1998 JAGUAR X308 vi number

m
ember. The quick-fit connector O-rings are not serviceable.
Special tool JD 182 is required to disconnect the quick-fit connector.
Hydraulic System


P
arts List
Hydraulic System

Op
erating Principle
The rot
ary motion of the steering wheel is converted, via the st
eering rack pinion, to the lateral motion of the rack. Steering
assistance is provided by pressurized fluid being directed against a piston operating within the rack cylinder. Rack
movement is achieved by diffe rential pressures being applied on either si de of the rack piston, caused by unequal
restrictions within the hydraulic control valve.
The main components of the hydraulic control valve are the rota ry distributor, control sleeve and hydraulic reaction piston.
It
em
Par
t Number
De
scription
1—F

luid reservoir
2—Pum

p
3—Pressure and fl

ow limiting valve
4—Supply line
5—R

eturn line
6—Steeri

ng rack
7—Pin

ion
8—O

perating cylinder and piston
9—Hydrau

lic control valve
10—Hydraulic reaction

piston
11—Control

sleeve
12—R

otary distributor
13—F

luid cooler


A
quick-fit connector with double O-ring se
als is incorporated in the return line and is clipped to the right-hand chassis side

The rotary distri
butor and control sleeve turn relative to ea
ch other, forming the unequal restrictions which create the
differential pressures to operat e the rack piston; the displacement of the di stributor and sleeve being controlled by the
elastic deformation of a torsion bar which is concentric with the pinion and valve. Refer to Positive Center-Feel Torsion Bar
in this sub-sectio n.
The hydraulic reaction piston moves axially, relative to th e rotary distributor, and is connected to the control sleeve by a
three-bearing helical screw. Pressure applied either side of the hydraulic reaction piston is translated into a rotational force
which increases steering effort. For detail s of Servotronic speed-sensitive steering control, refer to Servotronic Control in
this sub-section.
When the vehicle is travelling straight ah ead, the valve restrictions are balanced, thus providing equal pressures on either
side of the rack piston. When load is a pplied at the steering wheel, the two halves of the control valve (rotary distributor
and control sleeve) are displaced making the restrictions unequa l. The resulting differential pressures on either side of the
rack piston, assist the steering rack to mo ve to left or right. As the turning load is removed, the pressures equalize again
and the steering return s to the straight ahead position , aided by suspension geometry.
Serv
otronic Control

P a
rts List
The Servotronic system provides steering assistance which is pr oportional to vehicle speed. It comprises the steering control
module, and Servotronic valve forming part of the hydraulic control valve assembly.
The Servotronic valve is an electro-hydrauli c device with a variable orifice, which varies in size according to the position of a
needle valve. The needle valve is controlled by a solenoid in response to a variable current input from the steering control
Ite
m
Part
Number
Descr
iption
1—Vehi
cl
e speed input
2—Steeri
ng control
module
3—Servotronic valve
4—Hydraulic

control valve housing
5—PAS stee
rin
g pump
6—Batt
ery

Power Steering - Power Steering
Diagn
osis and Testing
Refer to the Description and Operation sub-section for details of the power operated steering system and Servotronic control
system.
Power Steer ing Pressure Test

Test Equ
i
pment

Parts List
In
stalling Test Equipment
To
in
stall the pressure test equipment:
Pla
c
e a suitable drain tray below the PAS pump.
Install a hose clamp
on
the re
servoir to pump hose prior to disconnecting any hoses, to avoid unnecessary loss of
fluid.
Di sc
onnect the hose from the PAS pump high pres
sure outlet.
Ins
tall the pump outlet to hose ad
aptor. Do not omit the O-ring.
Conn
ect the pump adaptor to control valve hose of the test equipment.
Install th
e adaptor in the high pressure hose previ
ously re
moved from the pump outlet.
Conne
ct the connector of the test equipment hose to the adaptor.
R
e
move the hose clamp fro
m the reservoir hose.
Start th
e engine.
With the control valve OPEN and the engine idling , the following system pressures may be checked:
Du
ring turning.
W
h
en the steering is
held on full lock.
With
the steeri
ng at rest.
• WARNINGS:
TO AVOID EXCESSIVE HEATING OF THE PAS PUMP, DO NOT CLOSE THE VALVE FOR LONGER THAN NECESSARY.
Ite
m
Par
t
Number
De
scr
iption
1—Pressure

gauge hose
2—Pump return hose
3—Pump return hose connector
4—Test equi
pment to
HP hose adaptor
5—Pump HP outlet to hose adaptor
6—Pump adaptor
to control valve hose
7—Control valve

DO NOT DRIVE THE VEHICLE WITH THE TEST EQUIPMENT INSTALLED.
With the control valve CLOSED the pump maximum output pressure can be checked.
Remov
ing Test Equipment
T
o remove the test equipment:
Install a hose clamp

on the
reservoir to pump hose.
Re
moving the test equipmen
t is a reversal of the installation instructions.
Install a new O-r
ing to the PAS pump high
pressure outlet to hose connection.
Inst
all the original hose to the PAS pump.
R

emove the clamp from the reservoir to pump hose.
Top-up the reservoi

r fluid.
B

leed the PAS system; refe
r to this section.
Refer to PDU
User Guide
T
he PDU will diagnose all electrical components of the system.
Before changing a component, chec k fuse No. 12 (10A) in the left-hand heelboard fu se box. However, if this fuse is faulty a
number of other components wi ll also fail to function.

Steering
Linkage - Steering Linkage
Descriptio
n and Operation

Parts List
The left- and right-hand tie rod assemblies:
T
ransmit steering forces from the steering rack to the st
eering arms which are integral with the vertical links.
Comprise the tie rod, inner
ball joint,
outer tie rod end and outer ball joint.
P
rovide front road wheel toe setting by adju
stment of the threaded outer tie rod ends.
• NOTE: Steering geometry adjustments must only be carried out wi th the vehicle on turn plates to allow the wheels to move
during adjustment.
The left- and right-hand steering rack gaiters:
Are
installed between the steering rack and the tie bars.
Are

of the concertina type.
R

etain lubricant and prevent th
e ingress of foreign matter.
P
ermit movement of the steering rack and tie rods.


ItemPa
rt Number
Descript
ion
1—St

eering rack assembly
2—St

eering rack gaiter
3—I

nner ball joint
4—Tie

rod
5—O

uter tie rod end
6—Lo

ck-nut
7—Oute

r ball joint
8—O

uter ball joint nut

Steering Column - Steering Column
Description an
d Operation
Stee

ring Wheel

T
he steering wheel assembly incorporates:
The s

peed control switchpack.
The i

n-car entertainment (ICE) switchpack.
The h

orn pad.
The driver ai

r bag module; refer to Section
501
-20A Safety Belt
System
Sectio
n
501
-2
0B Supplemental Restraint
Sy

stem
.
I

CE Switchpack

The
in-car entertainment (ICE) switchpack is installed to the le
ft of the steering wheel center, controlling the ICE functions
and telephone (where fitted). The switchpack overrides the corresponding bu ttons on the ICE control panel and performs
the following functions:
1. 1. Increase the volume of the select ed audio output or telephone.
It
em
Par
t Number
De
scription
1-Spe

ed control switchpack
2-I

CE switchpack
3-Horn pad
4-Air bag lo

cation
It

em
Par
t Number
De
scription
1-Vol

ume increase

2-ICE func
tions/teleph
one mode select
3-Volum
e decrease
4-ICE pres

ets/telephone memory select

2.2. Press and rel e
ase to cycle through radio FM, radio AM,
tape cassette, or CD player. Press and hold for two
seconds to select telephone mode.
3. 3. Decrease the volume of the select ed audio output or telephone.
4. 4. Press and release to select the next pr eset radio station, or the next track on tape or CD. Press and hold for two
seconds to select the next radio station on the waveband upwards, or the next CD loaded in the player, or to
change the side of tape. When in te lephone mode, press and release to scroll up to the next memory location.
Press and hold for two seconds to send and end a call.
Speed Control Switchpa ck

The s p
eed control switchpack is installed to the right of th
e steering wheel center and performs the following functions:
1. 1. Set the desired speed or increase the set speed.
2. 2. Resume the previously set speed.
3. 3. Decrease the set speed.
4. 4. Cancel speed control without erasing the set speed.
Horn and Driver Airbag Location

Ite
m
Par
t
Number
De
scr
iption
1-Se
t
speed or increase speed
2-Re
sum
e
3-De
creas
e speed
4-Cancel
Ite

m
Part
Number
Descr
iption
1-Horn operatin
g pad

The ho
rn operating pad is mounted in the central area of the steering wheel.
2-Driver air bag location

The driver air bag is moun
ted below the horn operat
ing pad area, adjacent to the steering wheel hub.
For air bag safety and service information, refer to Section 501
-20A Safety Belt
System
Sectio
n
501
-2
0B Supplemental
Re

straint System
.
Upper Steering Column


Motorized Upper Colu
mn Assembly

The motorized upper steering column:
Is adjustable for both til
t and reach.
Has a col

umn adjustment switch installed on
the left-hand side of the lower cowl.
W
ill automatically move to the uppermost tilt and innermost reach position, when the automatic driver entry and exit

function is selected.
Has an instrument li
ghti
ng dimmer switch installed on the left-hand side of the lower cowl.
The steering column adjustment switch:
Controls steeri
ng column reach by
movement of the switch towards an d away from the steering wheel.
Controls steeri
ng column tilt by mo
vement of the switch up and down.
Has two
rotary positions, AUTO and OFF, for selecting the
automatic entry and exit steering column tilt function.
It
em
Par
t Number
De
scription
1-Upper

cowl

2-Lower cowl
3-Ste
ering column adjustment switch
4-Di

mmer switch