2010 JAGUAR XFR park assist

Stoplamp Switch



The stoplamp switch is mounted on the brake pedal box. One of the prerequisites for releasing the parking brake is that the
foot brake is applied. The EPB module is able to determine the position of the footbrake by monitoring the status of the
stoplamp switch via a hardwired electrical connection.
The stoplamp switch also forms part of:
The ABS. Refer to: Anti-Lock Control - Stability Assist (206-09 Anti-Lock Control - Stability Assist, Description and Operation). The speed control system. For additional information, refer to:
Speed Control (310-03A, Description and Operation),
Speed Control (310-03B, Description and Operation),
Speed Control (310-03C, Description and Operation).

7 Brake fluid level switch 8 LH rear wheel speed sensor 9 RH rear wheel speed sensor 10 RJB (rear junction box) 11 High mounted stop lamp 12 LH stop lamp 13 RH stop lamp 14 Diagnostic socket 15 TCM (transmission control module) 16 Electronic parking brake module 17 ECM (engine control module) 18 Instrument cluster 19 ABS (anti-lock brake system) module 20 JaguarDrive selector module 21 Adaptive damping control module 22 Adaptive speed control module 23 Yaw rate and lateral acceleration sensor 24 Roof opening panel motor/module 25 Brake booster vacuum sensor (3.0L vehicles only) 26 Steering angle sensor


Anti-Lock Brake System System Operation

ABS controls the speed of all road wheels to ensure optimum wheel slip when braking at the adhesion limit. The wheels are prevented from locking to retain effective steering control of the vehicle.

The brake pressures are modulated separately for each wheel. Rear brake pressures are controlled to maintain rear stability on
split friction surfaces.

Dynamic Stability Control

DSC (dynamic stability control) uses brakes and powertrain torque control to assist in maintaining the yaw stability of the
vehicle. While the ignition is energized the DSC function is permanently enabled, unless selected off using the DSC switch.

DSC enhances driving safety in abrupt maneuvers and in under-steer or over-steer situations that may occur in a bend. The
ABS module monitors the yaw rate and lateral acceleration of the vehicle, steering input and individual wheel speeds, then selectively applies individual brakes and signals for powertrain torque adjustments to reduce under-steer or over-steer
conditions.
In general:

In an under-steer situation the inner wheels are braked to counteract the yaw movement towards the outer edge of the
bend.
In an over-steer situation the outer wheels are braked to prevent the rear end of the vehicle from pushing towards the
outer edge of the bend.

The ABS module monitors the tracking stability of the vehicle using inputs from the wheel speed sensors, the steering angle sensor, and the yaw rate and lateral acceleration sensor. The tracking stability is compared with stored target data. Whenever
the tracking stability deviates from the target data, the ABS module intervenes by applying the appropriate control strategy. The following interactions occur in an intervention situation:

High speed CAN signal to the ECM, to reduce engine torque. Application of braking to the appropriate corner of the vehicle.
Trac DSC

TracDSC is an alternative setting of DSC with reduced system interventions. With TracDSC engaged, traction may be somewhat
increased, although stability may be reduced compared to normal DSC. TracDSC is intended for use only on dry tarmac, by
suitably experienced drivers and should not be selected for other surfaces or by drivers with insufficient skill and training to
operate the vehicle safely with the TracDSC function engaged.

The less restrictive TracDSC setting may be preferred, for example, by expert drivers engaged in high performance driving on
dry Tarmac surfaces such as tracks and circuits.
Switching between DSC and Trac DSC:

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)

Steering nibble is a rotary oscillation or vibration of the steering wheel, which can be excited at a specific vehicle speed.
Nibble is driven by wheel and tire imbalance exciting a suspension recession mode, which then translates into steering gear
travel and finally steering wheel nibble.

Shudder (Judder)

Shudder is a low frequency oscillation of the entire steering system (tire, wheels, steering gear and linkage, etc.) when the
vehicle is steered during static-park or at low speeds. Shudder is very dependent on road surface.

Torque/Velocity Variation (Phasing/Effort Cycling)

Steering wheel torque variation occurring twice in one revolution is normally as a result of problems with the lower steering
column (intermediate shaft), but foul conditions generally result in either constant stiffness or single point stiffness.
Depending upon the orientation of the joints, the steering can feel asymmetric (torque falling off in one direction and rising in
the other) or else it can simply have pronounced peaks and troughs as the steering moves from lock to lock.

Wheel Fight (Kick Back)

Wheel fight is excess feedback of sudden road forces through the steering system and back to the driver. It is evaluated at all
vehicle speeds over cobblestones, rough roads, and potholes. The tires, wheels, and suspension generate forces into the
steering systems. Steering friction, hydraulic damping, hydraulic compliance, mechanical compliance, steering ratio, and assist
gain all affect how much is transmitted to the driver.

compartment, forward of the front suspension housing.

On petrol engine vehicles, a fluid cooler is located in front of the engine cooling radiator. Diesel models do not have a fluid
cooler.

Servotronic 2 adds electronic control and speed sensitive steering to the steering gear. The Servotronic 2 feature provides easy
and comfortable steering operation when parking, improved 'road feel' at increased road speeds and adds an integrated,
positive center feel feature which optimises steering wheel torque during high speed driving. The Servotronic 2 system is
controlled by software which is incorporated into the instrument cluster. The software responds to road speed signals and
controls the power assistance via a transducer valve located on the steering gear valve housing.

1 Return fluid control groove 2 Radial groove 3 Feed fluid control groove 4 Radial groove 5 Axial groove 6 Feed fluid control edge 7 Feed fluid radial groove 8 Return fluid control edge 9 Return fluid chamber 10 Cut-off valve 11 Radial groove 12 Servotronic transducer valve 13 Feed fluid radial groove 14 Radial groove 15 Orifice 16 Balls 17 Compression spring 18 Torsion bar 19 Power steering fluid reservoir 20 Valve rotor 21 Reaction piston 22 Reaction chamber 23 Centering piece 24 Pressure relief/flow limiting valve 25 Power steering pump 26 Inner tie-rod 27 Pinion 28 Valve sleeve 29 Steering gear rack 30 Steering gear housing 31 Power assist cylinder - right 32 Piston 33 Power assist cylinder - left When the steering wheel is turned to the right, the steering rack and piston moves to the left in the piston bore. The valve
rotor is rotated to the right (clockwise) and pressurized fluid is directed over the further opened feed fluid control edges and to
the associated axial grooves, the radial groove and via an external pipe to the left power assist cylinder chamber. The pressure
applied to the piston from the left power assist cylinder chamber provides the hydraulic assistance.

An adaptable pressure build-up is achieved by the partially or fully closed feed fluid control edges restricting or preventing a
connection between the fluid pressure inlet and the other axial grooves connected to the radial groove.

Simultaneously, the fluid pressure outlet to the pressurized axial grooves are restricted or partially restricted by the closing
return fluid control edges. The fluid displaced by the piston from the right power assist cylinder chamber, flows through an
external pipe to the radial grooves. From there the fluid passes to the associated axial grooves and on to the return fluid
control grooves, via the further opened return fluid control edges.

The return flow of fluid to the reservoir passes via interconnecting bores which lead to the return fluid chamber. When the
steering wheel is turned to the left the operating sequence is as above but the pressure is applied to the opposite side of the
piston.

Servotronic Operation

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

If a failure of the Servotronic valve or software occurs, the system will suspend Servotronic assistance and only normal power
steering wheel be available. Fault codes relating to the fault are stored, but no warning lamps are illuminated and the driver
may be aware of the steering being 'heavier' than usual.

When the vehicle is manoeuvred into and out of a parking space (or other similar manoeuvre), the Servotronic software uses
road speed data from the ABS module to determine the vehicle speed, which in this case will be slow or stationary. The
Servotronic software analyses the signals and outputs an appropriate control current to the Servotronic transducer valve. The
Servotronic valve closes and prevents fluid flowing from the feed fluid radial groove to the reaction chamber. An orifice also

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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DTC Description Possible Causes Action U0401-00
Invalid Data Received
From ECM/PCM A - No
sub type information
ECM did not respond
properly to speed control
cancel or auto brake
cancel request
Check ECM for related DTCs and refer to relevant
DTC Index U0401-67
Invalid Data Received
From ECM/PCM A -
Signal incorrect after
event
ECM did not respond
properly to speed control
resume request
Check ECM for related DTCs and refer to relevant
DTC Index U0401-81
Invalid Data Received
From ECM/PCM A -
Invalid serial data
received
Invalid data received
from engine control
module
Bus signal/message
failure
Speed control inhibited
by ECM
Check the Engine Control Module for related DTCs
and refer to relevant DTC Index. If U040181 is
logged as historic but no other DTCs have logged in
the engine control module at the same time and
distance, it may be caused by cranking with low
voltage conditions. Check battery and charging
system according to instructions in the battery care
manual. Install the latest Engine Control Module
software using the manufacturer approved diagnostic
system, contact Dealer Technical Support before
replacing components U0415-53
Invalid Data Received
From Anti-Lock Braking
System (ABS) Control
Module - De-activated
Event information
Deactivated
Check the Anti-Lock Braking System Module for
related DTCs and refer to the relevant DTC index U0415-81
Invalid Data Received
From Anti-lock Brake
System (ABS) Control
Module - Invalid serial
data received
Stability assist fault
Check ABS module for related DTCs and refer to
relevant DTC Index U0417-67
Invalid Data Received
From Park Brake
Control Module - Signal
incorrect after event
Parking brake module did
not respond properly to
apply request
Check parking brake module for related DTCs and
refer to relevant DTC Index U0417-81
Invalid Data Received
From Park Brake
Control Module -
Invalid serial data
received
Speed control inhibited
by parking brake module
Check parking brake module for related DTCs and
refer to relevant DTC Index U0418-68
Invalid Data Received
From Brake System
Control Module - Event
information
Event information
Check the Anti-Lock Braking System Module for
related DTCs and refer to the relevant DTC index U0421-81
Invalid Data Received
From Suspension
Control Module 'A' -
Invalid serial data
received
Invalid serial data
received
Check the Suspension Control Module for related
DTCs and refer to the relevant DTC index U0423-81
Invalid Data Received
From Instrument Panel
Control Module -
Invalid serial data
received
Speed control inhibited
by instrument cluster
Check instrument cluster, CJB and RJB for related
DTCs and refer to relevant DTC Index U1A00-88
Private Communication
Network - Bus off
Bus off
The module setting this code has disabled CAN
transmission. Check for other bus off codes. Check
the module and circuits. Refer to the electrical circuit
diagrams. Clear all DTCs and road test the vehicle. If
the concern reoccurs contact Dealer Technical
Support for further advice. Under no circumstance
should any parts be replaced to overcome this issue U1A14-49
CAN Initialisation
Failure - Internal
electronic failure
Internal electronic failure
Suspect the speed control module. Check and install
a new module as required, refer to the new
module/component installation note at the top of
the DTC Index U2101-00
Control Module
Configuration
Incompatible - No sub
type information
Data sent from RJB is
invalid
Check/amend Car Configuration File using the
manufacturer approved diagnostic system, clear DTC
and re-test. If DTC remains, re-configure RJB using
manufacturer approved diagnostic system, clear DTC
and re-test. If DTC remains check RJB for DTCs and