1998 JAGUAR X308 steering wheel

Brake System - General Inform
ation - Brake System
D
iagnosis and Testing
Principles of Operations
The brake system operates by transferring effort applied to th e brake pedal, by the driver to the brakes at each wheel.
The braking effort is distributed to each wheel, using a hydraulic system. The system is assisted using a vacuum brake
booster that reduces pedal effort for a given hydraulic pressure. The parking brake operates on the rear wheels and is
applied using a hand operated control.
I
nspection and Verification
•
NOTE: Prior to carrying out any diagno
sis, make sure that the brake system warning indicator is functional.
Visually examine the front and rear tire and wheel assemblies for damage such as un even wear patterns, tread worn out or
sidewall damage. Verify the tires are th e same size, type and, where possible, same manufacture. Replace the damaged
wheel or excessively worn tire. For a dditional information, refer toSection 204
-0
4 Wheels and Tires
.
W
heels and tires must be cleared of an
y foreign matter and tire pressures ad justed to the correct specification.
If the tires exhibit uneven wear or feathering, the cause must be corrected. Check the steering and suspension components
for damage or wear and, if ne cessary, check and adjust front wheel alignment. For additional information, refer toSection
204
-00 Suspen
sion System
- General Informati
on
.
Road Test


V
isual Inspection Chart
Carr

y out a road test to compare actual vehicle braking performance with the
performance standards expected by the
driver. The ability of the test driver to make valid compar isons and detect performance deficiencies will depend on
experience.
The driver should have a thorough knowledge of brake system operation and accepted general performance guidelines to
make good comparisons and de tect performance concerns.
An experienced brake technician will always establish a route that will be used for all br ake diagnosis road tests. The roads
selected will be reasonably smooth and level. Gravel or bump y roads are not suitable because the surface does not allow the
tires to grip the road equally. Crowned roads should be avoide d because of the large amount of weight shifted to the low set
of wheels on this type of road. Once th e route is established and consistently used, the road surface variable can be
eliminated from the test results.
Before a road test, obtain a complete description of the customer concerns or suspec ted condition. From the description, the
technician's experience will allow the te chnician to match possible causes with symptoms. Certain components will be
tagged as possible suspects while others wi ll be eliminated by the evidence. More importantly, the customer description can
reveal unsafe conditions which should be ch ecked or corrected before the road test. The description will also help form the
basic approach to the road test by narrowing the concern to specific components, vehicle speed or conditions.
Begin the road test with a general brake performance check. Keeping the description of the concern in mind, test the brakes
at different vehicle speeds using both ligh t and heavy pedal pressure. To determine if the concern is in the front or rear
braking system, use the brake pe dal and then use the parking brake control. If the condition (pull, vibration, pulsation)
MechanicalElectrical
Brake m
aster cylinder
Parkin
g brake switch
Brake ca

liper piston(s)
D
amaged or corroded wiring harness
Brake di

scs
B
rake master cylinder fluid level switch
Wh

eel bearin
gs
Brake pads
Power brake booster
Brake ped

al linkage
Boost

er vacuum hose
Tire

s
De

bris

oc
curs only with the parking brake, th
e concern is in the rear brake system.
If the concern becomes evident during this check, verify it fits the description given before the road test. If the concern is
not evident, attempt to duplicate the condition using the information from the description.
If a concern exists, use the Symptom Chart in order to isolate it to a specific sub-system and condition description. From
this description, a list of possible sources can be used to further narrow the cause to a specific component or condition.
Sym
ptom Chart
Sy
m
ptom
Possib
l
e Sources
Acti
o
n
Brakes
n
oisy
Brake pads.
Brake di
scs
.
*
*
GO to Pinpoint
Tes
t A.
*
Vibration wh
en brakes
are applied
Wh eels require bala
ncing.
Wheel hub nuts.
Caliper mounting bolts.
Brake pads.
Foreign material/scr atches/corrosion
on brake disc contact surfaces. Excessive brake disc thickness
variation. Excessive brake disc runout.
Wheel bearing wear or failure.
Suspension bush wear or failure.
Steering bush wear or failure.
*
*
*
*
*
*
*
*
*
*
Go to Pinpoint
Tes
t B.
*
The brakes pull or drif tTire pressures/wear.
Calipers.
Brake pads.
Brake di
scs.
Wheel alignment adjustment.
Wheel bearing.
Suspension bushes and ball joints.
*
*
*
*
*
*
*
GO to Pinpoint
Tes
t C.
*
The pedal feels spongyAir i
n brake system.
Leak in hydraulic system.
Brake booster/master cylinder.
Brake pads.
*
*
*
*
GO to Pinpoint Tes
t D.
*
The pedal goes down
fa s
t
Ai
r i
n brake system.
Leak in hydraulic system.
Brake booster/master cylinder.
Brake pads.
*
*
*
*
GO to Pinpoint
Tes
t E.
*
The pedal goes down
slowl yAir i
n brake system.
Brake booster/master cylinder.
*
*
Go to Pinpoint
Tes
t F.
*
Excessive brake pedal
effor tBrake pads.
Brake booster.
*
*GO to Pinpoint
Tes
t G.
*
Brake lockup du ring ligh
t

brake pedal force
Brake pads.
Calipers.
*
*GO to Pinpoint
Tes
t H.
*
Brakes d r
ag
Parkin
g brake con
trol
applied/malfunction. Seized parking brake cables.
Seized caliper slide pins.
Seized caliper.
Brake booster.
Pedal gear.
*
*
*
*
*
*
GO to Pinpoint
Tes
t I.
*
Exce ssi
ve/Erratic brake
pedal travel
Hydrau li
c system.
Brake pads.
Brake discs.
Hub and bearing assembly.
*
*
*
*
GO to Pinpoint
Tes
t J.
*
The red brak e warning
indi
cator is always on
Fl
ui
d level.
*
F I
LL the system to specification. CHECK for leaks.
*
Brake flu i
d level sensor.
*
I N
STALL a new brake master cylinder fluid
reservoir. For additional in formation, refer toSection
206
-0 6
Hydraulic Brake Actuation
.
*
Parkin
g brake con
trol.
*
REL
E
ASE and ADJUST the parking brake. For
additional information, refer toSection 206
-05
Parkin g Brake an
d Actuation
.
*
E
l
ectrical circuit.
*
F or additional
information, refer to PDU for
analysis/rectification of the concern.
*
Sl
ow or i
ncomplete brake

Brake peda
l binding.
*
GO to Pinpoint Tes
t K.
*

pedal retu rnBr
ake booster/master cylinder.
*

i
nstalled to prevent it fouling on the steering and suspension
components.
After installation the brake ho se must be aligned with the
center line as shown.

4. Install brake hose to
caliper.
Remove plugs f

rom caliper and hose.
Inst

all new sealing washers.
Align hos

e as shown above.
Install and tigh

ten union bolt to 22-26 Nm.
5. Remove special tool from brake pedal.
6. Fit wheels. Refer to operation 74.20.05.
7. NOTE: Make sure the brake hose is routed correctly.
Remove stands and lower vehicl e. Refer to section 100-02.
8. Bleed brake hydraulic system. Refer to operation 70.25.06.

Stee
ring System - General Information -
S
teering Linkage Specifications
Power Steering Pump Specifications
Lubricants, Fluids, Sealers and Adhesives


S
teering Linkage Free Play
Meas
urement (mm)
Meas
urement (in)
F

ree play (measured at
the steering wheel rim)
0-
6
0
-0.24
It

em
S
pecification
Power steeri

ng pump relief pressure
10
6-114 bar
It

em
S
pecification
Power steeri

ng fluid
De
xtron 3

Steering System - General Inform
ation - Steering System
D
iagnosis and Testing
I

nspection and Verification
1.
1. Verify t
he customer concern by driving the vehicle.
2. 2. Visually inspect for obvious signs of mechanical or electrical damage.
Mec
hanical Inspection Chart
Electrical Inspection Chart
Mechanical Checks
Incorrect
tire pressure, loose whee
l nuts, incorrect wheel alignment
Loose ti
e-rods
Loose dam

per and spring assemblies or ball joint
Loose s

teering column shaft universal joints
Loose pinc

h bolts on steering column shaft
Loose steeri

ng gear assembly
Check f

or external damage to the steering gear.
- Damaged tie-rods
-
CAUTION: If a steering gear assemb ly is returned under warranty with leaking 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 seals being damaged due to fore ign materials entering the steering gear boot and damaging the steering
gear seals thereafter.
Damaged steering gear boot
Damaged accessory driv
e belt
Bin

ding or misaligned steering co
lumn, pump or steering gear
Incorrect fluid
level
Hose leaks o

r line restrictions
Hose fou

ling bodywork
El

ectrical Checks/Tests
Make sure all

connectors are in plac
e (steering gear Servotronic solenoid and steering control module (SCM) - if
applicable)
Make su
re all the fuses are in place and not blown
D

ISCONNECT the steering gear transducer
and the steering should become heavy
TEST e
lectrical values:
- Power Supply to the SCM = 12 Volts
- Steering gear transducer resist ance 7.0 to 7.5 Ohms is normal
(
limits: less than 5 Ohms and greater than 9 Ohms would

be declared unacceptable)

- Steeri
ng gear transducer voltage = 6 Volts
- Steering gear transducer cu rrent = 840 mA at 0 mph reducing to 0 mA at maximum speed

•
NOTE: The following steps must be carried out with assistance.
1. 1. With the wheels in the straight ahead po sition, gently turn the steering wheel to the left and the right to check for
free play.
2. 2. Free play should be between 0 and 6 mm (0 and 0.24 in) at the steering wheel rim. If the free play exceeds this
limit, either the ball joints are worn, the lower steering column joints are worn or the backlash of the steering gear
is excessive.
CAUTION: DO NOT attempt to adjust the stee ring gear yoke. Failure to follow this instruction will result in the steering
gear warranty to become invalid.
3. 3. The backlash of the steering gear cannot be adjusted, in stall a new steering gear. For additional information,
REFER to Section 211
-0
2 Power Steering
.
4. 4. Grasp the steering wheel
firm
ly and move it up and down and to the left and right without turning the wheel to
check for column bearing wear, steering wheel or steering column. For additional information,
REFER to Section 211
-0
4 Steering Column
.
Power Steering Fluid Condition Check
1.
1. R
un the engine for 2 minutes.
2. 2. Check the power steering fluid system level.
3. 3. Observe the color and the odor. The color under normal circumstances should be dark reddish, not brown or
black.
4. 4. Allow the fluid to drip onto a faci al tissue and examine the stain.
5. 5. If evidence of solid material is foun d, the power steering fluid system should be drained for further inspection.
6. 6. If fluid contamination or steering co mponent failure is confirmed by the se diment in the power steering fluid
system, REFER to Steering Fault Diagnosis by Symptom Charts in this section.
Power Steer
ing Pressure Test
Test Equ
ipment

It
em
S
pecial Tool Number
De
scription
12

11-011
Pres
sure Gauge Hose
221

1-011-08
Pump Return Hose
321

1-011-07
Pump Return Hose Connector
42

11-011-03/2
Test Equ
ipment to High
Pressure Hose Adaptor

Function
al
Fl
uid
leakage
O
verfilled system.
CORRECT the
fluid leve
l as necessary.
Compon
ent leak.
•
NOTE: Record the position of the le
ak and some indication of the rate
of the leak on the Warra nty Return Record Sheet.
LOCATE
the suspect component or CHECK hose connections and
repair as necessary.
Damaged fluid cap. INST
ALL a new fluid cap.
Loose or damaged h

ose
fittings.
TI
GHTEN or INSTALL a new hose as necessary.
Leakage at

power
steering pump.
INST
ALL a new power steering
pump as necessary. For
additional information,
REFER to Section 211
-0
2 Power Steering
.
Fl

uid
leakage
Leakage
at steering hose
to steering gear connection.
CHECK
steering hose to
steering gear conn ection for leakage.
CHECK and TIGHTEN the steeri ng hose to steering gear
connection retaining bolt s/bolts as necessary.
Power steeri
ng fluid
leakage at O-ring seals.
CHECK
the power steering system fo
r signs of steering fluid loss
from O-ring seals.
INST
ALL new O-ring seals as necessary.
BLEE

D the power steering system.
For additional information,
REF
ER to Section 211
-0
0 Steering System
- Ge
neral
Informati

on
.
Power steeri

ng fluid
leakage from transfer pipes.
CHECK
the power steering system fo
r signs of steering fluid loss
from the transfer pipes.
CHECK
and TIGHTEN the transfer pipes if required, INSTALL new

transfer pipes as necessary.
BLEE
D the power steering system.
For additional information,
REF
ER to Section 211
-0
0 Steering System
- Ge
neral
Informati

on
.
Power steeri

ng fluid
leakage from the steering
gear.
CHECK
the power steering gear for signs of fluid loss.
INST

ALL a new steering gear as
necessary. For additional
information,
REFER to Section 211
-0
2 Power Steering
.
Power steeri

ng fluid
leakage from steering gear boot.
CHECK
the power steering gear for signs of fluid loss.
INST

ALL a new steering gear as
necessary. For additional
information,
REFER to Section 211
-0
2 Power Steering
.
Cond

ition
Possib
le Sources
Acti
on
F

ree play at steering wheel

Exce
ss play in the steering

linkage.
CHECK
the steering linkage for excess play.

For additional information, REFER to the
Steering Linkage Inspection and Backlash (Freeplay) Check in this section.
S
teering wheel loose.
CHECK
and TIGHTEN the steering wheel
retaining bolt/bolts as necessary. For additional information,
REFER to Section 211
-0
4 Steering Column
.
Lower steeri

ng column
pinch bolt loose.
CHECK
and TIGHTEN the lower steering
column pinch bolts as necessary. For additional information,
REFER to Section 211
-0
4 Steering Column
.
Exce

ssive wear in lower
steering column.
CHECK
for lower steering column for wear in

the universal joints. If wear is present,
INSTALL a new lower steering column as necessary.
W
ear in suspension joints.
CAU
TION: DO NOT attempt to adjust the
steering gear yoke. Failure to follow this instruction
will result in the steering gear warranty to become
invalid.
CHECK
for excess wear in the front
suspension joints. For additional information,
REFER to Section 204
-00
Suspension
Sy

stem
- General
Information
.

Vehicl
e wanders from side to

side on the road, when the vehicle is driven straight ahead and the steering wheel is held in a firm position
Incorrect ti re
pressure or
tire size.
CHECK and ADJ
UST the tire pressure. For
additional information,
REFER to Section 204
-0 4
Wheels and Tires
. IN
ST
ALL a new tire as necessary. For
additional information,
REFER to Section 204
-0 4
Wheels and Tires
.
Vehi
cl
e is unevenly or
excessively loaded.
A D
JUST the load evenly.
Loose/worn ti
e-
rods.
INST
ALL a ne
w tie-rod
end. For additional
information,
REFER to Section 211
-0 3
Steering Linkage
.
Steeri
ng gear bolts loose
o
r damaged.
TIGHTE
N or INSTALL
new bolts.
Loose or worn suspensi
on
ball jo
int(s).
INST
ALL a ne
w suspension ball joint
assembly. For additional information,
REFER to Section 204
-01 Fron
t Suspension
.
Steeri
ng column uni
versal
joint pinch bolt loose.
TI G
HTEN the steering column universal joint

pinch bolt. For additi onal information,
REFER to Section 211
-0 4
Steering Column
.
Incorre
ct
toe adjustment.

ADJUS
T as necessary. For additional
information,
REFER to Section 204
-00 Sus
pension
Sy
ste
m
- General

Information
.
Loose or worn rear
susp
ension.
TIGHTEN
loose, or IN
STALL new rear
suspension components. For additional information,
REFER to Section 204
-0 2
Rear Suspension
.
Vehicle t
e
nds to pull to one
side when driven on a level surface
Incorrect ti
re pressure.
Incorrect
ti
re size or
different tire/tread type.
Uneven tire wear
CHECK and ADJ
UST the tire pressure. For
additional information,
REFER to Section 204
-0 4
Wheels and Tires
. IN
ST
ALL a new tire as necessary. For
additional information,
REFER to Section 204
-04
Wheels and Tires
.
Vehicl

e is unevenly loaded
or overloaded.
Adjust the load
.
Incorre
ct
toe adjustment.

ADJUS
T as necessary. For additional
information,
REFER to Section 204
-00 Sus
pension
Sy
ste
m
- General

Information
.
Dam
a
ged front suspension

components.
I N
STALL new front suspension components
as necessary. For addi tional information,
REFER to Section 204
-01 Fron
t Suspension
.
Damaged rear
suspen
sion
components.
INST ALL ne
w rear suspension components
as necessary. For addi tional information,
REFER to Section 204
-0 2
Rear Suspension
.
Steeri
ng gear val
ve effort
out of balance.
SHIF T the
transmission into NEUTRAL while
driving at no more than 30 miles/hour (50 km/h) and turn the ignition to position I
(engine OFF-coasting). If the vehicle does
not pull with the engine off, INSTALL a new steering gear. For additional information,
REF E
R to Section 211
-0
2
Power Steering
. If t
he
vehicle does drift with the engine off,
CROSS SWITCH front wheel assemblies.
If the
vehicle pulls to
the opposite side,
SWITCH wheels that were on the rear to the
same side on the front.
If the v
ehicle pull dire
ction is not changed,
CHECK the front susp ension components
and toe adjustments. For additional information,
REFER to Section 204
-01 Fron
t Suspension
.
Chec
k
the front and rear
brakes for correct operation.
ADJUS
T as necessary. For additional
information,
REFER to Section 206
-0 0
Brake System
-
General Informati on.
Check fo
r bent rear
INST
ALL ne
w rear suspension components