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Published: 17-Feb-2012
Brake System - General Information - Front Brake Disc Runout Check - With
Wheel On Vehicles With: High Performance Brakes
General Procedures
1. NOTES:
Some variation in the illustrations may occur, but the essential
information is always correct.
RH illustration shown, LH similar
All measurements must taken with the wheel installed.
2. WARNING: Make sure to support the vehicle with axle stands.
Raise the front of the vehicle.
3. Mount the DTI Dial Test Indicator (DTI) gauge to the bolt as shown with tool 100-053.
4. Make sure the DTI is securely mounted.
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BRAKE CALIPERS System Operation
When hydraulic pressure is supplied to the caliper, the pistons extend to force the inner pad against the brake disc. The caliper
reacts and slides along two guide pins to bring the outer pad into contact with the brake disc.
BRAKE PAD WEAR SENSORS
When a brake pad incorporating a brake pad wear sensor is approximately 75% worn, the sensor wire within the pad material
is worn through and the brake pad wear sensor goes open circuit. When the instrument cluster detects the open circuit, it
illuminates the amber LED (light emitting diode) in the brake warning indicator, displays an appropriate warning in the
message center and sounds a warning chime.
Refer to: Instrument Cluster (413-01 Instrument Cluster, Description and Operation).
NOTE: A new pad wear sensor lead must be fitted whenever the brake pads are changed, irrespective of the brake pad
warning sensor being triggered.
BRAKE CALIPERS Component Description
Each caliper is mounted within a fixed carrier that is secured to the front wheel knuckle with two bolts. The inboard brake pad
of the LH (left-hand) brake incorporates a wear sensor.
Each outboard brake pad is installed with a pressed steel anti-rattle spring. On SC (supercharger) vehicles, a badge with the
'R' symbol is formed on the anti-rattle spring.
BRAKE PAD WEAR SENSORS
The brake pad wear sensor is wired in series with a wear sensor on the RH (right-hand) rear brake and the instrument cluster.
If the thickness of one of the brake pads connected to a wear sensor decreases to a predetermined limit, the instrument
cluster illuminates the brake warning indicator.
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6. NOTE: Left-hand shown, right-hand similar.
Secure the bottom arm of the anti-rattle spring
under the bottom anchor bracket of the caliper.
Compress the upper spring arm into the correct
position, under the upper anchor bracket, whilst
retaining the logo plate.
Using the screw-driver, tap the central locating tag
into the locked position.
7. CAUTIONS:
Always plug any open connections to prevent
contamination.
Make sure new sealing washers are installed.
NOTES:
To prevent the loss of brake fluid, using the special
tool apply the brake pedal and set to 40mm ( 1.6 in ) below
the rest position.
Left-hand shown, right-hand similar.
Torque: 42 Nm www.JagDocs.com
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7. NOTE: Left-hand shown, right-hand similar.
Secure the bottom arm of the anti-rattle spring
under the bottom anchor bracket of the caliper.
Compress the upper spring arm into the correct
position, under the upper anchor bracket, whilst
retaining the logo plate.
Using the screw-driver, tap the central locating tag
into the locked position.
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BRAKE CALIPERS System Operation
When hydraulic pressure is supplied to the caliper, the pistons extend to force the inner pad against the brake disc. The caliper
reacts and slides along two guide pins to bring the outer pad into contact with the brake disc.
BRAKE PAD WEAR SENSORS
When a brake pad incorporating a brake pad wear sensor is approximately 75% worn, the sensor wire within the pad material
is worn through and the brake pad wear sensor goes open circuit. When the instrument cluster detects the open circuit, it
illuminates the amber LED (light emitting diode) in the brake warning indicator, displays an appropriate warning in the
message center and sounds a warning chime.
Refer to: Instrument Cluster (413-01 Instrument Cluster, Description and Operation).
NOTE: A new pad wear sensor lead must be fitted whenever the brake pads are changed, irrespective of the brake pad
warning sensor being triggered.
BRAKE CALIPERS Component Description
Each caliper is mounted within a fixed carrier that is secured to the rear wheel knuckle with two bolts. Each outboard brake pad
is installed with a wire anti-rattle spring.
The brake calipers on SC (supercharger) vehicles are painted and also include a logo badge, secured with two screws, which
must be removed in order to change the brake pads.
The inboard brake pad of the RH (right-hand) brake incorporates a wear sensor.
BRAKE PAD WEAR SENSORS
The brake pad wear sensor is wired in series with a wear sensor on the LH (left-hand) front brake and the instrument cluster. If
the thickness of one of the brake pads connected to a wear sensor decreases to a predetermined limit, the instrument cluster
illuminates the brake warning indicator.
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center and an amber warning indicator will illuminate.
Refer to: Information and Message Center (413-08 Information and Message Center, Description and Operation).
As the wheel speed sensors are active devices, a return signal is available when the road wheels are not rotating. This enables
the ABS module to check the condition of the speed sensors while the vehicle is stationary.
Steering Angle Sensor
The steering angle sensor measures the steering wheel angle and the rate of change of the steering wheel angle. These
measurements are received by the ABS module and broadcast on the high speed CAN bus for use by other systems.
The steering angle sensor is mounted on the steering column upper shroud mounting bracket, immediately behind the
multifunction switches, and is secured by 2 screws. A fly lead connects the sensor to the passenger compartment wiring
harness via a 4 pin multiplug.
The sensor is housed in a 'U' shaped plastic casing and contains two offset LED (light emitting diode)s facing two detectors.
An encoder ring is mounted on the inner steering column shaft and intersects the LEDs and detectors. The encoder ring contains 60 slots which break and restore the light beams between the LEDs and the detectors as the steering wheel is
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beams change state. The LEDs and detectors are mounted in such a way that only one beam will change state, either to broken or restored, at any one time.
The center (straight ahead) position of the steering wheel has to be learned by the ABS module every time the ignition is switched ON. The steering angle sensor is unable to determine the center position so inputs from the yaw rate and lateral
acceleration sensor and wheel speed signals are also used by the ABS module to help it perform this process. If extreme weather conditions are present, for example ice causing extreme wheel spin or understeer/oversteer, the ABS module may not be able to determine the center position of the steering wheel. In this situation 'DSC NOT AVAILABLE' will be displayed in the
instrument cluster message center and the amber warning indicator will illuminate.
Refer to: Information and Message Center (413-08 Information and Message Center, Description and Operation).
'DSC NOT AVAILABLE' will also be displayed if the ABS module detects a steering angle sensor fault. The amber warning indicator will illuminate until the fault is rectified.
Yaw Rate and Lateral Acceleration Sensor
The yaw rate and lateral acceleration sensor is mounted on the rear parcel shelf. The sensor is secured by two screws and
connects to the vehicle wiring via a four pin multiplug.
When the ignition is ON, the sensor receives a power feed from the CJB. The ground path for the sensor is located behind the left hand rear seat back. The sensor measures the yaw rate and lateral acceleration of the vehicle, providing values to the ABS module via a dedicated, private high speed CAN bus connection. The ABS module broadcasts these values on the high speed CAN bus for use by other systems.
If a sensor fault is detected by the ABS module, 'DSC NOT AVAILABLE' will be displayed in the instrument cluster message center and the amber warning indicator will illuminate.
Refer to: Information and Message Center (413-08 Information and Message Center, Description and Operation).
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ABS Module
Item Description 1 LH front brake 2 RH rear brake 3 LH rear brake 4 RH front brake 5 Primary inlet 6 Secondary inlet The ABS module is located in the passenger side, rear engine bay and incorporates the HCU. The module is mounted on the rear face of the HCU, which it uses to control all braking and stability functions by modulating hydraulic pressure to the individual wheel brakes.
Two types of ABS modules are available; one for vehicles with standard Speed Control, one for vehicles fitted with Adaptive Speed Control.
If an ABS modulator fault is detected, 'ABS FAULT' will be displayed in the instrument cluster message center and the amber warning indicator will illuminate.
Refer to: Information and Message Center (413-08 Information and Message Center, Description and Operation).
CAUTION: The ABS module and the HCU comprise a single unit and must not be separated.
Hydraulic Control Unit
The HCU is a four channel unit, secured to a mounting bracket located in the passenger side, rear engine bay. The HCU modulates the supply of hydraulic pressure to the brakes under the control of the ABS module. Refer to: Hydraulic Brake Actuation (206-06 Hydraulic Brake Actuation, Description and Operation).
