1998 JAGUAR X308 speed control

Anti-Lock Control - Front Wheel Speed Sensor
Remo
val and Installation
Remov
a
l
Installation

1.
Ra
ise front of vehicle and support
on stands. Refer to section
100-02.

2. Remove wh
eel speed sensor.
Di
sc
onnect harness connector.
Re
mo
ve bolt.
3. Clean components and mating surfaces.

1. Inst al
l wheel speed sensor.
Posit
i
on sensor.
Install and tigh
ten bolt to 8-1
0 Nm.
Conne
ct
harness connector.
2. Remove stands an d lower vehicle.

Anti-Lock Control - Rear Wheel Speed Sensor
Re
moval and Installation
Remov

al
Installation

1.
R
aise rear of vehicle and support
on stands. Refer to section
100-02.

2. Re
move wheel speed sensor.
Di

sconnect harness connector.
Re

move bolt.
3. Clean components and mating surfaces.

1. Inst
all wheel speed sensor.
Posit

ion sensor.
Install and tigh

ten bolt to 8-10 Nm.
Conne

ct harness connector.
2. Remove stands an d lower vehicle.

Anti-Lock Control - Wheel Speed Se
nsor Ring
Re
mo
val and Installation
Remov
a
l
CAUTI
O
N: 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.
S p
ecial Tool(s)

Hub Holdin
g Tool
2
04-195 (JD 227)

ABS Rotor Nut Socket
2
06-
066A
1.
Op
en engine compartment and
fit paintwork protectors to
fenders.
2. Raise front of vehicle and support on stands. Refer to section
100-02.
3. Remove front wheel. Re fer to section 204-04.
4. Remove front brake disc. Refer to operation 70.10.12.
5. Remove vertical link and hub assembly. Refer to operation
60.25.38.90.

6. Re
move brake-disc shield from vertical link.
1. Remove screws.
2. Remove disc shield.
7. Using special tool, secure vertical link and hub assembly in a
vice.
Secure special tool
in a vice.
Posit
i
on hub in tool.
Fit and

tighten wheel nuts.

Steering System - General Inform
ation - Steering System
D
iagnosis and Testing
I

nspection and Verification
1.
1. Verify t
he customer concern by driving the vehicle.
2. 2. Visually inspect for obvious signs of mechanical or electrical damage.
Mec
hanical Inspection Chart
Electrical Inspection Chart
Mechanical Checks
Incorrect
tire pressure, loose whee
l nuts, incorrect wheel alignment
Loose ti
e-rods
Loose dam

per and spring assemblies or ball joint
Loose s

teering column shaft universal joints
Loose pinc

h bolts on steering column shaft
Loose steeri

ng gear assembly
Check f

or external damage to the steering gear.
- Damaged tie-rods
-
CAUTION: If a steering gear assemb ly is returned under warranty with leaking seals, but there is also
damage to the steering gear boot/boots the steering gear warranty will be invalid. This is due to the steering
gear seals being damaged due to fore ign materials entering the steering gear boot and damaging the steering
gear seals thereafter.
Damaged steering gear boot
Damaged accessory driv
e belt
Bin

ding or misaligned steering co
lumn, pump or steering gear
Incorrect fluid
level
Hose leaks o

r line restrictions
Hose fou

ling bodywork
El

ectrical Checks/Tests
Make sure all

connectors are in plac
e (steering gear Servotronic solenoid and steering control module (SCM) - if
applicable)
Make su
re all the fuses are in place and not blown
D

ISCONNECT the steering gear transducer
and the steering should become heavy
TEST e
lectrical values:
- Power Supply to the SCM = 12 Volts
- Steering gear transducer resist ance 7.0 to 7.5 Ohms is normal
(
limits: less than 5 Ohms and greater than 9 Ohms would

be declared unacceptable)

- Steeri
ng gear transducer voltage = 6 Volts
- Steering gear transducer cu rrent = 840 mA at 0 mph reducing to 0 mA at maximum speed

The
measurement of the maximum system pressure, (which is
governed by the pressure relief valve) is achieved by
inserting the Service Tool (pressure gauge and adaptors) into th e fluid circuit of the power steering system. Run the engine
at idle speed, turn the st eering from lock to lock and read the ma ximum pressure recorded on the gauge.
Installin
g Test Equipment
To
in
stall the pressure test equipment:
Pla
c
e a suitable drain tray be
low the power steering pump.
Install a hose clamp on
the re
servoir to pump hose prior to disconnecting any hoses, to avoid unnecessary loss of
fluid.
Disc
onnect the hose from the power st
eering pump high pressure outlet.
Install the pu
mp outlet to hose adaptor (5
). Do not omit the 'O' ring seal (9).
Connect the power steering
pump
adaptor to control valve hose (6) of the test equipment.
Install th e adaptor (4) in th
e high
pressure hose previously removed from the power steering pump outlet.
Conn
ect the connector (3) of the test equipment hose (2) to the adaptor (4).
R
e
move the hose clamp fro
m the reservoir hose.
Start th
e engine.
With the control valve (7) OPEN and the engine idli ng, 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.
• CAUTIONS:
To avoid excessive heating of the po wer steering pump, do not close the valve for longer than 5 seconds maximum.
Do not drive the vehicle with the test equipment installed.
With the control valve (7) CLOSED the power steering pump maximum ou tput pressure can be checked.
Removing Test Equipment
To
remove the test equipment:
Install a hose clamp
on
the reservoir to power steering pump hose.
Re
movi
ng the test equipmen
t is a reversal of the in stallation instructions.
Install a new '
O
' ring seal (9) to the power steering pump high pressu
re outlet to hose connection.
Instal
l the original hose to
the power steering pump.
Re
move the clamp from the reservoir to
the power steering pump hose.
Top-up the reservoir flui
d.
Ble
e
d the power steerin
g system. For additional information,
REFER to Power Steering System Bleeding
- in thi
s section.
Stee
ring Fault Diagnosis by Sympt
om Charts
Leakage
52
11-0
11-03/1
Pump High Pressure Ou
tlet
to Hose Adaptor
621
1
-011-02
Pump Adaptor
to Contro
l Valve Hose
721
1
-011-01
Control Valve
82
11-
011
Pressure Gauge
9-'O
'
Ring Seal
Cond
iti
on
Possib
l
e Sources
Acti
o
n
Co
nfirm
the position of the fluid
leak.
CLEAN th
e area of the leak.
In
s
pect the area and confirm the exact position of leak.
Make sure the fluid
is not from anoth
er system on
the vehicle.

Fo
r additional information, REFER to the
Electrical Checks and Tests in this section.
Steering control
module
(SCM) defective.
CHECK
the SCM and INSTALL a new SCM as

necessary.
Power steeri ng f
luid
delivery pressure or flow too low.
CHECK
the power stee
ring pressure. For
additional information, REFER to the Power Steering Pressure Test in this section.
INSTALL a ne
w power steering pump as
necessary. For additi onal information,
REFER to Section 211
-0 2
Power Steering
.
Internal steering gear
leakage.
CHECK
the power stee
ring pressure. For
additional information, REFER to the Power Steering Pressure Test in this section.
INSTALL a ne
w steering
gear as necessary.
For additional information,
REFER to Section 211
-0 2
Power Steering
.
Steeri
ng operati
on is very
heavy when driving, but when stationary
manoeuvring is good
Steering transducer open earl
y.
CHECK

steering transducer and INSTALL a
new steering transducer as necessary.
Carry out th
e electrical checks and tests.
For additional information, REFER to the
Electrical Checks and Tests in this section.
Steering transducer open
early,
steering control
module (SCM) fault.
CHECK
SCM and INSTALL a new SCM as
necessary.
Steering transducer open
earl
y, speedo signal error.
CHECK
speedo
circui
t. For additional
information, REFER to the wiring diagrams.

Steeri ng operati
on is very
light when driving, but when
stationary manoeuvring is good
Steering transducer not
o
pen, (no power steering
fluid flow).
CHECK
the power steering fluid condition.
For additional information, REFER to the
Power Steering Fluid condition check in this section.
Steering transducer not o
pen, steering control
module (SCM) fault.
CHECK
the SCM and INSTALL a new SCM as

necessary.
Carry out th
e electrical checks and tests.
For additional information, REFER to the
Electrical Checks and Tests in this section.
Steering transducer not
o
pen, speedo signal error.
CHECK

the speedo circ
uit. For additional
information, REFER to the wiring diagrams.

CHECK
the power steering
fluid low pressure pipe for restricted flow.
INSTALL a ne
w power steering fluid low
pressure pipe.
S t
eering heavy operation
during rapid manoeuvring
Ai r i
n power steering
system.
CHECK for an air l
eak into the power
steering system and re pair as necessary.
BLEED the
power steering system. For
additional information,
REFER to Power Steering System Bleeding
- in t hi
s section.
Fluid loss at the power
steering pump shaft seal.
CHECK the power steer
ing pump for signs o
f steering fl
ui
d loss.
INST
ALL a ne
w power steering pump as
necessary. For additi onal information,
REFER to Section 211
-0 2
Power Steering
.
Power steeri
ng f
luid
delivery pressure or flow too low.
CHECK the power steer
ing pump for signs o
f steering fl
ui
d loss.
CHECK

the power stee
ring pressure. For
additional information, REFER to the Power Steering Pressure Test in this section.
INSTALL a ne
w power steering pump as
necessary. For additi onal information,
REFER to Section 211
-02
Power Steering
.
Lower steeri
ng col
umn
interference.
CHECK
the steering co
lumn is free from
interference from the en gine harness, sound
proofing or the floor covering.
Incorrect steering geometry. CHE
CK the front wheel alignment. For
additional information,
REFER to Section 204
-00 Sus
pension
Sy
ste
m
- General

Information
.
CHECK

the power stee
ring pressure. For

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

modul
e. This regulates the fluid flow
through the hydraulic control valve, wh ich determines the amount of steering
assistance.
Steering Control Module
The steering control
module re
ceives the vehicle speed from the instrument cluster and outputs the corresponding current
values to the Servot ronic valve. At parking speeds, wh en maximum assistance is required , the current is at its maximum
value of 854 mA and the valve is closed. As the vehicle speed increases, the current progressively decreases to its minimum
value of 15 mA and the valve opens in sma ll increments. This results in an increasing amount of hydraulic pressure being
applied to the reaction piston, making the steering feel more precise and responsive.
The rate of progression and shape of the characteristic between parking and high speed operation, is determined by the
algorithm within the steering control module, and is matched to each suspension variant within the vehicle range.
Control Module Connections



It
em
De
scription
1Servotronic valve
2Steeri

ng control module
3No

t used
4Vehi

cle speed input
5Ground
6Ignition su

pply +12V
7Base of

steering control module