1998 JAGUAR X308 width

Mem
ory
Pulse Width ModulationPW

M
A
method of control in an electronic co
ntrol system in which the duration of
pulses in a pulse train is proportional to the amplitude of the modulating
signal
R
Ran
dom Access Memory
RAMF
ast access memory store which is accessible for entry or extraction of data
Re

ad-Only Memory
RO
M
F
ast access memory in which data
is fixed and may not be changed
Re
servoir
RESContaine
r, usually for oils,
coolants or hydraulic fluids
Re
turn
RTNA
dedicated sensor ground circuit
R

evolutions Per Minute
RP
M
Shaft speed o
f a device, us
ually an engine or motor
R
ight-hand
RH
Right-hand drive veh

icle
RHD
S
Scan T

ool
STDe
vice that interfaces with and comm
unicates information on a data link
Se
at Control Module
SCMModule
controlling the seat motor systems (not electric raise/lower-only
seats)
Secon
dary Air
Air pro
vided to the exhaust system
Secon

dary Air Injection
AIRSy
stem used for a period of time each
time the engine is started, unless
certain temperature criter ia are met. Pumps air directly into the exhaust
system which generates extra heat and reduces the time taken for the
catalytic converters to reach operating temperature
Secon
dary Air Injection
Bypass
AIRBVents secon
dary air to atmosphere
Secon

dary Air Injection
Check Valve
AIRCValve wh
ich prevents back-flow of exhaust gas to the AIR system when the
system is inoperative
Secon
dary Air Injection
Diverter
AIRDD
iverts secondary air to either
the catalyst or exhaust manifold
Secon
dary Air Injection
Magnetic Clutch
AIRP
C
Clu
tch mounted on the AIRP drive shaft
Secon

dary Air Injection
Pump
AIRPMe
chanically driven rotary vane
pump, driven through the AIRPC
Secon
dary Air Injection
Relay
AIRRCont
rols the injection of air into the exhaust system
Secon

dary Air Injection
Switchin
g Va
lve
AIRSV
acuum operated valve backing-up the AIRC
Secu

rity and Locking
Control Module
SLCMModul
e controlling the vehicle's security and closure-locking functions
SensorSGeneri

c name for a device
that senses either the absolute value or a change
in a physical quantity su ch as temperature, pressure or flow rate, and
converts that change into an electrical quantity signal
Servic
e Repair Operation
(number)
SRONu
mber generated by Jaguar Methods
and Techniques system which relates
to the time allowed to complete a repair operation. Further information on the
system can be found in the separate Jaguar Publications (for each model
range) entitled 'Repair Operation Times'
Shif
t signal
SDA
shift process signal to the TCM on SC vehicles
Shif

t Solenoid
SSControls shi
fting in an automatic transmission
Si

gnal return
SIG RTN
Slidin

g Roof Control
Module
SRCM
Society of Automotive

Engineers
SAE
Speed
Control Control
Module
SCCMModule con
trolling Speed Control System
Square c

entimeter
cm
2
Stan

dard
std
Stan

dard Corporate
Protocol
SCPA
high-speed, serial communications system linking all body system control
modules. Control messages and data ar e passed between modules at up to
786 messages per second
SuperchargerSCAn in
take system which utilizes a supercharger (mechanically driven device
that pressurizes intake air, thereby in creasing density of charge air and the
consequent power output from a given displacement)
Supercharger
Bypass
SCB
SwitchSW
T

Snow chain
s and the spike spider tr
action system must not be used on roads which are clear of snow.
The Jaguar recommended spike spider tracti on system can be used on all wheel and tire sizes, except the temporary spare
wheel.
Asym metric
Tires
Some
tir
es recommended by Jaguar are as
ymmetric. Inner and outer markers embossed on the tire walls must be observed
to ensure the correct installati on of the tire to the wheel.
Tread We
ar Indicator
• NO
TE: Tire condition must comply with prevailing local legislation.
Tread wear indicators are molded into the bottom of the tr ead grooves across the width of the tire. The tire must be
renewed when tread wear indicators become visible at the surface of the tread.

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 E
VAP canister purge valve controls th
e flow rate of fuel vapour drawn into the engine during the canister purge
operation. The valve is opened by a vacu um feed from the induction elbow : the vacu um feed is controlled by the integral
valve solenoid and is applied when the so lenoid is energised. The solenoid is pulsed on (energised) and off by a fixed
frequency (100Hz) variable pulse width control signal (pulse width modulation). By varying the pulse on to off time, the
ECM controls the duty cycle of the valve (time that the valve is open to time closed) and thus the vapour flow rate to the
engine.
With no ECM signal applied to the va lve solenoid, the valve remains closed.
Can
ister Purge Operation
The
following pre-conditions are ne
cessary for purging to commence :
aft
er battery disconnection/reconnection, engine
management adaptations must be re-instated.
engine has run for
at least 8 seconds.
engi

ne coolant temperature is not less than 70 °C.
engine

not running in the fuel
cut off condition (eg overrun).
t
he adaptive fuel correction
function has not registered a rich or lean failure
t
he evaporative emission leak test has not failed
no faults have been diagnosted in th
e rel
evant sensor and valve circuits -
Air Flow Meter (AFM), Engine Coolant
Temperature sensor, Evaporativ e Canister Purge valve and Canister Close Valve (CCV).
If these conditions have been satisfied, purging is started. If any failures are registered, purging is inhibited.
The canister(s) is purged during each driv e cycle at various rates in accordance with the prevailing engine conditions. The
engine management software st ores a map of engine speed (RPM) against engine load (grams of air inducted / rev). For
any given engine speed and load, a vapour purge rate is assigned (purge rate increases with engine speed and load).
The preset purge rates are base d on the assumption of a vapour concentratio n of 100%. The actual amount of vapour is
measured by the closed loop fueling system : the input of evaporative fuel into the engine causes the outputs from the
upstream oxygen sensors to change, the am ount of change providing a measure of the vapour concentration. This feedback
causes the original purge rate to be adju sted and also reduces the amount of fuel input via the injectors to maintain the
correct air to fuel ratio.
Engine speed/load mapping and the corresp onding purge rates are different for single canister, running loss and ORVR
evaporative systems.

Op
eration
The T
ransmission Control Module (TCM) is
able to monitor the state of the torque converter clut ch at all times.
There are three operating modes for the converter
1. 1. Fully open - Torque converter 'unlocked'
2. 2. Fully closed - Torque converter 'locked'
3. 3. Slip control - The TCM monitors slip and may apply sufficie nt pressure to allow a small degree of slip. This mode
maximises economy by reducing slip to a minimum whilst providing isolation from drive-line shunt and vibration.
The TCM constantly measures the slip within the torque conver ter by comparing engine speed (via CAN) and input (turbine
speed). Differences in these speeds indicate the amount of slip.
Clutch Hydraulic Pressure Regulation
The T
CM supplies an internally switched +1
2V supply to the #4 pressure regulator. The regulator is operated by switching
the other side of the operating winding to ground. Hydraulic pressure is controlled by 'pulse width modulation' (PWM) of the
ground switching signal i.e. the duty cycle; the time that the pressure regulator is switched on.
Hydraulic Control
- Transmission Pre
ssure Regulators an d Shift Solenoids

Opera
tion
F
l
uid flow within the transmission assembly is controlled
by three solenoid valves and five pressure regulators.
The TCM supplies an internally switched +12V supply to each sh ift solenoid and pressure regulator. Hydraulic pressure from
the pressure regulators is controlled by 'pulse width modulation' (PWM) of the ground switching signal i.e. the duty cycle;
the time that the pressure regu lator is switched on. Control of the solenoids is effected by switching one side to ground
through the TCM.
During normal operation the TCM monitors 'Switch On' of the so lenoids, regulators and the TCM output stages, but does not
check output stage 'Switch Off'.
It e
m
Par
t
Number
De
scr
iption
1—Shif
t Sole
noid #3
2—Shif
t Sole
noid #2
3—Shif
t Sole
noid #1
4—Pressure R
e
gulator #5
5—Pressure R
e
gulator #4
6—Pressure R
e
gulator #3
7—Pressure R
e
gulator #2
8—Pressure R
e
gulator #1

Voltage is monitored at the regulators and solenoids for continuity and shorts. For example, when a solenoid is ON the
voltage on the TCM side should be ground , when OFF the voltage should be +12.
Shift Solenoid

The function of the three soleno id valves is to control the flow of transmissi on oil to the various transmission components.
Three solenoid valves are located wi thin the transmission assembly, and are closed when not energized.
Pressure Regulator

The function of the five pressu re regulators is to modulate the oil pressure to the various transmission components. The
regulators are pulse width modulated by the TCM, switching to ground potential. The other side of the regulators being
connected, via an internal TCM relay, to battery voltage. The regulator is closed when not energized by the TCM.
Transmission Fluid Temperature Sensor

The functi
on of the parking aid is to prov
ide an audible warning to the driver of the distance to obstacles near the rear
bumper of the vehicle when parking or travelling at a slow sp eed. The system provides an assistance to the driver when
parking in order to help avoid collision with obstacles.
The sensor range at the rear of the vehicl e should be 1.8 meters. This should extend the full width of the rear bumper and
reduce to 50 cm at the vehicle co rners. The vertical range is adequate to protec t the highest and lowest points of the rear of
the vehicle. The system will detect curbs with heights of at least 18 cm. Obstacles, such as curbs, that are low enough to
pass under the vehicle until they make contact with the tires will not be detected.
The system activates a specific speaker with a tone signifying the distance to the obstacle. The tone consists of a beep and
defined space ratio which varies depending on the calculated distance. When the distance to the obstacle is less than 20 cm
the speaker tone is continuous.
The parking aid is continuously in operation, unless towing wh en the system automatically switches off. If the reverse aid
develops a fault the tone will sound continuously for three seconds when the igni tion is switched on or the reverse gear is
selected.
The parking aid system comprises of:
a
module mounted in the batte
ry junction box (BJB).
fou
r rear bumper mounted sensors which have a 90° angled electrical connector.
an audible speaker, moun

ted on
the rear parcel shelf.


It
em
Par
t Number
De
scription
1—Parkin

g aid module
2—Rear

parking aid speaker
3—Rear

parking aid sensors