1998 JAGUAR X308 ignition

It is a reciprocating two
-circuit pu
mp in which one brake circuit is as signed to each pump circuit.
It supplies th
e fluid pressure and vo
lume to supply the brake circuits under ABS and Traction control.
The pump is driven by an electri
c motor, with the pump
housing incorporating two lo w pressure accumulators and
damping chambers for each brake circuit.
The ac cu
mulator stores the pressure and smooths out the output pu
lses from the pump.
ABS Warning Lamp
The sys
tem will be set in a fail-safe mode if a problem is de
tected; a warning lamp on the instrument panel will notify the
driver there is a problem.
Anti-Lock Braking Sy
stem (ABS)
The AB
S components are combined with
an hydraulic booster and a tandem master cylinder to provide a two circuit braking
system. The system comprises, four wheel speed sensor s, a brake control modulator and an ABS warning lamp.
Should a wheel start to lock-up during braking a signal tr ansmitted from the wheel speed sensor to the brake control
modulator will start the hydraulic pump. The brake control modula tor will close the input valve of the line connected to the
locked-wheel to stop any increase in fluid pressure to the br ake caliper. If this fails to prevent the wheel locking, the
pressure in the caliper will be decreased by opening the return valve until th e wheel starts accelerating again. The fluid
pressure from the return va lve is directed into the low pressure accumulator, housed in the pump.
From the low pressure accumulator, fl uid is pumped through the damping cham ber to the brake master cylinder. The
pressure to the brake caliper will then be increased in small steps to maintain maximum adhesion between the tire and road
surface. This is achieved by closing the return valve, and opening the input valve and using the hydraulic pump to increase
the pressure.
Although the system senses all four wheels independently, the rear wheels are regulated as a pair. If a sensor on a rear
wheel detects a wheel decelerating rapidly, then the fluid pressure to both wheels is reduced. The fluid pressure is then
dictated by the wheel having the lowe st adhesion with the road surface.
The ABS system will be set in a fail-safe mode if a problem is detected; a warn ing lamp on the instrument panel will notify
the driver there is a problem. The brake system will still operate conventionally and with the same standard of performance
as a vehicle not equipped with ABS.
Automa tic Stability Control (ASC)

Th
e ASC utilizes the ABS sensing arrangement to provide the maximum traction force to propel the vehicle.
The ASC is switched on when the engine is started. The system can be switched off by pressing the 'ASC OFF' (the switched
is marked 'TRAC OFF' on vehicles fitted with traction control). The switch, which is situated in the center console switchpack,
lights up to warn that the system is sw itched off. An 'ASC' amber warning light flashes on the instrument panel when the
system detects a spinning wheel.
The ASC system uses engine intervention to reduce the torque delivered to the drive wheels to prevent them spinning.
Engine torque is re duced in three ways:
The
throttle is moved towards the closed position.
The ignition is retarded. F
u
el is cut-off at the cylinder injectors.
Wheel spin is detected by the wheel sp eed sensors and communicated to the AB S/TCCM. The ABS/TCCM uses information
from the controller area network (CAN) to calculate the torque that the engine should produce to stop the wheel spinning.
Torque reductions are then requested from the engine control module (ECM ) through the CAN. The throttle is then
positioned to provide the target torque, which has been calculated to prevent wheel spin. During the transient phase of
torque reduction the fuel is cut-off and th e ignition retarded Both the fuel cut-off an d ignition retard will be restored to
normal when the throttle is set to its new position.
The ASC uses a brake control modulator with six solenoid va lves: three normally open inlet valves and three normally

Pinpoint tests

W
S
S circuit: short
circuit to power
WSS f
ailure
C1
175Left -hand re
ar wheel speed
sensor (WSS) circuit failure
W S
S circuit: open
circuit
WS
S circuit: short
circuit to ground
W S
S circuit: short
circuit to power
WSS f
ailure
F
or l
eft-hand rear WSS test
s. GO to Pinpoint Test E.
C1267Modulat or valv
e failure
Supply volt
ages
to valve
solenoids or sensors out of range
Fo
r power and ground tests. GO to Pinpoint Test
A.
B1342CAN co
mmunication circuit
failure
CAN :
open circuit fault

CAN:
short circuit to
ground
CAN :
short circuit to
power
Fo
r CAN tests. GO to Pinpoint Test
F.
B1676Supply volt
age out of range
Supply voltage:
too
low
Supply volt age:
too
high
Check fo
r DTCs indicating a charging system fault.
Rectify as necesssary.
PI
NPOINT TEST A : MODULE
POWER AND GROUND SUPPLIES
TES
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
A
1
: CHECK THE POWER SUPPLY FUSES
Make sure the igniti
on is turned off. 1
Chec
k fuses 04, 16 and 18 of the engine compartment junction box.
2
Are th
e fus
es in good condition?
Yes GO to A2
.
No
Install a new f
use as
necessary. Check the syst em for normal operation. If the fuse fails again,
check the circuit for a short circuit to ground. Refer to the electrical guides.
A2: CHECK THE PERMANENT
POWER SUPPLY (1) TO THE MODULE
Disc

onnect the ABS module connector, LF27.
1
Measure the voltage between LF
2
7, pin 09 (NR) and ground.
2
Is the vol
t
age greater than 10 volts?
Yes GO to A3
.
No Re
pair the circuit between the engine compartment
junction box, fuse 16, and LF27 pin 09. Refer to
the electrical guides. Clear the DTC, check for normal operation.
A3: CHECK THE PERMANENT
POWER SUPPLY (2) TO THE MODULE
Meas
ure t
he voltage between LF27, pin 25 (NW) and ground.
1
Is the vol
t
age greater than 10 volts?
Yes GO to A4
.
No
Re
pair the circuit between the engine compartment ju
nction box, fuse 18, and LF27 pin 25. Refer to
the electrical guides. Clear the DTC, check for normal operation.
A4: CHECK
THE IGNITION POWER SUPPLY TO THE MODULE
Make sure the ignition is on. 1
Measure the
voltage between LF 2
7, pin 20 (WU) and ground.
2
Is the vol
t
age greater than 10 volts?
Yes GO to A5
.
No Re
pair the circuit between the engine compartment ju
nction box, fuse 04, and LF27 pin 20. Refer to
the electrical guides. Clear the DTC, check for normal operation.
A5: CHECK
THE GROUND SUPPLY TO THE MODULE

Make sure the ignition is turned off. 1
Meas
ure the resistances between LF27,
pins 08 and 24 (B) and ground.
2
Are
the resistances less than 5 ohms?
Yes The power and ground supplies to the module are ok . Recheck the DTCs for codes indicating a fault
elsewhere.
No Repair the high resistance circui t. Refer to the electrical guides. Clear the DTC, check for normal
operation.
PINPOINT TE
ST B : CHECK THE RIGHT-HAND FRONT WSS AND CIRCUITS
•
NOTE: Check connectors and pins for damage/corrosion
(see visual inspection).
•
NOTE: Check the WSS ring condition, whee
l bearing etc. Before beginning pinpoint test s refer to the visual inspection.
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
B1: CHECK

THE WSS OUTPUT
Disc

onnect the ABS sensor connector, FR01.
1
Connec

t a multimeter set
to read alternating curr ent volts (AC volts) between pins 1 and 2 of the
sensor.
2
Spin
the wheel by hand and check the meter display.
3
Doe

s the sensor generate a voltage?
Yes GO to B2
.
No

If the WSS ring is in good condition, install a new WSS.
REFER to: Front Wheel Speed Sensor
(20
6-09 Anti-Lock Control, Removal and Installation).
B2:

CHECK THE WSS SIGNAL CIRCUIT CONTINUITY
Make sure the ignition is off. 1
Di

sconnect the ABS module connector, LF27.
2
Meas

ure the resistance between LF27
, pin 03 (Y) and FR01, pin 02 (Y).
3
I
s the resistance less than 5 ohms?
Yes GO to B3
.
No

Repair the high resistance circui t. This circuit includes intermediate connector, LF02. Refer to the
electrical guides. Clear the DTC, check for normal operation.
B3:
CHECK THE WSS RETURN CIRCUIT CONTINUITY
Meas

ure the resistance between LF27
, pin 04 (G) and FR01, pin 01 (G).
1
I
s the resistance less than 5 ohms?
Yes The WSS and circuits are OK. Check for DTCs indicating a possible module failure.
No Repair the high resistance circui t. This circuit includes intermediate connector, LF02. Refer to the
electrical guides. Clear the DTC, check for normal operation.
P
INPOINT TEST C : CHECK THE LEFT-HAND FRONT WSS AND CIRCUITS
•
NOTE: Check connectors and pins for damage/corrosion
(see visual inspection).
•
NOTE: Check the WSS ring condition, whee
l bearing etc. Before beginning pinpoint test s refer to the visual inspection.
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
C1

: CHECK THE WSS OUTPUT
Disc

onnect the ABS sensor connector, FL01.
1
Connec

t a multimeter set
to read alternating curr ent volts (AC volts) between pins 1 and 2 of the
sensor.
2
Spin
the wheel by hand and check the meter display.
3
Doe

s the sensor generate a voltage?
Yes GO to C2
.
No

If the WSS ring is in good condition, install a new WSS.
REFER to: Front Wheel Speed Sensor
(20
6-09 Anti-Lock Control, Removal and Installation).
C2

: CHECK THE WSS SIGNAL CIRCUIT CONTINUITY

Make sure the ignition is off. 1
Disc
onnect the ABS module connector, LF27.
2
M
e
asure the resistance between LF27, pin 17 (W) and FL01, pin 02 (W).
3
I
s
the resistance less than 5 ohms?
Yes GO to C3
.
No
Re
pair the high resistance circui
t. This circuit includes intermed iate connector, LF02. Refer to the
electrical guides. Clear the DTC, check for normal operation.
C3: CH
ECK THE WSS RETURN CIRCUIT CONTINUITY
Measure

the resistance between LF27, pin 18 (R) and FL01, pin 01 (R).
1
Is

the resistance less than 5 ohms?
Yes The WSS and circuits are OK. Check for DTCs indicating a possible module failure.
No Repair the high resistance circui t. This circuit includes intermediate connector, LF01. Refer to the
electrical guides. Clear the DTC, check for normal operation.
PI
NPOINT TEST D : CHECK THE RIGH
T-HAND REAR WSS AND CIRCUITS
•
NOTE: Check connectors and pins for damage/corrosion
(see visual inspection).
• NO
TE: Check the WSS ring condition, whee
l bearing etc. Before beginning pinpoint test s refer to the visual inspection.
TES
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
D1: CHECK

THE WSS OUTPUT
Disc
onne
ct the ABS sensor connector, RA02.
1
Connec
t
a multimeter set
to read alternating curr ent volts (AC volts) between pins 1 and 2 of the
sensor.
2
Spin
the wheel by hand and check the meter display.
3
Doe
s
the sensor generate a voltage?
Yes GO to D2
.
No
If
the WSS ring is in good condition, install a new WSS.
REFER to: Rear Wheel Speed Sensor
(206-0
9 Anti-Lock Control, Removal and Installation).
D
2
: CHECK THE WSS SIGNAL CIRCUIT CONTINUITY
Make sure the ignition is off. 1
Disc

onnect the ABS module connector, LF27.
2
Measure t

he resistance between LF27
, pin 07 (O) and RA02, pin 01 (O).
3
Is
the resistance less than 5 ohms?
Yes GO to D3
.
No Re
pair the high resistance circui
t. This circuit includes intermed iate connector, LA02. Refer to the
electrical guides. Clear the DTC, check for normal operation.
D3:
CHECK THE WSS RETURN CIRCUIT CONTINUITY
Meas
ure t
he resistance between LF27
, pin 06 (Y) and RA02, pin 02 (Y).
1
Is
the resistance less than 5 ohms?
Yes The WSS and circuits are OK. Check for DTCs indicating a possible module failure.
No Repair the high resistance circui t. This circuit includes intermediate connector, CA09. Refer to the
electrical guides. Clear the DTC, check for normal operation.
PI
NPOINT TEST E : CHECK THE LEFT-HAND REAR WSS AND CIRCUITS
•

NOTE: Check connectors and pins for damage/corrosion
(see visual inspection).
• NO
TE: Check the WSS ring condition, whee
l bearing etc. Before beginning pinpoint test s refer to the visual inspection.
TES
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
E1
: CHECK THE W
SS OUTPUT
Disc
onne
ct the ABS sensor connector, LA02.
1
Connec
t
a multimeter set
to read alternating curr ent volts (AC volts) between pins 1 and 2 of the
sensor.
2

Spin
the wheel by hand and check the meter display.
3
Doe

s the sensor generate a voltage?
Yes GO to E2
.
No

If the WSS ring is in good condition, install a new WSS.
REFER to: Rear Wheel Speed Sensor
(20
6-09 Anti-Lock Control, Removal and Installation).
E2

: CHECK THE WSS SIGNAL CIRCUIT CONTINUITY
Make sure the ignition is off. 1
Di

sconnect the ABS module connector, LF27.
2
Meas

ure the resistance between LF27
, pin 21 (U) and LA02, pin 01 (U).
3
I
s the resistance less than 5 ohms?
Yes GO to E3
.
No

Repair the high resistance circui t. This circuit includes intermediate connector, LA02. Refer to the
electrical guides. Clear the DTC, check for normal operation.
E3
: CHECK THE WSS RETURN CIRCUIT CONTINUITY
Meas

ure the resistance between LF27
, pin 22 (U) and LA02, pin 02 (U).
1
I
s the resistance less than 5 ohms?
Yes The WSS and circuits are OK. Check for DTCs indicating a possible module failure.
No Repair the high resistance circui t. This circuit includes intermediate connector, CA29. Refer to the
electrical guides. Clear the DTC, check for normal operation.
P
INPOINT TEST F : CONT
ROLLER AREA NETWORK (CAN) INTEGRITY TEST
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
F

1: CHECK THE NETWORK INTEGRITY
FROM THE DIAGNOSTIC SOCKET
M
easure the resistance between pins 06 (Y) and 14 (G) of the diagnostic socket.
1
I

s the resistance 60 ohms?
Yes The CAN system is OK. Check for DTCs indicating a fault elsewhere.
No Check the CAN system for open an d short circuits. Refer to the electrical guides. Clear the DTC,
check for normal operation.

Vehicl
e wanders from side to

side on the road, when the vehicle is driven straight ahead and the steering wheel is held in a firm position
Incorrect ti re
pressure or
tire size.
CHECK and ADJ
UST the tire pressure. For
additional information,
REFER to Section 204
-0 4
Wheels and Tires
. IN
ST
ALL a new tire as necessary. For
additional information,
REFER to Section 204
-0 4
Wheels and Tires
.
Vehi
cl
e is unevenly or
excessively loaded.
A D
JUST the load evenly.
Loose/worn ti
e-
rods.
INST
ALL a ne
w tie-rod
end. For additional
information,
REFER to Section 211
-0 3
Steering Linkage
.
Steeri
ng gear bolts loose
o
r damaged.
TIGHTE
N or INSTALL
new bolts.
Loose or worn suspensi
on
ball jo
int(s).
INST
ALL a ne
w suspension ball joint
assembly. For additional information,
REFER to Section 204
-01 Fron
t Suspension
.
Steeri
ng column uni
versal
joint pinch bolt loose.
TI G
HTEN the steering column universal joint

pinch bolt. For additi onal information,
REFER to Section 211
-0 4
Steering Column
.
Incorre
ct
toe adjustment.

ADJUS
T as necessary. For additional
information,
REFER to Section 204
-00 Sus
pension
Sy
ste
m
- General

Information
.
Loose or worn rear
susp
ension.
TIGHTEN
loose, or IN
STALL new rear
suspension components. For additional information,
REFER to Section 204
-0 2
Rear Suspension
.
Vehicle t
e
nds to pull to one
side when driven on a level surface
Incorrect ti
re pressure.
Incorrect
ti
re size or
different tire/tread type.
Uneven tire wear
CHECK and ADJ
UST the tire pressure. For
additional information,
REFER to Section 204
-0 4
Wheels and Tires
. IN
ST
ALL a new tire as necessary. For
additional information,
REFER to Section 204
-04
Wheels and Tires
.
Vehicl

e is unevenly loaded
or overloaded.
Adjust the load
.
Incorre
ct
toe adjustment.

ADJUS
T as necessary. For additional
information,
REFER to Section 204
-00 Sus
pension
Sy
ste
m
- General

Information
.
Dam
a
ged front suspension

components.
I N
STALL new front suspension components
as necessary. For addi tional information,
REFER to Section 204
-01 Fron
t Suspension
.
Damaged rear
suspen
sion
components.
INST ALL ne
w rear suspension components
as necessary. For addi tional information,
REFER to Section 204
-0 2
Rear Suspension
.
Steeri
ng gear val
ve effort
out of balance.
SHIF T the
transmission into NEUTRAL while
driving at no more than 30 miles/hour (50 km/h) and turn the ignition to position I
(engine OFF-coasting). If the vehicle does
not pull with the engine off, INSTALL a new steering gear. For additional information,
REF E
R to Section 211
-0
2
Power Steering
. If t
he
vehicle does drift with the engine off,
CROSS SWITCH front wheel assemblies.
If the
vehicle pulls to
the opposite side,
SWITCH wheels that were on the rear to the
same side on the front.
If the v
ehicle pull dire
ction is not changed,
CHECK the front susp ension components
and toe adjustments. For additional information,
REFER to Section 204
-01 Fron
t Suspension
.
Chec
k
the front and rear
brakes for correct operation.
ADJUS
T as necessary. For additional
information,
REFER to Section 206
-0 0
Brake System
-
General Informati on.
Check fo
r bent rear
INST
ALL ne
w rear suspension components

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.

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