1998 JAGUAR X308 diagram

Pa
rts List
The pressure regulator is a diap hragm-operated valve that regula tes fuel-rail pressure at 3,0 bar above the intake manifold
pressure. A pipe connects the throttle induction elbow to the pressure regulator to provide the vacuum control signal. On
supercharged engines, the pressure regulator vacuum feed is taken from the top of the supercharger outlet duct.
The regulator is fitted between the rear end of the right-hand fuel rail (bank 1) and the fuel return line to the tank.
Circuit Diagram, Fuel Injection Syst em - Normally Aspirated Vehicles

Ite
m
Par
t
Number
De
scr
iption
1—F
u
el Return
2—F
u
el Pressure Regulator
3—Inta
k
e Manifold Pressure

Ci
rcuit references to injectors:
'A' refers to bank 1;
'B' refers to bank 2.
Fuel C
harging and Controls - Supercharged Vehicles
Ci
rcuit Diagram, Fuel Injection
System - Supercharged Vehicles
It
em
Par
t Number
De
scription
1—E

ngine compartment fuse-box
2—Engine

management fuse-box
3—Splice

- 12V to
other circuits
4—PI m
ain relay
5—Engine

control module (ECM)
6—Fue

l injector 1A - other injectors similar

(ECT) se
nsor
Blocked part-load breather
(s
ervice action S474)
Injec
t
or leak
Engine stalls
soon
after start
F
u
el pump relay
ECM relay Thr
o
ttle contaminated
CMP/CKP sen
s
or
synchronization malfunction
Harness Fuel
pump
MAF
s
ensor malfunction
Engine coolan
t
temperature
(ECT) sensor
Fue l
lines
Air leakage Fu

el pressure regulator
F
o
r fuel pump relay tests,
GO to Pinpoint Test E.
.
F or ECM
relay tests,
REFER to Section 303
-14 Elec tronic En
gine
Controls.
Check bull etins for throttl
e cleaning procedure. For

CMP/CKP sensor tests,
REFER to Section 303
-14 Elec tronic En
gine
Controls.
Chec k fu
el pressure,
REFER to Section 310
-00 Fu
el System
- Ge
n
eral
Informati
o
n
.
F or MAF sensor and
ECT sensor tests,
REFER to Section 303
-14 Electronic En
gine
Controls.
For fuel l
ine information,
REFER to Section 310
-01
Fuel Tank and Lines
.
F or i
ntake system information,
REFER to Section 303
-1 2
Intake Air Distribution
and F
ilt
ering
.
F o
r fuel pressure regulato
r check, GO to Pinpoint
Test D.
.
Engine h e
sitates/poor
acceleration
Fue l
pump
Exhaus
t gas
recirculation
(EGR)
Air leakage Stop lamp swi t
ch
Throttl
e
sensors
Throttl
e
motor
Spark plugs

fouled
Check f
o
r water ingress into
spark plug wells
Ignition coil fail
ure(s)
HT sho
rt to ground (tracking)
check rubber
boots for
cracks/damage
ECM failu r
e
Chec
k fu
el pressure,
REFER to Section 310
-00 Fu
el System
- Ge
n
eral
Informati
o
n
.
F o
r EGR information,
REFER to Section 303
-08 En gin
e Emission
Control.
F or i
ntake system information,
REFER to Section 303
-1 2
Intake Air Distribution
and F
ilt
ering
.
F or stop l
amp switch in
formation, refer to the
wiring diagrams. For throttle position sensor and throttle motor relay tests,
REFER to Section 303
-14 Elec tronic En
gine
Controls.
For ign i
tion system,
REFER to Section 303
-07 En
gine Ignition
.
Contact dealer techn i
cal
support for advice on
possible ECM failure.
Engine ba ckfiresFuel
pump
Air leakage MAF s
e
nsor
HO2 sensors Spark plugs
Check fo
r water ingress into
spark plug wells
HT short to ground (tracking) check rubber
boots for
cracks/damage
Ignition coil fail
ure(s)
Chec
k fu
el pressure,
REFER to Section 310
-00 Fu
el System
- Ge
n
eral
Informati
o
n
.
F or i
ntake system information,
REFER to Section 303
-1 2
Intake Air Distribution
and F
ilt
ering
.
For MAF and HO2
sensor circuit tests,
REFER to Section 303
-14 Electronic En
gine
Controls.
For igni
tion system,
REFER to Section 303
-07 En
gine Ignition
.
Engine
s
urges
Air leakage Fue
l
pump
Stop lamp swi
t
ch
MAF s
e
nsor
Harness Throttl
e
sensors
Throttl
e
motor
Spark plugs
Check fo
r water ingress into
spark plug wells
HT sho rt to ground (tracking)
check rubber
boots for
cracks/damage
ECM failu r
e
F
or i
ntake system information,
REFER to Section 303
-1 2
Intake Air Distribution
and F
ilt
ering
.
Chec k fu
el pressure,
REFER to Section 310
-00 Fu
el System
- Gen
e
ral
Informati
o
n
.
F or stop l
amp switch in
formation, refer to the
wiring diagrams. For MAF se nsor, throttle position
sensor and throttle motor relay tests,
REFER to Section 303
-14 Elec tronic En
gine
Controls.
For ign i
tion system,
REFER to Section 303
-07 En
gine Ignition
.
Contact dealer techn i
cal
support for advice on
possible ECM failure.

ci
rcuit includes the EMS fuse box,
fuse 05, and the fuel injection relay. For additional information,
refer to the wiring diagrams. CLEAR DTC. TEST the system for normal operation.
A4: CHECK
THE INJECTOR GROUND
CIRCUIT FOR HIGH RESISTANCE
Turn the ignition swi
tch to the OFF
position.
1
Di
sconnect the battery negative terminal.
2
D

isconnect the ECM electrical connector, (EM15, vehi
cles with AJ26 engine, EM84, vehicles with AJ27
engine).
3
Meas
ure the resistance between the relevant injector harness electrical connector (IJ03 to IJ10,
vehicles with AJ26 engine, PI07 to PI14, vehicles with AJ27 engine), pin 01 and the ECM electrical
connector, pins as follows -
Vehicles with AJ26 engine:
Cy
l 1 IJ03, pin 01 (BU) and EM15, pin 07
Cy

l 2 IJ07, pin 01 (BU) and EM15, pin 18
Cy

l 3 IJ04, pin 01 (BN) and EM15, pin 17
Cy

l 4 IJ08, pin 01 (BN) and EM15, pin 05
Cy

l 5 IJ05, pin 01 (BG) and EM15, pin 16
Cy

l 6 IJ09, pin 01 (BG) and EM15, pin 04
Cy

l 7 IJ06, pin 01 (BW) and EM15, pin 06
Cy

l 8 IJ10, pin 01 (BW) and EM15, pin 15
Vehicles with AJ27 engine:
Cy
l 1 PI07, pin 01 (B
G) and EM84, pin 02
Cy
l 2 PI11, pin 01 (BW) and EM84, pin 06
Cy

l 3 PI08, pin 01 (BO) and EM84, pin 21
Cy

l 4 PI12, pin 01 (BW) and EM84, pin 04
Cy

l 5 PI09, pin 01 (B
G) and EM84, pin 14
Cy
l 6 PI13, pin 01 (BO) and EM84, pin 03
Cy

l 7 PI10, pin 01 (BW) and EM84, pin 05
Cy

l 8 PI14, pin 01 (BR) and EM84, pin 13
4
Is th

e resistance greater than 5 ohms?
Yes REPAIR the circuit between the relevant injector harness electrical connector pin 01 and the engine
control module electrical connecto r. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No GO to A5
.
A5: CHECK
THE INJECTOR GROUND CI
RCUIT FOR SHORT CIRCUIT TO BATTERY
R
econnect the battery negative terminal.
1
Meas

ure the voltage between the relevant injector harness electrical connector (IJ03 to IJ10, vehicles

with AJ26 engine, PI07 to PI14, vehicles with AJ27 engine), pin 01 and GROUND.
2
Is th
e voltage greater than 3 volts?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to A6
.
A6: CHECK
THE INJECTOR GROUND CI
RCUIT FOR SHORT CIRCUIT TO GROUND
Meas
ure the resistance between the relevant injector harness electrical connector (IJ03 to IJ10,
vehicles with AJ26 engine, PI07 to PI14, vehicles with AJ27 engine), pin 01 and GROUND.
1
Is
the resistance less than 10,000 ohms?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No Contact dealer technical support for advice on possible ECM failure.
P
INPOINT TEST B : DTC P0460; FUEL
LEVEL SENSE SIGNAL PERFORMANCE
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
B1: CHECK

THE FUEL LEVEL SENSOR REFERENCE GROUND
Di

sconnect the fuel level sensor electrical connector, BT15.
1

Measure t
he resistance
between BT15 and GROUND.
2
Is the res
istance greater than 5 ohms?
Yes GO to B2
.
No
GO to B3
.
B2: CHECK THE FUEL
LEVEL SENSOR REFERE
NCE GROUND CIRCUIT FOR HIGH RESISTANCE
Disc
onnect the instrument cluster electrical connector, FC25.
1
Meas
ure t
he resistance between FC25, pin 14 (RW) and BT15 (RW).
2
Is the res

istance greater than 5 ohms?
Yes REPAIR the high resistance circui t. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No GO to B3
.
B3: CHECK THE FUEL
LEVEL SENSOR (EMPTY)
Di
sc
onnect the fuel level sensor electrical connectors, BT14 and BT15.
1
Empty the fuel
tank. 2
Measure t
he resistance between the
fuel level sensor connections.
3
Is t
he resistance 900 ohms?
Yes GO to B4
.
No
INST
ALL a new fuel level sensor.
REFER to Section 310
-0 1
Fuel Tank and Lines
.
CLEAR t h
e DTC. TEST the system for normal operation.
B4:
CHECK
THE FUEL LEVEL SENSOR (FULL)
Fi
ll
the fuel tank.
1
Meas
ure t
he resistance between the
fuel level sensor connections.
2
Is
the resistance 80 ohms?
Yes GO to B5
.
No
INST
ALL a new fuel level sensor.
REFER to Section 310
-0 1
Fuel Tank and Lines
.
CLEAR t h
e DTC. TEST the system for normal operation.
B
5
: CHECK THE FUEL LEVEL SENSOR SIGNAL WIRE FOR HIGH RESISTANCE
Di
sc
onnect the instrument cluster electrical connector, FC25.
1
Meas
ure t
he resistance between FC25, pin 13 (BW) and BT14 (BW).
2
Is th
e res
istance greater than 5 ohms?
Yes REPAIR the high resistance circui t. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No INSTALL a new instrument cluster.
REFER to Section 413
-01
Instrume
nt Cluster
.
CLEAR t h
e DTC. TEST the system for normal operation.
P
INPOINT TEST C : DTC P1646; FU
EL PUMP 2 (SC) RELAY MALFUNCTION
•
NO
TE: This DTC applies only to the
supercharged system fuel pump 2.
TES
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
C
1
: CHECK THE FUEL PUMP 2 RELAY POWER SUPPLY
R
e
move the fuel pump 2 relay.
1
Turn the ignition swi
t
ch to the
ON position.
2
Meas
ure t
he voltage between the
relay base, pin 01 and GROUND.
3
Is the volt
age less than 10 volts?
Yes REPAIR the circuit between the rela y base, pin 01 and battery. This circuit includes the trunk fuse
box, the ignition positive relay, and the high power protection module. For additional information,
refer to the wiring diagrams. CLEAR the DTC. TEST the system for normal operation.
No GO to C2
.

C2: CHECK THE FUEL
PUMP 2 RELAY TO ECM CIRCUIT
Di

sconnect the battery negative terminal.
1

D
isconnect the ECM electrical connector, EM13.
2

Meas
ure the resistance between the rela
y base, pin 02 and EM13, pin 09 (KB).
3

Is th
e resistance greater than 5 ohms?
Yes REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. CLEAR the

DTC. TEST the system for normal operation.
No INSTALL a new fuel pump 2 relay. CLEAR the DT C. TEST the system for normal operation.
P
INPOINT TEST D : CHECK THE FUEL PRESSURE REGULATOR FUNCTION
CAUTI
ON: Do not run the engine for more than
30 seconds with the vacuum hose disconnected.
T
EST CONDITIONS
D
ETAILS/RESULTS/ACTIONS
D

1: CHECK FOR FUEL PRESSURE CHANGE
WHEN THE REGULATOR IS DISCONNECTED
Connect a
fuel pressure gauge set,
REFER to Section 310
-00
Fuel System
-

General Informati
on
. 1

St
art the engine.
2

N
ote the fuel pressure readin
g with the fuel pressure regu lator vacuum hose connected.
3

Di
sconnect the fuel pressu
re regulator vacuum hose.
4

N
ote the new reading.
5

Doe
s the fuel pressure increase when the hose is disconnected?
Yes Check for DTCs. Carry out the pinpoint tests indicated.
No INSTALL a new fuel presssure regulator. TEST the system for normal operation.
P
INPOINT TEST E : DTC P1230;
FUEL PUMP RELAY MALFUNCTION
•
NOTE: This DTC applies only to the N/A system si
ngle fuel pump, and the S/C system fuel pump 1
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
E1

: CHECK THE FUEL PUMP
RELAY BATTERY SUPPLY
R
emove the fuel pump relay.
1

Meas
ure the voltage between the
relay base, pin 03 and GROUND.
2

Is th
e voltage less than 10 volts?
Yes REPAIR the circuit between the rela y base, pin 03 and the battery power bus. This circuit includes the
trunk fuse box and the high power protection module . For additional information, refer to the wiring
diagrams. CLEAR the DTC. TEST th e system for normal operation.
No GO to E2
.
E2
: CHECK THE FUEL PUMP RELAY IGNITION SWITCHED SUPPLY
Turn the ignition swi

tch to the
ON position.
1

Meas
ure the voltage between the
relay base, pin 01 and GROUND.
2

Is th
e voltage less than 10 volts?
Yes REPAIR the circuit between the rela y base, pin 01 and battery. This circuit includes the trunk fuse box,

fuse 16 of the left-hand fuse box, the ignition po
sitive relay and the high power protection module.
For additional information, refer to the wiring diagrams. CLEAR the DTC. TEST the system for normal
operation.
No GO to E3
.
E3
: CHECK THE FUEL PUMP RELAY TO
ECM CIRCUIT FOR HIGH RESISTANCE
Di
sconnect the battery negative terminal.
1

D
isconnect the ECM electrical connector, EM83.
2

Meas
ure the resistance between EM83, pi
n 04 (WR) and the relay base, pin 02.
3

Is th
e resistance greater than 5 ohms?
Yes REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. CLEAR the
DTC. TEST the system for normal operation.
No

INSTALL a new fuel pump relay. CLEAR the DTC. TEST the system for normal operation. If the DTC is
repeated, contact dealer technical support for advice on possible ECM failure.

The il
lustration above is a simplified expl
anation of how the starting system operates in conjunction with the Body Processor
Module (BPM) and the Engine Control Module (ECM).
Refer to the Starting Circuit Diagram in the Electrical Guide.
I g
nition Switch to ON Position
W
h
en the ignition key is set to the normal run position, the following sequence occurs:
The
is
olation relay in each fusebox is
energised to supply battery power to the fuses and associated circuits.
The BPM 'IGN
ON' terminal
is taken to 0V by the ignition switch.
The BPM
checks that various parameters are correct e.g. -
inertia switch is in the active condition - transmission is in
PARK - security system has been correctly disabled.
It e
m
De
scr
iption
1Batt
ery
2To Re ar
Fusebox
3Hi
gh Power Pr
otection Module
4To Front
Fu
seboxes
5Starter Re
lay
6Body Processor M
odule (BPM)
7Engine
C
ontrol Module (ECM)
8Ignition Switch
9CRANK Signal
10Ignition ON Signal
11Inertia Switch
12St
arte
r Motor and Solenoid
Starting System Operation

The BPM
'CRANK SELECTED' terminal is ta
ken to 0V by the ignition switch.
The BPM
'O/P ENGINE CRANK' terminal pr
ovides a path to ground for the starte r relay coil, via Fuse 5 (10A) located
in the engine compartment front fusebo x. This path to ground also indicates to the ECM 'I/P ENGINE CRANK'
terminal, by taking it to 0V, that the engine has been requested to crank.
Wi
th the starter relay contacts closed,
power via Fuse 3 (25A) in the engine compartment rear fusebox, is supplied
to the pull-in winding of the starter solenoid.
The s
olenoid main contacts close and are held
closed by the solenoid hold-in winding.
Battery power is supplied
to
the starter motor through the solenoid main contacts, direct from the battery and the
High Power Protection Module.
Starter
Motor Internal Connections

Re
fer to the Starting Circuit Diagram in the Electrical
Guide for the actual layout and connection details.
The starter motor and solenoid in the previous figure are shown diagrammaticall y to indicate simply, the electrical circuit
and various connections.


It
em
De
scription
1Batt

ery
2Ignition Switch
3So

lenoid Contacts
4So

lenoid Pull-In Winding
5So

lenoid Hold-In Winding
6So

lenoid
7St

arter Motor Main Body
I
gnition Switch at CRANK Position
W
hen the ignition key is set to the crank position, the following sequence occurs: