2010 JAGUAR XFR change wheel

DSC becomes active whenever the engine is running. A momentary press of the switch allows the driver to toggle between the
standard DSC settings and the optimized 'Trac DSC' settings. The message 'Trac DSC' or 'DSC on' will temporarily be displayed
in the instrument cluster message center. The amber DSC warning indicator in the instrument cluster remains illuminated while
'Trac DSC' is selected.
The DSC can be switched off by pressing and holding the switch for more than 10 seconds.

In each case the message 'DSC OFF' will be displayed in the instrument cluster message center to confirm DSC has been
switched off. The amber DSC warning indicator in the instrument cluster will remain illuminated. The system can be switched
back on again by simply pressing and releasing the switch. The message 'DSC ON' will then temporarily appear in the
instrument cluster message center to confirm the system is on.


NOTE: Switch requests may be delayed if the switch is pressed while a DSC operation is taking place. The switch request
will be displayed in the instrument cluster but the ABS module will not initiate any stability changes until it is safe to do so.
If a fault is detected with the DSC switch, the ABS module defaults to the 'DSC ON' setting and any switch requests are ignored.


WARNING: It is recommended that when using snow chains, Trac DSC is switched off and JaguarDrive control winter mode
is selected.

Wheel Speed Sensors



Item Description 1 Front wheel speed sensor 2 Rear wheel speed sensor An active wheel speed sensor is installed in each wheel hub to provide the ABS module with a rotational speed signal from each road wheel. The head of each front wheel speed sensor is positioned close to a magnetic encoder ring incorporated into
the inboard seal of the wheel bearing. The head of each rear wheel speed sensor is positioned close to a magnetic encoder
ring incorporated into the rear wheel bearing assembly. Each encoder ring contains 46 north and south poles. A fly lead
connects each sensor to the vehicle harness.

The wheel speed sensors each have a signal and a return connection with the ABS module. When the ignition is ON the ABS module supplies a signal feed to the wheel speed sensors and monitors the return signals. Any rotation of the road wheels
induces current fluctuations in the return signals, which are converted into individual wheel speeds and overall vehicle speed
by the ABS module. The ABS module broadcasts the individual wheel speeds and the vehicle speed on the high speed CAN bus for use by other

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).

between moving components such as the steering wheel to steering column shroud.

Grunt (Squawk/Whoop)

Grunt is a 'honking' sound elicited when coming off one of the steering stops. Grunt is generally excited during parking
manoeuvres with a low to medium speed steering input.

Hiss (Swish)

Hiss or Valve Hiss is a high-frequency sound coming from the steering gear when the system is loaded. It is a rushing or
'swish' noise that doesn't change frequency with RPM. Hiss is the general noise generated by the flow of hydraulic fluid through
restrictions in the steering system. Restrictions include the rotary steering valve, power steering tubes, connectors, tuning
orifices, etc. Hiss can be air-borne and structure-borne, but the structure-borne path through the steering intermediate shaft is
usually dominant.

Moan (Groan)

Moan is the general structure-borne noise of the steering system. Moan is primarily transmitted to the driver via the body
structure through the pump mount, engine mounts, power steering lines and power steering brackets. On some vehicles, moan
is a loud humming noise, often present when the wheel is turned and the system is loaded. It may change frequency with
engine RPM and if the system is loaded or unloaded.

Steering Gear Knock (Steering Gear Slap)


CAUTION: DO NOT attempt to adjust the steering gear yoke. Failure to follow this instruction will invalidate the steering
gear warranty.

Steering gear knock is a rattle sound and steering wheel vibration caused by separation of the steering gear and pinion while
driving over bumps. It is a structure-borne noise transmitted through the intermediate shaft and column. Steering gear knock
can also be heard as a 'thump' or impact noise that occurs with the vehicle stationary when the steering wheel is released
from a loaded position and allowed to return to rest. Noise occurs with the engine on or off.

Rattles

Rattles are noises caused by knocking or hitting of components in the steering system. Steering rattles can occur in the engine
compartment, the suspension, or the passenger compartment. Rattles can be caused by loose components, movable and
flexible components, and improper clearances.

Squeaks/Scrapes

Squeaks/Scrapes are noises due to friction or component rubbing anywhere in the steering system. Squeaks/Scrapes have
appeared in steering linkages and joints, in column components and in column and steering wheel trim.

Weep

Weep is an air-borne noise, occasionally generated when turning the steering across lock at a constant rate. When present on
a vehicle the noise, once initiated can often be maintained across a large proportion of the available steering movement.

Whistle

Whistle is similar to hiss but is louder and of a higher frequency. It is also more of a pure tone noise than hiss. Whistle is
air-borne and is generated by a high flow rate of hydraulic fluid through a small restriction.

Zip

Zip noise is the air-borne noise generated by power steering pump cavitation when power steering fluid does not flow freely
through the suction hose from the reservoir to the pump. Zip primarily occurs during cold weather at start-up.

Steering System Vibrations and Harshness
Buzz
Buzz is a tactile rotary vibration felt in the steering wheel when steering inputs are slow. Buzz can also be called a grinding
feel and it is closely related to grunt and is caused by high system gain with low damping. Buzz is generally excited during
parking manoeuvres with low to medium speed steering input.

Buzz (Electrical)

A different steering buzz can be caused by pulse width modulated (PWM) electric actuators used in variable assist steering
systems. This buzz is felt by turning the ignition key to run without starting the engine and holding onto the steering wheel.
In extreme cases, the buzz can be felt with the engine running also.

Column/Steering Wheel Shake

Column shake is a low frequency vertical vibration excited by primary engine vibrations.

Nibble (Shimmy)

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.
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1 Steering wheel 2 Gear change paddle switch 3 Column adjust switch 4 Lower shroud 5 Rake adjustment housing 6 Reach adjustment housing 7 Column adjustment motor 8 Lower column - Upper collapse shaft 9 Bulkhead bearing and seal assembly 10 Lower column - Lower collapse shaft 11 Electric steering lock mechanism 12 Column mounting plate 13 Upper shroud

16 Ball (12 off) 17 Distance keeper 18 Crash tube The column comprises a cast magnesium mounting bracket which provides the attachment to the cross-beam. Attached to the
mounting bracket is a rake lever which is attached to the mounting bracket at the lower end with two pivot bearings. The
bearings allow the rake lever to rotate upwards or downward to adjust the column rake.

The rake lever also provides for the attachment of the rake housing which can slide within the lever to provide the reach
adjustment. Within the rake housing is the axial housing which is supported on each side with 6 ball bearings which allow the
rake housing to move forward or backwards. The bearings on each side are arranged in groups of 3 bearings and are separated
by a distance keeper which allows the housing to supported on bearings along its length. Within the axial housing is a tube
which is supported at the upper end of the column on the upper bearing. The tube has a central splined hole which provides for
the fitment of the splined shaft. The splined shaft can slide within the tube on the splines when the column reach is adjusted
or the column collapses in a crash condition. The splined shaft also passes rotary motion from the steering wheel through the
length of the column to the outer clamping yoke which is supported on the lower bearing.

The electric steering column lock is attached to the top of the rake lever. A lock bolt within the steering column lock engages in
one of 8 slots in the locking sleeve located at the lower end of the column preventing rotation of the steering wheel. The
locking sleeve is retained by a tolerance ring which in turn is located on the outer diameter of the tube yoke. The tolerance
ring allows a specified amount of torque to be applied to the splined shaft before it slips, preventing damage to the column
lock due to excessive force being applied to the steering wheel when the lock is engaged. The tolerance ring is designed to
slip on the splined shaft when the applied torque exceeds the fitted slip load of 200 Nm minimum. Repeated rotation of the
lock collar will reduce its slipping torque to 100 Nm minimum. The lock is controlled by the CJB.
A steering angle sensor is located at the upper end of the steering column and is attached to the crash adaptor. The sensor
measures steering rotation via a toothed wheel located on the splined tube at the upper end of the column. The sensor
receives a power supply from the CJB and supplies 2 signals (A and B) relating to the steering rotation to the ABS (anti-lock brake system) module. The module transmits this data on the high speed CAN bus for use by other vehicle systems. Refer to: Anti-Lock Control - Stability Assist (206-09 Anti-Lock Control - Stability Assist, Description and Operation).
The steering column is adjustable electrically, for reach and rake. The adjustment mechanism comprises an electric adjustment
motor, a lead screw, a rake solenoid, a reach solenoid, a reach clutch and a rake clutch. The column adjustment is controlled
manually using a joystick switch located on the LH (left-hand) side of the column lower cowl. The joystick can be moved
forward and backward to adjust the column reach in and out and moved up and down to adjust the rake. The switch selection
energizes the adjustment motor in the applicable direction and also engages the applicable solenoid and clutch.

When the joystick switch is rotated to the 'auto' position, the steering column will adjust to the uppermost rake position when
the ignition is switched off. It will re-adjust to the position corresponding to the memory position for the remote handset when
the ignition is switched on.

The memory function of the electric column is linked to and controlled by the driver's seat module. The module provides for the
storage of three separate memory positions which are stored against 3 individual remote handsets.
Refer to: Seats (501-10 Seating, Description and Operation).
The steering wheel locates on a splined shaft in the upper column assembly and is secured with a bolt. The steering wheel
houses the driver's airbag and switches for the audio system, gear change and speed control. A clockspring is used to connect
the steering wheel electrical components to the vehicle harness.

Two plastic shrouds are fitted to the upper column assembly. The lower shroud is fitted with an energy absorbing foam pad to
minimize leg injury in the event of an accident.
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path is completed and a signal voltage is returned to the instrument cluster via a resistor. The returned reference voltage is
detected by the instrument cluster and performs the requested trip function.

RIGHT HAND MULTIFUNCTION SWITCH
The instrument cluster outputs 4 separate reference voltages to the following switch functions:
Wash/wipe switch
Intermittent wipe switch
Master wiper switch
Flick wipe switch.
Wash/Wipe Switch

The reference voltage is supplied to one of two resistors connected in parallel. When the switch is not being operated the
current flows through one resistor and the returned signal voltage is monitored by the instrument cluster. When the wash/wipe
switch is operated, a connection is made and the current flows through the second resistor. The change in signal voltage is
detected by the instrument cluster which outputs a message on the medium speed CAN bus to the CJB to activate the wash/wipe function.
Intermittent Delay/Auto Wipe Switch

The reference voltage is supplied to the switch and can pass through up to 7 resistors, connected in series, for intermittent
delay selections and the auto wipe function.

When the rotary switch is in the auto position the reference voltage flows through 1 resistor. The returned signal voltage is
detected by the instrument cluster which determines auto wipe is selected. The instrument cluster outputs a message on the
medium speed CAN bus to the CJB to activate the auto wipe function.
With the rotary switch in one of the intermittent positions, the reference voltage is routed through up to 7 of the resistors
depending on the delay period selected. The returned signal voltage is detected by the instrument cluster which determines
selected delay period. The instrument cluster outputs a message on the medium speed CAN bus to the CJB to activate the selected intermittent wipe function.


NOTE: The delay period for the intermittent selections can vary according to vehicle speed.

Master Wiper Switch

The reference voltage supplied from the instrument cluster to the master wiper switch. The voltage can pass through up to 4
resistors connected in series.

When the switch is in the off position, the reference voltage passes through 4 resistors and the returned voltage is monitored
by the instrument cluster. The instrument cluster outputs a message on the medium speed CAN bus to the CJB that no wiper selections have been requested.

With the switch in the intermittent, slow wipe or fast wipe position, the reference voltage passes through 3, 2 or 1 resistors
respectively. The returned signal voltage is detected by the instrument cluster which determines selected delay period. The
instrument cluster outputs a message on the medium speed CAN bus to the CJB to activate the selected wipe function. Flick Wipe Switch

The reference voltage is supplied to one of two resistors connected in parallel. When the switch is not being operated the
current flows through one resistor and the returned signal voltage is monitored by the instrument cluster. When the flick wipe
switch is operated, a connection is made and the current flows through the second resistor. The change in signal voltage is
detected by the instrument cluster which outputs a message on the medium speed CAN bus to the CJB to activate the flick wipe function.

STEERING COLUMN ADJUSTMENT SWITCH

The instrument cluster supplies 2 reference voltages to the column adjustment switch.

The first reference voltage is supplied to the joystick switch. When the switch is moved to one of its 4 positions, the switch
contact is completed and the reference voltage is passed through one of 4 different resistors with different values. The
returned signal voltage is measured by the instrument cluster which determines the selected column adjust request. The
instrument cluster outputs a supply to the steering column adjustment motor and energizes the applicable clutch solenoid to
move the column to the desired position.

The second reference voltage is supplied to the auto/manual selection of the switch. When the switch is in the auto position,
the reference voltage passes directly through the switch contacts and is measured by the instrument cluster. The instrument
cluster outputs a message on the medium speed CAN bus to the driver seat module which responds with the recorded memory position setting. The instrument cluster then activates the column adjustment motor and clutch solenoids to move the column
to the memorized position. When the switch is in the manual position the reference circuit is broken. The instrument cluster
detects the broken circuit and allows manual operation of the column adjustment switch to move the column.

HEATED STEERING WHEEL

The heated steering wheel receives a battery power supply via the CJB. The heated steering wheel is controlled by the driver using a selection on the TSD. When the driver selects the heated steering wheel to be active, the request is passed from the
TSD on the MOST ring to the information and entertainment module. The information and entertainment module converts the