1998 JAGUAR X308 valve

Mem
ory
Pulse Width ModulationPW

M
A
method of control in an electronic co
ntrol system in which the duration of
pulses in a pulse train is proportional to the amplitude of the modulating
signal
R
Ran
dom Access Memory
RAMF
ast access memory store which is accessible for entry or extraction of data
Re

ad-Only Memory
RO
M
F
ast access memory in which data
is fixed and may not be changed
Re
servoir
RESContaine
r, usually for oils,
coolants or hydraulic fluids
Re
turn
RTNA
dedicated sensor ground circuit
R

evolutions Per Minute
RP
M
Shaft speed o
f a device, us
ually an engine or motor
R
ight-hand
RH
Right-hand drive veh

icle
RHD
S
Scan T

ool
STDe
vice that interfaces with and comm
unicates information on a data link
Se
at Control Module
SCMModule
controlling the seat motor systems (not electric raise/lower-only
seats)
Secon
dary Air
Air pro
vided to the exhaust system
Secon

dary Air Injection
AIRSy
stem used for a period of time each
time the engine is started, unless
certain temperature criter ia are met. Pumps air directly into the exhaust
system which generates extra heat and reduces the time taken for the
catalytic converters to reach operating temperature
Secon
dary Air Injection
Bypass
AIRBVents secon
dary air to atmosphere
Secon

dary Air Injection
Check Valve
AIRCValve wh
ich prevents back-flow of exhaust gas to the AIR system when the
system is inoperative
Secon
dary Air Injection
Diverter
AIRDD
iverts secondary air to either
the catalyst or exhaust manifold
Secon
dary Air Injection
Magnetic Clutch
AIRP
C
Clu
tch mounted on the AIRP drive shaft
Secon

dary Air Injection
Pump
AIRPMe
chanically driven rotary vane
pump, driven through the AIRPC
Secon
dary Air Injection
Relay
AIRRCont
rols the injection of air into the exhaust system
Secon

dary Air Injection
Switchin
g Va
lve
AIRSV
acuum operated valve backing-up the AIRC
Secu

rity and Locking
Control Module
SLCMModul
e controlling the vehicle's security and closure-locking functions
SensorSGeneri

c name for a device
that senses either the absolute value or a change
in a physical quantity su ch as temperature, pressure or flow rate, and
converts that change into an electrical quantity signal
Servic
e Repair Operation
(number)
SRONu
mber generated by Jaguar Methods
and Techniques system which relates
to the time allowed to complete a repair operation. Further information on the
system can be found in the separate Jaguar Publications (for each model
range) entitled 'Repair Operation Times'
Shif
t signal
SDA
shift process signal to the TCM on SC vehicles
Shif

t Solenoid
SSControls shi
fting in an automatic transmission
Si

gnal return
SIG RTN
Slidin

g Roof Control
Module
SRCM
Society of Automotive

Engineers
SAE
Speed
Control Control
Module
SCCMModule con
trolling Speed Control System
Square c

entimeter
cm
2
Stan

dard
std
Stan

dard Corporate
Protocol
SCPA
high-speed, serial communications system linking all body system control
modules. Control messages and data ar e passed between modules at up to
786 messages per second
SuperchargerSCAn in
take system which utilizes a supercharger (mechanically driven device
that pressurizes intake air, thereby in creasing density of charge air and the
consequent power output from a given displacement)
Supercharger
Bypass
SCB
SwitchSW
T

Tacho
meter
TACHA
ci
rcuit that provides input for
an electronic tachometer display
Thermal Vacuu
m Valve
TVVControls vacuum l
e
vels or
routing based on temperature
Throttle
Body
TBDe
vi
ce containing the throttle
Throttl
e
Position
TP
Throttl
e
Position Sensor
TPSInterprets throttl
e

position and movement to iden tify idle, acceleration and
full-power demands
Top Dead CenterTDC
Torque Converter C
lutch
TCC
To
tal
indicator reading
TIRThe t
o
tal indicated movement on a DTI with the test piece rotated through
360°
Transm
ission Control
Module
TCMControls
the shifting pattern
of the (automatic) transmission
Transm
ission Control
Switch
TCSModifi es
the operation of electronically controlled transmissions
Transmission Oil
TemperatureTOTIndi
cat
es temperature of transmission fluid
Transmission RangeTRThe ran
g
e in which the transmission is operating
Transmission Spe
e
d
Sensor
TSSIndi cat
es rotational speed of transmission output shaft or turbine shaft
V
Vacuu
m
Solenoid Valve
VSVVacuu
m
operated valve used in the speed control system
Vacuu
m
Solenoid Valve
(atm)
VSV VAVacuu m
atmospheric valve used in the speed control system
Vacuu
m
Solenoid Valve
(rel)
VSV VRVacuu m
release valve used in the speed control system
Vacuu
m
Solenoid Valve
(vac)
VSV VVVacuu m
valve used in the speed control system
Variable Valve TimingVVTA
s
ystem by which the relationship of the crankshaft and camshaft may be
altered during engine running
Vehi cl
e Battery Adapter
VBAProvide
s
electrical power to the PDU
and supplies a battery reference level
Vehicl
e Condition Monitor
VCMInst
rum
ent panel display which warns of faults
Ve
hic
le Emission Control
Information Label
VECI Label
Vehi cl
e Identification
Number
VINN u
mber assigned to the vehicle by the manufacturer, primarily for licensing
and identification purposes
Vehi cl
e Interface Adapter
VIAExtends the
PDU ca
pability and provid
es a parallel interface to vehicle
harnesses and ECMs
Vehicle Spe e
d Sensor
VSSSens
or which provides ve
hicle speed information
Viscosity In
dexVI
Voltage RegulatorVRDe
vice which regulates the variable output voltage of a generator
W
Wat
tWSI unit of power (1 hp = 7
45.7 watts)
W
i
de Open Throttle
WO
TFu
ll throttle position

Upper
Wishbones
Each
upper wi
shbone assembly is a on
e-piece steel forging incorporating:
A pres
s-fit ball joint.
Press-fi

t bushes for location of the upper fulcrum bolt.
Lower Wishbones
Each l
o
wer wishbone comprising
forged steel front and rear arms bolted together, incorporates:
A p
ress-fit ball joint in the outer extremity of the rear arm.
Press-f
i
t bushes for location of the lower fulcrum bolts
Locati
on for the shock absor
b
er lower mounting plates.
Vertica l Links

The vertical
links are of forged steel
wi
th integral steering arms. Each is suppo rted between the upper and lower wishbones
by two ball joints and carries:
Front hub

Brake ca
liper and disc shield assembly

ABS se
nsor
.
Front Hub
s

Each f
o
rged steel front hub accommodates sealed for life cartridge
type wheel bearings, and carries:
The brake rotor assembl
y.
A
h
ub nut with toothed, integral ABS rotor.
Su
s
pension spring pi
n locking device.
Front Road
Springs
The road spri
ng
s are of coil type with their
rating dependent upon vehicle specification
Ea
ch spring is installed between the suspension crossbeam location and the lower wishbone spring pan.
Ru
bber seats ar
e installed betw
een the spring and the crossb eam and the spring pan.
Front Shock A
bsorbers
Th
e
shock absorbers are telescopic hydrau
lically operated units. Optional adaptive damping units incorporate a solenoid-
operated control valve at their upper extremity.
Each shoc
k absorber is installed between the lowe
r wishbone rear arm and a recess in the body.
The l
o
wer end of the shock absorber is se
cured to plates on the wishbone by a bolt that also serves as a pivot.
The u
pper en
d of each shock absorber is secured to the body location by a single nut.
Front Sta
b
ilizer Bar
A
front stabil
izer bar installed on all vehicles
is rated according to suspension specification.
Opera
tion
As each road wheel r
i
ses, move
ment is transmitted through the vertical link assembly to the lower wishbone. The resulting
rise of the wishbone compresses the road spring and partially telescopes the shock absorber. During this action, the spring
absorbs associated shocks and the shock absorber minimizes sprin
g os c
illation.

Du

ring cornering, vehicle weight
is transferred to the outer road wheel with a resulting tendency for the inner wheel to lift.
The stabilizer bar assists in minimizing this tendency by transf erring a proportion of potential lift of the inner wheel to the
outer wheel. This result s in enhanced body stability with improved corner ing capabilities.

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

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.

Hydrau
lic Brake Actuation - Brake Pedal and Bracket, Brake Booster and
Brake Master Cylinder
Re mo
val and Installation
Remova

l
• C
A
UTIONS:
Replacement of nuts and bolts: Various thread-locking de vices 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.
Remove brake fluid spilla ge immediately from paint work, with clean water.
1. Position vehi cl
e on a four-post lift.
2. Open engine compartment and fit paint work protection covers
to fenders.
3. Disconnect battery ground cable (IMPORTANT, refer to
operation 86.15.19 for fu rther information).
4. Remove engine compartment rear cover. Refer to operation
76.11.35.

5. Reposi
tion the mounting bracket of the cruise control vacuum-
valves for access (if installed).
R e
move screws.
Reposition bracket.


6. Disc
onnect low-level warning connector from master cylinder.
7. Disconnect vacuum pipe from brake booster.
1. Disconnect pipe.
2. Remove and discard seal.

8. Conne ct
low-level warning connector to master cylinder.

9. Inst al
l cruise control vacuum-valves, mounting bracket.
Install and tigh
ten bolts.

10 . Conne
ct stop lamp switch connector.
Conne
ct
connector.
Re
posi
tion carpet.
11. Connect battery ground cable (IMPORTANT, see operation
86.15.15 for further information).
12. Bleed brake system. See operation 70.25.03.
13. Install engine compartment rear cover. Refer to operation
76.11.35.
14. Remove paint-work protection covers and close engine
compartment.

15 . Conne
ct battery ground cable (I
MPORTANT, refer to operation
86.15.19 for further information).