1998 JAGUAR X308 Amp

WHE
N CHANGING A WHEEL, ENSURE THAT THE VEHICLE CANNOT MOVE. ALWAYS APPLY THE PARK BRAKE AND
SELECT TRANSMISSION 'P' POSITION.
NEVER RUN THE ENGINE WITH ONE WHEEL OFF THE GROUND, FOR EXAMPLE, WHEN CHANGING THE WHEEL. THE
VEHICLE COULD MOVE.
TIGHTEN THE WHEEL NUTS TO SPECIFICATION. WHEELS MAY COME LOOSE IF OVER OR UNDER TIGHTENED.
USE WHEELS AND WHEEL NUTS DESI GNED FOR XJ SERIES VEHICLES ONLY. AFTERMARKET WHEELS OR WHEEL
NUTS MAY NOT FIT OR FUNCTION PROPERLY AND COULD CAUSE INJURY OR DAMAGE.
In
spection and Verification
To maximize ti
re performance, inspec
t the tires frequently for signs of:
Unev
en wear.
Incorrect
ti
re pressure.
Wh
ee
l imbalance.
Cuts. Abrasi
ons.

B
u
lges (blister).
Ply s
e
paration.
Embedded objects. Impact damage.
Inspe c
tion should be
more frequent when:
Continuo
us high speed op
eration is required.
Ra
pid or extreme temperatures changes occur.
R
o
ad surfaces are rough.
Roads ar
e littered
with debris.
Tread W
e
ar Indicator
•
NO
TE: Tire condition must comply with prevailing local legislation.
New tires must be installed if the wear in dicators are exposed or if there is severe shoulder wear. Shoulder wear is usually
caused by either excessive camber or toe on tires.
T i
re Vibration Diagnosis
A
tir
e vibration diagnostic procedure always
begins with a road test. The road test and the custom er interview (if available)
will provide much of the information need ed to find the source of vibration.
During the road test, drive the vehicle on a road that is smooth and free of undulations. If vibration is apparent, note and
record the following:
The s p
eed at which the vibration occurs.
W
h
at type of vibration occurs in each
speed range - mechanical or audible.
How the vibrati
on is affected
by changes in the following:
- -engine torque
- -vehicle speed
- -engine speed.
Type of v i
bration - sensitivity:
- - torque sensitive,
- - vehicle speed sensitive,
- - or engine speed sensitive.

Vehicle Dynamic Suspension - Vehicle Dynamic Suspension
Description an
d Operation
Front Sho

ck Absorbers

The front shock absorber
comprises:
A

coil-type road spring, mounted between the lower wish
bone spring pan and the front suspension crossbeam;
different spring rates are used according to model.
A
telescopic, hydraulically controlled, damper mounte
d between the lower wishbone and the vehicle body.
It
em
De
scription
1Front

suspension crossbeam
2Front

hub assembly
3Ro

ad spring
4Dam

per

The rear shock ab
sorber comprises:
A
c
oil-type road spring mounted between the lower wish
bone and the upper spring seat on the vehicle body;
different spring rates are used according to model.
A te
lescopic, hydraulically controlled, damper, co-axial wi
th the road spring, mounted between the lower wishbone
and the upper spring seat on the vehicle body.
Damp
ing Principle
D
a
mping is achieved by controlling the flow of fluid from one
end of the damping chamber to the other. The more the flow
of fluid is restricted, the firmer the damping action.
Ite
m
De
scr
iption
1Dam
p
er
2Ro
ad s
pring
3Lower wishbon
e
4Upper sprin
g seat

Rear Shock A
b
sorbers

The
Nivomat ride levelling system improves ride quality by al
lowing the use of softer road springs, while controlling the
effects on the suspension of a fully laden vehicle. The system uses special rear dampers in place of the normal units. There
are no other components in th e system. The ride levelling system is comple tely automatic, requiring no input from the
driver.
Ride levelling may be specified as an opti on on certain models; it is not available in north American markets. Ride levelling
and adaptive damping are mu tually exclusive options.
The Nivomat damper:
Su
pplements the load-carrying capacity of th
e road springs at high vehicle loads.
Uses road inputs to the
suspension to power the levelling function.
De

tects suspension height dire
ctly from road wheel travel.
Provi
des load-dependent spring rates; the ac
cumulator gas pressure increases with load.
Pr
ovides load-dependent damping; the fluid pressure increases with load.
Op

eration
F
ollowing an increase in vehicle loading,
the dampers adapt to maintain the height of the vehicle within its design range.
The system uses road inputs to the suspension to power the levelling action, and requires up to approximately two
kilometers of travel, following a change in load, to complete the process.
Normal movement of the suspension caus es a pumping action to occur within the damper, as a result of extension and
compression of the pump rod in the pump chamber. Hydraulic fluid is pumped from the pump cham ber into a high pressure
gas accumulator. The increase in gas pressure augments the force developed between th e vehicle axle and the body,
thereby providing lift.
It
em
De
scription
1Pi

ston rod
2Pum

p chamber
3High

pressure
gas accumulator
4Diaphragm
5Co
ntrol orifice
6Pump rod
7Low pressure gas ch

amber
8Low pressure oil

reservoir


Ride Levelling

A c
ontrol orifice in the pump rod determines the levelling height. When the damper is compressed, this orifice is covered.
When the damper extends, the control orif ice is uncovered, pressure is released to the low pressure oil reservoir and the
system ceases to rise. When the vehicle is high after unloading, the opened control or ifice allows fluid to be returned to the
low pressure oil reservoir, and the suspensi on returns to its normal unladen height.
Ad
aptive Damping

•
NOTE: Items 2 and 5 are ALWAYS located
on the passenger side of the vehicle
Adaptive damping enhances vehicle handli ng by the use of special dampers which are controlled by a dedicated control
module.
Adaptive damping may be specified as an option on certai n models. Adaptive damping and ride levelling are mutually
exclusive options. The adaptive damping system is completely automatic, requiring no input from the driver.
A d
aptive Dampers
The adaptiv
e dampers:
Are inst

alled in place of the normal dampers.
Can be identified

by the cable and connector at the top of the unit.
Have two settings; fi
rm and so
ft.
It
e
m
De
scr
iption
1Dam
p
er, front right-hand
2Accel
e
rometer, lateral
3Accel
e
rometer,
front vertical
4D
a
mper, rear right-hand
5Adaptive dampin
g control module (A
DCM)
6Accel
e
rometer, rear vertical
7D
amper, rear l
eft-hand
8Dam
p
er, front left-hand

R
equire no adjustment and are non-serviceable items.
Accelerometers


The three accelerometers:
Sense veh
icle body movement.
Gen

erate an analogue voltag
e (maximum +5 volts) proportional to body movement.
Pr
ovide inputs to the adapti
ve damping control module.
The two vertical acce lerometers are mounted on the bulkhead and in the trunk.
The lateral accelerometer is mounted in the ECM housing.
Ada
ptive Damping Control Module (ADCM)

The ADCM
:
Is

mounted on the fascia support bracket.
Controls the four adaptiv

e dampers in re
sponse to analogue and digital inputs.
It
em
De
scription
1Battery su

pply
2Ignition su

pply
3Ground
4Input from verti

cal accelerometer, front
5Input from verti

cal accelerometer, rear
6Input from later

al accelerometer
7F

ootbrake operation signal
8Vehi

cle speed input
9D

amper control signals
10Ou

tput to message center
11D

iagnostic connector serial link

Is hard-wi
red to the instrume
nt cluster message center.
Is hard
-wired to the J1962 diagnostic connector.
Op
era
tion
Th
e
system selects the soft or
firm damper setting according to the current ro ad and driving conditions, to optimise vehicle
ride and handling.
With the vehicle stationary, the dampers are in the firm setting, but will normally switch to the soft setting when the vehicle
exceeds 8 km/h (5 mile/h); all dampers are switched simultaneously.
Sudden movement of the vehicle body, in response to road inputs, is detected by the vertical accelerometers, and the ADCM
switches the dampers to the firm setting to give improved damping of the resultant oscillations.
When cornering forces are detected by th e lateral accelerometer, the ADCM switches the dampers to the firm setting to
reduce the roll rate an d improve wheel control.
After the event has passed, the dampers revert to the soft setting.
When the footbrake is applied, the ADCM re ceives a signal and calculates the rate of vehicle deceleration. If the deceleration
rate is greater than a certain threshold, the dampers are switched to the firm setting to reduce the pitch rate and improve
wheel control.
If a system failure occurs, the ADCM grounds the output line to the instrument cluster message center, which displays a
text warning SUSPENSION FAULT and illuminates the amber warning lamp. Under fault conditions the system always fails to
the firm setting, so that the vehicle will be safe to drive un der all road and driving conditions.
Connector Pin Identity Chart for EM068

Pin
Number
Ci
rcui
t
Circuit Functi
on
1System erro
r output to instrument
cluster
2Not
used
3O/
P a
ccelerometer ground
4 to

9
Not
used
10K-
li
ne to diagnostic socket
11Ignition su
pply +12V
12Not
used
13Control signal (+ve) output
to l
eft-hand rear damper
14Control signal (+ve) output
to right-hand front damp
er
15Control signal (+ve) output
to right-hand rear
damper
16
a
nd 17
No
t
used
18Ground
19No
t
used
20Lateral
accelerometer i
nput
21Front vertical ac
celerometer in
put
22Rear vertical
acce
lerometer input
23No
t
used
24R
o
ad speed input from
instrument cluster
25Power output +5V to suppl y accelerometers
26Brake peda
l input

27Battery su
pply +12V
28L-

line to diagnostic socket
29No

t used
30Control signal (+ve) output

to left-hand front damper
31Control signal (-v

e) output to left-hand front damper
32Control signal (-v

e) output
to left-hand rear damper
33Control signal (-v
e) output
to right-hand front damper
34Control sign
al (-ve) output to ri
ght-hand rear
damper
35No

t used