1994 JAGUAR XJ6 brakes

12.2 FAULT DIAGNOSIS AND TESTING
rrouble
-ong brake pedal
dibration during braking
'oor braking performance
3rakes pull to one side
3rakes do not release
ixcessive pedal travel
Cause
Brake caliper piston or caliper guide
pins sticking
Worn
I damaged brake pads
Worn
1 damaged brake pads
Loose caliper mounting bolts
Insufficient grease on sliding parts
Foreign material
or scratches on
brake rotor contact surface
Damaged brake rotor contact surface
Leak
in hydraulic system
Air
in system
Worn
I damaged brake pads
Foreign material on brake pads
Brake caliper piston malfunction
Tandem master cylinder malfunction
Vacuum booster fault
Disconnected
or damaged vacuum
hose
Low brake
fluid level
Worn
I damaged brake pads
Foreign material on brake pad
Failing valves
in ABS valve block
Abnormal wear or distortion on front
brake rotor
Incorrect wheel alignment
Incorrect tire pressure
No brake pedal free play
Vacuum booster
binding
Tandem master cylinder return port faulty
Faulty valve
in ABS valve block
Leak
in hydraulic system
Air
in system
Remedy
Service or renew caliper or caliper
guide pins
Renew brake pads
Renew brake pads
Tighten caliper mounting bolts
Apply grease where necessary
Clean brake rotor contact surface
Renew brake
rotor
Repair leak. Check all pipework con-
nections. Refill and bleed the system
Check the system
for leaks and bleed
brakes
Renew brake pads
Examine brake pads and clean
or
renew as necessary
Renew faulty brake caliper piston
Service
or renew tandem master cyl- inder
Renew vacuum booster
Renew vacuum hose
Check for leaks, refill and bleed the
system
Renew brake pads
Examine brake pads and clean
or renew as necessary
Renew valve block
Examine front brake
rotor and service
or renew as necessary
Carry out wheel alignment. Refer to
Section
11, iv Service Data
Inflate tire
to correct pressure
Adjust brake pedal free play
Renew vacuum booster
Clean return
port on tandem master cy I i nder
Renew valve block
Repair leak. Check all pipework con
- nections. Refill and bleed the system
Check the system
for leaks and bleed
brakes
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Issue 1 August 1994 16 X300 VSM

12.2 (continued)
rrouble
Excessive pedal travel (Cont'd)
Brakes grab
Brakes drag
Hard brake pedal when pressed
Excessive brake noise
Cause
Worn tandem master cylinder piston
seals or scored cylinder bore
'knock back'. Excessive brake rotor
run
-out or loose wheel bearings
Brake pads contaminated by grease
or brake fluid
Brake pads distorted, cracked or
loose
Loose caliper mounting bolts or
guide pins
Seized or incorrectly adjusted parking
brake or cable
Broken or weak parking brake return
springs
Caliper pistons seized
Brake pedal binding
at pivot points
Vacuum booster binding
Tandem master cylinder faulty
Lack of vacuum
at the vacuum
booster
Tandem master cylinder
pushrod
binding
Frozen tandem master cylinder pis
-
ton
Brake caliper piston or caliper guide
pins seized
Worn brake pads
Bent or cracked parking brake shoes
Foreign objects in brake pads or
park- ing brake shoes
Broken
/ loose parking brake hold
down springs or return springs
Loose caliper mounting bolts
Remedy
Renew tandem master cylinder
Check brake rotor run
-out and renew
as necessary. Adjust wheel bearing
Renew brake pads. Check
pipework for leaks
Renew brake pads
Check caliper and repair
/ renew as
necessary
Examine parking brake and repair
/
renew as necessary
Renew parking brake return springs
Examine calipers and repair
/ renew
as necessary
Examine brake pedal bushings and
repair
/ renew as necessary
Renew vacuum booster
Examine tandem master cylinder and
repair
/ renew as necessary
Check vacuum hose. Repair or renew
as necessary
Renew tandem master cylinder
Renew tandem master cylinder
Examine caliper and renew/ repair as
necessary
Renew brake pads
Renew parking brake shoes
Examine brake pads and and parking
brake shoes. Clean or renew as
necessary
Examine parking brake assembly.
Re- pair or renew as necessary
Re
-torque caliper mounting bolts

12.3 BRAKE FLUID LEVEL CHECK
WARNING: AVOID SKIN / EYE CONTACT OR INGESTION OF BRAKE FLUID. IF SKIN OR EYES ARE ACCIDENTALLY
SPLASHED WITH BRAKE FLUID, RINSE THE AFFECTED AREA IMMEDIATELY WITH PLENTY OF WATER
AND SEEK MEDICAL AlTENTlON IMMEDIATELY.
Checking the fluid level
CAUTION: Fluid must not be allowed to contact the vehicle paintwork. Remove any spilt fluid from the paintwork
by rinsing away with running water. Methylated spirit (denatured alcohol) must not be used to clean the contaminated area.
Correct brake fluid level is essential for the efficient oper- ation of the brake system. Check that the fluid level is be- tween the MAXand MIN marks on the fluid reservoir (Fig. 1). Top up if necessary with recommended brake fluid.
BMQ: The efficiency of the brakes may be impaired if fluid
is used which does not meet specifications. Use
ONLY brake and clutch fluid that conforms to
a mini- mum DOT 4 specification. Also do not use brake
fluid that has been exposed to atmosphere for any
length of time. Moisture absorbed from the atmos
- phere impairs the efficiency of the brake fluid.
JLX- 081
Fig. 1
Issue 1 August 1994 18 X300 VSM

Brakes
12.4 BRAKE SYSTEM BLEEDING
WAR-: GREAT CARE MUST BE EXERCISED WHEN SERVICING OR REPAIRING THE SYSTEM. AVOID SKIN/ EYE
CONTACT OR INGESTION OF BRAKE FLUID. IF SKIN OR EYES ARE ACCIDENTALLY SPLASHED WITH
BRAKE FLUID,
RINSETHE AFFECTED AREA IMMEDIATELY WITH PLENTY OF WATER AND SEEK MEDICAL
ATTENTION. IF BRAKE FLUID IS INGESTED, SEEK MEDICAL ATTENTION IMMEDIATELY.
CAUm: Fluid must not be allowed to contact the vehicle paintwork. Remove any spilt fluid from the paintwork
by rinsing away with running water. Methylated spirit (denatured alcohol) must not be used to clean the
contaminated area.
CAUTION: Never use methylated spirit (denatured alcohol) for component cleaning purposes. Use only a proprietary
brake cleaning fluid.
WARNING : THROUGHOUT THE FOLLOWING MAINTENANCE / SERVICE OPERATIONS, ABSOLUTE CLEANLINESS
MUST BE OBSERVED TO PREVENT FOREIGN MATTER CONTAMINATING THE BRAKE SYSTEM.
12.4.1 System Bleeding - General Instructions
Use a brake bleeder bottle with a clear bleeder tube. Also recommended is a filler unit with a fill pressure of 1.0 bar. If a filler unit is not used, ensure that their is sufficient brake fluid in the reservoir throughout the bleeding procedure.
m: Always bleed the caliper furthest away from the actuation unit first. On right hand drive vehicles, bleed in the
following order: front
left (FL),front right (FR), rear left (RL) and rear right (RR). On left hand drive vehicles bleed in the following order: FR, FL, RR and RL.
12.4.2
. Ensure that the vehicle is standing level. Switch the igni-
tion off.
Check that the fluid level in the reservoir is between the min and max marks.
. Connect the bleeder bottle tube to the relevant front cali- per (see'note' above) bleeder screw (1 Fig. 1) and open the
screw.
rn Bleed until new, clear, bubble free fluid is observed in the
tube and then close the bleeder screw.
. Repeat this procedure at each remaining caliper.
With the motorrunning check brake pedal travel.
If excess- ive, check for leaks and repeat the bleed procedure.
Fill the reservoir to the max level.
System Bleeding After Brake Fluid Renewal
12.4.3 System Bleeding After Tandem Master Cylinder
Renewal
Ensure that the vehicle is standing level. Switch the igni- tion off.
rn Check that the fluid level in the reservoir is between the min and max marks.
Connect the bleeder bottle tube to the relevant front cali- per (see'note'above) bleederscrew(1 Fig. 1) and open the
screw.
Ficr. 1
X300 VSM 19 Issue 1 August 1994

Brakes
a 12.5 GENERAL FI77lNG lNSTRUCTlONS
12.5.1 Brake Fluid
WARNING: BRAKE FLUID IS CORROSIVE. EXTREME CARE MUST BE TAKEN WHEN HANDLING. AVOID SKIN OR EYE
CONTACT. AVOID INGESTION. IF SKIN OR EYES ARE ACCIDENTALLY SPLASHED WITH BRAKE FLUID,
RINSE THE AFFECTED AREA IMMEDIATELY WITH PLENTY OF WATER AND SEEK MEDICAL ATTENTION.
IF BRAKE FLUID
IS INGESTED, SEEK MEDICAL ATTENTION IMMEDIATELY.
CAUTION:
Fluid must not be allowed to contact the vehicle paintwork. Remove any spilt fluid from the paintwork
by rinsing away with running water. Methylated spirit (denatured alcohol) must not be used to clean the
contaminated area.
Cleaning Solvents
CAUTION: Never use methylated spirit (denatured alcohol) for cleaning purposes. Use only a proprietary brake
cleaning fluid.
m: THROUGHOUT THE FOLLOWING MAINTENANCE / SERVICE OPERATIONS, ABSOLUTE CLEANLINESS
MUST BE OBSERVED TO PREVENT GRIT OR OTHER FOREIGN MATTER CONTAMINATING THE BRAKE
TION. TO CLEAN BRAKE SYSTEM COMPONENTS, WASH
IN A PROPRIETARY BRAKE CLEANING FLUID.
REMOVE ALL TRACES OF CLEANING FLUID BEFORE REASSEMBLY. ALL BRAKE SYSTEM RUBBER COh PONENTS MUST BE DIPPED IN CLEAN BRAKE FLUID AND ASSEMBLED USING THE FINGERS ONLY.
SYSTEM.
IFTHE SYSTEM IS TO
BE FLUSHED, USE CLEAN BRAKE FLUID TO MINIMUM DOT 4 SPECIFICA-
12.5.2 Hoses
Fully release the unions (1 Fig. 1) securing each end of the
hose to the fluid pipes. Withdraw the pipe unions (1 Fig. 1) from the hose ends.
Plug the ends of the pipes (2 Fig. 1) to prevent the loss of
fluid and the ingress of dirt.
Remove the mounting bracket locknut (3 Fig. 1) and re- move the hose (4 Fig. 1).
Thoroughly clean the hose and examine for any signs of
wear or damage. Renew the hose if there is any doubt
about its condition. Thoroughly clean the bore of the hose
using compressed air.
. Remove all blanking plugs and fit the new hose to the cali- per / connector. Secure the hose to the mounting bracket.
. Before fully tightening the locknut, ensure that the hose is
neither kinked nor twisted.
. Bleed the brakes.
12.5.3 Pipes
. Fully release the pipe unions (1 Fig. 1).
. Withdraw the pipe (5 Fig. 1) from the vehicle. Plug the
pipes (2 Fig. 1) to prevent the loss of fluid or the ingress of dirt. Thoroughly clean and examine the pipe for signs of damage or deterioration. Renew the pipe if there is any
doubt about its condition.
Thoroughly clean the bore of the pipe using compressed
air.
. Remove all blanking plugs and fit the new pipe to the ve- hicle. Secure the pipe to the body.
. Bleed the brakes.
17
Fig. 1
X300 VSM 21 Issue 1 August 1994

Brakes
12.7 HYDRAULICCONTROL MODULE- RENEW
SRO 70.60.18
70.60.1
9
Refer to Section 12.4, Brake System Bleeding before carrying out this procedure. Pay particular attention to the warn- ings and cautions relating to brake fluid, cleanliness and cleaning materials.
W: The illustration shows the hydraulic control module of a 6 cyl. vehicle with traction control. Hydraulic control
modules on non-traction control vehicles have only three outlet ports. Apart from this, the removal procedure
is the same for all vehicles.
. Raise the vehicle.
Displace the bleeder screw dust cap of the front LH caliper.
The dust cap will remain captive
on the bleed screw.
. Connect a bleeder tube and bottle to the bleeder screw (1
Fig. 1) and open the bleeder screw.
. Fit a brake pedal hold-down tool (JDS-9013) between the
brake pedal and the steering wheel. Adjust the tool to op
- erate the brake pedal 60mm down. This operation is
necessary to prevent fluid loss from the reservoirthrough
. Re-tighten the front LH caliper bleeder screw. Disconnect
the bleeder tube from the bleeder screw and remove the
tube and bottle. Refit the bleeder screw dust cap.
Undo the securing bolt of the multi-plug connector (1 Fig. 2). The bolt will remain captive. Disconnect the multi-plug
connector and reposition safely.
. Place absorbent material underneath the hydraulic con-
trol module to absorb any spillages.
Undo the tandem master cylinder CTMC) brake pipe gland
nuts (2 Fig.2) and disconnect the brake pipes.
. Fit plugs immediately to the brake pipes and the hydraulic
control module to prevent fluid
loss.
. Undo the rear brake pipe gland nuts (3 Fig. 2) at the pres- sure conscious reducing valves (PCRVs) (4 Fig. 2). Remove
the rear brake pipes.
disconnected brake pipes.
Note: Take necessary steps to prevent rotation of the
PCRVs when removing the rear brake pipes.
Fit plugs immediately to the brake pipes and the PCRVs to
. Undo and remove the PCRVs. Fit plugs immediately to the
Place PCRVs aside to be fitted later to the new hydraulic
. Undo the front brake pipe gland nuts (5 Fig. 2) and remove
. Fit plugs immediately to the brake pipes and the hydraulic
. Undo and remove the three securing nuts (6 Fig. 2) and re-
0 prevent fluid loss.
PCRVs and the hydraulic control module.
control module.
the front brake pipes.
control module to prevent fluid
loss.
move the hydraulic control module. Fia.
1
3 1 J70 296
Fia. 2
Issue 1 August 1994 X300 VSM 23

Brakes
12.8
SRO 70.60.21
PRESSURE CONSCIOUS REDUCING VALVES - RENEW
Refer to Section 12.4, Brake System Bleeding before carrying out this procedure. Pay particular attention to the warn- ings and cautions relating to brake fluid, cleanliness and cleaning materials.
Note: The illustration shows the hydraulic control module of a 6 cyl. vehicle with traction control. Hydraulic control
modules on non-traction control vehicles have only three outlet ports. Apart from this, the removal procedure
is the same for all vehicles.
. Raise the vehicle.
Displace the bleeder screw dust cap of the front LH caliper.
The dust cap will remain captive on the bleed screw.
rn Connect a bleeder tube and bottle to the bleeder screw (1 Fig. 1) and open the bleeder screw.
Fit a brake pedal hold-down tool (JDS-9013) between the
brake pedal and the steering wheel. Adjust the tool to op- erate the brake pedal 60mm down. This operation is
necessary to prevent fluid
loss from the reservoir through
disconnected brake pipes.
. Re-tighten the front LH caliper bleeder screw. Disconnect
the bleeder tube from the bleeder screw and remove the
tube and bottle. Refit the bleeder screw dust cap.
rn Place absorbent material underneath the hydraulic con- trol module to absorb any spillages.
. Undo the rear brake pipe gland nuts (1 Fig. 2) at the pres- sure conscious reducing valves (PCRVs) (2 Fig. 2). Remove
the rear brake pipes.
m: Take necessary steps to prevent rotation of the
PCRVs when removing the rear brake pipes.
Fit plugs immediately to the brake pipes and the PCRVs to
Undo and remove the PCRVs. Fit plugs immediately to the
. Clean the surrounding area.
. Fit new PCRVs to the hydraulic control module, removing
plugs immediately priorto connection. Tighten the PCRVs.
. Connect the rear hydraulic brake pipes to the PCRVs, re- moving the plugs immediately prior to connection.
Tighten the gland nuts.
prevent
fluid loss.
PCRVs
and the hydraulic control module.
0
Note: Take necessary steps to prevent rotation of the
PCRVs when fitting the rear brake pipes.
. Removethe absorbent material and clean the surrounding
. Ensure that all fixings are torque tightened to specified tol-
Release the brake pedal hold-down tool and remove.
. Bleed the brake system (refer to sub-section 12.4.4).
. Examine the hydraulic control module for leaks.
area.
erances. Fia.
1
Fia. 2
X300 VSM 25 Issue 1 August 1994

e LmmJ
Power assisted, ventilated discs,
sliding calipers: FN60 single piston
60mm Power assisted, ventilated discs,
FN48 single piston sliding calipers
48mm Mechanical, operating
on rear
drums within bell of the rear brake
discs.
291mm
305mm
28mm. wear limit 27mm
20mm, wear limit 18,5mm
Vacuum power, hydraulic operation
Bore diameter:
25,4mm
Jurid 518
Jurid 101
Ferodo 3612
6,51 vacuum
Electrical inductive sensors at the
wheels which detect rotational
speed.
Hydraulic: vehicles
with traction
control - contains four solenoid
valves, one for each wheel; vehicles
without traction control
- contains
three solenoid valves, one for each front wheel and one for both rear
wheels.
Solid state digital
unit (integral with hydraulic module).
Specification
Braking System
Front brakes: all vehicles.. ........ .................... ........... ...
Caliper piston diameter: ..........
Rear brakes: all vehicles ..........
...
...
....................
....................
...........
...........
Caliper piston diameter ...........
Parking brake ....................
...
...
....................
....................
...........
...........
Disc diameter:
Front
.........................
Rear .........................
Front .........................
Rear .........................
Brake operation .................
Master cylinder ..................
Main brake friction pad material:
Front
........................
Rear ........................
Parking brake friction shoe material
Brake
servo booster assembly
Boost ratio
......................
Disc thickness:
...
... ....................
....................
...........
...........
...
...
...
...
....................
....................
....................
....................
...........
...........
...........
...........
...
...
.. ....................
....................
....................
...........
...........
...........
... .................... ...........
Anti-lock braking system (ABSI
Wheel sensors ................... ... .................... ...........
ABS modulator .................. ... .................... ...........
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0
Control module type ............. ... .................... .........
Issue 1 August 1994 X300 VSM AI-95MY 3