ECU JAGUAR XFR 2010 1.G Repair Manual

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.

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

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).

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).

Steering System - General Information - Steering System
Diagnosis and Testing

Principle of Operation Published: 11-May-2011

For a detailed description of the steering system operation, refer to the relevant Description and Operation sections of the
workshop manual. REFER to:

Power Steering (211-02 Power Steering, Description and Operation), Power Steering (211-02 Power Steering, Description and Operation), Power Steering (211-02 Power Steering, Description and Operation), Steering Linkage (211-03 Steering Linkage, Description and Operation), Steering Linkage (211-03 Steering Linkage, Description and Operation), Steering Linkage (211-03 Steering Linkage, Description and Operation), Steering Column (211-04 Steering Column, Description and Operation), Steering Column (211-04 Steering Column, Description and Operation), Steering Column (211-04 Steering Column, Description and Operation), Steering Column Switches (211-05 Steering Column Switches, Description and Operation), Steering Column Switches (211-05 Steering Column Switches, Description and Operation), Steering Column Switches (211-05 Steering Column Switches, Description and Operation).
Inspection and Verification

1. Verify the customer concern.

2. Visually inspect for obvious signs of damage and system integrity.

Visual Inspection
Mechanical Electrical
Tire condition/pressure
Fluid level
Leaks
Security, condition and correct installation of suspension components
Security, condition and correct installation of steering system components
Fuses
Harnesses for damage/corrosion
Electrical connector(s)
Damaged/corroded pins
CAUTION: If a steering gear assembly is returned under warranty with leaking output shaft seals, but there is also
damage to the steering gear boot/boots the steering gear warranty will be invalid. This is due to the steering gear output
shaft seals being damaged due to foreign materials entering the steering gear boot and damaging the steering gear output
shaft seals thereafter.

3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to
the next step.
4. If the concern is not visually evident, verify the symptom and refer to the symptom chart.

Symptom Charts


WARNING: It is not possible to CHECK the torque of a patchlock bolt, if the torque is suspected to be low, the bolt must
be REMOVED/DISCARDED and a new bolt MUST be INSTALLED and torque to the correct value.


NOTE: If the module or a component is suspect and the vehicle remains under manufacturer warranty, refer to the
Warranty Policy and Procedures manual (section B1.2), or determine if any prior approval programme is in operation, prior to
the installation of a new module/component.

Fluid Leakage


NOTE: Confirm the location of the fluid leak. CLEAN the area of the leak, inspect the area and confirm the exact position.
Ensure the fluid is not from another system on the vehicle.

Symptom Possible Causes Action

Power steering
fluid leakage
Overfilled system
Correct the fluid level as required
Steering gear
Check and install new steering gear as required, refer to the new
module/component installation note at the top of the Symptom
Charts

5. CAUTION: Be prepared to collect escaping fluids.


NOTE: Make sure the extended pipe is not kinked or
twisted and is correctly secured with hose clips.

Attach a suitable pipe to the power steering return hose to
allow the fluid to drain.









6. NOTES:


The suitable funnel should have the a capacity of 4
litres and O-ring seal


The suitable funnel must be tightly sealed to the
power steering fluid reservoir to avoid fluid leakage.

Install a suitable funnel onto the power steering fluid
reservoir.












7. WARNING: Do not work on or under a vehicle supported only by a jack.
Always support the vehicle on safety stands.
Raise and support the vehicle with the wheels just clear of the ground.

8. CAUTIONS:


Steps 8 and 9 must be carried out within 2 - 3 seconds of each
other. Failure to follow this instruction may result in damage to the
power steering system.


Be prepared to collect escaping fluids.

Using the suitable funnel, top up the power steering system with the
specified fluid. Make sure the fluid level is maintained at two thirds full
in the funnel.

1 Locknut ( 2 off) 2 RH (right-hand) tie-rod 3 Steering gear boot (2 off) 4 Steering gear 5 Bolt and washer (3 off) 6 Servotronic valve 7 Valve unit 8 Input shaft 9 LH (left-hand) tie-rod 10 Steering gear mounting bushes The steering gear is located at the rear of the engine and attached to the front sub-frame. The gear is secured to the
sub-frame with 3 bolts and washers which screw into threaded tubes in bushes which are integral with the sub-frame.

The steering gear comprises an aluminum, cast, valve housing which contains the hydraulic valve unit and Servotronic valve.
The mechanical steering rack and the hydraulic actuator are located in a steel cylinder which is attached to the cast valve
housing.

The steering gear uses a rack with an integrated piston which is guided on plain bearings within the cylinder and the valve
housing. The pinion, which is attached to the valve unit, runs in bearings and meshes with the rack teeth. The rack is pressed
against the pinion by a spring loaded yoke which ensures that the teeth mesh with the minimum of play. The pinion is
connected to the valve unit via a torsion bar. The rotary motion of the steering wheel is converted into linear movement of the
rack by the rack and pinion mechanism and is initiated by the valve unit. This movement is transferred into movement of the
road wheels by adjustable tie-rods.

18 Pinion 19 Steering gear rack bar 20 Valve sleeve The valve unit is an integral part of the steering gear. The principle function of the valve unit is to provide power assistance
(i.e. when parking) to optimize the effort required to turn the steering wheel.

The pinion housing of the valve is an integral part of the main steering gear casting. The pinion housing has four machined
ports which provide connections for pressure feed from the power steering pump, return fluid to the reservoir and pressure
feeds to each side of the cylinder piston.

The valve unit comprises an outer sleeve, an input shaft, a torsion bar and a pinion shaft. The valve unit is co-axial with the
pinion shaft which is connected to the steering column via the input shaft. The valve unit components are located in the
steering gear pinion housing which is sealed with a cap.

The outer sleeve is located in the main bore of the pinion housing. Three annular grooves are machined on its outer diameter.
PTFE (polytetrafluoroethylene) rings are located between the grooves and seal against the bore of the pinion housing. Holes
are drilled radially in each annular groove through the wall of the sleeve. The bore of the outer sleeve is machined to accept
the input shaft. Six equally spaced slots are machined in the bore of the sleeve. The ends of the slots are closed and do not
continue to the end of the outer sleeve. The radial holes in the outer sleeve are drilled into each slot.

The input shaft has two machined flats at its outer end which allow for the attachment of the steering column intermediate
shaft yoke. The flats ensure that the intermediate shaft is fitted in the correct position. The inner end of the input shaft forms
a dog-tooth which mates with a slot in the pinion shaft. The fit of the dog-tooth in the slot allows a small amount of relative
rotation between the input shaft and the pinion shaft before the dog-tooth contacts the wall of the slot. This ensures that, if
the power assistance fails, the steering can be operated manually without over stressing the torsion bar. The central portion of
the input shaft has equally spaced longitudinal slots machined in its circumference. The slots are arranged alternately around
the input shaft.

The torsion bar is fitted inside the input shaft and is an interference fit in the pinion shaft. The torsion bar is connected to the
input shaft by a drive pin. The torsion bar is machined to a smaller diameter in its central section. The smaller diameter allows
the torsion bar to twist in response to torque applied from the steering wheel in relation to the grip of the tyres on the road
surface.

The pinion shaft has machined teeth on its central diameter which mate with teeth on the steering gear rack. A slot, machined
in the upper end of the pinion shaft mates with the dog-tooth on the input shaft. The pinion shaft locates in the pinion
housing and rotates on ball and roller bearings.

Servotronic Valve

The Servotronic transducer valve is located in a port in the side of the steering gear valve housing. The valve is sealed in the
housing with an O-ring seal and is secured with two long screws into threaded holes in the housing. The Servotronic valve is a
transducer controlled valve which responds to control signals supplied from Servotronic software in the instrument cluster.

The Servotronic valve determines the hydraulic reaction at the steering gear rotary valve and controls the input torque required
to turn the steering wheel. The Servotronic system allows the steering to be turned with the optimum effort when the vehicle
is stationary or manoeuvred at slow speed. The hydraulic reaction changes proportional to the vehicle speed, with the required
steering effort increasing as the vehicle moves faster. At high speeds, the Servotronic system provides the driver with a good
feedback through the steering providing precise steering and improved stability.

The instrument cluster receives road speed signals from the ABS module and calculates the correct controlling signal for the Servotronic valve. The Servotronic software within the instrument cluster has a diagnostic capability which allows a Jaguar
approved diagnostic system to check the tune of the steering and retrieve fault codes relating to the Servotronic valve. Two
fault codes are stored relating to the valve for positive connection short to ground or battery and negative connection short to
ground or battery.

The Servotronic software within the instrument cluster also contains a number of steering maps which are selected via the car
configuration file depending on the vehicle model and tire fitment.

If a failure of the Servotronic valve or software occurs, the system will suspend Servotronic assistance and only a default level
of assistance will be available. Fault codes relating to the fault are stored in the instrument cluster. No warning lamps are
illuminated and the driver may be aware of the steering being 'heavier' than usual.
www.JagDocs.com

Published: 11-May-2011
Steering Linkage - Steering Linkage - System Operation and Component Description
Description and Operation


TIE-ROD System Operation

The threads on the tie rods allow the position of the outer tie rod to be adjusted in order to set the correct toe angle for each
front wheel.


TIE-ROD Component Description

Each tie rod comprises two parts; an inner and outer tie rod. The inner and outer tie rods are screwed into each other and
locked with a locknut to prevent inadvertent movement.

The outer tie rod incorporates a non-serviceable tapered ball joint which locates in a tapered hole in the front wheel knuckle
and is secured with a self-locking nut. The ball joint has an internal hexagonal drive which enables the joint to be held
stationary when the self-locking nut is tightened.

STEERING COLUMN Component Description



Item Description 1 Rake housing 2 Electric steering column lock 3 Mounting plate 4 Rake lever 5 Crash tube 6 Distance keeper 7 Steering wheel mounting splines 8 Steering angle sensor ring 9 Crash adaptor 10 Rake lever pivot bearing (2 off) 11 Flanged locknut (4 off) - mounting to cross-beam 12 Rake solenoid 13 Rake clutch 14 Spindle 15 Reach solenoid 16 Reach clutch 17 Column adjustment motor 18 Outer clamping yoke 19 Clamp bolt 20 Inner tube yoke
WARNING: Do not attempt to dismantle the steering column. The crash safety of the unit will be compromised.

The steering column is attached to the in-vehicle cross-beam and secured with 4 flanged lock nuts onto 4 studs integral with
the cross-beam.