1998 JAGUAR X308 ignition

system fo
r normal operation.
No GO to A3
.
A3
: CHECK THE IGNITION COIL GROUND CIRCUIT FOR HIGH RESISTANCE
Turn the ignition swi

tch to the OFF
position.
1
Disc
onnect the relevant ignition module
electrical connector(s), EM27 and EM29.
2
Meas
ure the resistance between:
Cy

l 1 PI18, pin 2 (GU) and EM27, pin 08 (GU)
Cy

l 2 PI22, pin 2 (GB) and EM29 pin 08 (GB)
Cy

l 3 PI19, pin 2 (GR) and EM29, pin 11 (GR)
Cy

l 4 PI23, pin 2 (GS)
and EM27, pin 07 (GS)
Cy
l 5 PI20, pin 2 (GO) and EM29, pin 07 (GO)
Cy

l 6 PI24, pin 2 (GK) and EM27, pin 12 (GK)
Cy

l 7 PI21, pin 2 (GW) and EM27, pin 11 (GW)
Cy

l 8 PI25, pin 2 (GP) an
d EM29, pin 12 (GP)
3
Is th
e resistance greater than 5 ohms?
Yes REPAIR the high resistance circui t. This circuit includes in-line connector, PI01. For additional
information, refer to the wiring diagrams. CLEAR the DTCs. TEST the system for normal operation.
No GO to A4
.
A4:
CHECK THE POWER SUPPLIES TO THE IGNITION MODULES
Turn the ignition swi

tch to the ON
position.
1
Meas
ure the voltage between EM27, pin 10 (PW) and GROUND.
2
Meas

ure the voltage between EM29, pin 10 (PW) and GROUND.
3
Are both

voltages greater than 10 volts?
Yes GO to A5
.
No

REPAIR the circuit between EM27, pin 10 (PW) and/or EM29, pin 10 (PW). This circuit includes the
ignition coil relay, and the harness splice, EMS22. For additional information, refer to the wiring
diagrams.
A5:
CHECK THE GROUNDS TO THE IGNITION MODULES
Turn the ignition swi

tch to the OFF
position.
1
Meas
ure the resistance between EM27, pin 09 (B) and GROUND.
2
Meas

ure the resistance between EM27, pin 09 (B) and GROUND.
3
Is either resi

stance
greater than 5 ohms?
Yes REPAIR the high resistance circui t. This circuit includes the harness splice, EMS04. For additional
information, refer to the wiring diagrams. CLEAR the DTCs. TEST the system for normal operation.
No GO to A6
.
A6: CHECK
THE CIRCUIT BETWEEN THE IGNITION
MODULES AND THE ECM FOR HIGH RESISTANCE
Di
sconnect the battery negative terminal.
1
D

isconnect the ECM electrical connector, EM13.
2
Meas

ure the resistance between the following:
Cy

l 1 EM27, pin 02 (LGU) and EM13, pin 26 (LGU)
Cy

l 2 EM29, pin 02 (LGP) and EM13, pin 34 (LGP)
Cy

l 3 EM29, pin 05 (LGW) and EM13, pin 25 (LGW)
Cy

l 4 EM27, pin 03 (LGS) and EM13, pin 33 (LGS)
Cy

l 5 EM29, pin 03 (LGO) and EM13, pin 24 (LGO)
Cy

l 6 EM27, pin 06 (LGR) and EM13, pin 32 (LGR)
Cy

l 7 EM27, pin 05 (LGK) and EM13, pin 23 (LGK)
Cy

l 8 EM29, pin 06 (LGY) and EM13, pin 31 (LGY)
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
DTCs. TEST the system for normal operation.
No INSTALL a new ignition module for the affected cy linder(s). CLEAR the DTCs. TEST the system for
normal operation. If the DTC is re peated, contact dealer technical support for advice on possible ECM
failure.

PINPOINT TEST B : CHECK SPARK PLUG
TE S
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
B1
: CH
ECK SPARK PLUG
•
NOTE
: Some spark plug types cannot
be regapped and must be replaced.
Re
move the suspect spark plug(s).
REFER to: Spark Plugs
(30
3-07 Engine Ignition,
Removal and Installation).
1
Visuall
y inspect the spark plug for cracks, damage,
carbon buildup or wet fouling, check the condition
of the ground electrode, the center electrode tip and the spark plug HT contact and confirm that the
spark plug gap is correctly set usin g a wire gauge taking care not to cause damage to the center or
ground electrode tips.
REFER to: Specifications
(30
3-07 Engine Ignition, Specifications).
2
Is th
e s
park plug condition good,
and the spark plug gap correct ?
Yes Check ignition coil and circuits. See possible sources list for misfire.
No Install a new spark pl ug(s) as required.
REFER to: Spark Plugs
(30
3-07 Engine Ignition, Removal and Installation).
CLEAR the DTC. TEST the syst em for normal operation.

Engine Igni
tion - Ignition Coil-On-Plug LH
Re
moval and Installation
Remov

al
Installation
1. Disc
onnect battery ground cable (IMPORTANT, see SRO
86.15.19 for further information).

2. Re
move the coolant expansion tank for access.
R

emove screw.
Position tank aside an

d secu
re with suitable tie.

3. Re
move coil on-plug cover.
R

emove six bolts.
R

emove cover.
Cle

an mating faces.

4. D
etach harness from retain
ing clips as necessary and
disconnect relevant coil connector.

5. R
emove relevant ignition coil.
Re

move bolts.
Re

move coil.

Engine Igni
tion - Ignition Coil-On-Plug RH
Re
moval and Installation
Remov

al
Installation
1. Disc
onnect battery ground cable (IMPORTANT, see SRO
86.15.19 for further information).
2. Remove the air intake tube / meter / air cleaner cover for
access; refer to 19.10.30.

3. Re
move coil on-plug cover.
R

emove six bolts.
R

emove cover.
Cle

an mating faces.

4. D
etach harness from retain
ing clips as necessary and
disconnect relevant coil connector.

5. R
emove relevant ignition coil.
Re

move bolts.
Re

move coil.
1. Installation is a reversal of the removal procedure.

Engine Igni
tion - Ignition Module
Re
moval and Installation
Remov

al
Installation

1.
Disc
onnect battery ground cable (IMPORTANT, see SRO
86.15.19 for further information).

2. Disc
onnect connector from ignition control module.

3. Re
move fixings securing module.
Re

move module
1. Installation is a reversal of the removal procedure.

Engine Ignition - Spark
Plugs
Re
mo
val and Installation
Remov
a
l
Installation

1.
Disc onne
ct battery ground cable (IMPORTANT, see SRO
86.15.19 for further information).
2. Remove air intake tube / meter / air cleaner cover for access;
refer to 19.10.30.
3. Remove ignition coils; refer to 18.20.41 (bank 1) and 18.20.42
(bank 2).

4. Re
move spark plugs.
5. Clean all components as necessary.

1. Installation
is a reversal
of the removal procedure.
Check ele
ctrode gap is to the
correct specification. Refer
to the Specification Section and current Service Bulletins.
Apply su
itable lubricant e.
g. Neverseez Compound, to
lower four threads of spark plug(s) adjacent to the
electrodes.
The lubrican t must be applied
to full thread depth for at
least 180° of the thread circumference.
T h
e electrodes must not be
contaminated during this
process.

2.

Engine Emission
Control - Engine Emission Control
D
iagn
osis and Testing
I
n
spection and Verification
1.
1. Veri fy the customer concern.
2. 2. Vis
ually inspect for obvious signs of mechanical
or electrical damage, correct fitment, etc.
Vi
sual Inspection Chart
3.
3. Veri fy the foll
owing syst
ems are working correctly:
Air intake
system
Coo
ling system

Charging system
Fu
el charging system
Ignition sys
t
em
4. 4. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding
to the next step
5. 5. Where the Jaguar approved diagnostic sy stem is available, complete the S93 report before clearing any or all fault
codes from the vehicle.
• NOTE: If a DTC cannot be cleared, then there is a permanent fault present that flag s again as soon as it is cleared (the
exception to this is P1260, which will only clear following an ignition OFF/ON cycle after rectification).
6. 6. If the cause is not visually evident and the Jaguar approv ed diagnostic system is not available, use a fault code
reader to retrieve the fault codes be fore proceeding to the Diagnostic Trou ble Code (DTC) Index Chart, or the
Symptom Chart if no DTCs are set.
7. 7. Using the Jaguar approved diagnostic system where available, and a scan tool where not, check the freeze frame
data for information on the conditions applicable when the fault was flagged. The format of this will vary,
depending on the tool used, but can pr ovide information useful to the technician in diagnosing the fault.
CAUTION: When probing connectors to take measurements in the course of the pinpoint tests, use the adaptor kit,
part number 3548-1358-00.
• NOTE: When performing electrical voltag e or resistance tests, always use a digital multimeter (DMM) accurate to 3
decimal places, and with an up-t o-date calibration certificate. When testing resistance, always take the resistance of the
DMM leads into account.
• NOTE: Check and rectify basic faults before beginning diagnostic ro utines involving pinpoint tests.
Sym
ptom Chart
MechanicalElectrical
Engi
ne
oil level
Coo
ling system coolant level

Fue
l
level
Fuel contaminatio
n
/
grade/quality
Throttle body Poly
-ve
e belt
Engine breath
er
system
pipework/connections
EGR pipework
condition (cracking, etc)
F
u
ses
W
i
ring harness
E
l
ectrical connector(s)
Sens
o
r(s)
Engine
control module (E
CM)
Sy
m
ptom
(general)
S y
mptom (specific)
Possib
l
e source
Acti
o
n
Poor
dr iveabilityEngine h e
sitates/poor
acceleration
Fue l
pump
Air leakage F
u
el pressure regulator
Chec
k fu
el pressure,
REFER to Section 310
-00 Fu
el
Sy
ste
m
- General Informati
on.

Diagnostic Trouble Code (D
TC) Index
Pinpoint Tests
Fue
l lines
Harness damage


Throttl

e sensors
Throttl

e motor
Spark plugs

fouled
Ignition coil

failure(s)
HT sho

rt to ground (tracking) check
rubber boots for cracks/damage
Exhaus
t gas recirculation (EGR)
F
or air intake syst
em information,
REFER to Section 303
-12
Intake Air

Distribu
tion and Filtering
.
F
or fuel pressure
regulator tests,
REF
ER to Section 303
-04
Fuel
Charging and Con

trols
.
F
or fuel line information,
REFER to Section 310
-01
Fuel Tank

and Lines.
F
or throttle sensor
circuit tests,
REFER to Section 303
-14
Electronic
Engine

Controls
.
Fo
r throttle motor
circuit tests,
REFER to Section 303
-04
Fuel
Charging and Con

trols
.
For ign
ition system tests,
REFER to Section 303
-07
Engine
Ignition.
Inspe
ct EGR components, for circuit
tests, GO to Pinpoint Test A.
.
DT
C
De
scription
Possib
le Source
Acti
on
P0400Exhaus

t gas
recirculation (EGR) flow malfunction
EGR
valve connector pins high
resistance
EGR pipe/exhaust manifold leak EGR pipe block
ed
EGR val

ve stuck open/closed,
blocked
EGR
valve failure
Check the EGR pi
pe, valve and manifold for
leaks/blockages. Check the EGR valve function.
For EGR valve circuit tests,GO to Pinpoint Test A.
.
P0405Exhaus
t gas
recirculation (EGR) drive
circuits open circuit
EGR valve power supply circuit o
pen circuit
EGR valve t

o ECM drive circuit
pair - EGR pins 1/3, 4/6 open circuit, high resistance
EGR val
ve failure (stepper motor
open circuit)
F
or EGR valve circuit tests,GO to Pinpoint Test
A.
.
P0406Exhaus
t gas
recirculation (EGR) drive
circuits short circuit
EGR valve t
o ECM drive circuit
pair - EGR pins 1/3, 4/6 short
circuit to ground or high voltage
EGR val
ve failure (stepper motor
short circuit)
F
or EGR valve circuit tests,GO to Pinpoint Test
A.
.
P
INPOINT TEST A : DTC P0400, P0405; EGR VALV
E FLOW MALFUNCTION/DRIVE CIRCUITS OPEN
CIRCUIT
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
A1: CHECK

THE EMS POWER SU
PPLIES TO THE EGR VALVE
D
isconnect the EGR valve electrical connector, PI34.
1
Turn the ignition swi

tch to the ON
position.
2
Make sure the EMS re lay i
s energized.
Vehicles with AJ26 engine:
Me
asure the voltage between PI34, pins 02 and 05 (WP) and GROUND
Vehicles with AJ27 engine:
Me
asure the voltage between PI34, pins 02 and 05 (WU) and GROUND
3
Is th

e voltage at either pin less than 10 volts?
Yes