5B6 ABS-TCS – GEN III V8 Page 5B6–1
Page 5B6–1
Section 5B6
ABS-TCS – GEN III V8
ATTENTION
Before performing any service operation or other procedure described in this Section, refer to Section 00
Warnings, Cautions and Notes for correct w orkshop practices wi th regard to safety and/or property damage.
1 General Information...............................................................................................................................6
1.1 Definition of Wheel Slip......................................................................................................................................... 6
Longitudinal Wheel Slip........................................................................................................................................6
Lateral Wheel Slip.................................................................................................................................................. 7
Limitation of the Conventional Braking System ................................................................................................. 7
1.2 Definition of ABS-TCS Active Braking ................................................................................................................. 8
Antilock Braking System....................................................................................................................................... 8
Electronic Brake-force Distribution System........................................................................................................ 8
Traction Control System ....................................................................................................................................... 8
2 Component Description and Operation...............................................................................................9
2.1 Component Location............................................................................................................................................. 9
2.2 Electronic Control Unit........................................................................................................................................ 10
Electronic Control Unit Inputs............................................................................................................................ 10
Electronic Control Unit Outputs......................................................................................................................... 10
Electronic Control Unit Self-test Initialisation Sequence................................................................................. 10
2.3 Hydraulic Modulator Assembly........................................................................................................................... 11
Hydraulic Circuit Components ........................................................................................................................... 12
2.4 Wheel Speed Sensors ......................................................................................................................................... 13
Wheel Speed Sensor Principles of Operation................................................................................................... 13
Front Wheel Speed Sensor ................................................................................................................................. 13
Rear Wheel Speed Sensor................................................................................................................................... 14
Testing Wheel Speed Sensor Using an Oscilloscope ...................................................................................... 14
2.5 Stop Lamp Switch-A............................................................................................................................................ 15
2.6 Traction Control System Switch......................................................................................................................... 16
3 System Operation.................................................................................................................................17
3.1 Non-ABS Braking................................................................................................................................................. 17
Non-ABS Braking Operation............................................................................................................................... 17
Condition Description ....................................................................................................................................... 17
Normal Braking Hydraulic Circuit...................................................................................................................... 18
3.2 Antilock Braking System..................................................................................................................................... 19
ABS Phase – Maintaining Pressure.................................................................................................................... 20
Condition Description ....................................................................................................................................... 20
Control Action................................................................................................................................................... 20
ABS Phase Hydraulic Circuit – Maintaining Pressure....................................................................................... 21
ABS Phase – Reducing Pressure ....................................................................................................................... 22
Condition Description ....................................................................................................................................... 22
Control Action................................................................................................................................................... 22
ABS Phase Hydraulic Circuit – Reducing Pressure.......................................................................................... 23
ABS Phase – Increasing Pressure...................................................................................................................... 24
Condition Description ....................................................................................................................................... 24
Control Action................................................................................................................................................... 24
ABS Phase Hydraulic Circuit – Increasing Pressure ........................................................................................ 25
Techline
Techline
Techline
5B6 ABS-TCS – GEN III V8 Page 5B6–2
Page 5B6–2
3.3 Electronic Brake-force Distribution System...................................................................................................... 26
EBD System Keep Alive Function ...................................................................................................................... 26
EBD Phase – Maintaining Pressure.................................................................................................................... 26
Condition Description ....................................................................................................................................... 26
Control Action................................................................................................................................................... 26
EBD Phase Hydraulic Circuit – Maintaining Pressure ...................................................................................... 27
EBD Phase – Reducing Pressure....................................................................................................................... 28
Condition Description ....................................................................................................................................... 28
Control Action................................................................................................................................................... 28
EBD Phase Hydraulic Circuit – Reducing Pressure.......................................................................................... 29
EBD Phase – Increasing Pressure...................................................................................................................... 30
Condition Description ....................................................................................................................................... 30
Control Action................................................................................................................................................... 30
3.4 Traction Control System ..................................................................................................................................... 31
TCS Mode – Engine Torque Reduction.............................................................................................................. 31
TCS Mode – Brake Intervention.......................................................................................................................... 31
TCS Mode Hydraulic Circuit – Brake Intervention............................................................................................ 32
4 Wiring Diagram and Connector Chart................................................................................................33
4.1 Wiring Diagram .................................................................................................................................................... 33
4.2 Connector Chart................................................................................................................................................... 34
4.3 Connector Information ........................................................................................................................................ 35
Electronic Control Unit – A37 ............................................................................................................................. 35
Front and Rear Wheel Speed Sensor – B52L, B52R, B76L and B76R............................................................. 36
5 Diagnostics...........................................................................................................................................37
5.1 Diagnostic General Descriptions........................................................................................................................ 37
Diagnostic Trouble Code Tables........................................................................................................................ 37
Diagnostic Trouble Codes .................................................................................................................................. 38
Status of DTCs................................................................................................................................................. 38
Action Taken When a DTC Sets....................................................................................................................... 38
Conditions for Clearing DTCs........................................................................................................................... 38
6 ABS-TCS Diagnostic Starting Point...................................................................................................39
6.1 Basic Requirements ............................................................................................................................................ 39
Basic Know ledge Required................................................................................................................................. 39
Basic Diagnostic Tools Required....................................................................................................................... 39
6.2 Diagnostic Precautions....................................................................................................................................... 40
6.3 Preliminary Checks.............................................................................................................................................. 41
6.4 Diagnostic System Check................................................................................................................................... 42
Description........................................................................................................................................................... 42
Test Description................................................................................................................................................... 42
7 Intermittent Faults................................................................................................................................43
7.1 Intermittent Fault Diagnostic Table.................................................................................................................... 43
Description........................................................................................................................................................... 43
5B6 ABS-TCS – GEN III V8 Page 5B6–3
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8 Diagnostic Trouble Codes...................................................................................................................45
8.1 DTC List................................................................................................................................................................ 45
8.2 DTC 21, 23, 25, 27, 31, 33, 35 or 37 – Wheel Speed Sensor Circuit.................................................................. 46
DTC Description................................................................................................................................................... 46
Circuit Description............................................................................................................................................... 46
Additional Information......................................................................................................................................... 46
Conditions for Running the DTC........................................................................................................................ 46
Conditions for Setting the DTC .......................................................................................................................... 46
Action Taken When the DTC Sets ...................................................................................................................... 46
Conditions for Clearing the DTC........................................................................................................................ 46
Test Description................................................................................................................................................... 47
DTC 21, 23, 25, 27, 31, 33, 35 or 37 Diagnostic Table........................................................................................ 47
8.3 DTC 28 – Wheel Speed Frequency Error............................................................................................................ 49
DTC Description................................................................................................................................................... 49
Circuit Description............................................................................................................................................... 49
Additional Information......................................................................................................................................... 49
Conditions for Running the DTC........................................................................................................................ 49
Conditions for Setting the DTC .......................................................................................................................... 49
Action Taken When the DTC Sets ...................................................................................................................... 49
Conditions for Clearing the DTC........................................................................................................................ 49
Test Description................................................................................................................................................... 49
DTC 28 Diagnostic Table..................................................................................................................................... 50
8.4 DTC 41, 42, 45, 46, 55 or 56 – Hydraulic Modulator Solenoid Valve Circuit.................................................... 52
DTC Description................................................................................................................................................... 52
Circuit Description............................................................................................................................................... 52
Additional Information......................................................................................................................................... 52
Conditions for Running the DTC........................................................................................................................ 52
Conditions for Setting the DTC .......................................................................................................................... 52
Action Taken When the DTC Sets ...................................................................................................................... 52
Conditions for Clearing the DTC........................................................................................................................ 52
Test Description................................................................................................................................................... 52
DTC 41, 42, 45, 46, 55 or 56 Diagnostic Table.................................................................................................... 53
8.5 DTC 61 – Hydraulic Modulator Pump Motor Circuit.......................................................................................... 54
DTC Description................................................................................................................................................... 54
Circuit Description............................................................................................................................................... 54
Additional Information......................................................................................................................................... 54
Conditions for Running the DTC........................................................................................................................ 54
Conditions for Setting the DTC .......................................................................................................................... 54
Action Taken When the DTC Sets ...................................................................................................................... 54
Conditions for Clearing the DTC........................................................................................................................ 54
Test Description................................................................................................................................................... 54
DTC 61 Diagnostic Table..................................................................................................................................... 55
8.6 DTC 63 – ECU Internal Solenoid Valve Relay Circuit........................................................................................ 56
DTC Description................................................................................................................................................... 56
Circuit Description............................................................................................................................................... 56
Additional Information......................................................................................................................................... 56
Conditions for Running the DTC........................................................................................................................ 56
Conditions for Setting the DTC .......................................................................................................................... 56
Action Taken When the DTC Sets ...................................................................................................................... 56
Conditions for Clearing the DTC........................................................................................................................ 56
Test Description................................................................................................................................................... 56
DTC 63 Diagnostic Table..................................................................................................................................... 57
5B6 ABS-TCS – GEN III V8 Page 5B6–4
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8.7 DTC 67 – Brake Swit ch Circuit............................................................................................................................ 58
DTC Description................................................................................................................................................... 58
Circuit Description............................................................................................................................................... 58
Additional Information......................................................................................................................................... 58
Conditions for Running the DTC........................................................................................................................ 58
Conditions for Setting the DTC .......................................................................................................................... 58
Action Taken When the DTC Sets ...................................................................................................................... 58
Conditions for Clearing the DTC........................................................................................................................ 58
Test Description................................................................................................................................................... 58
DTC 67 Diagnostic Table..................................................................................................................................... 59
8.8 DTC 71 – ECU Internal Fault................................................................................................................................ 60
DTC Description................................................................................................................................................... 60
Circuit Description............................................................................................................................................... 60
Additional Information......................................................................................................................................... 60
Conditions for Running the DTC........................................................................................................................ 60
Conditions for Setting the DTC .......................................................................................................................... 60
Action Taken When the DTC Sets ...................................................................................................................... 60
Conditions for Clearing the DTC........................................................................................................................ 60
Test Description................................................................................................................................................... 60
DTC 71 Diagnostic Table..................................................................................................................................... 61
8.9 DTC 85 – Battery Voltage Out of Range............................................................................................................. 62
DTC Description................................................................................................................................................... 62
Circuit Description............................................................................................................................................... 62
Additional Information......................................................................................................................................... 62
Conditions for Running the DTC........................................................................................................................ 62
Conditions for Setting the DTC .......................................................................................................................... 62
Action Taken When the DTC Sets ...................................................................................................................... 62
Conditions for Clearing the DTC........................................................................................................................ 62
Test Description................................................................................................................................................... 62
DTC 85 Diagnostic Table..................................................................................................................................... 63
9 Service Operations...............................................................................................................................64
9.1 Safety and Precautionary Measures................................................................................................................... 64
9.2 ABS-TCS Brake Bleeding Procedure ................................................................................................................. 66
9.3 Electronic Control Unit / Hydraulic Modulator Assembly................................................................................. 67
Remove................................................................................................................................................................. 67
Disassemble......................................................................................................................................................... 68
Inspect .................................................................................................................................................................. 69
Reassemble.......................................................................................................................................................... 69
Reinstall................................................................................................................................................................ 70
9.4 Front Wheel Speed Sensor ................................................................................................................................. 71
9.5 Front Wheel Speed Sensor Lead........................................................................................................................ 72
Remove................................................................................................................................................................. 72
Reinstall................................................................................................................................................................ 73
9.6 Rear Wheel Speed Sensor................................................................................................................................... 74
Remove................................................................................................................................................................. 74
Reinstall................................................................................................................................................................ 75
9.7 Front Wheel Speed Sensor Pulse Ring.............................................................................................................. 76
9.8 Rear Wheel Speed Sensor Pulse Ring............................................................................................................... 77
9.9 Traction Control System Switch......................................................................................................................... 78
Replace................................................................................................................................................................. 78
Test ....................................................................................................................................................................... 78
5B6 ABS-TCS – GEN III V8 Page 5B6–5
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10 Specifications.......................................................................................................................................79
11 Torque Wrench Specifications ...........................................................................................................80
12 Special Tools ........................................................................................................................................81
5B6 ABS-TCS – GEN III V8 Page 5B6–6
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1 General Information
The antilock braking system-traction control system (ABS-TCS) utilises the existing components of the conventional
braking system and incorporates an electronic control unit (ECU), hydraulic modulator, wheel speed sensors and the
functionality of engine torque reduction from the engine control management system. This allows the ABS-TCS to apply
active braking and engine torque reduction to prevent wheel slip when driving under various vehicle load and road
surface conditions.
1.1 Definition of Wheel Slip
Longitudinal Wheel Slip
Longitudinal wheel slip is the loss of traction between the tyres and the road surface, which happens when the vehicle is
moving in a straight ahead direction and the braking or acceleration forces applied to the tyres exceeds the tyre traction
available to the vehicle. Refer to Figure 5B6 – 1 for the illustration of the following:
• At 0% slip, the tyre rolls freely (A).
• At 100% slip, the tyre locks-up (B) as the weight of the vehicle pushes the non-rotating tyre along the road
surface (C).
When the tyres are locked-up, the vehicle's forward energy is converted into braking energy (friction) between the
tyre and the road surface (1). This will result in an unstable and inefficient braking due to the effect of the following
factors:
• Asphalt, cement, gravel or dirt road surfaces provide different degree of tyre traction.
• Oil puddles, ice spots or other contaminants that cause a sudden change in the road surface condition.
• Wet, dry, smooth, rough road surface condition affects tyre traction.
Figure 5B6 – 1
When none of the wheels are locked during braking, the heat energy produced by the braking action is transferred to the
brake pads and the brake disc. The friction surfaces between the brake pads and the brake disc are designed to provide
a stable and controlled braking action. Therefore, a vehicle that is braked without locking the wheels will stop in a shorter
distance while maintaining directional stability and steering capability. Maximum braking efficiency is achieved when a
wheel lock slip is prevented.
5B6 ABS-TCS – GEN III V8 Page 5B6–7
Page 5B6–7
Lateral Wheel Slip
Lateral wheel slip is the loss of traction between the tyres and the road surface, which occurs when the vehicle is
cornering or when excessive engine torque is applied to the vehicle and the following forces applied to the tyres exceeds
the tyre traction available to the vehicle:
• cornering forces,
• acceleration force, or
• braking force.
In addition, steering control depends upon tyre traction. A locked wheel in a 100% slip condition delivers poor braking and
directional control.
The front tyre direction (A) has minimal steering effect while
the vehicle skids in direction (B). The tyres must regain their
traction before steering control is restored to the vehicle.
Figure 5B6 – 2
Limitation of the Conventional Braking System
Skilled drivers prevent wheel lock-up during hard or emergency hard braking situations by controlling the braking force
applied to the brake pedal, which limits the braking force applied to the vehicle. The braking force applied must be limited
to a point just short of a wheel lock-up to achieve the shortest possible stopping distance.
However, wheel slip on wet roads or other reduced traction conditions is difficult to prevent through the conventional
braking system. Even skilled drivers cannot control the brake pressure applied to the vehicle precisely enough to prevent
wheel lock-up under all road surface conditions.
In addition, when only one wheel slips, increasing or reducing brake pedal pressure increases or reduces the braking
force applied to all four wheels.
5B6 ABS-TCS – GEN III V8 Page 5B6–8
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1.2 Definition of ABS-TCS Active Braking
Antilock Braking System
The antilock braking system (ABS) incorporates sensors that constantly monitor and compare the rotational speed of
each wheel to determine the vehicle reference speed and to detect a possible wheel lock-up condition.
When the ABS detects the beginning of a wheel lock-up condition or when one or more wheels are decelerating faster
than the vehicle reference speed, it actively modulates the brake fluid pressure applied to the affected wheel to prevent
the wheel lock-up condition. Refer to 3.2 Antilock Braking System for information on the ABS operation.
Electronic Brake-force Distribution System
The electronic brake-force distribution (EBD) system is part of the ABS-TCS software programmed into the electronic
control unit (ECU) and is designed to replace the rear brake proportioning valve in preventing rear wheel lock-up during
moderate braking.
This functionality enables the EBD system to apply dynamic front to rear brake proportioning, which responds to changes
in vehicle loads, road surface conditions and brake pressure application.
Refer to 3.3 Electronic Brake-force Distribution System for further information on the EBD system.
Traction Control System
The traction control system (TCS) prevents wheel slip by applying active braking and engine torque reduction when
driving under various vehicle load and road surface conditions. Refer to 3.4 Traction Control System for further
information on the TCS.
5B6 ABS-TCS – GEN III V8 Page 5B6–9
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2 Component Description and
Operation
2.1 Component Location
Figure 5B6 – 3
Legend
1 Front Wheel Speed Sensor
2 Front Wheel Speed Sensor Lead
3 Electronic Control Unit (ECU)
4 Hydraulic Modulator Assembly
5 TCS Switch
6 Rear Wheel Speed Sensor
7 Rear Wheel Speed Sensor Pulse Ring
5B6 ABS-TCS – GEN III V8 Page 5B6–10
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2.2 Electronic Control Unit
The electronic control unit (ECU) (1) is the control centre of
the antilock braking system-traction control system (ABS-
TCS). It is integrated with the hydraulic modulator (2) to form
one assembly.
Figure 5B6 – 4
Electronic Control Unit Inputs
The ECU constantly monitors and evaluates input signals from the following:
• wheel speed sensors,
• stop lamp switch,
• ignition on input,
• battery voltage, and
• serial data communication circuit.
Electronic Control Unit Outputs
Based on the inputs received, the ECU sends output signals to the following:
• instrument cluster multi-function display (MFD),
• diagnostic link connector,
• hydraulic modulator solenoid valves,
• hydraulic modulator pump motor, and
• serial data communication circuit.
Electronic Control Unit Self-test Initialisation Sequence
When the ignition is switched on, the ECU constantly performs a self-test that detects and isolates ABS-TCS faults. In
addition, the ECU performs one Self-test Initialisation Sequence for each ignition cycle. This Initialisation Sequence
commences when the vehicle reaches approximately 15 km/h.
NOTE
The Initialisation Sequence may be heard and felt
while it is taking place, which is considered part of
the normal system operation.
Refer to 3.2 Antilock Braking System.
During the Initialisation Sequence, the ECU sends a control signal to the hydraulic modulator to cycle each of the
solenoid valves as well as operate the pump motor to check for correct component operation. If the pump or any solenoid
valves fail to operate, the ECU sets a diagnostic trouble code (DTC).
Refer to 5.1 Diagnostic General Descriptions for information on action taken by the ECU when a DTC sets.
When the vehicle speed exceeds 15 km/h, the ECU continuously monitors the ABS-TCS by comparing the logical
sequence of input and output signals with the normal operating parameters stored in the ECU. If any of the input or
output signals are outside the normal operating parameters, the ECU sets a DTC.
5B6 ABS-TCS – GEN III V8 Page 5B6–11
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2.3 Hydraulic Modulator Assembly
NOTE
Figure 5B6 – 5 shows an illustration of the
hydraulic modulator components while in ABS
pressure reducing phase. Refer to this illustration
for the following hydraulic circuit components.
The hydraulic modulator assembly (1) modulates the brake fluid pressure (A) based on the control signal sent by the
electronic control unit (ECU).
To allow individual control of each wheel brake fluid circuit, a four-channel circuit configuration with a front/rear split is
used. Each of the brake fluid circuits are hydraulically isolated, which enables continued braking ability if a leak develops
in any of the brake fluid circuits. The hydraulic modulator components consist of the following:
• Two return pumps (2) – each pump draws excess brake fluid from the accumulators (3) and brake callipers (4)
allowing the hydraulic modulator to return brake fluid to the brake master cylinder (5) against brake fluid pressure
(C) during the ABS-TCS pressure reducing phase. In addition, the return pump applies pressure to the brake
callipers during TCS brake intervention phase.
• One electric motor (M) – the electric motor drives the return pump.
• Two accumulators – the accumulators store the excess brake fluid during the ABS-TCS pressure reducing phase
that enables the hydraulic modulator to apply instant pressure reduction.
• Four inlet valves (6) – at rest position, each inlet valve allows brake fluid pressure to be applied to the brake
callipers. When active, each inlet valve isolates a brake calliper from the brake master cylinder.
• Four outlet valves (7) – at rest position, each outlet valve isolates a brake calliper from the accumulator and return
pump. When active, each outlet valve directs excess brake fluid to the accumulator and return pump that allows
pressure reduction.
• One isolating solenoid valve (8) – the isolating solenoid valve isolates the rear brake fluid circuits from the brake
master cylinder which prevents the return of the brake fluid to the brake master cylinder during TCS operation.
• One rear priming valve (9) – allows brake fluid to be drawn from the brake master cylinder into the hydraulic pump
during TCS operation.
5B6 ABS-TCS – GEN III V8 Page 5B6–12
Page 5B6–12
Hydraulic Circuit Components
Figure 5B6 – 5
Legend
1 Hydraulic Modulator Assembly
2 Return Pump
3 Accumulator
4 Brake Calliper
5 Brake Master Cylinder
6 Inlet Valves
7 Outlet Valves
8 Isolating Solenoid Valve
9 Priming Solenoid Valve
A Normal (conventional) brake fluid pressure
B Stopped brake fluid pressure flow (solenoid valve closed)
C Pump generated brake fluid pressure flow
D Brake pedal applied
M Motor
5B6 ABS-TCS – GEN III V8 Page 5B6–13
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2.4 Wheel Speed Sensors
Wheel Speed Sensor Principles of Operation
The wheel speed sensor (1) in conjunction with a pulse ring
(2) generates an AC signal voltage where the amplitude and
frequency of the signal generated is proportional to the
wheel speed.
The following wheel speed sensor sine waves compares the
signal generated by the wheel speed sensor at high speed
and low speed:
• The continuous line (3) represents the voltage
generated by the wheel speed sensor versus time (t)
at high wheel speed.
• The dotted line (4) represents the voltage generated
by the wheel speed sensor versus time (t) at low wheel
speed.
Signals generated by the wheel speed sensor are
transmitted to the electronic control unit (ECU). The ECU
uses this signal voltage to determine the rotational speed of
each wheel. Figure 5B6 – 6
Front Wheel Speed Sensor
The front wheel speed sensors (1) are incorporated as part
of the front wheel hub assembly.
There is a specific right and left front wheel hub which
incorporates the wheel speed sensor and a 48 tooth magnet
impulse ring. The front wheel hub assembly is a sealed for
life unit.
The front wheel hub assembly part numbers are etched on
the outer surface (2) of the hub wheel flange.
If the front wheel hub assembly requires
replacement, the correct replacement part
must be installed. Otherwise, ABS-TCS
malfunction w ill occur.
Figure 5B6 – 7
5B6 ABS-TCS – GEN III V8 Page 5B6–14
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Rear Wheel Speed Sensor
The rear wheel speed sensors (1) is located in a bracket
which is part of the final drive rear cover.
The rear wheel speed sensor pulse ring (2) is part of the
final drive inner axle flanges and is not serviced separately.
Refer to Section 4B1 Rear Final Drive and Drive Shafts for
the final drive inner axle flange service procedures.
If the final drive inner axle flange requires
replacement, the correct replacement part
must be installed. Otherwise, ABS-TCS
malfunction w ill occur.
Figure 5B6 – 8
Testing Wheel Speed Sensor Using an Oscilloscope
Using an oscilloscope to display the output signal voltage of a suspected wheel speed sensor will enable the service
technician to graphically view a pulse ring related wheel speed sensor fault that may be difficult to detect otherwise.
A normal wheel speed sensor signal produces a sine
wave (1) with the height of the amplitude (A) and the width
of the frequency (B) proportional to the wheel speed.
If the pulse ring is out of round or if it is incorrectly aligned
with the wheel speed sensor, the air gap between the wheel
speed sensor and the pulse ring will vary as the wheel
rotates. This fault will produce a wheel speed sensor signal
with varying amplitude (2).
If the pulse ring teeth are missing or damaged, the
oscilloscope sine wave pattern will display flat spots (3) that
represent the missing or damaged pulse ring teeth.
Figure 5B6 – 9
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2.5 Stop Lamp Switch-A
The stop lamp switch A (1) is a normally open switch that
closes when the brake pedal is depressed.
The electronic control unit (ECU) uses the stop lamp switch
signal voltage to determine when the brake pedal is
depressed.
For stop lamp switch service operations, refer to
Section 12B Lighting System.
Figure 5B6 – 10
5B6 ABS-TCS – GEN III V8 Page 5B6–16
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2.6 Traction Control System Switch
The traction control system (TCS) switch (1) is located in the
floor console. It is a momentary contact switch that sends a
ground output signal to the powertrain interface module
(PIM).
The PIM converts this signal into GM LAN protocol and
sends a signal to the ECU via the serial data bus to perform
the following functions:
• Pressing the TCS switch once deactivates the TCS for
the duration of that ignition cycle. The antilock braking
system (ABS) will still function normally when the TCS
is deactivated.
• Pressing the TCS switch again when the TCS is
deactivates, activates the TCS.
• Pressing the TCS switch for more than 60 seconds will
be interpreted as a short circuit. Consequently, a
Powertrain interface module (PIM) DTC will be logged
and the TCS will be deactivates for the duration of that
ignition cycle.
If there are no current TCS DTC logged, the T CS resets to
enabled at the next ignition cycle. Refer to
Section 6E3 Powertrain Interface Module – GEN III V8 for
further information on the TCS switch.
Figure 5B6 – 11
5B6 ABS-TCS – GEN III V8 Page 5B6–17
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3 System Operation
3.1 Non-ABS Braking
Under normal braking and driving conditions, the antilock braking system (ABS) functions like a conventional braking
system. Refer to Section 5A Service and Park Braking System for further information on the conventional braking system.
Non-ABS Braking Operation
When the brakes are applied (D), the brake booster assists the brake master cylinder (1) in providing brake fluid pressure
(A) to the brake callipers (2) without any intervention from the hydraulic modulator (3). Refer to
Figure 5B6 – 12.
However, the electronic control unit (ECU) constantly monitors each wheel for wheel slip. When the ECU detects a wheel
slip, it switches to the appropriate mode. Refer to 3.2 Antilock Braking System.
Condition Description
At normal braking, all the valves in the hydraulic modulator are in their normal rest positions allowing for uninterrupted
flow of brake fluid from the master cylinder to the brake callipers. The hydraulic modulator provides conventional non-
ABS braking by allowing the brake fluid to flow between the brake master cylinder and the brake calliper in either
direction.
5B6 ABS-TCS – GEN III V8 Page 5B6–18
Page 5B6–18
Normal Braking Hydraulic Circuit
Figure 5B6 – 12
Legend
1 Brake Master Cylinder
2 Brake Calliper
3 Hydraulic Modulator Assembly
A Normal (conventional) brake fluid pressure
B Stopped brake fluid pressure flow (solenoid valve closed)
D Brake pedal applied
5B6 ABS-TCS – GEN III V8 Page 5B6–19
Page 5B6–19
3.2 Antilock Braking System
The antilock braking system (ABS) prevents wheel lock-up during hard or emergency braking by modulating the brake
fluid pressure applied to the appropriate wheels. The ABS cycles through the following phases when the electronic
control unit (ECU) detects the beginning of a wheel lock-up:
• maintaining pressure,
• reducing pressure, and
• increasing pressure.
NOTE
The following are conditions that may be
experienced when the ABS is active and are
considered normal:
• During ABS controlled braking, the braking
pressure of the affected wheel is automatically
adjusted to prevent wheel lock-up, regardless
of pressure applied to the brake pedal.
• A series of rapid pulsations are felt through
the brake pedal – these pulsations occur as
solenoid valves within the hydraulic modulator
change position to modulate the brake
hydraulic pressure.
• A ticking or popping noise in the hydraulic
modulator occurs as the hydraulic modulator
solenoid valves cycle rapidly to modulate the
hydraulic brake pressure.
• Intermittent chirping noises may be heard as
the tyres approach slipping on dry pavement.
• Electric motor and pump noise and rapid
brake pedal pulsation caused by the operation
of the hydraulic modulator pump during the
ABS reducing or increasing pressure phase or
the ECU self-test.
5B6 ABS-TCS – GEN III V8 Page 5B6–20
Page 5B6–20
ABS Phase – Maintaining Pressure
Condition Description
When the brakes are applied (A) and the ECU detects that a
wheel reaches a point (1) where it is beginning to lock-up,
the hydraulic modulator controls the brake fluid pressure of
the affected wheel to maintain its brake fluid pressure (B)
and prevent a wheel lock-up.
Figure 5B6 – 13
Control Action
NOTE
The following ABS situation assumes the rear left
wheel is beginning to lock-up. Refer to
Figure 5B6 – 14 for the illustration of the
ABS Phase Hydraulic Circuit – Maintaining
Pressure.
The ECU monitors and compares signals from each wheel speed sensor to determine wheel slip. If a wheel lock-up is
detected during braking, the ECU switches to the maintaining pressure phase and sends a control signal to the hydraulic
modulator (1) to close the rear left inlet valve (2).
With both the rear left inlet valve and outlet valve (3) closed, the rear left brake fluid circuit is isolated and the rear left
brake fluid pressure is kept constant (B) regardless of the brake fluid pressure (A) exerted by the brake pedal (D).
5B6 ABS-TCS – GEN III V8 Page 5B6–21
Page 5B6–21
ABS Phase Hydraulic Circuit – Maintaining Pressure
Figure 5B6 – 14
Legend
1 Hydraulic Modulator Assembly
2 Inlet Valve
3 Outlet Valve
A Normal (conventional) brake fluid pressure
B Stopped brake fluid pressure flow (solenoid valve closed)
D Brake pedal applied
5B6 ABS-TCS – GEN III V8 Page 5B6–22
Page 5B6–22
ABS Phase – Reducing Pressure
Condition Description
If the ECU detects the affected wheel is still locking-up while
the ABS is already in the maintaining pressure phase (B),
the ABS switches to reducing pressure phase (C) at a
predetermined point (1).
The hydraulic modulator modulates the brake fluid circuit of
the affected wheel to reduce its brake fluid pressure and
prevent wheel lock-up.
Figure 5B6 – 15
Control Action
NOTE
The following ABS situation assumes the rear left
wheel is still locking-up while the ABS is already
in maintaining pressure phase. Refer to
Figure 5B6 – 16 for the illustration of the
ABS Phase Hydraulic Circuit – Reducing
Pressure.
The ECU monitors and compares signals from each wheel speed sensor to determine wheel slip. If the rear left wheel
lock-up is still detected when the ABS is already in the maintaining pressure phase, the ECU switches to the ABS
reducing pressure phase. The ECU sends a control signal to the hydraulic modulator (1) to:
• Close rear left inlet valve (2).
• Open the rear left outlet valve (3).
• Operate the hydraulic modulator pump (4). The hydraulic modulator pump will remain operational for the duration of
the ABS phase.
This results in the following actions during the reducing pressure phase:
1 The rear left brake fluid is initially directed towards the accumulator (5) to guarantee instant pressure reduction
when the rear left outlet valve is opened.
2 The accumulator stores the excess rear left brake fluid.
3 The hydraulic modulator pump builds-up the rear left brake fluid return flow pressure that will allow the brake fluid
released from rear left brake calliper (6) to be returned back to the brake master cylinder (7) against brake pedal
pressure (D). Because the brake pedal is still being depressed during this phase, the released pressure from the
brake calliper has to be greater than the brake fluid pressure applied by the master cylinder.
5B6 ABS-TCS – GEN III V8 Page 5B6–23
Page 5B6–23
ABS Phase Hydraulic Circuit – Reducing Pressure
Figure 5B6 – 16
Legend
1 Hydraulic Modulator Assembly
2 Inlet Valve
3 Outlet Valve
4 Hydraulic Pump
5 Accumulator
6 Brake Calliper
7 Brake master cylinder
A Normal (conventional) brake fluid pressure
B Stopped brake fluid pressure flow (solenoid valve closed)
C Hydraulic modulator pump generated brake fluid pressure
flow
D Conventional brake pressure combined with released brake
fluid pressure
5B6 ABS-TCS – GEN III V8 Page 5B6–24
Page 5B6–24
ABS Phase – Increasing Pressure
Condition Description
If the reduction in the brake fluid pressure in the reducing
pressure phase (C) results in the pressure reaching a point
(1) where insufficient braking force is applied to the affected
wheel, the ECU determines the affected wheel is now under-
braked.
The ABS switches from reducing pressure phase to
increasing pressure phase (A). In this phase, the hydraulic
modulator modulates the affected wheel brake fluid circuit to
increase its brake fluid pressure, which increases braking
force and balances wheel speed during braking.
Figure 5B6 – 17
Control Action
NOTE
The following ABS situation assumes the rear left
wheel speed is under-braked as a result of the
reduced braking force applied during the ABS
reducing pressure phase. Refer to
Figure 5B6 – 18 for the illustration of the
ABS Phase Hydraulic Circuit – Increasing
Pressure.
The ECU monitors and compares signals from each wheel speed sensor to determine wheel slip. If the ECU detects the
rear left wheel speed is higher than the other three wheels as a result of the reduced braking force applied during the
reducing pressure phase, the ECU switches to the increasing pressure phase. The ECU sends a control signal to the
hydraulic modulator (1) to:
• Close (normal position) the rear left outlet valve (3).
• Open (normal position) the rear left inlet valve (2).
• Continue operation of the hydraulic modulator pump (4) for the duration of the ABS phase.
The master cylinder (5) brake fluid pressure (A) is again directed to the rear left brake calliper (6) as in normal brake
operation. The previously reduced rear left brake fluid pressure is now increased to reduce the rear left wheel speed.
These ABS phases are repeated until the ECU detects the wheel speeds are balanced or the brake pedal pressure
removed. There are approximately four to six control cycles per second depending on the road surface condition.
5B6 ABS-TCS – GEN III V8 Page 5B6–25
Page 5B6–25
ABS Phase Hydraulic Circuit – Increasing Pressure
Figure 5B6 – 18
Legend
1 Hydraulic Modulator Assembly
2 Inlet Valve
3 Outlet Valve
4 Hydraulic Pump Assembly
5 Brake Master Cylinder
6 Brake Calliper
A Normal (conventional) brake fluid pressure
B Stopped brake fluid pressure flow (solenoid valve closed)
C Hydraulic modulator pump generated brake fluid pressure
flow
D Brake pedal applied
5B6 ABS-TCS – GEN III V8 Page 5B6–26
Page 5B6–26
3.3 Electronic Brake-force Distribution
System
The electronic brake-force distribution (EBD) system is part of the ABS software programmed into the electronic control
unit (ECU). It is designed to replace the rear brake proportioning valve in reducing rear wheel slip during moderate
braking.
The EBD system utilises the existing ABS active controls to regulate the vehicle's rear brake fluid pressure. This enables
the EBD system to provide dynamic front to rear brake proportioning under various vehicle loads, driving manoeuvres, or
road conditions.
In some situations, when the EBD system is activated, a brake pedal height drop of approximately 10 mm will be
experienced when the driver varies the brake pedal pressure while performing brake stops. This is caused by the
hydraulic modulator performing an adjustment on the rear brake fluid pressure and is considered normal.
EBD System Keep Alive Function
The EBD system plays an important role in vehicle stability during braking. For this reason, the EBD system has a Keep
Alive Function integrated in its software. When the ECU detects a fault in the ABS, depending on the type of failure,
certain parts of the system are kept alive. This allows the EBD system to apply some rear wheel brake proportioning even
under certain ABS fault conditions.
EBD Phase – Maintaining Pressure
Condition Description
When the brakes are applied (A) and the ECU determines
the rear wheels reach a point (1) where their rotational
speed is decelerating faster than the front wheels, the
hydraulic modulator modulates the rear wheel brake fluid
pressure (B) to maintain the rear braking force and prevent
a wheel lock-up.
NOTE
The EBD system operation takes effect before
the increased slip rate required for an ABS brake
intervention.
Figure 5B6 – 19
Control Action
NOTE
The following EBD situation assumes the rear
wheels are beginning to slip. Refer to
Figure 5B6 – 20 for the illustration of the
EBD Phase Hydraulic Circuit – Maintaining
Pressure.
The ECU monitors and evaluates signals from each wheel speed sensor to determine wheel slip. When the ECU
determines the rear wheels are decelerating faster than the front wheels but the rate of deceleration doesn't reach a point
where it requires ABS intervention, the ECU switches to EBD maintaining pressure phase.
As a first step during the EBD maintaining pressure phase, the ECU sends a control signal to the hydraulic modulator (1)
to close the rear inlet valves (2) and isolate the rear brake fluid circuit from the brake master cylinder. This maintains the
rear brake fluid pressure regardless of the brake fluid pressure (A) exerted by the brake pedal (D).
5B6 ABS-TCS – GEN III V8 Page 5B6–27
Page 5B6–27
EBD Phase Hydraulic Circuit – Maintaining Pressure
Figure 5B6 – 20
Legend
1 Hydraulic Modulator Assembly
2 Rear Inlet Valve
A Normal (conventional) brake fluid pressure
B Stopped brake fluid pressure flow (solenoid valve closed)
D Brake pedal applied
5B6 ABS-TCS – GEN III V8 Page 5B6–28
Page 5B6–28
EBD Phase – Reducing Pressure
Condition Description
If maintaining the brake fluid pressure in the EBD system
maintaining pressure phase (B) did not prevent the rear
wheels from decelerating faster than the front wheels, the
EBD system switches from maintaining pressure phase to
reducing pressure phase (C) at a predetermined point (1).
The hydraulic modulator modulates the rear wheel brake
fluid circuits to reduce its brake fluid pressure and prevent
wheel lock-up.
NOTE
The EBD system operation takes effect before the increased
slip rate required for an ABS brake intervention. Figure 5B6 – 21
Control Action
NOTE
The following EBD system situation assumes the
rear wheels are still decelerating faster than the
front wheels while the EBD system is already in
maintaining pressure phase. Refer to
Figure 5B6 – 22 for the illustration of the
EBD Phase Hydraulic Circuit – Reducing
Pressure.
If the ECU detects the rear wheels are still decelerating faster than the front wheels while the EBD system is already in
maintaining pressure phase, the ECU switches to the reducing pressure phase. The ECU sends a control signal to the
hydraulic modulator (1) to:
• Close the rear inlet valves (2).
• Open the rear outlet valves (3).
This results in the following actions during the reducing pressure phase:
1 The rear brake fluid is directed towards the accumulator (4) to allow brake fluid pressure reduction.
2 The accumulator stores the excess rear brake fluid. It is capable of storing all the excess brake fluid during an EBD
system operation. However, if the accumulator has been filled to its limit and the ECU still determines the rear
wheels are decelerating faster than the front wheels, the ECU operates the hydraulic modulator pump (5) and
returns the excess brake fluid to the brake master cylinder (6).
5B6 ABS-TCS – GEN III V8 Page 5B6–29
Page 5B6–29
EBD Phase Hydraulic Circuit – Reducing Pressure
Figure 5B6 – 22
Legend
1 Hydraulic Modulator Assembly
2 Rear Inlet Valve
3 Rear Outlet Valve
4 Accumulator
5 Hydraulic Modulator Pump
6 Brake Master Cylinder
A Normal (conventional) brake fluid pressure
B Stopped brake fluid pressure flow (solenoid valve closed)
C Hydraulic modulator pump generated brake fluid pressure
flow
D Brake pedal applied
5B6 ABS-TCS – GEN III V8 Page 5B6–30
Page 5B6–30
EBD Phase – Increasing Pressure
Condition Description
If reducing the rear brake fluid pressure in the EBD reducing
pressure phase (C) causes the brake fluid pressure to drop
to a point (1) where the front and rear wheels are now
rotating at the same speed or almost at the same speed, the
EBD system switches from reducing pressure phase to
increasing pressure phase (A).
In this phase, the ECU sends a signal to the hydraulic
modulator to allow normal brake master cylinder pressure to
be applied to the rear wheels as in normal brake operation.
Figure 5B6 – 23
Control Action
NOTE
The following EBD system operation assumes the
front and rear wheels are now rotating at the
same speed or almost at the same speed, as a
result of the reduced braking force applied during
the EBD reducing pressure phase.
The ECU monitors and compares signals from each wheel speed sensor to determine wheel slip. If the ECU detects the
front and rear wheels are now rotating at the same speed or almost at the same speed as a result of the reduced braking
force applied during the EBD reducing pressure phase, the EBD system switches from reducing pressure phase to
increasing pressure phase.
The ECU sends a control signal to the hydraulic modulator to return the rear outlet valves and the rear inlet valves to their
normal rest position.
The master cylinder brake fluid pressure is directed to the rear brake callipers as in normal brake operation. The
previously reduced rear brake fluid pressure is now increased to normal brake master cylinder pressure and the front and
rear wheels brake fluid pressures are again equal. Refer to 3.1 Non-ABS Braking for information on normal brake
operation.
These EBD phases are repeated until the ECU detects the wheel speeds are balanced or the brake pedal pressure
removed. There are approximately four to six control cycles per second depending on the road surface condition.
5B6 ABS-TCS – GEN III V8 Page 5B6–31
Page 5B6–31
3.4 Traction Control System
The traction control system (TCS) utilises the active braking controls in the ABS and the engine torque reduction function
of the engine management system to prevent longitudinal wheel spin during vehicle acceleration. Refer to
Section 6C3-1 Engine Management – GEN III V8 – General Information for information on engine torque reduction.
TCS Mode – Engine Torque Reduction
NOTE
The following TCS situation assumes the rear left
wheel is beginning to slip. Refer to
Figure 5B6 – 24 for the illustration of the
TCS Mode Hydraulic Circuit – Brake Intervention.
The ECU monitors and compares signals from each wheel speed sensor to determine wheel slip. If the ECU detects a
longitudinal wheel spin due to a slippery road surface or excessive engine torque and the brakes are not applied, the
ECU switches to the TCS mode.
During TCS Mode, the ECU initially sends a serial data communication signal to the engine control module (ECM)
requesting engine torque reduction.
NOTE
Slight engine power loss may be experienced
when the TCS is active. This is caused by the
engine torque reduction functionality of the engine
management system.
If the rear left wheel spin is still detected while the ECM is already applying engine torque reduction, the ECU applies
brake intervention.
TCS Mode – Brake Intervention
The ECU monitors and compares signals from each wheel speed sensor to determine wheel slip. If the ECU detects the
rear left wheel still slips while the ECM is already applying engine torque reduction due to a slippery road surface or
excessive engine torque and the brakes are not applied, the ECU switches to the TCS brake intervention mode. During
this mode, the ECU sends a signal to the hydraulic modulator (1) to:
• close the isolating valve (2),
• open the prime valve (3),
• close the rear right inlet valve (4), and
• operate the hydraulic modulator pump (5).
This results in the following operations during the TCS Mode:
• The rear isolation valve is closed to isolate the rear brake fluid circuits from the master cylinder and prevent the
brake fluid returning to the brake master cylinder when the hydraulic pump builds-up the brake fluid pressure.
• The rear right inlet valve is closed to isolate the rear right wheel hydraulic circuit allowing the hydraulic modulator to
supply brake fluid pressure only to the rear left wheel.
• The rear priming valve is open to allow brake fluid to be drawn from the master cylinder into the hydraulic pump.
• The hydraulic pump applies brake fluid pressure (C) to the rear left brake calliper to stop it the rear left wheel from
spinning.
• The hydraulic modulator modulates the rear left inlet valve (4a) and rear left outlet valve (6) to assist in obtaining
maximum road surface traction in the same manner as ABS. The difference between ABS and TCS is that during
TCS mode, the brake fluid pressure is increased to reduce wheel spin. In contrast, during the ABS, the brake fluid
pressure is decreased to avoid wheel lock-up.
NOTE
If at any time during TCS mode the brakes are
manually applied, the brake switch sends a signal
to the ECU to exit the TCS brake intervention
mode and allow for manual braking.
5B6 ABS-TCS – GEN III V8 Page 5B6–32
Page 5B6–32
TCS Mode Hydraulic Circuit – Brake Intervention
Figure 5B6 – 24
Legend
1 Hydraulic Modulator Assembly
2 Isolating Valve
3 Prime Valve
4 Rear Right Inlet Valve
4a Rear Left Inlet Valve
5 Hydraulic Pump
6 Rear Left Outlet Valve
B Stopped brake fluid pressure flow (solenoid valve closed)
C Hydraulic modulator pump generated brake fluid pressure
flow
M Pump motor
5B6 ABS-TCS – GEN III V8 Page 5B6–33
Page 5B6–33
4 Wiring Diagram and Connector
Chart
4.1 Wiring Diagram
Figure 5B6 – 25
5B6 ABS-TCS – GEN III V8 Page 5B6–34
Page 5B6–34
4.2 Connector Chart
Figure 5B6 – 26
5B6 ABS-TCS – GEN III V8 Page 5B6–35
Page 5B6–35
4.3 Connector Information
Electronic Control Unit – A37
Figure 5B6 – 27
Pin Circuit No. Function
1 883 Rear Right Wheel Speed Sensor Low Ref
2 882 Rear Right Wheel Speed Sensor Signal
3 — Not Connected
4 833 Front Right Wheel Speed Sensor Low Ref
5 872 Front Right Wheel Speed Sensor Signal
6 873 Front Left Wheel Speed Sensor Low Ref
7 830 Front Left Wheel Speed Sensor Signal
8 885 Rear Left Wheel Speed Sensor Low Ref
9 884 Rear Left Wheel Speed Sensor Signal
10 — Not Connected
11 1061 UART Secondary Serial Data Circuit
12 799 ABS Diagnostic Enable
13 463 MMR
14 20 Stop Lamp Switch 12 V Signal
15 839 12 V Ignition Supply Voltage – Fuse 27
16 350 Relays, Valves, and Pump Motor Main Ground
17 542 12 V Uninterrupted Supply Voltage – Fuse 103
18 542 12 V Uninterrupted Supply Voltage – Fuse 103
19 150 ECU Ground
20 — Not Connected
21 — Not Connected
22 — Not Connected
23 — Not Connected
24 — Not Connected
25 — Not Connected
26 — Not Connected
27 464 MMI
28 1687 Spark Retard Control Signal
29 — Not Connected
30 121 Tachometer Signal
31 1571 TCS Switch Ground Signal
5B6 ABS-TCS – GEN III V8 Page 5B6–36
Page 5B6–36
Front and Rear Wheel Speed Sensor – B52L, B52R, B76L and B76R
Figure 5B6 – 28
Pin Circuit No. Function
A B52L – 830
B52R – 872
B76L – 884
B76R – 882
Wheel Speed Sensor Signal
B B52L – 873
B52R – 833
B76L – 885
B76R – 883
Wheel Speed Sensor Low Reference
5B6 ABS-TCS – GEN III V8 Page 5B6–37
Page 5B6–37
5 Diagnostics
5.1 Diagnostic General Descriptions
The ABS-TCS diagnostic procedure is organised in a logical structure that begins with the Diagnostic System Check. The
Diagnostic System Check directs the diagnostic procedure to the logical steps or appropriate diagnostic table required to
diagnose an ABS-TCS fault.
The diagnostic tables locate a faulty circuit or component through a logic based on the process of elimination.
Understanding and the correct use of the diagnostic tables is essential to reduce diagnostic time and to prevent
misdiagnosis.
However, the diagnostic information covered in this Section covers faults only in the ABS-TCS. If there are faults with the
conventional braking system such as the following, these faults must be corrected before attempting to rectify any
suspected ABS-TCS fault:
• brake noise.
• spongy brake pedal feel.
• brake pedal or vehicle vibration during normal brake application.
• brake pulling to one side.
• parking brake problem.
Refer to Section 5A Service and Park Braking System for the diagnosis and repair procedure of the conventional braking
system.
Diagnostic Trouble Code Tables
The diagnostic procedure is directed to the diagnostic trouble code (DTC) tables if there are DTCs currently stored in the
electronic control unit (ECU).
The diagnostic tables are designed to locate a faulty circuit or component through a logic based on the process of
elimination. These diagnostic tables are developed with the following assumptions:
• the vehicle functioned correctly at the time of assembly,
• there are no multiple faults, and
• the problem currently exists.
If there are multiple DTCs stored in the ECU, the diagnostic process must begin with the most likely DTC that may trigger
other DTCs. The following situation is an example of a DTC that may trigger other DTCs to set.
• If there is a battery supply voltage fault in the ECU, DTC C0800 Battery Voltage Out of Range may set.
• Insufficient battery supply voltage to an ABS-TCS component such as the hydraulic modulator pump motor
may cause incorrect hydraulic modulator operation. This fault will cause incorrect ABS-TCS operation and
may trigger DTC C0110 to also set.
• A battery supply voltage to the ECU that is too high may cause damage to other ABS-TCS components. If this
charging system fault is not rectified and an ABS-TCS component is replaced, premature failure of the
replacement component may occur.
Therefore, knowledge of the ABS-TCS and Tech 2 limitations are important to reduce diagnostic time and to prevent
misdiagnosis. Refer to 6.1 Basic Requirements.
5B6 ABS-TCS – GEN III V8 Page 5B6–38
Page 5B6–38
Diagnostic Trouble Codes
The ECU performs a self-test that detects and isolates ABS-TCS faults. When a fault is detected, the ECU will log a
diagnostic trouble code (DTC) that represents the fault detected. The DT Cs stored in the ECU may be accessed using
Tech 2. Refer to Section 0C Tech 2 for information on Tech 2.
Status of DTCs
The ECU designates the DTCs logged into a Current or History DTC.
Current DTCs
If the fault that triggers the DTC is present during the last ECU self-diagnostics, that DTC will be designated as a current
DTC.
History DTCs
If the fault that triggers the DTC is not present during the last ECU self-test, that DTC will be designated as a History
DTC.
Action Taken When a DTC Sets
• The ECU disables the ABS-TCS for the duration of the ignition cycle.
• One or all of the following warning indicators may activate:
• ABS-TCS warning indicator,
• ABS-TCS warning display,
• brake failure indicator, and/or
• Trac-off warning display.
Conditions for Clearing DTCs
• The current DTC moves into a history DTC when there is no DTC logged during the current ECU self-test.
• Use Tech 2 to clear the DTC.
5B6 ABS-TCS – GEN III V8 Page 5B6–39
Page 5B6–39
6 ABS-TCS Diagnostic Starting
Point
6.1 Basic Requirements
Basic Knowledge Required
A lack of basic understanding regarding
electronics, electrical wiring circuits and use
of electrical circuit testing tools when
performing the ABS-TCS diagnostic
procedures could result in incorrect
diagnostic results or damage to components.
A general understanding of basic electronics, electrical wiring circuits and the correct use of the basic ABS-TCS electrical
circuit testing tools is required to perform the diagnostic procedures detailed in this Section.
Refer to Section 12P Wiring Diagrams for information on electrical circuits.
In addition, a general understanding of the ABS-TCS and its component operation is essential to prevent misdiagnosis
and component damage.
Basic Diagnostic Tools Required
Use of incorrect electrical circuit diagnostic
tools when performing the ABS-TCS
diagnostic procedures could result in
incorrect diagnostic results or damage to
components.
The following electrical circuit testing tools are required to perform the diagnostic procedures detailed in this Section.
• Tech 2, refer to Section 0C Tech 2,
• test lamp, refer to Section 12P Wiring Diagrams,
• digital multimeter with 10 MΩ impedance, refer to Section 12P Wiring Diagrams.
• connector test adapter kit Tool No. J35616-A.
5B6 ABS-TCS – GEN III V8 Page 5B6–40
Page 5B6–40
6.2 Diagnostic Precautions
In addition to the safety and precautionary
measures listed in 9.1 Safety and
Precautionary Measures, the following
Diagnostic Precautions must be observed
when performing any ABS-TCS diagnostic
procedure.
• If there is a fault in the conventional braking system, rectify that fault before proceeding with the ABS-TCS
diagnostics.
• Use only the test equipment specified in the diagnostic tables: other test equipment may either give incorrect results
or may damage good components.
• The vehicle drive wheels must be chocked and the parking brake firmly applied while checking any system.
• Do not clear any DTCs unless instructed.
• The fault must be present when using the DTC Diagnostic Tables. Otherwise, misdiagnosis or replacement of good
parts may occur.
• Always use connector adaptors such as those contained in connector test adapter kit Tool No. J35616-A to prevent
connector terminal damage.
• Thorough inspection of the wiring circuits and connectors that are part of diagnostic procedure must be performed,
otherwise misdiagnosis may occur.
• Inspect the electrical circuitry or connector terminals that are suspected to be causing the complaint for the
following conditions:
• backed-out connector terminals,
• improper wiring connector mating,
• broken wiring connector locks,
• damaged connector terminals, and
• physical damage to the wiring harness.
• Before replacing a component, inspect its connector terminal for corrosion or deformation that may cause the fault.
• If Tech 2 was used for diagnosis, disconnect it from the DLC and switch the ignition off for at least 10 seconds
before road testing. This is necessary to reset the ECU as it is disabled during most Tech 2 diagnostic procedures.
• After completing the required diagnostic and repair operations, road test the vehicle to ensure correct ABS-TCS
operation.
5B6 ABS-TCS – GEN III V8 Page 5B6–41
Page 5B6–41
6.3 Preliminary Checks
The Preliminary Checks are an examination of easily accessible components that could cause problems with the ABS-
TCS. This visual and physical inspection procedure may quickly identify the fault and eliminate the need for additional
diagnosis.
• Is the fault specifically isolated to this system? If unsure, refer to Section 0D Vehicle Diagnostics.
• Refer to Service Techlines for relevant information regarding the fault.
• Ensure that only the recommended tyres and wheel size are fitted to the vehicle.
• Check the hydraulic modulator for external leaks.
• Check the ABS-TCS fuses.
• Check the ABS-TCS warning indicator fuse and stop lamp indicator fuse.
Refer to Section 12O Fuses, Relays and Wiring Harnesses.
• Ensure the battery is fully charged.
• Check the battery connections for corrosion or a loose terminal.
• Perform a visual and physical inspection of the following:
• ABS-TCS component wiring harness and terminals for proper connections, pinches or cuts.
• Wiring harness routing which may be positioned very close to a high voltage or high current device such as
the following:
• secondary ignition components,
• motors and generators, and
• aftermarket stereo amplifiers
NOTE
High voltage or high current devices may induce
electrical noise on a circuit, which can interfere
with normal circuit operation.
• ABS-TCS related components for poor mating of the connector halves or a terminal not fully seated in the
connector body.
• ABS-TCS components are sensitive to Electro-magnetic Interference (EMI). Check for incorrect aftermarket
theft deterrent devices, lights or mobile phone installations if an intermittent malfunction is suspected.
5B6 ABS-TCS – GEN III V8 Page 5B6–42
Page 5B6–42
6.4 Diagnostic System Check
Description
The diagnostic procedure is organised in a logical structure that begins with the Diagnostic System Check which directs
the technician to the logical steps necessary to diagnose an ABS-TCS fault.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
4 Tests the operation of Tech 2.
6 Tests the integrity of the GM LAN serial data communication circuit. A PIM DTC sets if the PIM detects a fault in the
communication circuit. A fault on the serial data communication circuit may trigger multiple DTCs on other sensors
and components.
Step Action Yes No
1 Have you read the Basic Requirements? Go to Step 2 Refer to 6.1 Basic
Requirements
2 Have you read the Diagnostic Precautions?
Go to Step 3
Refer to 6.2
Diagnostic
Precautions
3 Have you performed the Preliminary Checks? Go to Step 4 Refer to 6.3
Preliminary Checks
4 1 Switch off the ignition.
2 Connect Tech 2 to the Diagnostic Link Connector (DLC).
3 Switch on the ignition with the engine not running.
4 Press the Tech 2 power button on.
Does the Tech 2 screen illuminate and display Tech 2? Go to Step 5 Refer to Section 0C
Tech 2
5 Using Tech 2, attempt to communicate with the PIM.
Does the PIM fail to communicate?
Refer to Section
6E3 Powertrain
Interface Module –
GEN III V8 Go to Step 6
6 Using Tech 2, view and record DTCs set at the PIM.
Does DTC U1064, U2100, U2105, U2106, U2108, B1009, B1013,
B1014, B1000, B1019, B3057, B3924, P0633, P1611 or P1678 set in
the PIM?
Refer to Section
6E3 Powertrain
Interface Module –
GEN III V8 Go to Step 7
7 Using Tech 2, view and record any ABS-TCS DTCs.
Does Tech 2 display any DTC? Go to Step 8
Refer to 7.1
Intermittent Fault
Diagnostic Table
8 Does Tech 2 display multiple DTCs?
Go to Step 9
Go to the DTC
Table of the DTC
displayed. Refer to
8.1 DTC List
9 Refer to the DTC Table of the fault that is most likely to trigger multiple
DTCs. Refer to 5.1 Diagnostic General Descriptions for information
on multiple DTCs fault. — —
When all diagnosis and repairs are completed, check the system for correct operation.
5B6 ABS-TCS – GEN III V8 Page 5B6–43
Page 5B6–43
7 Intermittent Faults
7.1 Intermittent Fault Diagnostic Table
Description
A fault is intermittent if one of the following exists:
• the fault is not always present,
• the fault cannot be presently duplicated, and
• there is no Current DTC but a History DTC is stored.
Checks Actions
Preliminary • Perform the Preliminary Checks. Refer to 6.3 Preliminary Checks.
• Gather information from the customer regarding the conditions that trigger the
intermittent fault such as:
• At what vehicle speed range does the fault occur?
• Does the fault occur when operating aftermarket electrical equipment inside
the vehicle?
• Does the fault occur on rough roads or in wet road conditions?
• If a wheel speed sensor fault is present only during wet road conditions,
inspect the wheel speed sensor electrical circuit for signs of water intrusion.
If the DTC is not current, simulate the effect of a wet road condition by
performing the following:
1 Mix two teaspoons of salt with 35 ml water.
2 Spray the saltwater solution to the suspected area.
3 Road test the vehicle at various road conditions.
4 Accelerate the vehicle at speed greater than 40 km/h for at least 30
seconds.
5 If the suspected wheel speed sensor sets a current DTC, refer to the
appropriate DTC diagnostic table.
Tech 2 Tests The following are lists of Tech 2 diagnostic tests that may be used to diagnose
intermittent faults:
• Wriggle test the suspected ABS-TCS component wiring harness and connectors
while observing the Tech 2 operating parameters of the circuit being tested. If the
Tech 2 read-out fluctuates during this procedure, check the wiring harness circuit
for loose connection.
• Road test the vehicle in the conditions that triggers the intermittent fault while an
assistant observes the suspected Tech 2 operating parameter data.
• Capture and store data in the Snapshot mode when the fault occurs. The stored
data may be played back at a slower rate to aid in diagnostics. Refer to the Tech 2
User Instructions for more information on the Snapshot function.
• Operate suspected ABS-TCS components to test their operation using Tech 2
Output Control Data.
5B6 ABS-TCS – GEN III V8 Page 5B6–44
Page 5B6–44
Checks Actions
Warning Indicator The following conditions may cause an intermittent Warning Indicator fault with no DTC
listed.
• Electromagnetic interference (EMI) caused by a faulty relay.
• Incorrect installation of aftermarket electrical equipment such as the following:
• Mobile phones
• Theft deterrent alarms
• Lights
• Radio equipment
• Stereo amplifier
• Warning indicator circuit is intermittently shorted to ground.
• Electronic control unit (ECU) ground connections are loose.
Wheel Speed Sensors • 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 loose
components.
• With the aid of an assistant, monitor the Tech 2 wheel speed sensor data display
while test driving the vehicle. Check for any wheel speed sensor that displays
erratic speed range.
Additional Tests • Incorrect installation of aftermarket electrical equipment such as the following:
• Mobile phones
• Theft deterrent alarms
• Lights
• Radio equipment
• Stereo amplifier
• Electromagnetic interference (EMI) caused by a faulty relay. The fault is triggered
when the relay or solenoid is activated.
• Test the A/C compressor clutch and some relays that contain a clamping diode or
resistor.
• Test the generator for a faulty rectifier bridge that may allow the A/C noise into the
ECU electrical circuit
When all diagnosis and repairs are completed, check the system for correct operation.
5B6 ABS-TCS – GEN III V8 Page 5B6–45
Page 5B6–45
8 Diagnostic Trouble Codes
8.1 DTC List
DTC Description Diagnostic Table
DTC 21 Right Front Wheel Speed Sensor Incorrect Signal 8.2 DTC 21, 23, 25, 27, 31, 33, 35 or 37 –
Wheel Speed Sensor Circuit
DTC 23 Right Front Wheel Speed Sensor Short Circuit or Open
Circuit 8.2 DTC 21, 23, 25, 27, 31, 33, 35 or 37 –
Wheel Speed Sensor Circuit
DTC 25 Left Front Wheel Speed Sensor Incorrect Signal 8.2 DTC 21, 23, 25, 27, 31, 33, 35 or 37 –
Wheel Speed Sensor Circuit
DTC 27 Left Front Wheel Speed Sensor Short Circuit or Open
Circuit 8.2 DTC 21, 23, 25, 27, 31, 33, 35 or 37 –
Wheel Speed Sensor Circuit
DTC 28 Wheel Speed Frequency Error 8.3 DTC 28 – Wheel Speed Frequency Error
DTC 31 Right Rear Wheel Speed Sensor Incorrect Signal 8.2 DTC 21, 23, 25, 27, 31, 33, 35 or 37 –
Wheel Speed Sensor Circuit
DTC 33 Right Rear Wheel Speed Sensor Short Circuit or Open
Circuit 8.2 DTC 21, 23, 25, 27, 31, 33, 35 or 37 –
Wheel Speed Sensor Circuit
DTC 35 Left Rear Wheel Speed Sensor Incorrect Signal 8.2 DTC 21, 23, 25, 27, 31, 33, 35 or 37 –
Wheel Speed Sensor Circuit
DTC 37 Left Rear Wheel Speed Sensor Short Circuit or Open
Circuit 8.2 DTC 21, 23, 25, 27, 31, 33, 35 or 37 –
Wheel Speed Sensor Circuit
DTC 41 Right Front Hydraulic Modulator Inlet Solenoid Valve Circuit
Fault 8.4 DTC 41, 42, 45, 46, 55 or 56 – Hydraulic
Modulator Solenoid Valve Circuit
DTC 42 Right Front Hydraulic Modulator Outlet Solenoid Valve
Circuit Fault 8.4 DTC 41, 42, 45, 46, 55 or 56 – Hydraulic
Modulator Solenoid Valve Circuit
DTC 45 Left Front Hydraulic Modulator Inlet Solenoid Valve Circuit
Fault 8.4 DTC 41, 42, 45, 46, 55 or 56 – Hydraulic
Modulator Solenoid Valve Circuit
DTC 46 Left Front Hydraulic Modulator Inlet Solenoid Valve Circuit
Fault 8.4 DTC 41, 42, 45, 46, 55 or 56 – Hydraulic
Modulator Solenoid Valve Circuit
DTC 55 Rear Axle Hydraulic Modulator Inlet Solenoid Valve Fault 8.4 DTC 41, 42, 45, 46, 55 or 56 – Hydraulic
Modulator Solenoid Valve Circuit
DTC 56 Rear Axle Hydraulic Modulator Outlet Solenoid Valve Fault 8.4 DTC 41, 42, 45, 46, 55 or 56 – Hydraulic
Modulator Solenoid Valve Circuit
DTC 61 Hydraulic Modulator Pump Motor Circuit Fault 8.5 DTC 61 – Hydraulic Modulator Pump Motor
Circuit
DTC 63 ECU Internal Solenoid Valve Relay Circuit 8.6 DTC 63 – ECU Internal Solenoid Valve
Relay Circuit
DTC 67 Brake Switch Circuit 8.7 DTC 67 – Brake Switch Circuit
DTC 71 ECU Internal Fault 8.8 DTC 71 – ECU Internal Fault
DTC 85 Battery Voltage Too Low 8.9 DTC 85 – Battery Voltage
5B6 ABS-TCS – GEN III V8 Page 5B6–46
Page 5B6–46
8.2 DTC 21, 23, 25, 27, 31, 33, 35 or 37 –
Wheel Speed Sensor Circuit
DTC Description
This diagnostic procedure supports the following DTCs:
• DTC 21 – Right Front Wheel Speed Sensor Incorrect Signal.
• DTC 23 – Right Front Wheel Speed Sensor Short Circuit or Open Circuit.
• DTC 25 – Left Front Wheel Speed Sensor Incorrect Signal.
• DTC 27 – Left Front Wheel Speed Sensor Short Circuit or Open Circuit.
• DTC 31 – Right Rear Wheel Speed Sensor Incorrect Signal.
• DTC 33 – Right Rear Wheel Speed Sensor Short Circuit or Open Circuit.
• DTC 35 – Left Rear Wheel Speed Sensor Incorrect Signal.
• DTC 37 – Left Rear Wheel Speed Sensor Short Circuit or Open Circuit.
Circuit Description
The ECU supplies ground to the wheel speed sensor low reference circuit. The wheel speed sensor in conjunction with a
pulse ring generates an AC signal voltage. The amplitude and frequency of the signal generated is proportional to the
wheel speed.
The ECU monitors each wheel speed sensor signal circuit to determine the rotational speed of each wheel and calculate
wheel slip.
Refer to 4 Wiring Diagram and Connector Chart to aid in diagnosis.
Additional Information
• For intermittent fault conditions, Refer to 7.1 Intermittent Fault Diagnostic Table.
• High voltage or high current devices such as spark plugs and spark plug wires may induce electrical noise on the
front left wheel speed sensor circuit. This electrical noise can interfere with normal wheel speed sensor operation.
Ensure that the wheel speed sensor wiring harness is routed away from these high voltage or high current devices.
• Refer to 2.4 Wheel Speed Sensors for the following information:
• Wheel speed sensor description and operation,
• wheel speed sensor connector illustration and terminal assignment, and
• wheel speed sensor test procedure using an oscilloscope.
Conditions for Running the DTC
The ignition is switched on.
Conditions for Setting the DTC
If the ECU detects a short to voltage, short to ground, open circuit or erratic signal fault condition in the wheel speed
sensor signal circuit and/or wheel speed sensor low reference circuit.
Action Taken When the DTC Sets
Refer to 5.1 Diagnostic General Descriptions for information on action taken by the ECU when a DTC sets.
Conditions for Clearing the DTC
Refer to 5.1 Diagnostic General Descriptions for information on the conditions for clearing DTCs.
5B6 ABS-TCS – GEN III V8 Page 5B6–47
Page 5B6–47
Test Description
The following numbers refer to the step numbers in the diagnostic table:
2 Verifies that the fault condition that triggers the DTC currently exists.
3 Tests the front left wheel speed sensor internal circuitry.
4 Tests for a fault condition in the wheel speed sensor pulse ring.
5 Tests the front left wheel speed sensor output voltage capacity.
DTC 21, 23, 25, 27, 31, 33, 35 or 37 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2
Refer to
6.4 Diagnostic
System Check
2 1 Switch off the ignition for 10 seconds.
2 Road test the vehicle at speed above 40 km/h.
3 Using Tech 2, view DTCs.
Does DTC 21, 23, 25, 27, 31, 33, 35 or 37 fail this ignition cycle? Go to Step 3
Refer to Additional
Information in this
Section
3 1 Disconnect the appropriate wheel speed sensor connector.
2 Using a digital multimeter, measure the resistance across the
wheel speed sensor connector.
Does the multimeter display 1.3 – 1.8 kΩ @ 20°C? Go to Step 4 Go to Step 7
4 1 Raise the appropriate side of the vehicle and support on safety
stands. Refer to Section 0A General Information for location of
the jacking points.
2 Connect an oscilloscope to the wheel speed sensor connector
terminals.
3 Observe the wheel speed sensor output signal pattern while
spinning the appropriate wheel. Refer to 2.4 Wheel Speed
Sensors for information on testing a wheel speed sensor using
an oscilloscope.
NOTE
If an oscilloscope is not available, perform the following
visual inspection:
• Inspect the wheel speed sensor pulse ring for damaged
teeth.
• While rotating the wheel, check the wheel speed
sensor alignment to the pulse ring.
• Check the wheel speed sensor run-out.
• Check the wheel speed sensor or pulse ring for dirt or
other contaminants that may affect its operation.
Was any fault found and rectified? Go to Step 11 Go to Step 5
5 Using a digital multimeter, measure the AC signal voltage across the
front speed sensor connector while spinning the front left wheel.
Does the multimeter display greater than 100 mV? Go to Step 6 Go to Step 7
6 Test the wheel speed sensor signal circuit and low reference circuit for
a high resistance, open circuit, short to voltage, short to ground or
shorted together fault condition. Refer to Section 12P Wiring Diagrams
for information on electrical fault diagnosis.
Was any fault found and rectified? Go to Step 11 Go to Step 8
5B6 ABS-TCS – GEN III V8 Page 5B6–48
Page 5B6–48
Step Action Yes No
7 Inspect for shorted terminals or poor connections at the appropriate
wheel speed sensor wiring connector. Refer to Section 12P Wiring
Diagrams for information on electrical fault diagnosis.
Was any fault found and rectified? Go to Step 11 Go to Step 9
8 Inspect for shorted terminals or poor connections at the ECU wiring
connector. Refer to Section 12P Wiring Diagrams for information on
electrical fault diagnosis.
Was any fault found and rectified? Go to Step 11 Go to Step 10
9 Replace the faulty wheel speed sensor. Refer 8 Service Operations.
Was the repair completed? Go to Step 11 —
10 Replace the ECU. Refer to 9.3 Electronic Control Unit / Hydraulic
Modulator Assembly.
Was the repair completed? Go to Step 11 —
11 1 Using Tech 2, clear the DTCs.
2 Switch off the ignition for 10 seconds.
3 Operate the vehicle within the conditions for running DTCs 21,
23, 25, 27, 31, 33, 35 or 37.
Does any of the wheel speed sensor circuit DTCs fail this ignition
cycle? Go to Step 2 Go to Step 12
12 Using Tech 2, select the DTC display function.
Does Tech 2 display any DTCs?
Go to the
appropriate DTC
Table. System OK
When all diagnosis and repairs are completed, check the system for correct operation.
5B6 ABS-TCS – GEN III V8 Page 5B6–49
Page 5B6–49
8.3 DTC 28 – Wheel Speed Frequency Error
DTC Description
This diagnostic procedure supports DTC 28 – Wheel Speed Frequency Error.
Circuit Description
The ECU supplies ground to the wheel speed sensor low reference circuit. The wheel speed sensor in conjunction with a
pulse ring generates an AC signal voltage. The amplitude and frequency of the signal generated is proportional to the
wheel speed. The ECU monitors the wheel speed sensor signal voltage to determine the rotational speed of each wheel
and to calculate the vehicle reference speed.
Refer to 4 Wiring Diagram and Connector Chart to aid in diagnosis.
Additional Information
• For intermittent fault conditions, refer to 7.1 Intermittent Fault Diagnostic Table.
• Refer to 2.3 Hydraulic Modulator Assembly for the hydraulic modulator description and operation.
Conditions for Running the DTC
The ECU receives a wheel speed sensor output signal.
Conditions for Setting the DTC
If the ECU detects that there is a deviation of more than 6 km/h between a wheel speed and the vehicle speed and the
ECU cannot specifically identify which wheel speed sensor is causing the fault condition.
Once the ECU identifies the wheel speed sensor that triggers DTC 28, it will take the following actions:
• The ECU will set the DTC that represents the faulty wheel speed sensor.
• The ECU will designate DTC 28 as a history DTC.
Action Taken When the DTC Sets
Refer to 5.1 Diagnostic General Descriptions for information on action taken by the ECU when a DTC sets.
Conditions for Clearing the DTC
Refer to 5.1 Diagnostic General Descriptions for information on the conditions for clearing DTCs.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
2 Verifies that the fault condition that triggers this DTC currently exists.
3 Tests for specific wheel speed sensor fault condition.
6 Tests for a fault condition in the wheel speed sensor pulse ring.
5B6 ABS-TCS – GEN III V8 Page 5B6–50
Page 5B6–50
DTC 28 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2
Refer to
6.4 Diagnostic
System Check
2 1 Switch off the ignition for 10 seconds.
2 Road test the vehicle at speed above 40 km/h.
3 Using Tech 2, view the DTCs.
Does DTC 28 fail this ignition cycle? Go to Step 3
Refer to Additional
Information in this
Section
3 Does DTC 21, 23, 25, 27, 28, 31, 33, 35 or 37 also fail this ignition
cycle? Refer to 8.2 DTC
21, 23, 25, 27, 31,
33, 35 or 37 –
Wheel Speed
Sensor Circuit Go to Step 4
4 Inspect for incorrect tyre size, incorrect tyre pressure or other fault
condition that may cause false wheel speed reading.
Was any fault found and rectified? Go to Step 9 Go to Step 5
5 1 Raise the front and rear of the vehicle and support on safety
stands. Refer to Section 0A General Information for location of
the jacking points.
2 Inspect all wheel speed sensors, their pulse ring and wiring
harness for signs of physical damage or conditions that may
trigger intermittent fault. Refer to 7 Intermittent Faults.
Was any fault found and rectified? Go to Step 9 Go to Step 6
6 1 Connect an oscilloscope to the front left wheel speed sensor
connector terminals.
2 Spin the front left wheel.
3 Observe the wheel speed sensor output signal display. Refer to
2.4 Wheel Speed Sensors.
NOTE
If an oscilloscope is not available, perform the following
visual inspection:
1 Inspect the front left wheel speed sensor pulse ring for
damaged teeth
2 While rotating the front left wheel, check the wheel speed
sensor alignment to the pulse ring.
3 Check the front left wheel speed sensor run-out.
4 Check the front left wheel speed sensor or pulse ring for
dirt or other contaminants that may affect its operation.
5 Perform the visual inspection procedure to the remaining
wheel speed sensors.
4 Perform the testing procedure to the remaining wheel speed
sensors.
Was any fault found and rectified? Go to Step 9 Go to Step 7
5B6 ABS-TCS – GEN III V8 Page 5B6–51
Page 5B6–51
Step Action Yes No
7 Inspect for poor connections at the ECU wiring connector. Refer to
Section 12P Wiring Diagrams for information on electrical fault
diagnosis.
Go to Step 9 Go to Step 8
8 Replace the ECU. Refer to 9.3 Electronic Control Unit / Hydraulic
Modulator Assembly.
Was the repair completed? Go to Step 9 —
9 1 Using Tech 2, clear the DTCs.
2 Switch off the ignition for 10 seconds.
3 Operate the vehicle within the conditions for running DTC 28.
Does any of the wheel speed sensor signal output DTCs fail this
ignition? Go to Step 2 Go to Step 10
10 Using Tech 2, select the DTC display function.
Does Tech 2 display any DTCs?
Go to the
appropriate DTC
Table. System OK
When all diagnosis and repairs are completed, check the system for correct operation.
5B6 ABS-TCS – GEN III V8 Page 5B6–52
Page 5B6–52
8.4 DTC 41, 42, 45, 46, 55 or 56 – Hydraulic
Modulator Solenoid Valve Circuit
DTC Description
This diagnostic procedure supports the following DTCs:
• DTC 41 – Right Front Hydraulic Modulator Inlet Solenoid Valve Fault
• DTC 42 – Right Front Hydraulic Modulator Outlet Solenoid Valve Fault
• DTC 45 – Left Front Hydraulic Modulator Inlet Solenoid Valve Fault
• DTC 46 – Left Front Hydraulic Modulator Outlet Solenoid Valve Fault
• DTC 55 – Rear Axle Hydraulic Modulator Inlet Solenoid Valve Fault
• DTC 56 – Rear Axle Hydraulic Modulator Outlet Solenoid Valve Fault
Circuit Description
The ECU energises the solenoid valve relay when the ignition is switched on. When energised, the solenoid valve relay
applies battery voltage to the hydraulic modulator solenoid valve coils. The solenoid valve relay remains energised until
the ignition is switched off or the ABS is disabled.
The ECU controls the operation of each solenoid valve by applying ground to the solenoid valve coil control circuit to
modulate the brake fluid pressure of each brake circuit.
The ECU monitors the solenoid valve relay and the solenoid valves circuit for correct operation.
Refer to 4 Wiring Diagram and Connector Chart to aid in diagnosis.
Additional Information
• For intermittent fault conditions, refer to 7.1 Intermittent Fault Diagnostic Table.
• Refer to 2.3 Hydraulic Modulator Assembly for the hydraulic modulator description and operation.
Conditions for Running the DTC
Runs in conjunction with the ECU Self-test initialisation sequence.
Conditions for Setting the DTC
If the ECU detects a short to voltage, open circuit or invalid signal fault condition in any of Inlet and outlet solenoid valves.
Action Taken When the DTC Sets
Refer to 5.1 Diagnostic General Descriptions for information on action taken by the ECU when a DTC sets.
Conditions for Clearing the DTC
Refer to 5.1 Diagnostic General Descriptions for information on the conditions for clearing DTCs.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
2 Verifies that the fault condition that triggers the DTC currently exists.
3 Verify the integrity of the ECU internal circuitry. Internal fault within the ECU may trigger this fault code.
5B6 ABS-TCS – GEN III V8 Page 5B6–53
Page 5B6–53
DTC 41, 42, 45, 46, 55 or 56 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed? Go to Step 2 Refer to
6.4 Diagnostic
System Check
2 Using Tech 2, perform the hydraulic modulator pump motor test.
Does the hydraulic modulator pass the test? Go to Step 3 Go to Step 4
3 1 Switch off the ignition for 10 seconds.
2 Road test the vehicle at speed above 15 km/h.
3 Using Tech 2, view DTCs.
Does DTC 41, 42, 45, 46, 55 or 56 fail this ignition cycle? Go to Step 4
Refer to Additional
Information in this
Section
4 Is DTC 71 also set? Refer to 8.8 DTC
71 – ECU Internal
Fault Go to Step 5
5 1 Test all ground circuits of the ECU for a high resistance or an
open circuit fault condition. Refer to Section 12P Wiring
Diagrams for information on electrical fault diagnosis.
2 Test the ABS fuses and replace as required. Refer to Section
12O Fuses, Relays and Wiring Harnesses.
3 Test the ECU battery supply voltage circuit for a high resistance,
open circuit or short to ground fault condition. Refer to
Section 12P Wiring Diagrams for information on electrical fault
diagnosis.
Was any fault found and rectified? Go to Step 8 Go to Step 6
6 Inspect for poor connections at the ECU wiring connector. Refer to
Section 12P Wiring Diagrams for information on electrical fault
diagnosis.
Was any fault found and rectified? Go to Step 8 Go to Step 7
7 Replace the hydraulic modulator. Refer to 9.3 Electronic Control Unit /
Hydraulic Modulator Assembly.
Was the repair completed? Go to Step 8 —
8 1 Using Tech 2, clear the DTCs.
2 Switch off the ignition for 10 seconds.
3 Operate the vehicle within the conditions for running DTCs.
Does DTC 41, 42, 45, 46, 55 or 56 fail this ignition cycle? Go to Step 2 Go to Step 9
9 Using Tech 2, select the DTC display function.
Does Tech 2 display any DTCs?
Go to the
appropriate DTC
Table. System OK
When all diagnosis and repairs are completed, check the system for correct operation.
5B6 ABS-TCS – GEN III V8 Page 5B6–54
Page 5B6–54
8.5 DTC 61 – Hydraulic Modulator Pump
Motor Circuit
DTC Description
This diagnostic procedure supports DTC 61 – Hydraulic Modulator Pump Motor Circuit Fault.
Circuit Description
The ECU operates the hydraulic modulator pump motor by grounding the pump motor relay control circuit to build-up the
brake fluid pressure and allow the released brake fluid pressure from the slipping wheel to be returned to the brake
master cylinder reservoir against brake pedal pressure.
The ECU monitors the pump motor relay and the pump motor circuit for correct operation.
Refer to 4 Wiring Diagram and Connector Chart to aid in diagnosis.
Additional Information
• For intermittent fault conditions, refer to 7.1 Intermittent Fault Diagnostic Table.
• Refer to 2.3 Hydraulic Modulator Assembly for the hydraulic modulator description and operation.
Conditions for Running the DTC
Runs in conjunction with the ECU Self-test Initialisation Sequence.
Conditions for Setting the DTC
• If the pump motor relay is activated and there is no pump motor system voltage present after 60 milliseconds.
• If the pump motor system voltage is present for more than 2.5 seconds and the pump motor relay did not activate.
• If there is no pump motor run down voltage after the pump motor relay is deactivated.
Action Taken When the DTC Sets
Refer to 7.1 Intermittent Fault Diagnostic Table for information on action taken by the ECU when a DTC sets.
Conditions for Clearing the DTC
Refer to 7.1 Intermittent Fault Diagnostic Table for information on the conditions for clearing DTCs.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
2 Verifies that the fault condition that triggers the DTC currently exists.
3 Verify the integrity of the ECU internal circuitry. Internal fault within the ECU may trigger this fault code.
5B6 ABS-TCS – GEN III V8 Page 5B6–55
Page 5B6–55
DTC 61 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed? Go to Step 2 Refer to
6.4 Diagnostic
System Check
2 Using Tech 2, perform the hydraulic modulator pump motor test.
Does the pump motor pass the test? Go to Step 3 Go to Step 4
3 1 Switch off the ignition for 10 seconds.
2 Operate the vehicle within the conditions for running these DTCs
or road test the vehicle at speed above 15 km/h.
3 Using Tech 2, view DTCs.
Does DTC 61 fail this ignition cycle? Go to Step 4
Refer to Additional
Information in this
Section
4 Is DTC 85 also set? Refer to 8.9 DTC
85 – Battery Voltage Go to Step 5
5 Is DTC 71 also set? Refer to 8.8 DTC
71 – ECU Internal
Fault Go to Step 6
6 1 Test all ground circuits of the ECU for a high resistance or an
open circuit fault condition. Refer to Section 12P Wiring
Diagrams for information on electrical fault diagnosis.
2 Test the ABS fuses and replace as required. Refer to Section
12O Fuses, Relays and Wiring Harnesses.
3 Test the ECU battery supply voltage circuit for a high resistance,
open circuit or short to ground fault condition. Refer to
Section 12P Wiring Diagrams for information on electrical fault
diagnosis.
Was any fault found and rectified? Go to Step 9 Go to Step 7
7 Inspect for poor connections at the pump motor to ECU wiring
connector. Refer to Section 12P Wiring Diagrams for information on
electrical fault diagnosis.
Was any fault found and rectified? Go to Step 9 Go to Step 8
8 Replace the hydraulic modulator. Refer to 9.3 Electronic Control Unit /
Hydraulic Modulator Assembly.
Was the repair completed? Go to Step 9 —
9 1 Using Tech 2, clear the DTCs.
2 Switch off the ignition for 10 seconds.
3 Operate the vehicle within the conditions for running DTC 61.
Does DTC 61 fail this ignition cycle? Go to Step 2 Go to Step 10
10 Using Tech 2, select the DTC display function.
Does Tech 2 display any DTCs?
Go to the
appropriate DTC
Table System OK
When all diagnosis and repairs are completed, check the system for correct operation.
5B6 ABS-TCS – GEN III V8 Page 5B6–56
Page 5B6–56
8.6 DTC 63 – ECU Internal Solenoid Valve
Relay Circuit
DTC Description
This diagnostic procedure supports DTC 63 – Electronic Control Unit Internal Solenoid Valve Relay Fault
Circuit Description
The ECU energises the solenoid valve relay when the ignition is switched on. When energised, the solenoid valve relay
applies battery voltage to the hydraulic modulator solenoid valve coils. The solenoid valve relay remains energised until
the ignition is switched off or the ABS is disabled.
The ECU controls the operation of each solenoid valve by applying ground to the solenoid valve coil control circuit to
modulate the brake fluid pressure of each brake circuit.
The ECU monitors the solenoid valve relay and the solenoid valves circuit for correct operation.
Refer to 4 Wiring Diagram and Connector Chart to aid in diagnosis.
Additional Information
• For intermittent fault conditions, refer to 7.1 Intermittent Fault Diagnostic Table.
• Refer to 2.3 Hydraulic Modulator Assembly for the hydraulic modulator description and operation.
Conditions for Running the DTC
The ignition is switched on.
Conditions for Setting the DTC
If the ECU detects a short to voltage, short to ground, low voltage, invalid signal or incorrect valve relay operation.
Action Taken When the DTC Sets
Refer to 5.1 Diagnostic General Descriptions for information on action taken by the ECU when a DTC sets.
Conditions for Clearing the DTC
Refer to 5.1 Diagnostic General Descriptions for information on the conditions for clearing DTCs.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
2 Verifies that the fault condition that triggers the DTC currently exists.
3 Verifies the condition of the battery supply voltage. Incorrect battery voltage may trigger this DTC
5B6 ABS-TCS – GEN III V8 Page 5B6–57
Page 5B6–57
DTC 63 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2
Refer to
6.4 Diagnostic
System Check
2 Using Tech 2, perform the hydraulic modulator solenoid valve test.
Does the hydraulic modulator pass the test? Go to Step 3 Go to Step 4
3 1 Switch off the ignition for 10 seconds.
2 Road test the vehicle at speed above 15 km/h.
3 Using Tech 2, view DTCs.
Does DTC 63 fail this ignition cycle? Go to Step 4
Refer to Additional
Information in this
Section
4 Is DTC 85 also set? Refer to 8.9 DTC
85 – Battery Voltage Go to Step 5
5 1 Test all ground circuits of the ECU for a high resistance or an
open circuit fault condition. Refer to Section 12P Wiring
Diagrams for information on electrical fault diagnosis.
2 Test the ABS fuses and replace as required. Refer to Section
12O Fuses, Relays and Wiring Harnesses.
3 Test the ECU battery supply voltage circuit for a high resistance,
open circuit or short to ground fault condition. Refer to Section
12P Wiring Diagrams for information on electrical fault diagnosis.
Was any fault found and rectified? Go to Step 7 Go to Step 6
6 Replace the ECU and Hydraulic Modulator Assembly. Refer to
9.3 Electronic Control Unit / Hydraulic Modulator Assembly.
Was the repair completed? Go to Step 7 —
7 1 Using Tech 2, clear the DTCs.
2 Switch off the ignition for 10 seconds.
3 Operate the vehicle within the conditions for setting DTC 63.
Does DTC 63 fail this ignition cycle? Go to Step 2 Go to Step 8
8 Using Tech 2, select the DTC display function.
Does Tech 2 display any DTCs?
Go to the
appropriate DTC
Table System OK
When all diagnosis and repairs are completed, check the system for correct operation.
5B6 ABS-TCS – GEN III V8 Page 5B6–58
Page 5B6–58
8.7 DTC 67 – Brake Switch Circuit
DTC Description
This diagnostic procedure supports DTC 67 – Brake Switch Circuit Malfunction.
Circuit Description
The stop lamp switch is a normally open switch that closes when the brake pedal is depressed. When the brake pedal is
depressed, the stop lamp switch supplies signal voltage to the stop lamp signal circuit.
The ECU monitors the brake switch signal voltage to determine when the brake is applied and to check stop lamp circuit.
Refer to 4 Wiring Diagram and Connector Chart to aid in diagnosis.
Additional Information
• For intermittent fault conditions, refer to 7.1 Intermittent Fault Diagnostic Table.
• Refer to Section 12B Lighting System for the following information:
• Stop lamp switch description and operation, and
• stop lamp switch connector illustration and terminal assignment.
Conditions for Running the DTC
The ignition is switched on.
Conditions for Setting the DTC
An open or high resistance condition in the following circuit:
• Stop lamp switch signal circuit,
• stop lamp ground circuit, or
• stop lamp.
Action Taken When the DTC Sets
• The ECU stores this information only for as long as the condition is present.
• The ABS remains functional.
Conditions for Clearing the DTC
Refer to 5.1 Diagnostic General Descriptions for information on the conditions for clearing DTCs.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
2 Tests the stop lamp circuit.
5B6 ABS-TCS – GEN III V8 Page 5B6–59
Page 5B6–59
DTC 67 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2
Refer to
6.4 Diagnostic
System Check
2 1 Check the stop lamps for correct operation.
2 If required, test the stop lamp circuit and the stop lamp switch for
correct adjustment. Refer to Section 12B Lighting System for
further information on the stop lamp switch adjustment.
Was any fault found and rectified? Go to Step 8 Go to Step 3
3 1 Using Tech 2, view the brake switch status parameter in the ABS
data list.
2 While observing the brake switch status parameter, depress the
brake pedal.
Does the brake switch status parameter display Applied? Go to Step 4 Go to Step 5
4 1 Switch off the ignition for 10 seconds.
2 Operate the vehicle within the conditions for setting DTC C0161.
3 Using Tech 2, select the DTC display function.
Does DTC 67 fail this ignition cycle? Go to Step 5
Refer to Additional
Information in this
Section
5 Test the stop lamp switch signal circuit for a high resistance, open
circuit or short to ground condition. Refer to Section 12P Wiring
Diagrams for information on electrical fault diagnosis
Was any fault found and rectified? Go to Step 8 Go to Step 6
6 Inspect for poor connections at the ECU wiring connector. Refer to
Section 12P Wiring Diagrams for information on electrical fault
diagnosis.
Was any fault found and rectified? Go to Step 8 Go to Step 7
7 Replace the ECU. Refer to 9.3 Electronic Control Unit / Hydraulic
Modulator Assembly.
Was the repair completed? Go to Step 8 —
8 1 Using Tech 2, clear the DTCs.
2 Switch off the ignition for 10 seconds.
3 Operate the vehicle within the conditions for running DTC 67.
Does DTC 67 fail this ignition? Go to Step 2 Go to Step 9
9 Using Tech 2, select the DTC display function.
Does Tech 2 display any DTCs?
Go to the
appropriate DTC
Table System OK
When all diagnosis and repairs are completed, check the system for correct operation.
5B6 ABS-TCS – GEN III V8 Page 5B6–60
Page 5B6–60
8.8 DTC 71 – ECU Internal Fault
DTC Description
This diagnostic procedure supports DTC 71 – Internal ECU Fault Condition.
Circuit Description
The Electronic Control Unit (ECU) is the control centre is the ABS. The programming and calibration needed by the ECM
to control the operation of the ABS are stored in the ECU Read Only Memory (ROM). The ECU constantly performs a
self-test that detects and isolates ABS faults.
Refer to 4 Wiring Diagram and Connector Chart to aid in diagnosis.
Additional Information
• For intermittent fault conditions, refer to 7.1 Intermittent Fault Diagnostic Table.
Conditions for Running the DTC
The ignition is switched on.
Conditions for Setting the DTC
If an internal ECU system fault exists.
Action Taken When the DTC Sets
Refer to 5.1 Diagnostic General Descriptions for information on action taken by the ECU when a DTC sets.
Conditions for Clearing the DTC
Refer to 5.1 Diagnostic General Descriptions for information on the conditions for clearing DTCs.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
2 Verifies that the fault condition that triggers this DTC currently exists.
3 Verifies the condition of the battery supply voltage. Incorrect battery voltage may trigger this DTC
4 Ensures that there is no fault in the ABS fuses. A blown ABS fuse may trigger this DTC.
5B6 ABS-TCS – GEN III V8 Page 5B6–61
Page 5B6–61
DTC 71 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2
Refer to
6.4 Diagnostic
System Check
2 1 Switch off the ignition for 10 seconds.
2 Road test the vehicle at speed above 15 km/h.
3 Using Tech 2, view the DTCs.
Does DTC 71 fail this ignition cycle? Go to Step 3
Refer to Additional
Information in this
Section
3 Is DTC 85 also set? Refer to 8.9 DTC
85 – Battery Voltage Go to Step 4
4 1 Test all ground circuits of the ECU for a high resistance or an
open circuit fault condition. Refer to Section 12P Wiring
Diagrams for information on electrical fault diagnosis.
2 Test the ABS fuses and replace as required. Refer to Section
12O Fuses, Relays and Wiring Harnesses.
3 Test the ECU battery supply voltage circuit for a high resistance,
open circuit or short to ground fault condition. Refer to Section
12P Wiring Diagrams for information on electrical fault diagnosis.
Was any fault found and rectified? Go to Step 6 Go to Step 5
5 Replace the ECU. Refer to 9.3 Electronic Control Unit / Hydraulic
Modulator Assembly.
Was the repair completed? Go to Step 6 —
6 1 Using Tech 2, clear the DTCs.
2 Switch off the ignition for 10 seconds.
3 Operate the vehicle within the conditions for running DTC 71.
Does DTC 71 fail this ignition cycle? Go to Step 2 Go to Step 7
7 Using Tech 2, select the DTC display function.
Does Tech 2 display any DTCs?
Go to the
appropriate DTC
Table System OK
When all diagnosis and repairs are completed, check the system for correct operation.
5B6 ABS-TCS – GEN III V8 Page 5B6–62
Page 5B6–62
8.9 DTC 85 – Battery Voltage Out of Range
DTC Description
This diagnostic procedure supports DTC 85 – Battery Voltage Out of Range.
Circuit Description
The ECU monitors the battery supply voltage available to the ECU. If the voltage available to the ECU is out of the
specified range, the following fault condition may occur:
• A low battery supply voltage to the ECU may cause incorrect ABS operation.
• A battery supply voltage to the ECU that is too high may cause damage to the ABS components.
Refer to 4 Wiring Diagram and Connector Chart to aid in diagnosis.
Additional Information
• For intermittent fault conditions, refer to 7.1 Intermittent Fault Diagnostic Table.
• Thorough inspection of the battery and the charging system must be performed.
Refer to Section 6D3-1 Charging System – GEN III V8 and Section 12A Battery.
• An electrical fault condition in the shared electrical circuits may trigger DTCs on the components or sensors that
shares in the faulty shared circuit. Test the electrical circuit of the appropriate sensors or components to isolate the
fault condition.
Conditions for Running the DTC
The ignition is switched on.
Conditions for Setting the DTC
DTC 85 sets if ECU battery supply voltage meets one of the following conditions while the vehicle speed is above 6 km/h:
• If the ECU battery supply voltage drops below 9.4 volts and the ABS is not active, or
• if the ECU battery supply voltage drops below 8.8 volts and the ABS is active.
Action Taken When the DTC Sets
Refer to 5.1 Diagnostic General Descriptions for information on action taken by the ECU when a DTC sets.
Conditions for Clearing the DTC
Refer to 5.1 Diagnostic General Descriptions for information on the conditions for clearing DTCs.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
2 Verifies if a fault exists in the battery or charging system.
3 Verifies that the fault condition that triggers this DTC currently exists.
5B6 ABS-TCS – GEN III V8 Page 5B6–63
Page 5B6–63
DTC 85 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2
Refer to
6.4 Diagnostic
System Check
2 Test the charging system and the battery. Refer to Section 6D3-1
Charging System – GEN III V8 and Section 12A Battery.
Was any fault found and rectified? Go to Step 10 Go to Step 3
3 1 Switch off the ignition for 10 seconds.
2 Road test the vehicle at speed above 15 km/h.
3 Using Tech 2, view the DTCs.
Does DTC 85 fail this ignition cycle? Go to Step 4
Refer to Additional
Information in this
Section
4 Test the ABS fuses and replace as required. Refer to Section 12O
Fuses, Relays and Wiring Harnesses.
Was any fault found and rectified? Go to Step 10 Go to Step 5
5 Test the ECU 12 volts ignition circuit for a high resistance, open circuit
or short to ground fault condition. Refer to Section 12P Wiring
Diagrams for information on electrical fault diagnosis.
NOTE
The ECU shares the 12 volts ignition circuit with the
steering angle sensor and the yaw-rate sensor. A fault
condition in the 12 volts ignition circuit may trigger DTCs
on components that share this circuit.
Was any fault found and rectified? Go to Step 10 Go to Step 6
6 Test the ECU Battery 1 and Battery 2 supply voltage circuit for a high
resistance, open circuit or short to ground fault condition. Refer to
Section 12P Wiring Diagrams for information on electrical fault
diagnosis.
Was any fault found and rectified? Go to Step 10 Go to Step 7
7 Test all ground circuits of the ECU for a high resistance or an open
circuit fault condition. Refer to Section 12P Wiring Diagrams for
information on electrical fault diagnosis.
Was any fault found and rectified? Go to Step 10 Go to Step 8
8 Inspect for shorted terminals or poor connections at the ECU wiring
connector. Refer to Section 12P Wiring Diagrams for information on
electrical fault diagnosis.
Was any fault found and rectified? Go to Step 10 Go to Step 9
9 Replace the ECU. Refer to 9.3 Electronic Control Unit / Hydraulic
Modulator Assembly.
Was the repair completed? Go to Step 10 —
10 1 Using Tech 2, clear the DTCs.
2 Switch off the ignition for 10 seconds.
3 Operate the vehicle within the conditions for running DTC 85.
Does DTC 85 fail this ignition cycle? Go to Step 2 Go to Step 11
11 Using Tech 2, select the DTC display function.
Does Tech 2 display any DTCs?
Go to the
appropriate DTC
Table System OK
When all diagnosis and repairs are completed, check the system for correct operation.
5B6 ABS-TCS – GEN III V8 Page 5B6–64
Page 5B6–64
9 Service Operations
9.1 Safety and Precautionary Measures
The following safety and precautionary
measures must be followed when servicing
and diagnosing the ABS-TCS, otherwise,
personal injury and/or improper braking
system operation may occur.
• If any ABS-TCS component is serviced, the complete ABS-TCS must be checked.
Refer to 6.4 Diagnostic System Check.
• Certain components in the ABS-TCS are not intended to be serviced individually and must be replaced as an
assembly. Attempting to service components, such as the solenoid valves or pump motor in the hydraulic
modulator, may result in improper system operation and/or personal injury.
• If the brake hydraulic system is serviced, the brake system must be bled and all brake hydraulic fittings must be
tested for leakage. Refer to Section 5A Service and Park Braking System.
• Whenever welding with electric welding equipment, disconnect the wiring harness connector from the electronic
control unit (ECU).
• Never disconnect or reconnect the ECU wiring harness connector when the battery is connected or the ignition is
switched on.
• Do not touch the ECU connector pins or soldered components on the ECU circuit board to prevent possible
Electrostatic Discharge damage.
• When pressure washing engines, do not direct the cleaning nozzle at ABS-TCS components.
• To avoid wiring connector terminal damage, always use suitable wiring harness test leads (such as those in Tool
No, J39700) when carrying test operation on the ECU or sensor wiring connector.
• As the ABS-TCS components are extremely sensitive to electromagnetic interference (EMI), ensure the ABS-TCS
wiring harnesses are routed correctly and securely fitted on their mounting clips when performing service
procedures.
• Due to the sensitive nature of the ABS-TCS circuitry, specific wiring repair procedures have been developed. These
procedures and instructions are detailed in Section 12P Wiring Diagrams and are the only recommended and
approved wiring repair methods.
• Ensure the brake lines and the wheel speed sensor wiring harness connections are assigned correctly.
• The ECU is calibrated to use tyres of a known rolling radius and pulse rings with a specific number of teeth. The
number of teeth on the pulse rings correspond directly to tyre size. If any of the tyres fitted to the vehicle are larger
or smaller than specified, the ECU will receive false wheel speed signals that could result in personal injury and/or
improper ABS-TCS operation.
• Do not allow the suspension components to hang by the wheel speed sensor cables.
• Ensure that all wiring harness connectors are seated correctly.
• Never disconnect the battery from the vehicle electrical system while the engine is running.
• Always disconnect the battery from the vehicle electrical system before charging.
• Do not use a fast charger for starting the vehicle.
• Ensure the battery cable terminals are secure.
• The ECU and the hydraulic modulator must never be disassembled. Repair of either of these two units is by
replacement only. Apart from the brake line connections and the screws securing the ECU to the hydraulic
modulator, no screws at the hydraulic modulator may be loosened. Once any screw is loosened, brake fluid leakage
from the hydraulic modulator may occur.
5B6 ABS-TCS – GEN III V8 Page 5B6–65
Page 5B6–65
• Replacement hydraulic modulator assemblies are pre-filled with brake fluid. To avoid unnecessary fluid spillage, do
not remove the sealing plugs from hydraulic modulator ports until the brake fittings are ready for fitment.
• Once a replacement hydraulic modulator has been fitted, the sealing plugs must be fitted to the original modulator
to prevent entry of dirt.
• To prevent entry of dirt into the hydraulic modulator ports, ensure the hydraulic modulator is clean before
disconnecting or reconnecting its brake pipe fittings.
• Remove the ECU from its packaging only when it is ready to be fitted to the hydraulic modulator.
• Before installing a new ECU or hydraulic modulator, ensure the correct type is fitted. Always refer to the latest spare
parts information.
• Even the slightest trace of mineral oil leads to failure of the brake system. If mineral oil is found in the brake system
or there is a suspicion of mineral oil being in the brake system, the complete brake system must be thoroughly
flushed with the correct type of brake fluid. In addition, the brake master cylinder must be replaced.
• Do not allow brake fluid to come in contact with the vehicle paintwork as the brake fluid causes paint damage.
• Store the brake fluid in well-sealed containers as the brake fluid absorbs moisture from the air thus reducing its
boiling point. If the brakes are subjected to a very severe loading, this can lead to vapour-bubble formation in the
brake system which may lead to brake failure.
In addition, the brake fluid absorbs moisture from the atmosphere as it is operated in the vehicle. Therefore, the
brake fluid must be replaced at the time or distance intervals as specified.
Refer to Section 0B Lubrication and Service.
• Only use the specified brake fluid.
• Do not remove the ECU seal as it is not available as a spare part.
5B6 ABS-TCS – GEN III V8 Page 5B6–66
Page 5B6–66
9.2 ABS-TCS Brake Bleeding Procedure
NOTE
The conventional brake system bleeding
procedure must be completed before performing
the ABS-TCS brake bleeding procedure. Refer to
Section 5A Service and Park Braking System.
1 Connect Tech 2 to the vehicle. Refer to Section 0C Tech 2 for information on the use of Tech 2.
2 Start the engine and allow to run at idle speed.
3 Perform the instructions listed in the Tech 2 Brake Bleed Procedure.
NOTE
Ensure the brake fluid level in the brake master
cylinder doesn't drop below the minimum level
during the duration of this procedure.
4 Turn the ignition switch off.
5 Disconnect Tech 2 from the DLC.
6 Fill the brake master cylinder reservoir to the maximum fill level with the specified brake fluid.
7 Perform another conventional braking system brake bleeding procedure.
Refer to Section 5A Service and Park Braking System.
8 With the ignition switched off, depress the brake pedal three to five times to deplete the brake booster vacuum
reserve.
9 Slowly depress the brake pedal. If the brake pedal feels spongy, repeat the ABS-TCS brake bleeding procedure.
10 If the brake pedal still feels spongy after repeating the ABS-TCS bleeding procedure, inspect the brake system for
external or internal leakage. Refer to Section 5A Service and Park Braking System.
If the brake fail indicator (1) remains
illuminated after a service procedure, do not
drive the vehicle until the fault is diagnosed
and repaired.
11 Turn the ignition switch on with the engine not running
and the park brake not applied. If the park brake /
brake fail indicator remains illuminated, diagnose and
repair the fault. Refer to
Section 5A Service and Park Braking System.
12 Road test the vehicle to allow ABS-TCS self test
initialisation to occur. If the brake pedal feels spongy,
repeat the ABS-TCS brake bleed procedure until a firm
brake pedal feel is obtained.
13 Check the ABS-TCS operation. Refer to
6.4 Diagnostic System Check.
Figure 5B6 – 29
5B6 ABS-TCS – GEN III V8 Page 5B6–67
Page 5B6–67
9.3 Electronic Control Unit / Hydraulic Modulator
Assembly
LT Section No. — 04–730
Remove
Disconnection of the battery affects certain
vehicle electronic systems. Refer to
Section 00 Warnings, Caution and Notes
before disconnecting the battery.
1 Disconnect the battery negative terminal.
2 Retract the release bar (1) to disengage the wiring
connector (2) from the electronic control unit (ECU)
(3).
3 Disconnect the wiring connector from the ECU and lay
aside with the connector pins side facing downwards.
4 Place shop rags around and beneath the hydraulic
modulator (4).
Immediately seal off the brake pipes and the
hydraulic modulator with dummy plugs to
prevent the loss of brake fluid and entry of
dirt.
5 Loosen and disconnect the hydraulic modulator brake
pipe fittings (5).
6 Carefully reposition the pipes away from the hydraulic
modulator ports. Do not to damage or kink the brake
pipes in any way.
Figure 5B6 – 30
7 Remove the nut (6), two places, securing the ECU / hydraulic modulator assembly to the mounting bracket (7).
8 Remove the ECU / hydraulic modulator assembly from the vehicle.
5B6 ABS-TCS – GEN III V8 Page 5B6–68
Page 5B6–68
Disassemble
If diagnosis indicates that the ABS ECU must
be replaced, then refer to the current
PartFinder™ release to determine the correct
replacement part and complete the following
procedure for the replacement operation.
However if the indications are that the
hydraulic modulator has failed, then the
complete ECU / hydraulic modulator assembly
must be replaced.
1 Disconnect the hydraulic modulator motor wiring
harness connector (1) from the ECU (2).
2 Remove the hydraulic modulator motor wiring from its
retainer.
3 Support the hydraulic modulator (2) in a horizontal
position with the ECU (3) on top.
4 Remove the screws (4) securing the ECU to the
hydraulic modulator.
5 Lift the ECU upwards and remove from the hydraulic
modulator.
6 Cover the hydraulic modulator valve body to prevent
damage or entry of dirt.
Figure 5B6 – 31
5B6 ABS-TCS – GEN III V8 Page 5B6–69
Page 5B6–69
Inspect
When cleaning the ECU to hydraulic
modulator mating surfaces, do not use
compressed air or chemical solvents.
Inspect the ECU and the hydraulic modulator for the following faults:
• Inspect the ECU to hydraulic modulator mating surfaces and seal. The seal is not available as a spare part and the
mating surfaces cannot be mechanically reworked. Therefore, if the ECU to hydraulic modulator seal or its mating
surfaces are damaged, the complete ECU / hydraulic modulator assembly must be replaced.
• Inspect the coils of the solenoid valves for correct alignment. The coils must not be adjusted under any
circumstance. If the coils are not aligned correctly, replace the ECU.
• Ensure the contacts pins of the hydraulic pump are aligned correctly.
Reassemble
1 Ensure that the ECU (1) to hydraulic modulator (2)
mating surface is clean.
2 Position the hydraulic modulator so that the solenoid
valves face upwards.
3 Remove the new control module from its protective
packaging
4 Align and then install the ECU into the hydraulic
modulator.
NOTE
Ensure that there is no gap between ECU and
the hydraulic modulator mating surface.
5 Install the six screws (3) retaining the ECU to the
hydraulic modulator.
6 Tighten the screws in the specified sequence (A to F)
and to the correct torque specification.
ECU retaining screw
torque specification..............................................3.0 Nm
Figure 5B6 – 32
7 Connect the hydraulic modulator motor wiring harness connector (4) and press the motor wiring harness into its
retainer.
NOTE
Ensure the hydraulic modulator motor wiring
harness connector is properly connected to the
ECU.
5B6 ABS-TCS – GEN III V8 Page 5B6–70
Page 5B6–70
Reinstall
Reinstallation of the electronic control unit / hydraulic modulator assembly is the reverse of the removal procedure, noting
the following:
1 Ensure the mounting bracket area is clean and free from brake fluid contamination.
2 Ensure the bottom hydraulic modulator rubber insulator is correctly fitted.
3 Tighten the nut (1), two places, securing the ECU /
hydraulic modulator assembly to the correct torque
specification.
Electronic control unit / hydraulic
modulator assembly securing
nut torque specification......................................12.0 Nm
If the brake pipe fittings are incorrectly fitted,
wheel lock-up will occur and personal injury
may result.
4 Install the brake pipe fittings (2) to the correct hydraulic
modulator ports and tighten to the correct torque
specification.
Brake pipe fitting
torque specification............................................15.0 Nm Figure 5B6 – 33
5 Bleed the ABS-TCS hydraulic circuit. Refer to 9.2 ABS-TCS Brake Bleeding Procedure.
6 Check the ABS-TCS operation. Refer to 6.4 Diagnostic System Check.
5B6 ABS-TCS – GEN III V8 Page 5B6–71
Page 5B6–71
9.4 Front Wheel Speed Sensor
The front wheel speed sensors are incorporated as part of the front suspension front wheel hub assembly. Apart from
wheel stud replacement, there are no serviceable items in the front wheel hub assembly.
Refer to Section 3A Front Suspension for service information on the front wheel hub assembly.
5B6 ABS-TCS – GEN III V8 Page 5B6–72
Page 5B6–72
9.5 Front Wheel Speed Sensor Lead
LT Section No. — 04–730
Remove
1 Raise the front of the vehicle and support on safety stands, Refer to Section 0A General Information for location of
the jacking points.
2 Remove the appropriate wheel. Refer to Section 10 Wheels and Tyres.
3 From within the engine compartment, remove the
appropriate wheel speed sensor wiring connector (1)
from its mounting clip.
Figure 5B6 – 34
4 Using a small screwdriver, disconnect the wheel speed
sensor wiring connector (1) from the wiring harness
connector.
5 Inspect the connector O-ring and replace if required.
NOTE
When removing the front left wheel speed sensor
lead, remove the Powertrain
Control Module (PCM) attaching screws to
allow the front left wheel speed
sensor connector to pass through the gap
between the PCM and the vehicle body.
Refer to Section 6C3 Engine Management for
information on the removal of the PCM attaching
screws. Figure 5B6 – 35
5B6 ABS-TCS – GEN III V8 Page 5B6–73
Page 5B6–73
6 Disengage the sensor lead grommet (1) from the inner
wheelhouse.
7 Disengage the sensor lead (2) from its front strut
mounting bracket (3).
8 Disconnect the wheel speed sensor connector (4) from
the wheel speed sensor.
9 Note the wheel speed sensor wiring harness routing.
10 Remove the sensor lead assembly from the vehicle.
Figure 5B6 – 36
Reinstall
Reinstallation of the wheel speed sensor lead is the reverse of the removal procedure, noting the following:
1 Ensure the wheel speed sensor wiring harness is routed correctly.
2 Check the ABS-TCS operation. Refer to 6.4 Diagnostic System Check.
5B6 ABS-TCS – GEN III V8 Page 5B6–74
Page 5B6–74
9.6 Rear Wheel Speed Sensor
LT Section No. — 04–730
Remove
1 Raise the rear of the vehicle and support using safety stands under trailing arms to support weight of vehicle. Refer
to Section 0A General Information.
2 Disconnect the appropriate sensor lead connector (1)
from its underbody mounting clip (2).
Figure 5B6 – 37
3 Using a small screwdriver, disconnect the wheel speed
sensor wiring connector (1) from the wiring harness
connector.
4 Inspect the connector O-ring and replace if required.
Figure 5B6 – 38
5B6 ABS-TCS – GEN III V8 Page 5B6–75
Page 5B6–75
5 Remove the screw (1) attaching the rear wheel speed
sensor (2) to final drive rear cover.
Do not use a screwdriver or other device to
prise the w heel speed sensor out. Otherw ise,
damage to the wheel speed sensor may
occur.
6 With a twisting motion, withdraw the rear wheel speed
sensor from the final drive cover bore.
7 Clean the wheel speed sensor to final drive cover
mating surface.
Figure 5B6 – 39
Reinstall
Reinstallation of the rear wheel speed sensor is the reverse of the removal procedure, noting the following:
A replacement wheel sensor must only be
taken out its packaging immediately before
installing on the vehicle.
1 With a twisting motion, install the rear wheel speed
sensor (1) to the final drive cover bore.
2 Install the screw (2) attaching the rear wheel speed
sensor to final drive rear cover and tighten to the
correct torque specification.
Wheel speed sensor attaching screw
torque specification...................................4.0 – 14.0 Nm
3 Check ABS-TCS operation.
Refer to 6.4 Diagnostic System Check.
Figure 5B6 – 40
5B6 ABS-TCS – GEN III V8 Page 5B6–76
Page 5B6–76
9.7 Front Wheel Speed Sensor Pulse Ring
If the front wheel hub assembly requires
replacement, the correct replacement part
must be installed. Otherwise, ABS-TCS
malfunction w ill occur.
The front wheel speed sensor pulse ring is incorporated into the front suspension front wheel hub assembly. Apart from
wheel stud replacement, there are no serviceable items in the front wheel hub assembly.
Refer to Section 3A Front Suspension for wheel hub assembly service information.
5B6 ABS-TCS – GEN III V8 Page 5B6–77
Page 5B6–77
9.8 Rear Wheel Speed Sensor Pulse Ring
If the final drive inner axle flange requires
replacement, the correct replacement part
must be installed. Otherwise, ABS-TCS
malfunction w ill occur.
The rear wheel speed sensor pulse ring is part of the final drive inner axle flange and is not serviced separately.
Refer to Section 4B1 Rear Final Drive and Drive Shafts for the final drive inner axle flange service procedure.
5B6 ABS-TCS – GEN III V8 Page 5B6–78
Page 5B6–78
9.9 Traction Control System Switch
Replace
Refer to Section 7C4 Automatic Transmission – 4L60E – On-vehicle Servicing for the TCS switch replacement
procedure.
Test
1 Using a digital multimeter, measure the resistance
across the switch terminals and compare the reading
against the specifications.
TCS switch at rest
Terminals 3 and 4...........................................continuity
Terminals 3 and 5.........................................open circuit
TCS switch when depressed
Terminals 3 and 4........................................open circuit
Terminals 3 and 5............................................continuity
Illumination lamp check
Terminals 2 and 6............... illumination lamp resistance
2 If the resistance is not within specifications, replace
the TCS switch or the illumination lamp.
Figure 5B6 – 41
5B6 ABS-TCS – GEN III V8 Page 5B6–79
Page 5B6–79
10 Specifications
Wheel Speed Sensor Winding Resistance ...............................................1.3 – 1.8 kΩ @ 20°c
Front and Rear Wheel Speed Sensor Air Gap..................................................Non-adjustable
Wheel Speed Sensor Pulse Rings...............................................................................48 teeth
Brake Fluid ......................................................................................................................Dot 4
5B6 ABS-TCS – GEN III V8 Page 5B6–80
Page 5B6–80
11 Torque Wrench Specifications
Electronic Control Unit Retaining Screw...............................................3.0 Nm
Electronic Control Unit / Hydraulic Modulator
Assembly Securing Nut......................................................................12.0 Nm
Brake Pipe Fitting....................................................................11.0 – 16.0 Nm
Hydraulic Modulator Brake Pipe Fitting ..............................................15.0 Nm
Wheel Speed Sensor Attaching Screw......................................4.0 – 14.0 Nm
5B6 ABS-TCS – GEN III V8 Page 5B6–81
Page 5B6–81
12 Special Tools
Tool Number Illustration Description Tool Classification
3588
Digital Multimeter
Also Previously released as J39200 or
equivalent.
NOTE: The instrument must have 10
MΩ impedance and be capable of
reading frequencies.
Mandatory
J35616
Connector Test Adaptor Kit
Used when carrying out electrical
diagnostic circuit checks.
Desirable
70000861
Tech 2 Diagnostic Scan Tool
Previously released.
Mandatory