake

mechanical problem, such as brake noise, brake pulsation (pedal or vehicle vibration during normal brake

application), brake pull or a parking brake problem, then these problems must be corrected before attempting to

rectify any suspected ABS/ETC problem. Refer to Section 5A STANDARD BRAKES of the VT Series I Service

Information for diagnosis and repair of the conventional braking system.

4.2 BASIC KNOWLEDGE REQUIRED

Before attem pting to diagnose the Anti-lock Brake System or Electronic Traction Control system , you m ust have a

good understanding of electrical system basics and the use of circuit testing tools. W ithout this basic knowledge it

will be difficult to use the diagnostic procedures detailed in this Section.

Some elec trical basics, troubleshooting procedures and hints as well as the use of circuit testing tools are covered

in Section 12P WIRING DIAGRAMS of the VT Series I Service Information.

Basic Electrical Circuits - You should understand the basic theory of electricity, series and parallel circuits, and

voltage drops across series resistors. You should know the meaning of voltage (volts), current (amps), and

resistanc e (ohms). You should understand what happens in a circuit with an open or shorted wire (shor ted either to

voltage or earth). You should also be able to read and understand a wiring diagram.

Use of Circuit Testing Tools - You should know how to use a jumper lead to test circuits. You should be familiar with

the use of a high input im pedance ( 10 Meg ohm) digital type multim eter such as tool No. J39200 or equivalent and

be able to measure voltage, current, and resistance. You should be familiar with the proper use of the TECH 2

Diagnostic Scan Tool.

4.3 VISUAL INSPECTION

When investigating any complaint of an ABS/ETC system problem or malfunction, start diagnosis with an ABS,

ABS/ETC visual inspection.

The ABS, ABS/ETC vis ual ins pec tion is an ex amination of eas ily access ible components that c ould caus e pr oblems

with the system. The visual inspection procedure may quickly identify the cause and eliminate the need for

additional diagnosis.

If the complaint condition cannot be resolved by a visual check of the system components, then proceed to the

ABS, ABS/ETC Functional Check following on after the Visual Inspection Chart.

ABS, ABS/ETC VISUAL INSPECTION CHART

ITEM INSPECT FOR CORRECTIVE ACTION

GENERAL

Wheel and Tyres Recommended tyre and wheel

size fitted to vehicle Fit recommended size tyres

and wheels

BRAKE SYSTEM COMPONENTS

Master Cylinder Fluid Reservoir Low fluid level Add fluid as required.

Determine cause of fluid loss

and repair

Hydraulic Modulator External leaks If leakage is excessive,

replace modulator

Brake Booster And Master

Cylinder Correct installation and

assembly Reinstall or reposition

components correctly

Park Brake Mechanism Mechanism fully releasing Operate lever to verify release.

Adjust cable or repair release

mechanism as required

FUSES

ENGINE COMPARTMENT

ABS Fusible Link FR Blown fusible link Replace fusible link. Inspect

for cause of failure

PASSENGER COMPARTMENT

ABS Fuse F27 Blown fuse Replace fuse. Inspect for

Warning Lamp Fuse F13

(Ignition Circuit) cause of fuse failure

Stop Lamp Fuse F5

WIRING CONNECTIONS

ENGINE COMPARTMENT

ABS/ETC control module Wiring

Harness Connector In all cases, inspect for:

Main W i ring Harness to Front

Wheel Speed Sensor

Connections Proper engagement.

Loose wires or terminals. Ensure proper engagement

Repair as required

Hydraulic modulator pump motor

wiring harness connector Corroded or broken

connections

PASSENGER COMPARTMENT

Main W i ring Harness to Body

Harness Connectors

UNDER VEHICLE

Front Wheel Speed Sensor Lead

to Front Wheel Hub Connections

Body Harness to Rear Wheel

Speed Sensor Connections

4.4 ABS OR ABS/ETC FUNCTIONAL CHECK

If the source of the system problem or malfunction was not isolated during the ABS, ABS/ETC visual inspection,

carry out the following ABS, ABS/ETC functional check. Also, use the check to verify normal ABS/ETC operation

during diagnosis or after making any system repairs.

ABS OR ABS/ETC FUNCTIONAL CHECK CHART

STEP ACTION YES NO

1•Has ABS, ABS/ETC Visual Inspection been

performed? Go to Step 2. Perform ABS, ABS/ETC

Visual Inspection as per

4.3 in this Section before

proceeding.

2. •While observing the Brake Failure warning lamp, turn

the ignition to the Bulb Check position (engine

cranking position).

•Does the Brake Failure warning lamp illuminate?

Go to Step 3. Check warning lamp

circuit, refer to Section

12C of the VT Series I

Service Information.

3. •Turn ignition OFF.

•Turn ignition ON whilst observing ABS or ABS and

TRAC OFF warning lamp.

•Do warning lamps illuminate for approximately three

seconds (five seconds for TRAC OFF lamp) then turn

OFF?

NOTE: If engine is started, warning lamps will illuminate

for only 2 seconds

Go to Step 7. Go to Step 4.

4. •Install TECH 2 to DL C.

•Select Chassis / ABS/ETC and press CONFIRM.

•Does TECH 2 communicate with the ABS by

displaying the System Identification Information?

Go to Step 5. Refer to DTC 72 -

SERIAL DATA FAULT

Diagnosis in this Section.

5. •With TECH 2 still connected, select Diagnostic

Trouble Codes / Read DTCs.

•Are any DTCs set?

Go to Step 6. Refer to Charts A1, A2

(WARNING LAMPS

INOP) or CHARTS C1,

C2 (WARNING LAMPS

ILLUMINATED

CONTINUOUSLY) in

Section 12L ABS &

ABS/ETC of the VT

Series I Service

Information.

6. •Select relevant DTC Function Key.

•Are the ignition cycles zero (0)? Refer to relevant

ABS/ETC DTC chart in

this Section or in

Section 12L ABS &

ABS/ETC of the VT

Series I Service

Information.

Refer to 4.5

INTERMITTENT

FAILURES in this

Section.

7. •Road test vehicle, ensuring to achieve at least a

speed of 35 km/h.

•Did the ABS warning lamp turn on during the road test

NOTE: Ensure TECH 2 is disconnected during road test.

Go to Step 5. Go to Step 8.

8. •During the road test, did the vehicle exhibit any

symptoms or improper operation that may be

mechanical in nature and/or did the Brake Failure

warning lamp turn ON ?

Refer to Section 5A

BRAKES of the VT

Series I Service

Information for

conventional braking

system repair details.

Go to Step 9.

9. •Install TECH 2 to DLC and turn ignition ON.

•Check for any ABS History DTCs.

•Are any History DTCs present (1 or more ignition

cycles)?

Refer to relevant

ABS/ETC DTC

diagnostic chart in this

Section or in Section

12L ABS & ABS/ETC of

the VT Series I Service

Information. Chart may

be used to identify and

isolate suspected

failures. Also, refer to

4.5, INTERMITTEN T

FAILURES in this

Section for more

information on isolating

suspected failures.

Clear all DTCs and

repeat this functional

check.

System OK, however, if

a fault is still suspected,

refer to 4.5,

INTERMITTENT

FAILURES in this

Section.

WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED, CLEAR ALL DTCs AND VERIFY CORRECT OPERATION

4.5 INTERMITTENT FAILURES

As with most electronic systems, intermittent failures may be difficult to accurately diagnose. The following is a

method to try to isolate an intermittent failure, especially wheel speed circuit failures.

If the control module detects an ABS fault, the ABS warning lamp will illuminate during the ignition cycle in which the

fault was detected and a Diagnostic Trouble Code (DTC) will be logged in memory of the control module.

If an ETC fault occurs, either the TRAC OFF and /or ABS warning lamp will illuminate, if the fault is specific to the

ETC system, both the TRAC OFF and the ABS warning lamps will illuminate, if the fault is common to both

systems.

If an intermittent problem occurs, the TRAC OFF and/or ABS warning lamp will go out (if the fault corrects itself)

after the ignition has been cycled off and on. Also stored in the control m odule memory, will be the history data of

the DTC at the time the fault occurred. This history data includes the number of Ignition Cycles since the DTC

occurred, if the Ignition Cycle is zero, then the DTC is Current, if the Ignition Cycles is greater than zero, then the

DTC is a history DTC. TECH 2 can be used to read ABS/ETC data;

1. If a system fault has been detected, record all current tr ouble codes and tr ouble code histor y information. Als o,

if available, record any specific driving condition during which the problem or failure occurs. This information

can help in duplicating the condition.

2. Clear any trouble codes that are stored in the control module memory, refer 'CLEARING DTCs' in this Section.

3. Using the TECH 2 in Snapshot Mode while test-driving the vehicle, try to duplicate the condition in which the

problem or fault occ urs. Refer to 4.7 TECH 2 Diagnostics in this Sect ion for additional inf ormation on the us e

of TECH 2.

NOTE: IN CERTAIN DIAGNOSTIC MODES, THE ANTI-LOCK BRAKING SYSTEM IS DISABLED WHILE TECH 2

IS COMMUNICATING WITH THE ABS OR ABS/ETC CONTROL MODULE.

If an intermittent condition is still undetected, or not related to the wheel speed circuitry, go to the appropriate

Diagnostic Tr ouble Code (DTC) or symptom c hart in this Sec tion. Follow through the Char t while m oving or wiggling

the associated ABS or ABS/ETC wiring harnesses and connectors, and at the same time looking for intermittent

type failures in the circuitry.

Most intermittent problems are caused by faulty electrical connections or wiring. When an intermittent failure is

encountered, check suspect circuits for:

a. Poor mating of connector body halves or terminals not fully seated in the connector body (backed out).

b. Improperly formed or damaged terminals. If damaged, carefully reform terminals in a suspected circuit.

c. Poor terminal to wire connection. This r equires r emoving the terminal f r om the c onnector body to inspec t ( refer

to Section 12P WIRING DIAGRAMS of the VT Series I Service Information).

Also, due to the sensitivity of ABS/ETC components to Electro-Magnetic Interference (EMI), the following checks

should be performed if an intermittent malfunction is suspected:

a. Check for proper installation of wiring harness es resulting f rom add-on options such as a C.B. radio or cellular

telephone etc.

b. Visually inspect wheel speed sensors and pulse rings for looseness, damage, foreign material accumulation

and proper mounting. Replace damaged components, remove any foreign material and/or properly attach all

components.

c. While test driving vehicle, monitor wheel speeds using TECH 2. If any wheel speed drops or displays erratic

speed, refer to the appropriate wheel speed DTC chart in this Section.

If detected, ABS failures will disable the anti-lock brake function of an entire ignition cycle, even if the condition

clears itself before the ignition is switched off. However, the clearing of low voltage failure conditions during an

ignition cycle will allow ABS operation to resume.

If an ETC only failure is detected, the traction control functions will be disabled for an entire ignition cycle, even if the

condition clears itself before the ignition is switched off. However, the clearing of low voltage failure conditions

during an ignition cycle will allow ABS and ETC operation to resume.

4.6 ABS & ABS/ETC SELF DIAGNOSTICS

DIAGNOSTIC TROUBLE CODES

The ABS/ETC control modules are equipped with a self diagnostic capability that can detect and isolate ABS/ETC

problem s or failures . When a pr oblem or failure is detected, the ABS/ETC contr ol module s ets a Diagnos tic T r ouble

Code (DTC) that represents that particular problem or failure. There are twenty nine DTCs on ABS/ETC systems for

vehicles with GEN III V8 engines that may be set by the ABS/ETC control module. Depending on the DTC set,

either the ABS, ETC or both ABS and ETC systems will be disabled. If the ABS is disabled, it will allow for

conventional non ABS brak ing only and the ABS warning lam p will be turned on. The ABS/ET C control m odule has

the capability of storing three DTCs.

NOTE: The warning lamp will illuminate whilst a fault is ac tive. If a fault has oc c urr ed and is not ac tive, the lamp will

not be illuminated and a fault code will be stored.

The control module performs an automatic test once during each ignition cycle when the vehicle reaches

approxim ately 6 km /h (or 18 k m/h if a stop lamp s ignal is received). T he automatic test cycles each solenoid valve

and the pump motor to check component operation. If any error is detected during this test, the ABS/ETC control

module will set a DTC. This test may be heard and felt while it is taking place and is a normal mode of operation.

The ABS/ETC control module can display the DTCs via the ABS warning lamp only when the 'Diagnostic Service

Mode' has been entered. Entering the diagnostic service mode is accomplished by either:

Earthing terminal 12 of the Data Link Connec tor (DLC) us ing a test lead fitted with suitable term inals and monitoring

the ABS warning lamp to flash system DTCs, refer to FLASH CODE DIAGNOSTICS DISPLAY in this Section.

Or by using TECH 2, refer to 4.7 TECH 2 DIA GNOSTICS in this Section.

TRAC

OFF LOW

TRAC

ABS

T212L011

Figure 12L-39

FLASH CODE DIAGNOSTICS DISPLAY

To enable the ABS warning lamp to flash system

DTCs, the vehicle must be stopped (vehicle speed

is less than 10 km/h), terminal 12, circuit 863

(Blue/Black wire) (12) of the DLC (1) earthed to

terminal 5, circuit 155 (Black/Yellow wire (5) of the

DLC using a test lead (2) fitted with suitable

terminals and then the ignition turned on. The flash

code diagnostics will remain enabled as long as

terminal 12 is earthed, serial data line

communication has not been initiated or until any

wheel speed is greater than 10 km/h.

Approximately three sec onds af ter earthing ter minal

12 (with the ignition ON) of the DLC, the ABS/ETC

control module will begin flashing the ABS warning

lamp.

The flash sequenc e will begin with DTC 12 to signal

the beginning of the f lash code display. DTC 12 will

flash three times. Each stored code will then be

displayed three times. After all codes have been

displayed, the sequence will repeat, starting with

DTC 12.

The charts on the next page set out all the possible

diagnostic trouble codes.

NOTE: Flash code diagnosis is not fully supported

on certain Diagnostic Trouble Codes involving the

solenoid valves or motor due to the valve relay

inside the control unit being disabled. Diagnostic

Trouble Codes 41, 42, 45, 46, 47, 48, 55, 56, 61

and 63 will prevent the ABS warning lamp from

turning off. These faults can only be read through

the DLC using TECH 2.

Figure 12L-40

Figure 12L-41

GEN III V8 ABS/ETC DIAGNOSTIC TROUBLE CODES

DTC CODE DESCRIPTION

12 No Fault

21 Front Right Wheel Speed Sensor Incorrect Signal

23 Front Right Wheel Speed Sensor Short Circuit or Open Circuit

25 Front Left Wheel Speed Sensor Incorrect Signal

27 Front Left Wheel Speed Sensor Short Circuit or Open Circuit

28 Wheel Speed Sensor Frequency Error

31 Rear Right Wheel Speed Sensor Incorrect Signal

33 Rear Right Wheel Speed Sensor Short Circuit or Open Circuit

35 Rear Left Wheel Speed Sensor Incorrect Signal

37 Rear Left Wheel Speed Sensor Short Circuit or Open Circuit

41 Front Right Inlet Valve Solenoid Fault

42 Front Right Outlet Valve Solenoid Fault

45 Front Left Inlet Valve Solenoid Fault

46 Front Left Outlet Valve Solenoid Fault

47 Priming Valve Solenoid Fault

48 Switching Valve Solenoid Fault

51 Rear Right Inlet Valve Solenoid Fault

52 Rear Right Outlet Valve Solenoid Fault

55 Rear Left Inlet Valve Solenoid Fault

56 Rear Left Outlet Valve Solenoid Fault

58 Throttle Relaxer PWM (Pulse Width Modulation) Interface Fault

61 Pump Motor or Relay Fault

62 RPM Signal Fault

63 Valve Solenoid Relay Fault

64 Throttle Relaxer Control Module Position Fault

65 Throttle Relaxer Motor Fault

66 Throttle Relaxer Control Fault

67 Stop Lamp Switch Circuit Fault

68 TPS (Throttle Position Switch) Monitoring Fault

71 Control Module Internal Fault

72 Serial Data Fault

73 Spark Retard Monitoring Fault

78 Incorrect Option Coding

85 System Voltage Too Low

NOTE: Diagnos tic char ts f or the DT Cs listed in bold tex t in the table above are the only DTCs that dif fer f rom those

previously published for V6 ABS/ETC s ystems. F or diagnostic charts covering DT Cs lis ted in norm al tex t, refer ence

to Section 12L ABS & ABS/ETC in the VT Series I Service Information should be made.

CLEARING DTCS

Any DTCs stored in the ABS/ETC control module's memory can be erased in one of three ways:

1. Diagnostic Request Line Procedure.

2. TECH 2 Clear Codes Selection.

3. Ignition Cycle Default.

These three methods are detailed as follows.

IMPORTANT: Whichever method is used, be sure to verify proper system operation and absence of any

DTCs when clearing procedure is completed. The ABS/ETC control module will not permit DTC clearing

until all of the codes have been displayed. Also, DTCs cannot be cleared by unplugging the ABS/ETC

control module, disconnecting the battery cables, or turning the ignition OFF (except on an ignition cycle

default).

Diagnostic Reques t Line Procedure

To clear trouble codes via the DLC (1) diagnostic

request line, terminal 12 (12), go through the

following procedure.

1. Turn ignition OFF.

2. Connect a test lead (2) fitted with suitable

term inals between DLC terminal 5, c ircuit 155,

black/yellow wire (5) and terminal 12, circuit

863, blue/black wire (12).

3. Turn ignition on (this will enable Flash Code

Diagnostics Display) and allow all codes to be

displayed.

4. Disconnect one end of test lead from DLC for

approximately one second then reconnect for

no less than one second. Repeat this step at

least two more times within 10 seconds,

leaving test lead connected to DLC upon

completion of final connection.

Observe flashing ABS warning lamp. Only DTC 12

should be flashed. If not, trouble codes have not

been properly cleared. Begin clearing code

procedure again at Step 1. If DTCs are cleared,

wait at least 15 seconds before turning ignition

'OFF'.

Figure 12L-42

Figure 12L-43

TECH 2 Clear Codes Procedure

Before clearing DTCs, check and note any history code data, as this information will also be cleared.

Select the appropriate menu, and s elect the Clear Codes f unction. Ver if y that DT Cs have been c leared by using the

TECH 2 to read ABS/ET C trouble codes. If any are present, either the DT Cs were not cleared, or an ABS/ETC f ault

still exists.

Refer to 4.8 TECH 2 TEST MODES AND SCREEN DISPLAYS FOR ABS AND ETC DIAGNOSIS

Ignition Cycle Default

If the ignition is cycled 100-times without a particular fault reappearing, that fault code will be erased from the

ABS/ETC control module memory, and the ignition cycle counter inside the control module will be reset to zero.

4.7 TECH 2 DIAGNOSTICS

IMPORTANT: When using TECH 2 in certain

diagnostic modes for ABS/ETC diagnosis, the

Anti-lock Brake System is disabled by the

ABS/ETC control module while it is

communicating with TECH 2. The ABS warning

lamp in the instrument cluster will be

illuminated, indicating only conventional (non

ABS) braking is possible.

TECH 2, with the appropriate software, cables and

adaptors, when connected to the Data Link

Connector (DLC) is capable of reading ABS/ETC

serial data. The DLC is connected to the instr ument

panel lower right hand trim, to the right of the

steering column.

For additional general information on connecting

and operating TECH 2, refer to

Section 0C TECH 2 of the VT Series I Service

Information.

1. DLC

2. DLC ADAPTOR

3. DLC CABLE

4. TECH 2

TECH 2 has five test modes for diagnosing the

Anti-lock Brake System and Electronic Traction

Control system. The five test modes are as follows:

Figure 12L-44

Mode F0: Normal Mode

In this mode, TECH 2 monitors the constant

communication between control modules on the

serial data line. The information displayed on the

TECH 2 screen in this mode is what the ABS/ETC

control module is communicating to the other

modules via the serial data line.

Mode F1: Diagnostic Trouble Codes

In this mode, TECH 2 will display a DTC selection

list. When the appropriate function key is selected,

TECH 2 will display a DTC Data Lis t. T he Data Lis t

contains relevant information relating to the DTC.

Mode F2: Data Display

In this test mode, the operator of TECH 2 has the

option of selecting an Active or Disabled data

stream that they can use to constantly monitor the

status of inputs and outputs of the ABS/ETC

system.

MODE F3: SNAPSHOT

In this test mode, the TECH 2 captures ABS/ETC

data before and after a forced manual trigger.

MODE F4: MISCELLANEOUS TESTS

In this test mode, TECH 2 performs system

functional tests to assist in pr oblem isolation during

troubleshooting.

Each test mode has specific diagnosis capabilities

that depend upon various function key entries on

TECH 2.

Also, included in the MISCELLANEOUS TESTS is

a procedure for ABS/ETC brake bleeding.

Figure 12L-4528

4.8 TECH 2 TEST MODES AND SCREEN DISPLAYS FOR ABS AND ETC DIAGNOSIS

WARNING: When using TECH 2 for ABS/ETC

diagnosis, in certain diagnostic modes, the

system will be disabled.

As a prerequisite to this diagnostic section is for the

user to be familiar with the proper use of TECH 2,

the following pages illustrate only the major TECH

2 screen displays and provide a brief explanation of

their function for diagnosing the ABS/ETC system s .

If additional information is required on the operation

of TECH 2, reference should be made to either

Section 0C TECH 2 of the VT Series I Service

Information or the TECH 2 OPERATORS

MANUAL.

System Select Menu

With TECH 2 connected to the DLC and F0:

DIAGNOST ICS selected f rom the MAIN MENU, the

appropriate MODEL YEAR and VEHICLE TYPE

must be selected for access to the SYSTEM

SELECT MENU.

Select F2: CHASSIS and press enter to continue.

System S elect Menu

(X) 1999 Commodore

F0: Engine

F1: Transmission

F2: Chassis

F3: Body

T212L027

Figure 12L-46

Vehicle Identification Menu

Once F2: CHASSIS has been selected from the

select menu, the ABS/ETC systems can be

selected.

Select ABS/ETC.

Once ABS/ETC is selected, the ABS/ETC

Application menu will be displayed, via the System

Identification screens which will require action.

NOTE: If DTC Check is selected, TECH 2 will

display information advising if any DTCs are set by

any control module. (If DTCs are set from another

module, ref er to the relevant Section in this Ser vice

Information CD). Figure 12L-47

System Identification

Turn the ignition ON (as requested) and press

CONFIRM soft key to continue.

System Iden tification

(X) 1999 Commodore

Electronic System : ABS / ETC

Turn On Ignition!

T212L028

Figure 12L-48

The SYSTEM IDENTIFICATION screen will then

display the control module part num ber and s ystem

identification. Press the CONFIRM soft key to

continue to the ABS/ETC APPLICATION MENU.

System Iden tification

(X) 1999 Commodore

Electronic System : ABS / ETC

Part Number XXXXXXXX

System I.D. XX

System ABS/ETC

T212L029

Figure 12L-49

ABS/ETC Application Menu

The following functions will now be available:

F0: Normal Mode

F1: Diagnostic Trouble Codes

F2: Data display

F3: Snapshot

F4: Miscellaneous Tests

Figure 12L-50

F0: NORMAL MODE

In the F0: Normal Mode, information that the

ABS/ETC control module is communicating to other

control modules, via the serial data line, is

displayed.

For example: As displayed opposite, the ETC

Warning lamp status is ON. This means the

ABS/ETC control module is communicating with the

instruments, requesting the ABS warning lamp to

be illuminated.

System S elect Menu

Stop Lamp Switch OFF

YES

OFF

NO DTCs

OFF

ABS Warnin g Lamp

ETC Warning Lamp

Low Traction

ETC Equipped

ABS Chi me

ABS DTC Status

T12L086

Figure 12L-51

F1: DIAGNOSTIC TROUBLE CODES

If the F0: READ DTCs is selected from this mode,

a listing of all (if any) DTCs that have been set by

the ABS/ETC control module will be displayed. To

obtain further information about a particular DTC,

press the relevant function key (i.e. F0) and a DTC

data list will be displayed. From the information

provided in this data list, you can determine when

the DTC occurred and the operating conditions of

the system at the time.

For a listing of all DTCs, refer to 4.6 ABS &

ABS/ETC SELF DIAGNOSTICS in this Section.

DTCs can be cleared by simply selecting F1 Clear

DTCs and pressing the ENTER key.

NOTE: If any DTCs are set, reference should be

made to the r elevant diagnostic char ts in either this

section or Section 12L ABS & ABS/ET C of the VT

Series I Service Information.

Figure 12L-52

F2: DATA DISPLAY

If the F2: DATA DISPLAY mode is selected, an additional application menu will appear giving the operator the

option of selecting ABS/ETC data while the system is either active or disabled.

F0: Active ABS/ETC

F1: ABS/ETC disabled

If the disabled data list is selected, the ABS warning lamp will be illuminated and the system will become disabled.

W hile the two data lists of fer sim ilar inform ation, the active data list has the advantage of m onitoring the ABS/ETC

systems while they are operational, aiding in the diagnosis of intermittent faults.

W hen monitor ing speed data, the T ECH 2 screen displays the signals being sent fr om the wheel speed sensor s to

the control module. In F0: Active ABS/ETC display mode, the vehicle can be driven while TECH 2 displays wheel

speed data. At this time, the readings may be compared with vehicle speed to check proper operation. Wheel

speed signals can also be compared with each other to determine whether they are within specification.

If one wheel speed signal differ s greatly from the other signals , impr oper operation of that partic ular sensor m ay be

indicated. Intermittent wheel speed signals can be detected in this mode by looking for signals that vary for no

apparent reason. This variation can oc c ur dur ing vehicle oper ation and can be c aptur ed during F 3: SNAPSHOT test

mode.

For additional information regarding the soft k eys while in the DATA DISPLAY mode, ref er to Section 0C TECH 2

of the VT Series I Service Information.

The table below lists each item contained in the data s tream f or both active and disabled lists, together with a brief

description of their meanings.

ACTIVE ABS/ETC

DATA STREAM / SCREEN DISPLAY DESCRIPTION

FR Wheel Speed (Front Right) Displays wheel speed sensor input (km/h) to the control module.

FL Wheel Speed (Front Left)

RR Wheel Speed (Rear Right)

RL Wheel Speed (Rear Left)

Pump Motor Displays current status of pump motor - either ON or OFF.

Pump Relay Displays current status of pump relay - either ON or OFF.

Valve Relay Displays current status of valve relay - either OPEN or CLOSED.

ETC Switch Displays current status of switch - will display OPEN when switch is in the

rest position and CLOSED when held down.

Requested Throttle N/A as of start of production, will always display 0%

(If available – will display the percentage of throttle opening the ABS/ETC

control module is requested the throttle relaxer control module to supply)

Actual Throttle Position N/A as of start of production, will always display 0%

(If available – will display the actual percentage the throttle body valve is

open)

ABS/ETC DISABLED

DATA STREAM / SCREEN DISPLAY DESCRIPTION

FR Wheel Speed (Front Right) Displays wheel speed sensor input (km/h) to the control module.

FL Wheel Speed (Front Left)

RR Wheel Speed (Rear Right)

RL Wheel Speed (Rear Left)

Stop Lamp Switch Displays current status of switch - displays OFF when switch is in the rest

position and ON when brake pedal is depressed.

Pump Monitor Will always display OFF as ABS and ETC are disabled in this mode.

Valve Relay Displays current status of valve relay - either OPEN or CLOSED.

Note: if displays OPEN in this mode, there is a fault in the valve relay circuit.

ETC Switch Displays current status of switch - displays OPEN when switch is in the rest

position and CLOSED when held down.

Engine Speed Displays the current engine speed in RPM.

Throttle Position Displays the current throttle position (percentage of throttle valve opening).

System ID Displays control module internal software identification number.

F3: SNAPSHOT

The snapshot mode will help to identify problems

caused by speed sensor signals that may cause

intermittent operation of the ABS/ETC systems.

The SNAPSHOT mode captures data before and

after a forced manual trigger condition.

Figure 12L-53

F4: MISCELLANEOUS TESTS

In the Miscellaneous Tests mode, functional tests

are available on the ABS/ETC systems that will

help identify proper operation. In this mode, error

conditions can be further identified by testing and

observing the test results.

Additionally, in this mode, the hydraulic modulator

can be bled (F2: BRAKE BLEED).

In the MISCELLANEOUS TESTS mode the

following tests can be performed:

F0: Solenoid

This test indicates whether spec ific s olenoid valves

in the hydraulic modulator release pressure to

assigned hydraulic wheel circuits and hold pr es sur e

in assigned hydraulic wheel circuits.

Figure 12L-54

NOTE: Use this procedure in conjunction with the

information displayed on the TECH 2 SCREEN

while in the F0: SOLENOID test mode.

The PRESSURE RELEASE part of the test

activates a selected hydraulic wheel circuit valve,

placing it in the pressure release position. Valve

action can then be verified by checking the

appropriate wheel for proper brake action.

The PRESSURE HOLD part of the test activates a

selected hydraulic wheel circuit valve, placing it in

the pressure hold position. Valve action can then be

verified by checking the appropriate wheel for

proper brake action.

These tests completely check each solenoid valve.

With an assistant, the pressure release and hold

tests can be verified as follows:

1. Ignition OFF.

2. Raise vehicle such that the wheels are at leas t

150 mm off the floor.

3. Install TECH 2 to the DLC.

4. Select Diagnostics / Chassis / ABS/ETC and

turn ignition on and confirm System

Identification information as instructed.

5. Select Miscellaneous Tests / Solenoids.

6. Select the relevant solenoid to be tested and

press ENTER.

7. Follow instructions on the TECH 2 display

screen while getting an assistant to try to spin

the road wheel being tested when requested

by TECH 2.

NOTE: This test verifies correct operation of the

hydraulic functioning of the solenoid valves.

Electrical function is verified by the constant

monitoring of the circuits by the ABS/ETC control

module during normal operation of the system. If

the control module detects an electrical problem,

such as an open or short to earth of a solenoid

circuit, a DTC will be set and the system will be

disabled.

F1: Auto Test

The AUTO test is performed automatically by the

control module once during each ignition cycle

when the vehicle reaches approximately 6 km/h.

The TECH 2 will perform this test automatically

during the ABS TESTS mode. The AUTO test

cycles each solenoid valve and the pump motor

briefly to check c om ponent operation. If any error is

detected during this tes t, the control m odule will set

a DTC and the ABS and or TRAC OFF warning

lamp will be illuminated. Perform the test as follows:

NOTE 1: Use this procedur e in conjunc tion with the

information displayed on the TECH 2 SCREEN

while in the F1: AUTO TEST, test mode.

NOTE 2: If there are any DTCs set, they will have

to be cleared before this test can be performed.

Procedure

1. Turn ignition OFF.

2. Install TECH 2 to the DLC.

3. Select Diagnostics / Chassis / ABS/ETC and turn ignition on and confirm System Identification information as

instructed.

4. Select Miscellaneous Tests / Auto Test and press the CONTINUE soft key on TECH 2 to start test (return

pump will be heard running for a short period).

5. Note any DTCs that are set when test is completed.

F2: Brake Bleed

This test pr ompts the tec hnic ian to bleed the brake system . T he tes t is divided into two par ts ; a primar y bleed and a

secondary bleed. A primary bleed is a manual bleed of each hydraulic circuit. During a secondary bleed, the

ABS/ETC control module activates the solenoid and pump motor so that any air in these components is expelled.

NOTE 1: The AUTO Test must be carried out prior to conducting the brake bleed procedure. If the automatic test

has not been conducted, carry out test as described under F1: AUTOMATIC Test.

The brake bleed procedure is as follows:

1. Install brake bleeding equipm ent to vehic le as rec ommended in Sect ion 5 BRAKES of the VT Series I Ser vice

Information.

2. Turn ignition OFF.

3. Install TECH 2 to DLC.

4. Select Diagnostics / Chassis / ABS/ETC and turn ignition on and confirm System Identification information as

instructed.

5. Select Miscellaneous Tests / Brake Bleed and follow instructions on the TECH 2 display screen.

NOTE 2: T he TECH 2 screen will display “RUN AUTO TEST PRIOR TO BRAKE BLEED. DONE ?” Select YES or

NO. The AUTOMATIC T EST mus t be c arr ied out prior to c onduc ting the brake bleed proc edur e. If the auto tes t has

not been conducted, select NO and carry out test as described under F1: AUTO TEST.

If the auto test has been completed, select YES and continue.

The procedure will begin with a manual bleed at the right hand rear brake calliper. Ensure a suitable size plastic

hose is installed over the bleed screw and that it leads into a container of brake fluid.

While following the bleed procedure, as per TECH 2 instructions, ensure that fluid is continuously fed into the

master cylinder, especially while the secondary circuit is being bled.

4.9 DIAGNOSTIC CHARTS

INTRODUCTION

The f ollowing diagnostic charts ar e designed to provide fas t and eff icient fault location of the ABS/ET C system s f or

vehicles with GEN III V8 engines. Each diagnostic chart consists of: a ‘diagnostic chart’, connector body terminal

assignments for connectors relevant to that particular diagnostic chart, and pertinent information including

Diagnostic Trouble Code (DTC) setting parameters and circuit diagrams.

NOTE 1: For diagnostic charts not published in this Section, refer to Section 12L ABS & ABS/ETC of the VT

Series I Service Information.

NOTE 2: Always refer to the latest GEN III V8 engine wiring diagrams of the VT Series II Service Inf ormation when

refer to the diagnostic charts in Section 12L ABS & ABS/ETC of the VT Series I Service Information.

The following figures illustrate the terminal layout of the various connectors used in the system. These figures

should be used in conj unc tion with the diagnostic c har t circ uit diagr ams when chec king circ uit f aults if the c onnec tor

diagram is not included in the chart.

When carrying out wiring checks as directed to by the diagnostic charts, rather than probe terminals and connectors

with incorrect sized multimeter connections, use the adaptors contained in connector test adaptor k it, such as KM-

609. This will prevent any possibility of spreading or damaging wiring harness terminals.

DIAGNOSTIC AID

It is very important that before any component be replaced, when recommended in a diagnostic procedure, that a

thorough inspection of the wiring and connectors be performed. Terminals should be checked for corrosion and

correct sizing. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing

unnecessary part replacement with reappearance of the malfunction.

ON-VEHICLE SERVICE

When a diagnostic chart in this Section makes reference to removing/reinstalling or checking a component for

proper mounting or operation, refer to the appropriate service operation in this Section or

Section 12L ABS & ABS/ETC of the VT Series I Service Information.

After all diagnosis and repairs are completed, road-test the vehicle to ensure proper ABS/ETC operation and the

ABS and TRAC O FF warning lam ps do not com e on, ref er to 4.4 FUNCT IONAL CHECK in this Section. If TECH 2

was used for diagnosis, disconnect it from the DLC and turn the ignition OFF for at least 10 seconds before road

testing. This is necessary to reset the ABS/ETC control module as it is disabled during most TECH 2 diagnostic

procedures, and does not reset until serial data communication is stopped and ignition power is lost.

WIRING HARNESS CONNECTORS

Figure 12L-55

Figure 12L-56

Figure 12L-57

DTC 58 - THROTTLE RELAXER PWM INTERFACE FAULT

Figure 12L-58

CIRCUIT DESCRIPTION:

W ith the ignition on, the ABS/ETC contr ol module c onstantly sends a Puls e W idth Modulated (PWM) signal at 90%

with a frequency of 100Hz to the throttle relaxer control module on the requested throttle position line (DKR), via

term inal 13, c irc uit 1426 (O r ange/White wire) . T his s ignal is to indic ate to the thr ottle relax er c ontrol module that the

traction control system (ETC) is in a state of readiness. If the ABS/ETC control module requests traction control,

throttle reduction, it signals to the throttle relaxer control module to reduce the throttle opening by varying the duty

cycle of this PWM signal.

DTC 58 will set if this frequency output signal deviates outside a frequency specification (95 – 105 Hz) or if the

signal stops for more than 50 milliseconds. The throttle relaxer control module monitors this line and, if the above

conditions are detected, the throttle relaxer control module sends a PWM signal of 93% on the actual throttle

position line (DKI), circuit 1427 (Black/White wire) back to the ABS/ETC control module. The ABS/ETC control

module interprets this signal (or if no PWM signal is returned) as a DKR of throttle relaxer control module fault.

If the ABS/ETC control module senses this fault, the ETC system will be disabled (ABS operation will operate

normally), the TRAC OFF warning lamp will be illuminated and DTC 58 will be set. The TRAC OFF warning lamp

will remain illuminated for the remainder of the ignition cycle. If the failure is intermittent, the control module will

enable the system at the next ignition cycle and the relevant history DTC will be set.

Test Description:

The numbers below refer to Step numbers in the diagnostic chart for DTC 58.

1. Checks for continuity in earth circuit 750.

2. Checks for continuity in earth circuit 750

3. Checks circuit 855 for an open or high resistance.

4. Checks circuit 1426 for an open, short to earth or short to voltage.

5. Checks circuit 1427 for an open, short to earth or short to voltage.

Notes on Diagnostic Chart:

1. For all wiring checking procedures, refer to Section 12P WIRING DIAGRAMS of the VT Series I Service

Information.

Figure 12L-59

STEP ACTION VALUE YES NO

1. •Disconnect the throttle relaxer control module

connector YE170.

•Check resistance between connector YE170,

terminal 28, circuit 750 (Black/Red wire) and earth

location E5/E15 (engine block) (refer to NOTE 1 on

previous page).

•Is value as specified?

0 – 5 ohms Go to Step 2. Repair circuit 750

as necessary,

recheck and

verify repair.

2. •With connector YE170 disconnected, check

resistance between connector YE170, terminal 55,

circuit 750 (Black/Red wire) and earth location

E5/E15 (refer to NOTE 1 on previous page).

•Is value as specified?

0 – 5 ohms Go to Step 3. Repair circuit 750

as necessary,

recheck and

verify repair.

3. •With connector YE170 disconnected, turn the

ignition switch to the ON position.

•Measure voltage between the throttle relaxer

control module connector YE170, terminals 1 and

28 (refer to NOTE 1 on previous page).

•Is voltage as specified?

Battery + Go to Step 4. Repair circuit 855

as necessary,

recheck and

verify repair.

4. •With connector YE170 disconnected, disconnect

the ABS/ETC control module connector YE98.

•Check integrity (open, short to earth and short to

voltage) of circuit 1426 (Orange/White wire)

between connector YE98 terminal 13 and

connector YE170 terminal 37 (refer to NOTE 1 on

previous page).

•Is integrity of circuit 1426 OK?

Go to Step 5. Repair circuit

1426 as

necessary,

recheck and

verify repair.

5. •With connectors YE170 and YE98 disconnected,

check integrity (open, short to earth and short to

voltage) of circuit 1427 (Black/White wire) between

connector YE98 terminal 27 and connector YE170

terminal 35 (refer to NOTE 1 on previous page).

•Is integrity of circuit 1427 OK?

Replace throttle

relaxer control

module, refer

3.1 THROTTLE

RELAXER

CONTROL

MODULE in this

Section. Recheck

and verify repair.

Repair circuit

1427 as

necessary,

recheck and

verify repair.

WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED, CLEAR ALL DTCs AND VERIFY CORRECT OPERATION

DTC 62 - RPM SIGNAL FAULT

Figure 12L-60

CIRCUIT DESCRIPTION:

The determine the requested amount of spark retard, and prevent the engine from stalling, the ABS/ETC control

module monitors the engine speed. An engine RPM signal is sent to terminal 30 of the ABS/ETC control module

from the PCM. This signal has a fixed duty cycle and a frequency that will vary with changing engine RPM.

DTC 62 will set if an RPM signal (engine speed signal) is not received by the ABS/ETC control module at terminal

30, provided the engine speed is greater than 480 RPM.

If the ABS/ETC control m odule senses this fault, only the ETC s ys tem will be disabled (ABS will operate norm ally),

the TRAC OFF warning lamp will be illum inated and the relevant DT C will be set. T he T RAC OFF warning lamp will

rem ain illuminated f or the rem ainder of the ignition cycle. If the f ailure is interm ittent, the c ontrol m odule will enable

the system at the next ignition cycle and the relevant history DTC will be set.

Test Description:

The numbers below refer to Step numbers in the diagnostic chart for DTC 62.

1. Checks for continuity in circuit 121.

Notes on Diagnostic Chart:

1. For all wiring checking procedures, refer to Section 12P WIRING DIAGRAMS of the VT Series I Service

Information.

Figure 12L-61

NOTE: The following diagnostic procedure assumes the instrument tachometer is functioning correctly. If the

instrument tachometer is not functioning correctly, or PCM DTC P0654 is set, refer to

Section 6C3 POWERTRAIN MANAGEMENT – GEN III ENGINE of the VT Series II Service Information.

STEP ACTION VALUE YES NO

1. •Disconnect ABS/ETC control module connector

YE98 and engine connector YE112.

•Check continuity of circuit 121 (Brown wire)

between ABS/ETC control module connector

YE98, terminal 30 and engine connector YE112,

(refer to NOTE 1 on previous page).

•Does continuity exist?

Replace

ABS/ETC control

module, refer to

Section 12L ABS

& ABS/ETC of

the VT Series I

Service

Information.

Recheck and

verify repair.

Check and repair

open in circuit

121. Recheck

and verify repair.

WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED, CLEAR ALL DTCs AND VERIFY CORRECT OPERATION

DTC 64 - THROTTLE RELAXER CONTROL MODULE POSITION FAULT

Figure 12L-62

CIRCUIT DESCRIPTION:

The ABS/ETC control module continuously receives a throttle position message every 200 milliseconds, via the

actual throttle position line (DKI), circuit 1427 (Black/White wire).

DTC 64 will set if a mes sage is not received from the throttle position s witch for m ore than six s econds. If this DTC

is set, there will probably be a PCM DTC set also. If a PCM DTC is set, remedy this fault first.

If the ABS/ETC control m odule senses this fault, only the ETC s ys tem will be disabled (ABS will operate norm ally),

the TRAC OFF warning lamp will be illuminated and the relevant DTC will be set. The ETC system will remain

disabled and TRAC OFF warning lamp will remain illuminated until the ABS/ETC control module receives five

consecutive throttle position messages. After five consecutive messages are received by the ABS/ETC control

module, the control module will enable the system, and the relevant history DTC will be set.

Test Description:

The numbers below refer to Step numbers in the diagnostic chart for DTC 64.

1. Determines if fault is related to the ABS/ETC system of the powertrain management system.

2. Checks circuit 417 for open or high resistance.

3. Checks circuit 416 for open or high resistance.

4. Checks circuit 452 for open or high resistance.

Notes on Diagnostic Chart:

1. For all wiring checking procedures, refer to Section 12P WIRING DIAGRAMS of the VT Series I Service

Information.

2. Refer to 4.7 TECH 2 DIAGNOSTICS in this Section for connecting and using TECH 2.

Figure 12L-63

STEP ACTION VALUE YES NO

1. •Install TECH 2 to the DLC (refer NOTE 2 on

previous page).

•Select Diagnosis / Engine / GEN III V8 / Diagnostic

Trouble Codes / Read DTC Info Ordered Priority.

•Are any PCM DTCs set (in particular DTCs related

to the throtle position switch)?

Rectify fault

causing PCM

DTC to set, refer

to Section 6C3

POWERTRAIN

MANAGEMENT -

GEN III V8

ENGINE of the

VT Series II

Service

Information

Go to Step 2.

2. •Disconnect throttle relaxer control module wiring

harness connector YB170, the throttle position

sensor wiring harness connector YE30 and the

PCM wiring harness connector YE122.

•Measure resistance between connector YB170,

terminal 40 and connector YE30, terminal C, circuit

417 (Blue wire)(refer to NOTE 1 on previous

page).

•Is resistance as specified?

0 – 5 ohms Go to Step 4. Check and repair

open or high

resistance in

circuit 417

between

connector YB170

and YE30.

Recheck circuit

to verify repair.

3. •With connectors YB170, YE30 and YE122

disconnected, measure resistance between

connector YB170, terminal 41 and connector YE30

terminal A, circuit 416 (Grey wire)(refer NOTE 1 on

previous page).

•Is resistance as specified?

0 – 5 ohms Go to Step 4. Check and repair

open or high

resistance in

circuit 416

between

connector YB170

and YE30.

Recheck circuit

to verify repair.

4. •With connectors YB170, YE30 and YE122

disconnected, measure resistance between

connector YB170, terminal 43 and connector YE30

terminal B, circuit 452 (Black/Yellow wire)(refer

NOTE 1 on previous page).

•Is resistance as specified?

0 – 5 ohms Replace throttle

relaxer control

module, refer 3.1

THROTTLE

RELAXER

CONTROL

MODULE in this

Section, recheck

and verify repair

Check and repair

open or high

resistance in

circuit 452

between

connector YB170

and YE30.

Recheck circuit

to verify repair.

WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED, CLEAR ALL DTCs AND VERIFY CORRECT OPERATION

DTC 65 - THROTTLE RELAXER MOTOR FAULT

Figure 12L-64

CIRCUIT DESCRIPTION:

The throttle relaxer is controlled at a commanded current rate by the throttle relaxer control module.

DTC 65 will set if the throttle relaxer motor or circuit is open, shorted to earth or shorted to voltage.

If the ABS/ETC control m odule senses this fault, only the ETC s ys tem will be disabled (ABS will operate norm ally),

the TRAC OFF warning lamp will be illum inated and the relevant DT C will be set. T he T RAC OFF warning lamp will

rem ain illuminated f or the rem ainder of the ignition cycle. If the f ailure is interm ittent, the c ontrol m odule will enable

the system at the next ignition cycle and the relevant history DTC will be set.

Test Description:

The numbers below refer to Step numbers in the diagnostic chart for DTC 65.

1.-2.Checks continuity of circuit 750.

3.-4.Checks integrity (open or short to earth) of circuit 490 (including fuse F36).

5. Determines if the throttle relaxer motor is faulty.

6.-7.Checks for open in circuit 456.

8.-9.Checks for open in circuit 466.

10. Checks for short to earth in circuit 456.

11. Checks for short to earth in circuit 466.

12. Checks for short to voltage in circuit 456.

13. Checks for short to voltage in circuit 466.

Notes on Diagnostic Chart:

1. For all wiring checking procedures, refer to Section 12P WIRING DIAGRAMS of the VT Series I Service

Information.

Figure 12L-65

STEP ACTION VALUE YES NO

1. •Disconnect the throttle relaxer control module

connector YE170.

•Check resistance between connector YE170,

terminal 28, circuit 750 (Black/Red wire) and earth

location E5/E15 (engine block) (refer to NOTE 1 on

this page).

•Is value as specified?

0 – 5 ohms Go to Step 2. Repair circuit 750

as necessary,

recheck and

verify repair.

2. •With connector YE170 disconnected, check

resistance between connector YE170, terminal 55,

circuit 750 (Black/Red wire) and earth location

E5/E15 (refer to NOTE 1 on this page).

•Is value as specified?

0 – 5 ohms Go to Step 3. Repair circuit 750

as necessary,

recheck and

verify repair.

3. •With connector YE170 disconnected, measure

voltage between the throttle relaxer control module

connector YE170, terminals 51 and 28 (refer to

NOTE 1 on this page).

•Is voltage as specified?

Battery + Go to Step 4. Repair circuit 490

(incl. fuse F36)

as necessary,

recheck and

verify repair.

4. •With connector YE170 disconnected, measure

voltage between the throttle relaxer control module

connector YE170, terminals 24 and 28 (refer to

NOTE I on previous page).

•Is voltage as specified?

Battery + Go to Step 5. Repair circuit 490

as necessary,

recheck and

verify repair.

5. •Turn the ignition switch to the OFF position.

•Disconnect throttle relaxer connector YE127.

•Disconnect all cables from the throttle relaxer

pulleys.

•Rotate pulleys on the throttle relaxer by hand fully

then release, allowing the pulleys to return to the

stop. Repeat this procedure three times.

•Check resistance between the throttle relaxer

terminals A and B (refer to NOTE 1 on previous

page).

•Is the resistance within the range as specified?

0.5 – 10

ohms Go to Step 6. Replace the

throttle relaxer

assembly, refer

to Section 6C3-3

POWERTRAIN

MANAGEMENT

– GEN III V8

ENGINE of the

VT Series II

Service

Information.

Recheck and

verify repair

6. •With the throttle relaxer connector YE127

disconnected, disconnect throttle relaxer control

module connector YB170.

•Check resistance of circuit 456 (Red/White wire)

between connector YB170 terminals 22 and

connector YE127 terminal A (refer to NOTE 1 on

previous page).

•Is resistance value as specified?

0 – 5 ohms Go to Step 7. Repair open in

circuit 456,

recheck and

verify repair.

STEP ACTION VALUE YES NO

7. • With the throttle relaxer connector YE127

disconnected, disconnect throttle relaxer control

module connector YB170.

• Check resistance of circuit 456 (Red/White wire)

between connector YB170 terminal 49 and

connector YE127 terminal A (refer to NOTE 1 on

previous page).

• Is resistance value as specified?

0 – 5 ohms Go to Step 8. Repair open in

circuit 456,

recheck and

verify repair.

8. • With the throttle relaxer connector YE127 and the

throttle relaxer control module connector YB170

disconnected, check resistance of circuit 466

(Red/Black wire) between connector YB170

terminal 26 and connector YE127 terminal B (refer

to NOTE 1 on previous page).

• Is resistance value as specified?

0 – 5 ohms Go to Step 9. Repair open in

circuit 466,

recheck and

verify repair.

9. • With the throttle relaxer connector YE127 and the

throttle relaxer control module connector YB170

disconnected, check resistance of circuit 466

(Red/Black wire) between connector YB170

terminal 53, and connector YE127 terminal B (refer

to NOTE 1 on previous page).

• Is resistance value as specified?

0 – 5 ohms Go to Step 10. Repair open in

circuit 466,

recheck and

verify repair.

10. • Reconnect the throttle relaxer connector YE127.

• Check resistance between terminals 22, circuit 456

(Red/White wire) and 28, circuit 750 (Black/Red

wire) on the throttle relaxer control module

connector YB170 (refer to NOTE 1 on previous

page).

• Is resistance value as specified?

Infinite ohms Go to Step 11. Repair short to

earth in circuit

456, recheck and

verify repair.

11. • Check resistance between terminals 26, circuit 466

(Red/Black wire) and 28, circuit 750 (Black/Red

wire) on the throttle relaxer control module

connector YB170 (refer to NOTE 1 on previous

page).

• Is resistance value as specified?

Infinite ohms Go to Step 12. Repair short to

earth in circuit

466, recheck and

verify repair.

12. • Reconnect the throttle relaxer control module

connector YB170.

• Disconnect the throttle relaxer connector YE127.

• Turn the ignition switch to the ON position.

• Using a voltmeter, check voltage at connector

YE127, terminal A, circuit 456 (Red/W hite wire)

(refer to NOTE 1 on previous page).

• Is voltage as specified?

Greater than

1 volt Repair short to

voltage in circuit

456, recheck and

verify repair.

Go to Step 13.

13. • With the throttle relaxer connector YE127 and the

throttle relaxer control module connector YB170

disconnected, and the ignition switch in the ON

position, check voltage at connector YE127,

terminal B, circuit 466 (Red/Black wire) (refer to

NOTE 1 on previous page).

• Is voltage as specified?

Greater than

1 volt Repair short to

voltage in circuit

466, recheck and

verify repair.

Replace throttle

relaxer control

module, refer to

3.1 THROTTLE

RELAXER

CONTROL

MODULE in this

Section. Recheck

and verify repair.

WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED, CLEAR ALL DTCs AND VERIFY CORRECT OPERATION

DTC 66 – THROTTLE RELAXER CONTROL FAULT

CIRCUIT DESCRIPTION:

DTC 66 is a throttle position control failure that is most likely due to a mechanical fault caused by a jammed or

binding throttle cable of throttle relaxer motor. DTC 66 can only be detected when the ABS/ETC control module is

modulating (or attempting to modulate) the throttle position.

If the throttle relaxer control module is unable to adjust the throttle position, as requested by the ABS/ETC control

module, via the requested throttle position line (DKR), the throttle relaxer control module will try to reduce the

throttle opening by increasing the current supplied to the throttle relaxer. This current will rise to a m aximum value

and if it stays there for m ore than three seconds , a mess age is sent to the ABS/ET C control m odule and a DTC 66

is set.

If the ABS/ETC control m odule senses this fault, only the ETC s ys tem will be disabled (ABS will operate norm ally),

the TRAC OFF warning lamp will be illum inated and the relevant DT C will be set. T he T RAC OFF warning lamp will

rem ain illuminated f or the rem ainder of the ignition cycle. If the f ailure is interm ittent, the c ontrol m odule will enable

the system at the next ignition cycle and the relevant history DTC will be set.

ACTION:

If DTC 66 sets, visually and physically check the following components:

• Check accelerator pedal, throttle and (if fitted) cruise control cables for binding or fouling.

• Remove the accelerator pedal, throttle and (if fitted) cruise control cables from the throttle relaxer. Check

operation of the throttle relaxer pulleys to ensure they rotate freely without binding or sticking.

Repair or replace components as necessary. Ensure all cables are routed correctly. Clear all DTCs and verify

correct operation.

NOTE 1: The throttle relaxer is a non serviceable component. If the throttle relaxer pulleys are found to be faulty,

replace the throttle relaxer assembly.

NOTE 2: To remove, reinstall and adjust the cables and throttle relaxer assembly, refer to

Section 6C3 POWERTRAIN MANAGEMENT – GEN III V8 ENGINE of the VT Series II Service Information.

DTC 68 – TPS (THROTTLE POSITION SWITCH) MONITORING FAULT

Figure 12L-66

CIRCUIT DESCRIPTION:

The ABS/ETC contr ol m odule m onitors the throttle position, when set by the throttle relaxer contr ol module, via the

actual throttle position (DKI) input, circuit 1427 (Black /W hite wire). At the sam e time, the ABS/ETC control m odule

monitors the throttle position, as read by the Throttle Position Switch (TPS), and communicated on the serial data

line (circuit 1220, Green/W hite wire) by the PCM/PIM. If the values from the two inputs do not correlate with each

other, the ABS/ETC control module will set DTC 68.

If the ABS/ETC control m odule senses this f ault, only the ETC s ys tem will be disabled (ABS will operate norm ally),

the TRAC OFF warning lamp will be illum inated and the relevant DT C will be set. T he T RAC OFF warning lam p will

rem ain illuminated f or the rem ainder of the ignition c ycle. If the f ailure is interm ittent, the c ontrol m odule will enable

the system at the next ignition cy cle and the relevant history DTC will be set.

Test Description:

The numbers below refer to Step numbers in the diagnostic chart for DTC 68.

1. Determines if fault is related to the ABS/ETC system of the powertrain management system.

2. Checks if ABS/ETC control module is receiving the correct signal.

Notes on Diagnostic Chart:

1. For all wiring checking procedures, refer to Section 12P WIRING DIAGRAMS of the VT Series I Service

Information.

2. Refer to 4.7 TECH 2 DIAGNOSTICS in this Section for connecting and using TECH 2.

Figure 12L-67

STEP ACTION VALUE YES NO

1. •Install TECH 2 to the DLC (refer NOTE 2 on this

page).

•Select Diagnosis / Engine / GEN III V8 / Diagnostic

Trouble Codes / Read DTC Info Ordered Priority.

•Are any PCM DTCs set ?

Rectify fault

causing PCM

DTC to set, refer

to Section 6C3

POWERTRAIN

MANAGE MENT -

GEN III V8

ENGINE of the

VT Series II

Service

Information.

Recheck and

verify repair.

Go to Step 2.

2. •Reconnect the throttle relaxer control module

connector YB170.

•Back probe ABS/ETC control module connector

YE98, terminal 27, circuit 1427 (Black/White wire)

with a volt meter to earth (refer NOTE 1 on

previous page).

•Turn ignition on.

•Vary the position of the throttle opening, while

taking not of voltage reading.

•Is voltage as specified?

Throttle

closed -

approx. 1 volt

WOT approx.

10 volts

Replace

ABS/ETC control

module, refer to

Section 12L ABS

& ABS/ETC of

the VT Series I

Service

Information.

Recheck circuit

to verify repair.

Replace throttle

relaxer control

module, refer to

3.1 THROTTLE

RELAXER

CONTROL

MODULE in this

Section. Recheck

and verify repair.

WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED, CLEAR ALL DTCs AND VERIFY CORRECT OPERATION

DTC 72 - SERIAL DATA FAULT

Figure 12L-68

CIRCUIT DESCRIPTION:

W ith the ignition ON, the ABS/ETC control module will be able to communicate with other control modules via the

serial data line, circuit 1220 (Gr een/W hite wire). If com m unication between the modules is dis rupted due to a short

or open circuit, DTC 72 will be set.

If the ABS/ETC control m odule senses this fault, only the ETC system will be disabled (ABS operation will operate

normally), the TRAC OFF warning lamp will be illuminated and the relevant DTC will be set. The TRAC OFF

warning lamp will remain illum inated for the remainder of the ignition cycle. If the failure is intermittent, the control

module will enable the system at the next ignition cycle and the relevant history DTC will be set.

There are several other control modules that are connected to the serial data circuit (PCM/PIM, BCM, ABS/ETC,

ECC, SRS, and the instrum ent c luster) . Any of these contr ol modules c ould c ause a fault in the serial data line. This

fault could result in TECH 2 not being able to display serial data.

Test Description:

The numbers below refer to Step numbers in the diagnostic chart for DTC 72.

1. This test determines if fault is current or not.

2. This test checks for connector or wiring problems which may cause an intermittent fault.

3. Determines if fault is in wiring or ABS/ETC control module.

4. Determines if fault is with BCM serial data communication (bus master).

5. Checks if fault is caused by other control modules that are communicating on the serial data line.

6. Checks circuit 1220 and determines if fault is in wiring or control module.

7. Checks for continuity in circuit 1220.

Notes on Diagnostic Chart:

1. For all wiring checking procedures, refer to Section 12P WIRING DIAGRAMS in the VT Series I Service

Information or in the VT Series II Service Information on this Service Information CD.

2. Refer to 4.7 TECH 2 DIAGNOSTICS in this Section for connecting and using TECH 2.

Diagnostic Aids:

A fault with the serial data circ uit could be caused by one or more of the several control m odules connected to the

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

restored.

Figure 12L-69

STEP ACTION VALUE YES NO

1. • Install TECH 2 to DLC.

• Select Diagnostics / Chassis / ABS/ETC /

Diagnostic Trouble Codes / Clear DTCs and clear

all DTCs (refer to NOTE 2 on opposite page).

• Road test vehicle.

• Does DTC 72 set again ?

NOTE: Go to Step 4 if TECH 2 will not communicate

with the ABS/ETC control module.

Go to Step 3. Go to Step 2.

2. • Inspect all system wiring and connections that

could cause intermittent faults. Check all wiring is

in good condition, terminals are clean and tight

and making good contact (refer NOTE 1 on

previous page).

• Is wiring OK ?

NOTE: Other control modules (SRS, Instruments, ECC,

BCM, PCM) that are connected to the serial data circuit

could cause DTC 72 to set, therefore, check wiring and

connectors that could cause intermittent faults at these

control modules also.

Fault not present.

Check all system

wiring harness

connectors and

terminals, in

particular the

modulator and

ABS/ETC control

module

connector

terminals.

Make repairs as

necessary,

recheck and

verify repair.

3. • In step 1, was TECH 2 able to communicate with

the ABS/ETC control module (refer NOTE 2 on

previous page)?

(With the ignition on and Chassis / ABS/ETC

selected, TECH 2 should display the ABS/ETC

control module part number, system identification

and actual system.)

Go to Step 4. Replace

ABS/ETC control

module, refer to

Section 12L ABS

& ABS/ETC of

the VT Series I

Service

Information,

recheck circuit to

verify repair.

4. • With TECH 2 connected, select Diagnostics / Body

/ Body Control Module and turn ignition on as

requested (refer NOTE 2 on previous page).

• Does TECH 2 display BCM system identification

information (BCM level and type) ?

Go to Step 5. Refer to BCM

Serial Data

Communication

diagnostics in

Section 12J-1

LOW SERIES

BCM or 12J-2

HIGH SERIES

BCM of the VT

Series II Service

Information.

5. • Using TECH 2, ch eck for similar DTCs (Seri al Data

faults) that have been set by other control

modules; instruments, SRS, and ECC if applicable

to model variant (refer NOTE 2 on previous page).

• Have similar DTCs been set by other control

modules ?

Go to Step 6. Go to Step 7.

6. • Check circuit 1220 (Green/White wire or

White/Green wire) for open, short to earth or short

to voltage between BCM and individual control

modules (refer NOTE 1 on previous page).

• Is circuit 1220 OK ?

NOTE: Disconnect each controller in circuit 1220 one

at a time to isolate the fault in the circuit or to identify

control module causing fault.

Replace faulty

module, refer to

relevant Section

in this Service

Information CD,

recheck and

verify repair.

Make repairs as

necessary,

recheck and

verify repair.

7. • Disconnect BCM connector YB164 (Low Series

BCM) or YB175 (High Series BCM) and ABS/ETC

control module connector YE98.

• Check for continuity between BCM connector

YB164 terminal D3 or YB175 terminal E9 and

ABS/ETC control module connector YE98, terminal

11, circuit 1220 (Green/White wire) (refer to NOTE

1 on previous page).

• Does continuity exist ?

Replace

ABS/ETC control

module, refer to

Section 12L ABS

& ABS/ETC of

the VT Series I

Service

Information,

recheck circuit to

verify repair.

Check and repair

open in circuit

1220 between

BCM and

ABS/ETC control

module, recheck

and verify repair.

WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED, CLEAR ALL DTCs AND VERIFY CORRECT OPERATION

DTC 73 – SP ARK RETARD MONITORING FAULT

Figure 12L-70

CIRCUIT DESCRIPTION:

Spark retard is simultaneously controlled by the ABS/ETC control module and the PCM. The PCM supplies a 12 volt

pull up voltage. This voltage is monitor ed by the PCM, the ABS/ETC c ontrol m odule request spark retard by pulling

this voltage low.

The ABS/ETC contr ol m odule continually m onitors circuit 1687. If the ABS/ETC control m odule detects a continuity

problem in circuit 1687 it will set a DTC 73.

If the ABS/ETC control m odule senses this fault, only the ETC s ys tem will be disabled (ABS will operate norm ally),

the TRAC OFF warning lamp will be illum inated and the relevant DT C will be set. T he T RAC OFF warning lamp will

rem ain illuminated f or the rem ainder of the ignition cycle. If the f ailure is interm ittent, the c ontrol m odule will enable

the system at the next ignition cycle and the relevant history DTC will be set.

Test Description:

The numbers below refer to Step numbers in the diagnostic chart for DTC 73.

1. Checks for 12 volt pull up from PCM.

2. Checks for short to voltage in circuit 1687.

3. Checks for open and short to earth in circuit 1687.

Notes on Diagnostic Chart:

1. For all wiring checking procedures, refer to Section 12P WIRING DIAGRAMS of the VT Series I Service

Information.

2. Refer to the PCM ON-BOARD DIAGNOSTIC SYSTEM CHECK in Section 6C3 POWERTRAIN

MANAGEMENT – GEN III V8 ENGINE before replacing PCM.

Figure 12L-71

STEP ACTION VALUE YES NO

1. •Disconnect ABS/ETC control module connector

YE98.

•Start engine.

•Check voltage at ABS/ETC control module

connector YE98, terminal 28, circuit 1687

(Grey/Black wire).

•Is voltage as specified?

Battery + Go to Step 2. Go to Step 3.

2. •With connector YE98 disconnected, disconnect

the PCM connector YE123.

•Turn ignition ON.

•Check circuit 1687 for short to voltage (refer to

NOTE 1 on previous page).

•Is circuit 1687 OK?

Replace

ABS/ETC control

module, refer to

Section 12L ABS

& ABS/ETC of

the VT Series I

Service

Information,

recheck circuit to

verify repair.

Repair short to

voltage in circuit

1687, recheck

and verify repair.

3. •With connector YE98 disconnected, disconnect

the PCM connector YE123.

•Turn ignition OFF.

•Check circuit 1687 for an open of short to earth

(refer NOTE 1 on previous page).

•Is circuit 1687 OK?

Check and if

necessary,

replace PCM,

refer Section 6C3

POWERTRAIN

MANAGEMENT

– GEN III V8

ENGINE (See

NOTE 2 on

before replacing

PCM).

Repair short to

earth or open in

circuit 1687,

recheck and

verify repair.

WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED, CLEAR ALL DTCs AND VERIFY CORRECT OPERATION

5. SPECIAL TOOLS

TOOL NO. REF IN TEXT TOOL DESCRIPTION COMMENTS

TECH 2 DIAGNOSTIC SCAN TOOL PREVIOUSLY RELEASED

J39200 DIGITAL MULTIMETER TOOL NO. J39200

PREVIOUSLY RELEASED, OR

USE COMMERCIALLY

AVAILABLE EQUIVALENT.

MUST HAVE 10 MEG OHM

INPUT IMPEDANCE AND BE

CAPABLE OF READING

FREQUENCIES

KM-609 ELECTRONIC KIT USED IN CONJUNCTION

WITH A MULTIMETER FOR

MEASURING VOLTAGES AND

RESISTANCE’S WITHOUT

DAMAGING WIRING

HARNESS CONNECTORS