1994 JAGUAR XJ6 tire pressure

@ Steering
Cause
Fluid level low?
Drive belt slack
(V12)
Pump drive loose (6cyl)
center pressures low
Air in system due to loose connection
Pump shaft seal faulty (fluid loss)
Delivery pressure or flow too low
Return flow restricted by blocked reser
-
voir filter
Both check valves blocked
Rack damper too
tight
Lower column incorrectly set
Excessive upper column friction
Faulty rotary valve or seal
Drive belt slack
(VI217
Engine idle speed too low
Pump drive loose
(6cyl)
Air in system due to loose connection
Pump shaft seal faulty (fluid
loss)
Delivery pressure or flow too low
Fluid level low?
tire pressures
high
Air in system due to loose connection
Stiff or seized steering joint
Rack damper too tight
Castor or tracking error
Lower column over extended
Fluid level low?
Air
in system due to loose connection
Pump shaft seal faulty (fluid
loss)
Rack damper loose
Pinion bearing faulty
Rack or column fixings loose
Rack mounting bracket loose
Rack mounting bush loose
Free play in column assembly
10.4 DIAGNOSTIC PROCEDURE
10.4.1 Introduction
The following diagnostic procedures are provided to rapidly pin-point mechanical faults which are not interrogated
by electrical means. Diagnostic procedures which require dedicated electrically operated equipment are dealt with in the 'Electrical Diagnostic Manual' (EDM) but may be mentioned here for reference.
10.4.2 Preliminary Action
Before any problem solving is undertaken it is essential that the fluid level and where applicable, belt tension, is
checked and if required corrected.
CAUTION: It is imperative that the power steering system does not become contaminated in any way. Always de cant fluid from a fresh sealed container and clean the area around the reservoir neck both before and after
topping-up. Never return drained fluid to the system.
10.4.2 Diagnostic Chart 1
Remedy
Rectify fluid loss and or top up
Re
-tension belt
Renew pump
Set to specification
Secure connection and bleed air out
Renew pump
Renew pump
Renew reservoir
Renew rack
Renew rack
Set to specification
Renew upper column
Renew rack
Retension belt
Reset idle speed
Renew
pump
Secure connection and bleed air out
Renew
pump
Renew pump
Rectify
fluid loss and or top up
Set to specification
Secure connection and bleed air out
Test and renew faulty joint
Renew rack
Check geometry and rectify
if required
Set to specification
Rectify fluid
loss and or top up
Secure connection and bleed air out
Renew pump
Renew rack
Renew rack
Tighten to specification
Renew rack
Renew rack
Check and rectify as required
Trouble
Heavy on both sides
Heavy on one side
Heavy when steering
rapidly
Vague feel about center
Knocking
1 vibration felt
at steering wheel
0
0
0
0
Issue 1 August 1994 6 X300 VSM

10.4.3 Diagnostic chart 2
0 Trouble
'lay at steering wheel
ieavy when stationary
Excessively heavy when
hiving, stationary effort
3K
Too easy when driving,
itationary effort OK
fffort not equal side to
;ide from center
dariation from heavy to
?asy when driving
:yclic load variation at steering wheel - 2 per
.evolution
:losely spaced cyclic
oad variation at steering
Nheel
Cause
Rack damper loose
Pinion bearing loose
Worn intermediate shaft joint
Worn suspension joint
Loose lower column 'pinch' bolt
Transducer not closed
Transducer not closed
- ground short
Transducer not closed
- no feed voltage
Transducer not closed
- defective cable
SCM defective
Delivery pressure or flow too low
Internal rack leakage
tire pressures low
Transducer open too early
Transducer open too early, incorrect SCM
h/Pe
Transducer open too early, incorrect
speedometer signal
Rack 'reaction limitation valve' CLOSED
or setting incorrect
Transducer not open (no oil flow)
Transducer not open, SCM faulty
Transducer not open, incorrect speedom
-
eter signal
Rack 'reaction limiting valve' OPEN or
setting incorrect
Low pressure pipe 'flattened' or re
-
stricted
Blocked reservoir filter
tire pressure high
Rack check valve leak
Rotary valve blockage Incorrect lower column assembly, see
'Cyclic load variations'
Incorrect speedometer signal
Transducer cable
/ connection faulty or
grounded
Lower column universal joint fitting error
Rack damper too tight
Remedy
Renew rack
Renew rack
Renew joint
Renew joint
Tighten to specification
Inspect and check for debris
Renew transducer*
Investigate and repair
Renew cable
Renew module*
Renew pump
Renew rack
Set to specification
Renew transducer*
Renew
SCM*
Renew speedometer transmitter*
Renew rack
Inspect and check for debris
Renew
SCM*
Renew speedometer transmitter*
Renew rack
Renew pipe
Renew filter
Set to specification
Renew rack
Renew rack
Rectify as required
Renew speedometer transmitter*
Investigate and repair
Verify that the lower column assembly is
correct for that drive.
RH and LH assem- blies MUST NOT be interchanged due to
joint phase differences
Renew rack
W: Items marked * should be validated using EDM test procedures.
X300 VSM 7 Issue 1 August 1994

may include:
0
0
Loose or worn wheel bearings.
Loose or worn suspensions or steering components.
0 Worn or damaged drive shaft slip yoke joint.
0 Front disc rotor runout.
o Loose engine or transmission supports.
0 Driveline alignment.
0 Engine driven accessories.
Suspension Systems
11.4 DIAGNOSIS AND TESTING
' 11.4.1 Tire Wear
Tires should be inspected as abnormal or excessive wear may becaused by incorrect wheel alignment, wheelbire im- balance, or incorrect tire pressure.
1 1.4.2 vibration and Roughness
Vibration, roughness, and shimmy conditions may be caused by excessive tire or wheel runout, worn or cupped tires,
or wheel and tire unbalance.
Most of these conditions are due to irregularities in the road surface, hence driving the vehicle on different types of
road surface will often indicate the cause of the condition.
Do not automatically suspect the tires when attempting to diagnose a vibration concern as other sources of vibration
Before investigating any other vibration concerns,
a roaG &est and a customer inter\,.dw (if possible) should be carried
out. This can provide much of the information needed to find the source of vibration.
Drive the vehicle on a road that is preferably smooth and free of undulation and
if vibration is apparent note, the speed at which thevibration occurs, whattype of vibration occurs in each speed range (mechanical or audible), howthevibra- tion is affected by changes in vehicle speed , engine speed and engine torque, and the type of vibration sensitivity
(torque sensitive, vehicle speed sensitive, or speed sensitive).
Some of the condition terms used when describing sources of vibration are explained as follows:
0 Torque Sensitive
This condition can be improved or worsened by accelerating, decelerating, coasting, maintaining
a steady
vehicle speed and application of engine torque.
0 Vehicle Speed Sensitive
This means that the vibration always occurs at the same vehicle speed and is not affected by engine torque,
engine rpm, or transmission gear selection.
B
0 Engine Speed Sensitive
This means that the vibration occurs
at varying vehicle speeds when a different transmission gear is selected.
It can sometimes be isolated by increasing or decreasing engine speed with the transmission in 'NEUTRAL', or
by stall testing with the engine in gear. If the condition is enginesensitive, the condition is not related to tires.
If the road tests indicates that the vibration is related to the tires or wheels,use a 'lire Wear Diagnosis Chart' to
investigate the cause of concern. Should the road test indicate that there is tire whine, but noshake or vibration,
the noise originates from the contact between the tire and the road surface.
X300 VSM 3 Issue 1 August 1994

Suspension Systems
11.4.3 Front End Inspection
Do not check and adjust front wheel alignment without carrying out the following inspection for front end damage and
wear:
. Check for specified air pressure in all four tires.
Raise front of vehicle off the floor; grasping upper and lower surface of the tire, shake each front wheel to check for
. Check front suspension lower arm ball joint and mounts for looseness, wear and damage.
Check steering gear mountings and all steering linkages for looseness.
. Renew parts if necessary.
. Grasp upper and lower surface of tire and shake each wheel to check wheel bearing end play.
. Check the action of the front dampers and the condition of their attachments, as sticking or binding front dampers
worn
bearings.
Check brake caliper mountings.
may not allow the vehicle to settle in to a normal level position, possibly affecting the front-wheel alignment.
m: Front wheel bearings are adjustable (0.001 to 0.003 in. endfloat).
11.4.4
. Check the wheel bearings.
. Inspect the front suspension upper joint and renew front suspension lower wishbone if needed.
Raise vehicle and position floor jacks beneath the front suspension lower wishbone.
Grasp the lower edge of the tire and move the wheel in and out.
While moving the wheel, observe the upper and lower wishbone.
. Movement between the vertical links and the wishbones indicates abnormal ball joint wear.
. Renew ball joints.
. Check the front wheel bearings.
. Check for excessive play and wear.
Upper / Lower Ball Joint Inspection
11.4.5 Damper Inspection
m: The gas-pressurized hydraulic front dampers are not serviceable, adjustable or refillable.
Verify that all attachments of the suspension components and the front dampers are tight. Renew any front damper
. Check front dampers for external damage.
. Check for oil leakage and vehicle sag.
that
has a damaged integral lower mounting bushing.
0 Oil Leak
Leakage is the condition in which the entire damper body is covered with oil and from where
it will drip on to
the pavement. Due to correct damper lubrication a light film of oil (weepage) can usually be seen on the upper
portion of the damper.
Should there be any leakage, ensure that the fluid does not originate from sources other than the front damper.
Renew worn or damaged dampers.
0 Vehicle Sag
Renewing front dampers will not correct the problem of vehicle sag, as basically this is controlled by the spring
units.
issue 1 August 1994 4 X300 VSM

Suspension Systems
1 1.4.6 Rear Suspension lnspe&on
Check damper operation.
Check condition of rear wishbone bushings and rear suspension strut bushings.
Renew damaged or worn components.
0 Check for evidence of fluid leaks on rear dampers.
11.4.7 Vehicle Inspection
Check all tires for correct inflation pressure.
Checktire condition to confirm correct front end alignment, tire balance and overall tire conditions such as separation
Check the vehicle attitude for evidence of possible overload or sagging.
Check luggage compartment area.
. Road test vehicle to confirm customer's concern.
or
bulges.
X300 VSM 5 Issue 1 August 1994 ~ ~~

Suspension Systems
1 1.4.8 Diagnostic Procedure
Condition
Hard steering
Shimmy
I----
Bump steer (unequal
side-to-side)
Sawtooth pattern or
t excessive tire wear
Uneven tire wear
(outer or inner
shoulder)
Fronvrear
suspension noises
Possible Cause
Side-to-side difference in caster.
Tire pressure Steering gear or linkage worn or defective.
Tire
conicity
Power steering gear or linkage worn,
damaged, or incorrect adjusted.
Wear of front suspension
lower/upper
wishbone ball joints.
Unequal tire pressure.
Brake system
fault(s)
Wheel/tire imbalance or runout.
Damaged tires, unbalanced or damaged
wheels.
Incorrect wheel alignment.
Steering system malfunction
Front damper malfunction.
Loose front damper mounting.
Damaged front suspension upper
or lower
ball joints.
Damaged or worn sub
-frame to body
mounting. Damaged or worn stabilizer bar insulators.
Damaged or worn stabilizer bar link.
Damaaed or worn wheel bearina.
Rear suspension damage.
Worn steering gear mounting bracket
housing insulators.
Excessive toe
-in (high edges inboard) or
toe-out (high edges outboard).
Incorrect tire pressure.
Excessive toe.
Excessive positive or negative camber.
Loose/missing front dampers and front
damper bolt to front suspension lower
wish bone.
Action
Check the alignment and if incorrect,
adjust the caster
if needed. Inspect
components for wear or damage.
Check for abnormal loading.
Check steering system
Inspect tire for excessive wear.
Check and adjust the tire air pressure.
Note: Excessively worn or uneven tires can
cause
pull/drift.
Check steering system.
Renew ball joints.
Inflate the tires to correct and uniform
pressure.
Check the brakes.
Check wheels and tires.
Check the tires and renew
if necessary.
Balance the wheels
if necessary.
Adjust wheel alignment.
Check steering system.
Renew front damper
if necessary.
Tighten front damper mounting.
-
Renew upper and lower ball joint.
Renew rear suspension bushing.
Renew insulators.
Renew link.
Renew/adjust wheel bearing.
If the caster is uniform, check and compare
the wheelbase at the right and left sides.
If
different, inspect the suspension
components for wear and damage.
Renew bracket housing insulators.
Check and adjust toe
-in.
Correct tire pressure.
Check toe and adjust
if needed.
Check the camber and
if incorrect inspect
the related components for wear or
damage.
Tighten/renew damper bolts.
Inspect wheel hubs.
0
0
0
lssue 1 August 1994 6 X300 VSM

Suspension Systems I.\" b-
1 1.4.8 Diagnostic Procedure (continued)
Condition
30dy 'rolls'
3ody leans
'oor ride comfort
Seneral driving
nstability
Steering wheel does
lot return properly
Steering wheel pulls
:o one side
4bnormal noise
from suspension
system
Possible Cause
Weak front stabilizer bar.
Damaged or worn lower wishbone stabilizer
bar insulator. Damaged or worn stabilizer bar link
Damaged or worn rear suspension
wishbone bushing.
Damper malfunction.
Worn or deteriorated rear stabilizer bar
bushing(s). (supercharged, sports and XJ12
only)
Damaged or worn rear wishbone bushing
and weak springs.
Worn or deteriorated rear stabilizer bar
bushing(s). (supercharged, sports and XJ12
only)
Front or rear damper malfunction.
Weak
spring(s1
Damaged tires or unbalanced wheels.
Incorrect wheel alignment.
Steering system malfunction.
Damaged front suspension lower and upper
ball joints.
Damaged or worn sub
-frame to body
mounting.
Damaged or worn stabilizer bar link
Damaged or worn lower wishbone stabilizer
bar insulator.
Weak
spring(s)
Worn or deteriorated rear stabilizer bushing
(s). (supercharged, sports and XJ12 only)
Damaged tires or unbalanced wheels and
incorrect tire pressure.
Incorrect wheel alignment.
Steering system malfunction.
Damaged front suspension lower and upper
ball joints.
Incorrect tire pressure.
Damaged front suspension lower and upper
ball joints. Braking system malfunction.
Steering system malfunction.
Damaged or worn sub
-frame to body
mounting.
Damaged tires, unbalanced wheels and
incorrect tire pressure.
Poor lubrication /wear of wheel bearing.
Wear of front suspension lower and upper
ball joints.
Damaged or worn front stabilizer bar
Damaged or worn stabilizer bar link.
Damaged or worn stabilizer bar bracket.
Looseness of suspension connections.
Damaged or worn rear wishbone bushing.
Front and rear damper malfunction.
Weak
spring.Worn or deteriorated rear
stabilizer bushing
(s). (supercharged, sports
and
XJ12 only)
Action
3enew front stabilizer bar.
3enew insulators.
3enew link.
Renew bushing.
Renew damper
if necessary.
Renew Bushina
Renew bushings and springs.
Renew Bushings.
Renew dampers.
Renew springs.
Check the tires.
Adjust the wheel alignment.
Check steering system.
Renew ball joints.
Renew bushing.
Renew link.
Renew insulator.
Renew springs.
Renew bushing
Check tires.
Adjust the wheel alignment.
Check steering system.
Renew ball joints.
Check and correct tire pressure.
Renew ball joints.
Check brakes.
Check steering system.
Renew bushing.
Check tires.
Renew wheel bearing.
Renew ball joints.
Renew stabilizer bar.
Renew link.
Renew bracket.
Tighten connections.
Renew bushing.
Renew dampers.
Renew bushing
Issue 1 August 1994 X300 VSM 7

From the low pressure accumulators,volume is pumped back into theTMC, forcing the brake pedal back. To optimize the friction coefficient between tire and road, brake pressure is increased in small steps by closing the outlet valve and
opening the inlet valve and re-charging brake pressure.
During the pressure build
up phase, the volume required for replenishment is supplied by the TMC and additionally
by the pump from the low pressure accumulators. Since the delivered flow is generally greater than volume flow
drained from the brake circuits, the low pressure accumulators serve as intermediate accumulators to compensate for
temporary volume flow peaks.
The TMC piston positions, and therefore the brake pedal, vary with the fluid displacement in the brake caliper. As con
-
trolled pressure in the brake caliper decreases and increases during ABS, the brake pedal 'cycles', informing the driver
that controlled braking is in progress.
Actuation of the brake pedal, causes the central valve (item
5) in the TMC to close. This action prevents damage to the
TMC piston seals.
At the end of a brake application, volume is restored to the TMC, at
low pressure from the fluid reservoir (item 6).
Issue 1 August 1994 X300 VSM 13