1998 JAGUAR X308 brake booster

                    Brake Pads  (70.40.02)  ‐ Vehicles  With:
 
High  Performance  Brakes 
 
             206‐04:  Rear  Disc  Brake  
                 Specification  
                 Description  and  Operation  
                     Rear Disc  Brake  
                 Removal and  Installation  
                     Brake Caliper  (70.55.03)  (70.55.25)  ‐ Vehicles  With: Standard  Brakes  
                     Brake Caliper  (70.55.03)  (70.55.25)  ‐ Vehicles  With: High  Performance  Brakes  
                     Brake Disc  (70.10.11)  ‐ Vehicles  With: Standard  Brakes 
                     Brake Dis
c (70.10.11)  ‐ Vehicles  With: High Performance  Brakes 
                     Brake Pads  (70.40.03)  ‐ Vehicles  With: Standard  Brakes 
                     Brake Pads  (70.40.03)  ‐ Vehicles  With: High Performance  Brakes 
 
             206‐05:  Parking  Brake and  Actuation  
                 Specification  
                 Description  and  Operation  
                     Parking Brake  
                 General Procedures  
                     Parking Brake  Cable  Adjustment  (70.35.10)  
                     Parking Brake  Shoe  and Li
ning  Adjustment  (70.35.37)  
                 Removal and  Installation  
                     Parking Brake  Control  (70.35.08)  
                     Parking Brake  Control  Shroud  (76.13.63)  
                     Parking Brake  Shoes  (70.40.05)  
                     Parking Brake  Warning  Indicator  Switch (86.65.45)  
 
             206‐06:  Hydraulic  Brake Actuation  
                 Specification  
                 Description  and  Operation  
                     Hydraulic Brake  Actuation  
                 Removal and  Installation  
                     Brake Fluid  Reservoir  (70.30.16)  
                     Brake Master  Cylinder  (70.30.
08) 
                     Brake Pedal  and  Bracket  (70.35.03)  
                     Brake Pedal  and  Bracket,  Brake  Booster  and  Brake  Master  Cylinder  (70.35.39)  
 

            206‐07:  Powe r Brake  Actuation  
                 Specif
ication
 
                 Description  and  Operation  
                     Brake Booster  
                 Removal and  Installation  
                     Brake Booster  (70.50.17)  
                     Brake Booster  and  Brake  Master  Cylinder  (70.50.18)  
 
             206‐09:  Anti ‐Lock  Control  
                 Specification  
                 Description  and  Operation  
                     Anti‐Lock  Control  
                 Diagnosis  and  Testing  
                     Anti‐Lock  Control  
                 Removal and  Installation  
                     Anti‐Lock  Brake  System  (ABS)  Module  (70.60.02)  
                     Front Wheel  Speed  Sensor  (70.60.03)  
                     Hydraulic Cont
rol Unit  (HCU) 
                     Rear Wheel  Speed  Sensor  (70.60.04)  
                     Wheel Speed  Sensor  Ring  (70.60.25)  
 
        211:  Steering  System  
 
             211‐00:  Steering  System ‐ General  Information  
                 Specification  
                 Description  and  Operation  
                     Steering System  
                 Diagnosis  and  Testing  
                     Steering Sy
stem  
                 General Procedures  
                     Power Steering  System Filling  and  Bleeding  
                     Power Steering  System Flushing  (57.15.08)  
                     Power Steering  System Vacuum  Filling  and  Bleeding  
                     Steering Gear  Centralizing  
 
  

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.
*

Do t
he disc brake caliper pistons
and pins bind, leak or stick?
Yes INSTALL new calipers as necessary. TE ST the system for normal operation.
No GO to C4
.
C4: INSPECT BR
AKE DISCS
Check the brake discs fo

r excess
ive damage, thickness variatio n or runout. For additional
information, refer to General Procedures in this section.
1
D
oes excessive damage or runout exist?
Yes INSTALL new brake discs and brak e pads as necessary. TEST the system for normal operation.
No GO to C5
.
C5: INSPECT THE FRONT HU
B AND WHEEL BEARING ASSEMBLY
Check the fr

ont hub and wheel bearing assembly.
For additional information, refer toSection 204
-00

Su

spension System
- General
Information
. 1
Are th

e wheel bearings OK?
Yes GO to C6
.
No

INSTALL new wheel bearings. For additional inform ation, refer toSection 204
-01
Front Suspension
.
TEST the system
for normal operation.
C

6: CHECK SUSPENSION BUSHES AND BALL JOINTS.
Chec

k all suspension bu
shes and ball joints.
1
Are th
e suspension bushes and ball joints OK?
Yes Vehicle is OK.
No INSTALL new front suspension bushes and ball joints as required. For additional information, refer
toSection 204
-01
Front Suspension
. INSTALL n
ew rear suspension bush
es and ball joints as required.
For additional informat ion, refer toSection 204
-0
2 Rear Suspension
.
P

INPOINT TEST D : THE PEDAL FEELS SPONGY
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
D

1: CHECK FOR SPONGY PEDAL (ENGINE OFF)
Check f

or a firm brake pedal.
1
Is th

e brake pedal effort an
d brake pedal travel normal?
Yes Vehicle is OK.
No GO to D2
.
D2:
CHECK BRAKE PEDAL RESERVE (ENGINE OFF)
Pump th

e brake pedal 10 times and
hold on the final application.
1
Does th
e brake pedal feel fi
rm on final application?
Yes GO to D3
.
No

BLEED the brake system. For additional information, re fer to General Procedures in this section. TEST
the system for normal operation.
D3:
CHECK BRAKE PEDAL RESERVE (ENGINE ON)
Engine is

idle.
1
Apply the brake pedal ligh

tl
y three or four times.
2
W
ait 15 seconds for the vacuum to recover.
3
Push down on

the brake pedal until it stops moving
downward or an increased resistance to the brake
pedal travel occurs.
4
Hol
d the brake pedal in the applied position while increasing the engine speed to 2000 revs/min.
5
Re

lease the accelerator pedal.
6
Does th

e brake pedal move downward as
the engine speed returns to idle?
Yes GO to D4
.
No

CHECK the vacuum to brake booster. For additional information, refer toSection 206
-0
7 Power Brake
Actuation.

Are th
ere any external brake system leaks?
Yes REPAIR as necessary. ADD fluid and BLEED the brak e system. For additional information, refer to
General Procedures in this section. TEST the system for normal operation.
No GO to F3
.
F
3: CARRY OUT A BRAKE MASTER CYLINDER BYPASS TEST
Te

st for brake master cylinder bypass condition. Re
fer to Brake Master Cylinder Component Test in
this section.
1
A
re any concerns found?
Yes INSTALL a new brake master cylinder, ADD flui d and BLEED the brake system. For additional
information, refer to General Proc edures in this section. TEST the system for normal operation.
No System is OK.
PINPO
INT TEST G : EXCESSIVE BRAKE PEDAL EFFORT
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
G1

: CHECK BRAKE PADS
Check the brake pads for wear, contamin

atio
n, correct installation, damage and type.
1
A
re any concerns found?
Yes INSTALL the front brake pads correctly or INSTALL ne w front brake pads if necessary. For additional
information, refer toSection 206
-03
Front Disc Brake
. INSTALL the
rear brake pads correctly or
INSTALL new rear brake pads if necessary. For additional information, refer toSection 206
-04
Rear
Di

sc Brake
. REPEAT road test.
No

GO to G2
.
G2:
CHECK VACUUM
Di

sconnect the vacuum booster hose from the booster.
1
Conne

ct a vacuum/pressure tester to the vacuum hose.
2
Ru

n the engine at normal operating temperature.
3
Re

cord the vacuum reading.
4
Is

the reading 40.5kPa (1
2 in-Hg) or greater?
Yes GO to G3
.
No

LOCATE and REPAIR the source of low vacuum . TEST the system for normal operation.
G3
: INSPECT SYSTEM
Swi

tch the engine off.
1
Re

connect the vacuum hose.
2
Inspect th

e brake booster, rubber grommet, and al
l vacuum plumbing for cracks, holes, damaged
connections, or missing clamps.
3
Pump th
e brake pedal several time
s to exhaust the vacuum. Push down on the brake pedal and hold.
4
Does th
e brake pedal move down
when the engine is started?
Yes Vacuum system is OK.
No GO to G4
.
G4
: CHECK POWER BRAKE BOOSTER VALVE
Check the brake booster valve. For
add
itional information, refer to
Brake Booster in this section.
1
Is th
e power brake booster valve OK?
Yes CHECK the brake booster. Fo r additional information, refer to Brak e Booster in this section. INSTALL a
new brake booster if necessary. TEST the system for normal operation.
No INSTALL a new brake booster valve. TEST the system for normal operation.
P
INPOINT TEST H : BRAKE LOCKUP
DURING LIGHT BRAKE PEDAL FORCE
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
H1

: TEST BRAKE LOCKUP

Road test the veh
icle and a
pply the brake pe dal lightly.
1
Do th
e brakes lockup?
Yes GO to H2
.
No
Vehicle is OK.
H2: INSPECT BRAKE PADS
Inspect brake pads for con
t
amination,
correct installation , damage and type.
1
Ar
e any concerns found?
Yes CHECK the front brake pads. For additi onal information, refer toSection 206
-03 Fr
ont Disc Brake
.
CHECK
the rear brake pads. For additi
onal information, refer toSection 206
-04
Rear Disc Brake
.
INST ALL new brake pads as ne ce
ssary. REPEAT
road test.
No GO to H3
.
H3: INSPECT BRAKE CALI
PERS
Inspect brake cali
pers for bindi
ng, leaking or sticking.
1
A
r
e any concerns found?
Yes CHECK the front brake calipers. For addi tional information, refer toSection 206
-03 Fr
ont Disc Brake
.
CHECK
the rear brake calipers. For addi
tional information, refer toSection 206
-04
Rear Disc Brake
.
IN ST
ALL the brake calipers correctly or INSTALL new
brake calipers as necessary. TEST the system for
normal operation. REPEAT road test if necessary.
No Vehicle is OK.
PI
NPOINT TEST I : BRAKES DRAG
TE
S
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
I1
:
ROAD TEST VEHICLE
Ro
ad t
est the vehicle
and apply the brakes.
1
Are the brakes
functioning correctly?
Yes Vehicle is OK.
No GO to I2
.
I2
: CHECK CALIPERS
Check the fr
on
t caliper pistons for binding, leakin
g or sticking. For additional information, refer
toSection 206
-03 Fr
ont Disc Brake
. Check the rear cal
i
per pistons for
binding, leaking or sticking. For
additional information, refer toSection 206
-04
Rear Disc Brake
.
1
Do t
h
e disc brake caliper pistons
and pins bind, leak or stick?
Yes INSPECT the brake calipers and pa rking brake cables. INSTALL new co mponents as necessary. Road
test vehicle.
No GO to I3
.
I3
: CHECK BRAKE BOOSTER
Check the brake booster con
n
ecting rod alignment
and travel. For additional information, refer
toSection 206
-0 7
Power Brake Actuation
. 1
Is the co
nnecti
ng rod OK?
Yes Vehicle is OK.
No INSTALL a new brake booster. For addi tional information, refer toSection 206
-07
Power Brake
Actuation. TEST
the system for
normal operation.
PINPO
I
NT TEST J : EXCESSIVE/ERRATIC BRAKE PEDAL TRAVEL
TE
S
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
J
1
: TEST ON ROUGH ROAD
R
oad test the vehi
cle on rough road conditions.
1
Apply the brakes slowly. 2
Is th
e brake pedal ef
fort an
d brake pedal travel normal?

Yes

Vehicle is OK.
No GO to J2
.
J
2: CHECK BRAKE FLUID LEVEL
Check the brake master cyli

nder reservoir fluid level.
1
Is the fl

uid level OK?
Yes GO to J3
.
No

CHECK brake master cylinder reservoir sealing points. For additional information, refer to Brake
Master Cylinder in this section. ADD brake fl uid and BLEED the brake system. For additional
information, refer to General Proc edures in this section. TEST the system for normal operation.
REPEAT road test if necessary.
J
3: CHECK BRAKE PEDAL RESERVE
Engine is

idle.
1
Apply the brake pedal ligh

tl
y three or four times.
2
W
ait 15 seconds for the vacuum to replenish.
3
Push down on

the brake pedal until it stops moving
downward or an increased resistance to the brake
pedal travel occurs.
4
Hol
d the brake pedal in the applied position while increasing the engine speed to 2000 revs/min.
5
Re

lease the accelerator pedal.
6
Does th

e brake pedal move downward as
the engine speed returns to idle?
Yes GO to J4
.
No

CHECK the vacuum to the brake booster. Fo r additional information, refer toSection 206
-0
7 Power
Brake Ac

tuation
.
J

4: CHECK THE FRONT HUB AND BEARING ASSEMBLY
Check the fr

ont hub and bearing assembly. Fo
r additional information, refer toSection 204
-01
Front
Suspe

nsion
. 1
Are th

e front wheel bearings loose?
Yes INSTALL a new front wheel bearin g if damaged. For additional information, refer toSection 204
-01

F

ront Suspension
. TEST
the system for normal operation.
No CHECK the front brake discs for thickness variances. For additional information, refer to General
Procedures in this section.
PINPO
INT TEST K : SLOW OR INCOMPLETE BRAKE PEDAL RETURN
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
K1: C

HECK FOR BRAKE PEDAL RETURN
Ru

n the engine at fast idle while
making several brake applications.
1
Pull the
brake pedal rearward with approximately 44.5 N (10lb) force.
2
Relea

se the brake pedal and measure
the distance to the toe board.
3
Make a hard brake
application.
4
Relea

se the brake pedal and measure the brake
pedal to toe board distance. The brake pedal
should return to its original position.
5
Does th
e brake pedal return
to its original position?
Yes Vehicle is OK.
No GO to K2
.
K
2: CHECK FOR BRAKE PEDAL BINDING
Check the brake pedal to make
s
ure it is operating freely.
1
Is th

e brake pedal operating freely?
Yes INSTALL a new brake booster. For addi tional information, refer toSection 206
-0
7 Power Brake
Actuation. TEST

the system for normal operation.
No REPAIR or INSTALL new brake pedal. TE ST the system for normal operation.