2010 JAGUAR XFR tire pressure

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

Symptom Possible Causes Action

Wear in steering gear tie-rod end ball joints
Check and install new tie-rod
ends as required, refer to the
new module/component
installation note at the top of
the Symptom Charts
NOTE: Inner ball joint wear is rare. The steering
gear installed to all Jaguar vehicles has a spring
loaded pinion to ensure the correct level of
engagement between the rack and pinion. This play
is optimized with the steering gear in the central
position and should not be confused with inner ball
joint wear. Check for vertical motion in the inner ball
joint with the steering gear in the central position.
Wear in steering gear inner ball joints


Check and install new steering
gear as required, refer to the
new module/component
installation note at the top of
the Symptom Charts
Wear in suspension ball joints/bushings
Check and install new
components as required















Veer under braking




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

Check and install a new steering
gear as required, refer to the
new module/component
installation note at the top of
the Symptom Charts


Contamination of brake pads and discs
Check and rectify the source of
the contamination and install
new brake pads and discs as
required, refer to the new
module/component installation
note at the top of the Symptom
Charts




Seized front brake caliper slide pins or piston
Damaged brake discs
Check and rectify sticking slide
pins and install new calipers as
required, refer to the new
module/component installation
note at the top of the Symptom
Charts
Check and install new brake discs
as required, refer to the new
module/component installation
note at the top of the Symptom
Charts








Vehicle pulls to one side
when driving on a level
surface




Uneven tire wear
Incorrect tire pressure
For information on diagnosis of
uneven tire wear.
REFER to: Suspension System (204-00 Suspension System -
General Information, Diagnosis
and Testing).
Check and adjust tire pressures
as required.
REFER to: Specifications (204-04 Wheels and Tires,
Specifications).


Incorrect geometry settings
NOTE: Dealerships must keep a
copy of the BEFORE and AFTER
geometry figures with job card for future
reference

Check and adjust geometry as
required. REFER to: (204-00

Symptom Possible Causes Action Suspension System - General
Information)
Camber and Caster Adjustment (General Procedures),
Front Toe Adjustment (General Procedures),
Rear Toe Adjustment (General Procedures).
Vehicle is unevenly loaded or overloaded
Notify the customer of incorrect
vehicle loading




Steering gear is not correctly adjusted
CAUTION: DO NOT attempt to
adjust the steering gear yoke. Failure to
follow this instruction will invalidate the
steering gear warranty

Check and install a new steering
gear as required, refer to the
new module/component
installation note at the top of
the Symptom Charts


Loose, damaged or worn front suspension
components
Check/tighten and install new
front suspension components as
required.
REFER to: Specifications (204-00 Suspension System - General
Information, Specifications).


Loose, damaged or worn rear suspension
components
Check/tighten and install new
rear suspension components as
required.
REFER to: Specifications (204-00 Suspension System - General
Information, Specifications).


Incorrect brake operation
For information on diagnosis of
the brake system.
REFER to: Brake System (206-00 Brake System - General
Information, Diagnosis and
Testing).

Incorrect underbody alignment
Set underbody alignment
referring to the Removal and
Installation procedures in section
502-00 of the workshop manual
for instruction








Vehicle wanders from
side to side when driven
straight ahead and the
steering wheel is held in
a firm position


Incorrect tire pressure or tire size
Check and adjust the tire
pressures as required.
REFER to: Specifications (204-04 Wheels and Tires,
Specifications).
Check and install a new tire as
required
Vehicle is unevenly or excessively loaded
Notify the customer of incorrect
vehicle loading



Incorrect toe adjustment
Check and adjust as required.
REFER to: (204-00 Suspension
System - General Information)
Camber and Caster Adjustment (General Procedures),
Front Toe Adjustment (General Procedures),
Rear Toe Adjustment (General Procedures).

Symptom Possible Causes Action
Knock
Loose fixings (universal joint
pinch bolt and steering column
fixings)
Tighten fixings to correct specification.
REFER to: Specifications (211-00 Steering System - General Information, Specifications).



Rattle
Foreign objects
Remove foreign objects from between steering
column shroud and steering wheel/steering
column rotating components
Loose fixings
Tighten steering column fixings to correct
specification.
REFER to: Specifications (211-00 Steering System - General Information, Specifications).



Noise while adjusting
column
Electric motor/solenoid
NOTE: Before carrying out repairs/replacement,
assess column adjustment noise levels against other
vehicles of the same model
Install new components as required
Motor spindle/lead screw
Lubricate lead screw Vibration

Symptom Possible Causes Action


Wheel Fight (Kick Back) - condition
where roughness is felt in the
steering wheel by the driver when
the vehicle is driven over rough
surfaces


Loose or worn steering
components/bushings
CAUTION: DO NOT attempt to adjust the
steering gear yoke. Failure to follow this
instruction will invalidate the steering gear
warranty.

Tighten and install new steering
components/bushings as required
Loose or worn suspension
components/bushings
Tighten and install new suspension
components/bushings as required

Nibble (Shimmy) - condition where
oscillation of the steering wheel
occurs (not vertical which is Shake).
This is driven by road wheel
imbalance

Road wheel and tire
condition
Check for wheel and tire damage. Install
new components as required
Check for tire uniformity. Install new
tire(s) as required
Road wheel imbalance
Check and adjust road wheel balance as
required
Shake - condition where vertical
vibration of the steering
wheel/column occurs (not
oscillation which is Nibble)
NOTE: Vibration smooths out
after several miles of driving

Road wheel imbalance due
to tire flat-spotting
Ensure tires installed are to Jaguar
specification. Install new tires as
required
Check and adjust tire pressures to
correct specification Component Tests

Steering Linkage Inspection and Backlash (Free play) Check


CAUTION: Steering gear boots must be handled carefully to avoid damage. Use new clamps when installing steering gear
boots.

Inspect the boots for cuts, deterioration, twisting or distortion. Check the steering gear boots to make sure they are tight.
Install new boots or clamps as required.


NOTE: The following steps must be carried out with assistance.

1. With the wheels in the straight ahead position, gently turn the steering wheel to the left and the right to check for free
play.

With the control valve (7) OPEN and the engine idling, the following system pressures may be checked:

During turning when static (dry parking pressure).
When the steering is held on full lock (maximum system pressure or pressure relief).
With the steering at rest (idle pressure or back pressure).
CAUTIONS:


To avoid excessive heating of the power steering pump when checking the pressure, do not close the valve for more than
5 seconds maximum.


When checking the pump pressure DO NOT drive the vehicle with the test equipment installed.

With the control valve (7) CLOSED the power steering pump maximum output pressure can be checked.

Removing Test Equipment

To remove the test equipment:

Install a hose clamp on the reservoir to power steering pump hose.
Removing the test equipment is a reversal of the installation instructions.
Install a new 'O' ring seal (9) to the power steering pump high pressure outlet to hose connection.
Install the original hose to the power steering pump.
Remove the clamp from the reservoir to the power steering pump hose.
Top-up the reservoir fluid.
Bleed the power steering system.
REFER to: Power Steering System Bleeding (211-00 Steering System - General Information, General Procedures).
Description of Terms General Steering System Noises
Boom
Rhythmic sound like a drum roll or distant thunder. May cause pressure on the ear drum.

Buzz

Low-pitched sound, like a bee. Usually associated with vibrations.

Chatter

Rapidly repeating metallic sound.

Chuckle

Rapid noise that sounds like a stick against the spokes of a spinning bicycle wheel.

Chirp

High pitched rapidly repeating sound, like chirping birds.

Click

Light sound, like a ball point pen being clicked.

Click/Thump

Heavy metal-to-metal sound, like a hammer striking steel.

Grind

Abrasive sound, like a grinding wheel or sandpaper rubbing against wood.

Groan/Moan

Continuous, low-pitched humming sound.

Groan/Howl

Low, guttural sound, like an angry dog.

Hiss

Continuous sound like air escaping from a tire valve.

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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Automatic braking is limited to approximately 30% of full pressure (0.3G deceleration) and is intended to provide a
smooth, gradual deceleration in follow mode conditions. Harsh braking by the target vehicle or following the target
vehicle down to very low speeds or to a halt will require driver override of the brakes.
While the radar sensor detects moving and stationary targets for assessment of the environment ahead, the system
does not react to or provide any control in situations other than follow mode conditions. Stationary or slow moving
vehicles (below 10 km/h), pedestrians, objects on the road and oncoming vehicles in the same lane are not recognized.


WARNING: The adaptive speed control system is not a collision warning or avoidance system and that, other than the
limited conditions of follow mode, driver intervention will be necessary to control the vehicle speed.
In follow mode, some situations may cause target ambiguities for the detection system. These situations include:
The nearby presence of a third vehicle when driving on a line slightly offset to the target vehicle.
Vehicles edging into the lane ahead which are not detected by the system until they have moved into the radar beam.

On the approach to, or exit from a bend, a target vehicle may be lost or a new target acquired as vehicles ahead change their
angular position with respect to the radar sensor. On a straight road, if the sensing vehicle is in follow mode below its selected
set speed, losing the target vehicle will cause the sensing vehicle to accelerate to this set speed. This acceleration is
undesirable either on, or entering a bend when the target is suddenly lost, and in this situation the system inhibits the
resumption of the set speed.

The speed control system compares vehicle speed data from the ABS system with the relative speed of an external object as
detected by the radar sensor to ascertain whether the object is stationary or not.


NOTE: If tires are fitted which are different in diameter from those specified for the vehicle, the vehicle speed calculated
by the ABS will not be the true road speed. This situation may cause stationary objects to be falsely identified as moving
vehicles and result in automatic deceleration on a clear road.



SPEED CONTROL SWITCHES Component Description

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