1998 JAGUAR X308 speed

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

No
ise
S
teering heavy operation in
one direction
F
aulty rotary valve/seal.
addi
tional information, REFER to the Power
Steering Pressure Test in this section.
INST
ALL a new steering
gear as necessary.
For additional information,
REFER to Section 211
-0
2 Power Steering
.
Ti

re fouling on the wheel
arch liner.
CHECK for
clearance be
tween the tire and
the wheel arch liner.
R
emove and refit the wheel arch liner or
INSTALL a new wheel arch liner as necessary.
S
teering heavy operation in
both directions
Low power steer
ing fluid.

CHE
CK steering system
for signs of steering
fluid loss.
BLEE
D the power steering system. For
additional information,
REFER to Section 211
-0
0 Steering System
- General Informati

on
.
Ai

r in power steering
system.
CHECK
the power steering pump for signs o
f steering fl

uid loss.
INST

ALL a new power steering pump as
necessary. For additi onal information,
REFER to Section 211
-0
2 Power Steering
.
Fluid loss at the power
steering pump shaft seal.
CHECK
the power steering pump for signs o
f steering fl

uid loss.
INST

ALL a new power steering pump as
necessary. For additi onal information,
REFER to Section 211
-0
2 Power Steering
.
Power steeri

ng fluid
delivery pressure or flow too low.
CHECK
the power steering pump for signs o
f steering fl

uid loss.
CHECK

the power stee
ring pressure. For
additional information, REFER to the Power Steering Pressure Test in this section.
INST
ALL a new power steering pump as
necessary. For additi onal information,
REFER to Section 211
-0
2 Power Steering
.
Steeri

ng operation varies
from heavy to light when
driving at constant speed
Lower steeri
ng column
interference.
CHECK
the steering co
lumn is free from
interference from the en gine harness, sound
proofing or the floor covering.
Incorre
ct sp
eedometer
signal.
CHECK
the speedo circ
uit. For additional
information, refer to the wiring diagrams.
Steeri
ng transducer
cable/connection faulty or grounded.
CHECK
the steering transducer circuit. For
additional information, refer to the wiring diagrams.
Carry ou
t the electrical checks and tests.
For additional information, REFER to the
Electrical Checks and Tests in this section.
Steeri
ng wheel varies from
light to heavy two times per revolution
Lower steeri
ng column
interference.
CHECK
the steering co
lumn is free from
interference from the en gine harness, sound
proofing or the floor covering.
Steeri
ng column universal
joints binding.
IN
STALL a new steering column. For
additional information,
REFER to Section 211
-0
4 Steering Column
.
Seized or damaged
ste
ering components.
CHECK
for wear or failure of suspension
bushes and ball join ts. For additional
information,
REFER to Section 204
-00
Suspension
Sy

stem
- General
Information
.
Cond

ition
Possib
le Sources
Acti
on
Acce

ssory drive
belt squeal
Incorre
ct accessory drive belt

tension or accessory drive belt glazed.
CHECK
accessory drive belt condition and INSTALL a
new accessory drive belt as necessary. For additional
information,
REFER to Section 303
-0
5 Accessory Drive
.
Chir

p noise in
the steering pump
Loose or worn accessory dr
ive belt.
CHECK
accessory drive belt condition and INSTALL a
new accessory drive belt as necessary. For additional
information,
REFER to Section 303
-0
5 Accessory Drive
.

High
-pitched sound like rubbing a clean window.
Squea

l
Continu
ous, high-pitched sound like runn
ing finger nails across a chalkboard.
Tap
Ligh
t, hammering sound like tapping pencil on edge
of table. May be rhythmic or intermittent.
Weep
Continu
ous mid-range sound (lower frequency
than squeal, higher frequency than groan).
Whir/
Whine
High
-pitched buzzing sound, like
an electric motor or drill.
Whistle

Sharp, shril
l sound, like wi
nd passing a small opening.
Description of Specific St eer
ing System Noise Types
Bel
t Squeal
Belt squea
l is a high frequency air-born
e noise generated by slippage of the ribbe d Vee belt on the power steering pump
pulley. Squeal increases with system loading and at the end of lock.
Clonk

Cl
onk is a structure-borne nois
e heard as a loose-sounding rattle or vibration coming from the steering column. Clonk can
be identified by driving and turning over cobblestones, rough roads, or high frequency bumps such as 25-50 mm tall tar
strips. Clonk requires a tie-rod load impact.
Column Knoc
k
Col
umn knock is a loose-sounding rattle or
vibration generated by the steering column shaft contacting other portions of the
column assembly. The noise is both audible and tactile. Column knock is generate d by driving over cobblestones or rough
pavement. It is not necessary to turn the steering wheel to create this noise.
Column Ra
ttle
Co
lumn rattle is a metallic sounding no
ise created when applying a highly impuls ive force to the steering wheel. Column
rattle is often used to combine the more general group of column noises includin g clonk and column knock. Column rattle
noises can be caused by clonk, knock, l oose column components, bonus parts etc. A series of parked, straight-line driving,
and cornering test should be carried out to isolate the source/sources.
Gr
inding/Scrape
Gr

inding is a low frequency noise in the column when the st
eering wheel is turned. Is generally caused by interference
between moving components such as the st eering wheel to steering column shroud.
Gr
unt (Squawk)
Grunt

is a "honking" sound elicited when coming off one of
the steering stops. Grunt is generally excited during parking
manoeuvres with a low to me dium speed steering input.


Squea
k

Hiss (Swish)
Hiss or Val
ve Hiss is a high-frequency so
und coming from the steering gear when the system is loaded. It is a rushing or
"swish" noise that doesn't change frequency with RPM. Hiss is the general noise generated by the flow of hydraulic fluid
through restrictions in the steer ing system. Restrictions include the rotary stee ring valve, power steering tubes, connectors,
tuning orifices, etc. Hiss can be air- borne and structure-borne, but the structure-borne path through the steering
intermediate shaft is usually dominant.
Moan (Groan)
Moan is the general structu r
e-borne noise of the steering system. Moan is primarily transmitted to the driver via the body
structure through the pump mount, engine mounts, power steering lines and power steering brackets. On some vehicles,
moan is a load humming noise, often present when the wheel is turned and the system is loaded. It may change frequency
with engine RPM and if the sy stem is loaded or unloaded.
Rack Knock (R
ack Slap)
CAU
T
ION: DO NOT attempt to adjust the stee
ring gear yoke. Failure to follow this instruction will result in the steering
gear warranty to become invalid.
Rack Knock is a rattle sound an d steering wheel vibration caused by separation of the steering gear and pinion while driving
over bumps. It is a structure-borne noise transmitted throug h the intermediate shaft and column. Rack knock can also be
heard as a "thump" or impact noise that occurs with the vehicle stationary when the steering wheel is released from a
loaded position and allowed to return to rest . Noise occurs with the engine on or off.
Rattles
Ra
ttles are noises caused by knocking or hitting with components in the steering system. Steering rattles can occur in the
engine compartment, the suspension, or the passenger compartment . Rattles can be caused by loose parts, movable and
flexible parts, and improper clearances.
Squea k
s/Scrapes
Squeaks/Scrapes are noises due
to fri
ction or component rubbi
ng anywhere in the steering system. Squeaks/Scrapes have
appeared in steering linkages and jo ints, in column components and in co lumn and steering wheel trim parts.
Weep
We
ep is an air-borne noise, occasionally
generated when turning the steering across lock at a constant rate. When present
on a vehicle the noise, once initiated can often be maintained across a large proportion of the available steering movement.
Whistle
Wh
istle is similar to hiss but is louder and of a higher frequency. It is also more
of a pure tone noise than hiss. Whistle is
air-borne and is generated by a high flow rate of hydraulic fluid through a small restriction.
Zip

Zip n
o
ise is the air-borne noise
generated by power steerin g pump cavitation when power steering fluid does not flow freely
through the suction hose from the rese rvoir to the pump. Zip primarily occurs during cold weather at start-up.
Steering System Vibrations and Harshne
ss
Buzz
Buzz is a tactile rotary vi

bration felt in
the steering wheel for slow steering inputs. Buzz can also be called a grinding feel
and it is closely related to grunt and is caused by high system gain with low damping. Buzz is generally excited during
parking manoeuvres with low to medium speed steering input.

Buzz (E
lectrical)
A
different steering buzz can be caused by
pulse width modulated (PWM) electric actuators used in variable assist steering
systems. This buzz is felt by turning the ignition key to run without starting the engine and holding onto the steering wheel.
In extreme cases, the buzz can be felt with the engine running also.
Column/Steering Wheel
Shake
Column shake is a low f
requenc
y vertical vibration excited by primary engine vibrations.
Nibble (Shimm
y)
Steeri
ng nibble is a rotary oscillation or
vibration of the steering wheel, which can be excited at a specific vehicle speed.
Nibble is driven by wheel and tire imbalance exciting a suspensi on recession mode, which then translates into steering gear
travel and finally steering wheel nibble.
Shudder (Judd
er)
Shudder i
s a low frequency oscillation of th
e entire steering system (tire, wheels, st eering gear and linkage, etc.) when the
vehicle is steered during static-park or at low sp eeds. Shudder is very dependent on road surface.
Torque Ri
pple
Torque rippl
e is a concern with Electric Power Steering (EPS) sy
stems. Torque ripple is most evident at static-park steering
the wheel very slowly from lock to lock. Torque ripple is primarily caused by motor commutation.
Torque/Veloc
ity Variation
(Phasing/Effort Cycling)
Steeri
ng wheel torque variation oc
curring twice in one revolution is normally as a result of problems with the lower steering
column (intermediate shaft), but foul cond itions generally result in either constant stiffnes s or single point stiffness.
Depending upon the orientation of the joints, the steering can fe el asymmetric (torque falling off in one direction and rising
in the other) or else it can simply have pronounced peaks and troughs as the steering moves from lock to lock.
Wheel Fight
(Kick Back)
W
heel fight is excess feedback of sudden road forces through th
e steering system and back to the driver. It is evaluated at
all vehicle speeds over cobblestones, rough roads, and potholes . The tires, wheels, and suspension generate forces into the
steering systems. Steering friction, hydraulic damping, hydr aulic compliance, mechanical compliance, steering ratio, and
assist gain all affect how much is transmitted to the driver.
Stee
ring Linkage
CAUTI
ON: Steering gear boots must be
handled carefully to avoid damage. Use new clamps when installing steering
gear boots.
Inspect the boots for cuts, deterioration, tw isting or distortion. Check the steering gear boots to make sure they are tight.
Install new boots or clamps as necessary.
• NOTE: The following steps must be carried out with assistance.
1. 1. With the wheels in the straight ahead po sition, gently turn the steering wheel to the left and the right to check for
free play.
2. 2. Free play should be between 0 and 6 mm (0 and 0.24 in) at the steering wheel rim. If the free play exceeds this
limit, either the ball joints are worn, the lower steering column joints are worn or the backlash of the steering gear
is excessive.

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

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