1998 JAGUAR X308 brake vacuum

            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

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

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.

Comp
onent Tests
Bra
k
e Booster
1.
1. Chec k all
hoses and connections. All unused vacuum connectors should be capped. Hoses and their connections
should be correctly secured and in good condition with no holes and no collapsed areas. Inspect the valve on the
brake booster for damage.
2. 2. Check the hydraulic brake system for leaks or low fluid.
3. 3. With the transmission in PARK, stop the engine and apply the parking brake. Pump the brake pedal several times
to exhaust all vacuum in the system.
4. 4. With the engine switched off and all vacuum in the system exhausted, appl y the brake pedal and hold it down.
Start the engine. If the vacuum system is operating, the brake pedal will tend to move downward under constant
foot pressure. If no motion is felt, the vacuum booster system is not functioning.
5. 5. Remove the vacuum hose from the brake booster. Manifold vacuum should be available at the brake booster end
of the hose with the engine at idle speed and the transm ission in PARK or NEUTRAL. Make sure that all unused
vacuum outlets are correctly capped, hose connectors are correctly secured and vacuum hoses are in good
condition. When it is established that manifold vacuum is available to the brake booster, connect the vacuum hose
to the brake booster and repeat Step 3. If no downward movement of the brake pedal is felt, install a new brake
booster.
6. 6. Operate the engine for a minimum of 10 seconds at a fast idle. Stop the engine and allow the vehicle to stand for
10 minutes. Then, apply th e brake pedal with approximately 89 N ( 20lb) of force. The pedal feel (brake
application) should be the same as that noted with the engine running. If the brake pedal feels hard (no power
assist), install a new valve and then re peat the test. If the brake pedal still feels hard, in stall a new brake booster.
If the brake pedal movement feels spongy, bleed the brak e system. For additional information, refer to General
Procedures in this section.
Bra k
e Master Cylinder
Usual
l
y, the first and strongest
indicator of anything wrong in the brake syst em is a feeling through the brake pedal. In
diagnosing the condition of the brake master cylinder, check pedal feel as evidence of a brake concern. Check for brake
warning lamp illumination and the brake fluid le vel in the brake master cylinder reservoir.
Normal Conditio
ns
The fo
llowing conditions are considered norm
al and are not indications that the brake master cylinder is in need of repair.
New bra
ke systems are designed to produc
e a pedal effort that is not as hard as in the past. Complaints of light
pedal efforts should be compared to the pedal effort s of another vehicle of the same model and year.
The fl
uid level will fall with brake pad wear.
Abnormal Conditions
•

NOTE: Prior to carrying out any diag
nosis, make sure the brake system warning indicator is functional.
Changes in the brake pedal feel or brake pedal travel are in dicators that something could be wrong in the brake system. The
diagnostic procedure and techniques use brake pedal feel, warning indicator illu mination and low brake fluid level as
indicators to diagnosing brake system co ncerns. The following conditions are cons idered abnormal and indicate that the
brake master cylinder is in need of repair:
Brake ped a
l goes down fast. Th
is could be caused by an ex ternal or internal leak.
Brake pedal goes down slowly
. This could be
caused by an internal or external leak.
Brak
e pedal is low or feels spongy. This condition may be ca
used by no fluid in the brake master cylinder, reservoir

cap ven
t holes clogged or air in the hydraulic system.
Brake ped

al effort is excessive. This ma
y be caused by a bind or obstruction in the pedal/linkage, a faulty non return
valve, booster or insuffi cient booster vacuum.
R
ear brakes lock up during light pedal force. This may
be caused by damaged brake pads, an incorrectly adjusted
parking brake, a partially applied parking brake, a damaged ABS sensor or bearing failure.
Brake ped
al effort erratic. This condition could be caused by the brake booste
r or incorrectly installed brake pads.
Brake warning indicator i
s on. This may be caused
by low fluid level or float assembly damaged.
No
n Pressure Leaks
Any reduced fluid v
olume in the brake ma
ster cylinder reservoir condition may be caused by two types of none pressure
external leaks.
Type 1: An external leak may be occur at the master cylinder reservoir cap because of incorre ct positioning of gasket and
cap. Reposition cap and gasket.
Type 2: An external leak may occur at th e reservoir mounting seals. Repair such a leak by installing new seals and make
sure that the reservoir retainin g bolt is correctly installed.

Fr
ont Brake Disc Runout Check Vehicles With: Brembo Brakes
Special Service tools
Di
al Test Indicator Gauge and Stand.
1.


WA
RNING:
BRAKE DUST, IF INHALED CAN DAMAGE YOUR HEALTH. ALWAYS REMOVE BRAKE DUST USING A VACUUM BRUSH. DO NOT USE A COMPRESSED-AIR LINE TO DISPERSE BRAKE DUST
INTO THE ATMOSPHERE.
CA
UTION:
Replacement of nuts and bolts: Various thread-locking devices are used on nuts and bolts
throughout the vehicle. These devices restrict the number of times a nut or bolt can be used. See
section <<100-00>> for information.
CA
UTION:
The Brembo caliper is aligned to the brake disc when it is first installed to the vehicle, therefore,
care must be taken not to disturb this alignment. When removing the caliper; remove the bolts
that secure the anchor bracket to the vertical link only. DO NOT loosen any other caliper bolts.
Raise front of vehicle and support on stands. Refer to section <<100-02>>.
2. Remove wheel. Refer to section <<74.20.05>>.