Datasheet exj_8d Datasheet

XJ IGNITION SYSTEM 8D - 1

IGNITION SYSTEM

TABLE OF CONTENTS

page page

DESCRIPTION AND OPERATION

IGNITION SYSTEM........................1

DISTRIBUTOR-2.5L ENGINE.................2

SPARK PLUGS ...........................2

SPARK PLUG CABLES-2.5L ENGINE ..........2

IGNITION COIL-2.5L ENGINE................3

IGNITION COIL—4.0L ENGINE...............3

CRANKSHAFT POSITION SENSOR............4

CAMSHAFT POSITION SENSOR-2.5L ENGINE...4
CAMSHAFT POSITION SENSOR—4.0L

ENGINE ...............................5

IGNITION SWITCH AND KEY LOCK

CYLINDER .............................5

DIAGNOSIS AND TESTING

DISTRIBUTOR CAP-2.5L ENGINE.............6

DISTRIBUTOR ROTOR-2.5L ENGINE ..........6

SPARK PLUG CABLES .....................7

SPARK PLUG CONDITIONS .................8

IGNITION SWITCH AND KEY LOCK

CYLINDER .............................9

REMOVAL AND INSTALLATION

SPARK PLUG CABLES ....................10

SPARK PLUGS ..........................10

IGNITION COIL—2.5L ENGINE..............12

IGNITION COIL—4.0L ENGINE..............12

CRANKSHAFT POSITION (CKP) SENSOR .....13

CAMSHAFT POSITION SENSOR—2.5L

ENGINE ..............................14

CAMSHAFT POSITION SENSOR—4.0L

ENGINE ..............................15

DISTRIBUTOR—2.5L ENGINE ..............17

IGNITION SWITCH AND KEY CYLINDER......20

SHIFTER/IGNITION INTERLOCK.............22

SPECIFICATIONS

IGNITION TIMING........................23

ENGINE FIRING ORDER—2.5L 4-CYLINDER

ENGINE ..............................23

ENGINE FIRING ORDER—4.0L 6-CYLINDER

ENGINE ..............................23

SPARK PLUGS ..........................23

SPARK PLUG CABLE RESISTANCE ..........23

IGNITION COIL RESISTANCE—2.5L ENGINE . . 23
IGNITION COIL RESISTANCE—4.0L ENGINE . . 23

TORQUE CHART.........................24

DESCRIPTION AND OPERATION

IGNITION SYSTEM

DESCRIPTION

Two different ignition systems are used. One type
is used for the 2.5L 4–cylinder engine. The other is
used for the 4.0L 6–cylinder engine.

OPERATION

2.5L 4–Cylinder Engine:

The ignition system is controlled by the Powertrain
Control Module (PCM).

The ignition system consists of:

• Spark Plugs

• Ignition Coil

• Secondary Ignition Cables

• Distributor (contains rotor and camshaft position

sensor)

• Powertrain Control Module (PCM)

• Crankshaft Position, Camshaft Position, Throt-

tle Position and MAP Sensors

4.0L 6–Cylinder Engine:

The 4.0L 6–cylinder engine uses a one-piece coil
rail containing three independent coils. Although cyl­inder firing order is the same as 4.0L engines of pre­vious years, spark plug firing is not. The 3 coils dual­fire the spark plugs on cylinders 1–6, 2–5 and/or 3–4.
When one cylinder is being fired (on compression
stroke), the spark to the opposite cylinder is being
wasted (on exhaust stroke). The one-piece coil bolts
directly to the cylinder head. Rubber boots seal the
secondary terminal ends of the coils to the top of all
6 spark plugs. One electrical connector (located at
the rear end of the coil rail) is used for all three coils.

Because of coil design, spark plug cables (second­ary cables) are not used on either engine. A distrib-
utor is not used with the 4.0L engine.

The ignition system is controlled by the Powertrain
Control Module (PCM).

The ignition system consists of:

• Spark Plugs

• Ignition Coil(s)

• Powertrain Control Module (PCM)

8D - 2 IGNITION SYSTEM XJ

DESCRIPTION AND OPERATION (Continued)

• Crankshaft Position Sensor

• Camshaft Position Sensor

• The MAP, TPS, IAC and ECT also have an effect

on the control of the ignition system.

DISTRIBUTOR-2.5L ENGINE

DESCRIPTION

The 2.5L engine is equipped with a camshaft
driven mechanical distributor (Fig. 1) containing a
shaft driven distributor rotor. The distributor is also
equipped with an internal camshaft position (fuel
sync) sensor (Fig. 1).

Fig. 1 Distributor and Camshaft Position Sensor-

2.5L Engine

1 – SYNC SIGNAL GENERATOR
2 – CAMSHAFT POSITION SENSOR
3 – PULSE RING
4 – DISTRIBUTOR ASSEMBLY

SPARK PLUGS

DESCRIPTION

Resistor type spark plugs are used.

Spark plug resistance values range from 6,000 to
20,000 ohms (when checked with at least a 1000 volt
spark plug tester). Do not use an ohmmeter to

check the resistance values of the spark plugs.
Inaccurate readings will result.

OPERATION

To prevent possible pre-ignition and/or mechanical
engine damage, the correct type/heat range/number
spark plug must be used.

Always use the recommended torque when tighten­ing spark plugs. Incorrect torque can distort the
spark plug and change plug gap. It can also pull the
plug threads and do possible damage to both the
spark plug and the cylinder head.

Remove the spark plugs and examine them for
burned electrodes and fouled, cracked or broken por­celain insulators. Keep plugs arranged in the order
in which they were removed from the engine. A sin­gle plug displaying an abnormal condition indicates
that a problem exists in the corresponding cylinder.
Replace spark plugs at the intervals recommended in
Group O, Lubrication and Maintenance

Spark plugs that have low mileage may be cleaned
and reused if not otherwise defective, carbon or oil
fouled. Also refer to Spark Plug Conditions.

CAUTION: Never use a motorized wire wheel brush
to clean the spark plugs. Metallic deposits will
remain on the spark plug insulator and will cause
plug misfire.

OPERATION

The distributor does not have built in centrifugal
or vacuum assisted advance. Base ignition timing
and all timing advance is controlled by the Power­train Control Module (PCM). Because ignition timing
is controlled by the PCM, base ignition timing is

not adjustable.

The distributor is locked in place by a fork with a
slot located on the distributor housing base. The dis­tributor holddown clamp bolt passes through this slot
when installed. Because the distributor position is
locked when installed, its rotational position can not
be changed. Do not attempt to modify the dis-

tributor housing to get distributor rotation.
Distributor position will have no effect on igni­tion timing. The position of the distributor will
determine fuel synchronization only.

All distributors contain an internal oil seal that
prevents oil from entering the distributor housing.
The seal is not serviceable.

SPARK PLUG CABLES-2.5L ENGINE

DESCRIPTION

Spark plug cables are used only on the 2.5L
engine. They are sometimes referred to as secondary
ignition wires.

OPERATION

The spark plug cables transfer electrical current
from the ignition coil(s) and/or distributor, to individ­ual spark plugs at each cylinder. The resistive spark
plug cables are of nonmetallic construction. The
cables provide suppression of radio frequency emis­sions from the ignition system.

XJ IGNITION SYSTEM 8D - 3

DESCRIPTION AND OPERATION (Continued)

IGNITION COIL-2.5L ENGINE

DESCRIPTION

A single ignition coil is used with the 2.5L 4–cylin­der engine. The coil is not oil filled. The coil windings
are embedded in an epoxy compound. This provides
heat and vibration resistance that allows the coil to
be mounted on the engine.

OPERATION

The Powertrain Control Module (PCM) opens and
closes the ignition coil ground circuit for ignition coil
operation.

Battery voltage is supplied to the ignition coil pos­itive terminal from the ASD relay. If the PCM does
not see a signal from the crankshaft and camshaft
sensors (indicating the ignition key is ON but the
engine is not running), it will shut down the ASD cir­cuit.

Base ignition timing is not adjustable. By con­trolling the coil ground circuit, the PCM is able to set
the base timing and adjust the ignition timing
advance. This is done to meet changing engine oper­ating conditions.

IGNITION COIL—4.0L ENGINE

DESCRIPTION

A one-piece coil rail assembly containing three
individual coils is used on the 4.0L 6–cylinder engine
(Fig. 2). The coil rail must be replaced as one assem­bly. The bottom of the coil is equipped with 6 individ­ual rubber boots (Fig. 2) to seal the 6 spark plugs to
the coil. Inside each rubber boot is a spring. The
spring is used for a mechanical contact between the
coil and the top of the spark plug. These rubber boots
and springs are a permanent part of the coil and are
not serviced separately.

(1) The coil is bolted directly to the cylinder head
(Fig. 3). One electrical connector (located at rear of
coil) is used for all three coils.

Fig. 2 Ignition Coil Assembly—4.0L 6–Cylinder

Engine

1 – CYL. #6
2 – CYL. #5
3 – CYL. #4
4 – CYL. #3
5 – CYL. #2
6 – CYL. #1
7 – COILS (3)
8 – MOUNTING BOLTS (4)
9 – BOLT BASES (4)
10 – RUBBER BOOTS (6)

OPERATION

Although cylinder firing order is the same as 4.0L
Jeep engines of previous years, spark plug firing is
not. The 3 coils dual-fire the spark plugs on cylinders
1–6, 2–5 and/or 3–4. When one cylinder is being fired
(on compression stroke), the spark to the opposite
cylinder is being wasted (on exhaust stroke).

Battery voltage is supplied to the three ignition
coils from the ASD relay. The Powertrain Control
Module (PCM) opens and closes the ignition coil
ground circuit for ignition coil operation.

Base ignition timing is not adjustable. By con­trolling the coil ground circuit, the PCM is able to set
the base timing and adjust the ignition timing

Fig. 3 Coil Location—4.0L Engine

1 – COIL RAIL
2 – COIL MOUNTING BOLTS (4)
3 – COIL
4 – COIL ELECTRICAL CONNECTION

8D - 4 IGNITION SYSTEM XJ

DESCRIPTION AND OPERATION (Continued)

advance. This is done to meet changing engine oper­ating conditions.

The ignition coil is not oil filled. The windings are
embedded in an epoxy compound. This provides heat
and vibration resistance that allows the ignition coil
to be mounted on the engine.

Because of coil design, spark plug cables (second­ary cables) are not used. The cables are integral
within the coil rail.

CRANKSHAFT POSITION SENSOR

DESCRIPTION

The Crankshaft Position (CKP) sensor is located
near the outer edge of the flywheel (starter ringear).

OPERATION

Engine speed and crankshaft position are provided
through the CKP sensor. The sensor generates pulses
that are the input sent to the Powertrain Control
Module (PCM). The PCM interprets the sensor input
to determine the crankshaft position. The PCM then
uses this position, along with other inputs, to deter­mine injector sequence and ignition timing.

The sensor is a hall effect device combined with an
internal magnet. It is also sensitive to steel within a
certain distance from it.

The flywheel/drive plate has groups of four notches
at its outer edge. On 2.5L 4-cylinder engines there
are two sets of notches (Fig. 4). On 4.0L 6-cylinder
engines there are three sets of notches (Fig. 5).

The notches cause a pulse to be generated when
they pass under the sensor. The pulses are the input
to the PCM. For each engine revolution there are two
groups of four pulses generated on 2.5L 4-cylinder
engines. There are 3 groups of four pulses generated
on 4.0L 6-cylinder engines.

The trailing edge of the fourth notch, which causes
the pulse, is four degrees before top dead center
(TDC) of the corresponding piston.

The engine will not operate if the PCM does not
receive a CKP sensor input.

Fig. 4 Sensor Operation—2.5L 4-Cyl. Engine

1 – CRANKSHAFT POSITION SENSOR
2 – NOTCHES
3 – FLYWHEEL

CAMSHAFT POSITION SENSOR-2.5L ENGINE

DESCRIPTION

On the 2.5L 4–cylinder engine the Camshaft Posi­tion (CMP) sensor is located in the distributor.

OPERATION

The sensor contains a hall effect device called a
sync signal generator to generate a fuel sync signal.
This sync signal generator detects a rotating pulse
ring (shutter) on the distributor shaft. The pulse ring
rotates 180 degrees through the sync signal genera­tor. Its signal is used in conjunction with the Crank-

Fig. 5 Sensor Operation—4.0L 6-Cyl. Engine

1 – CRANKSHAFT POSITION SENSOR
2 – FLYWHEEL
3 – FLYWHEEL NOTCHES

shaft Position (CKP) sensor to differentiate between
fuel injection and spark events. It is also used to syn­chronize the fuel injectors with their respective cylin­ders.

XJ IGNITION SYSTEM 8D - 5

DESCRIPTION AND OPERATION (Continued)

When the leading edge of the pulse ring (shutter)
enters the sync signal generator, the following occurs:
The interruption of magnetic field causes the voltage
to switch high resulting in a sync signal of approxi­mately 5 volts.

When the trailing edge of the pulse ring (shutter)
leaves the sync signal generator, the following occurs:
The change of the magnetic field causes the sync sig­nal voltage to switch low to 0 volts.

CAMSHAFT POSITION SENSOR—4.0L ENGINE

DESCRIPTION

The Camshaft Position Sensor (CMP) on the 4.0L
6–cylinder engine is bolted to the top of the oil pump
drive shaft assembly (Fig. 6). The sensor and drive
shaft assembly is located on the right side of the
engine near the oil filter (Fig. 7).

Fig. 6 CMP and Oil Pump Drive Shaft—4.0L Engine

1 – CAMSHAFT POSITION SENSOR
2 – MOUNTING BOLTS (2)
3 – PULSE RING
4 – DRIVE GEAR (TO CAMSHAFT)
5 – OIL PUMP DRIVESHAFT
6 – SENSOR BASE (OIL PUMP DRIVESHAFT ASSEMBLY)

OPERATION

The CMP sensor contains a hall effect device called
a sync signal generator to generate a fuel sync sig­nal. This sync signal generator detects a rotating

Fig. 7 CMP Location—4.0L Engine

1 – OIL FILTER
2 – CAMSHAFT POSITION SENSOR
3 – CLAMP BOLT
4 – HOLD-DOWN CLAMP
5 – MOUNTING BOLTS (2)
6 – ELEC. CONNECTOR

pulse ring (shutter) on the oil pump drive shaft (Fig.

6). The pulse ring rotates 180 degrees through the
sync signal generator. Its signal is used in conjunc­tion with the crankshaft position sensor to differenti­ate between fuel injection and spark events. It is also
used to synchronize the fuel injectors with their
respective cylinders.

When the leading edge of the pulse ring (shutter)
enters the sync signal generator, the following occurs:
The interruption of magnetic field causes the voltage
to switch high resulting in a sync signal of approxi­mately 5 volts.

When the trailing edge of the pulse ring (shutter)
leaves the sync signal generator, the following occurs:
The change of the magnetic field causes the sync sig­nal voltage to switch low to 0 volts.

IGNITION SWITCH AND KEY LOCK CYLINDER

DESCRIPTION

The electrical ignition switch is located on the
steering column. It is used as the main on/off switch­ing device for most electrical components. The
mechanical key lock cylinder is used to engage/disen­gage the electrical ignition switch.

8D - 6 IGNITION SYSTEM XJ

DESCRIPTION AND OPERATION (Continued)

OPERATION

Vehicles equipped with an automatic trans-

mission and a floor mounted shifter: a cable is

used to connect the interlock device in the steering
column assembly, to the transmission floor shift
lever. This interlock device is used to lock the trans­mission shifter in the PARK position when the key
lock cylinder is rotated to the LOCKED or ACCES­SORY position. The interlock device within the steer­ing column is not serviceable. If repair is necessary,
the steering column assembly must be replaced.
Refer to Group 19, Steering for procedures.

If the ignition key is difficult to rotate to or from
the LOCK or ACCESSORY position, it may not be
the fault of the key cylinder or the steering column
components. The brake transmission shift interlock
cable may be out of adjustment. Refer to Brake
Transmission Shift Interlock Cable Adjustment in
Group 21, Transmissions for adjustment procedures.

Vehicles equipped with an automatic trans­mission and a steering column mounted shifter:

an interlock device is located within the steering col­umn. This interlock device is used to lock the trans­mission shifter in the PARK position when the key
lock cylinder is in the LOCKED or ACCESSORY
position. If it is difficult to rotate the key to or from
the LOCK or ACCESSORY position, the interlock
device within the steering column may be defective.
This device is not serviceable. If repair is necessary,
the steering column assembly must be replaced.
Refer to Group 19, Steering for procedures.

Vehicles equipped with a manual transmis­sion and a floor mounted shifter: on certain mod-

els, a lever is located on the steering column behind
the ignition key lock cylinder. The lever must be
manually operated to allow rotation of the ignition
key lock cylinder to the LOCK or ACCESSORY posi­tion. If it is difficult to rotate the key to the LOCK or
ACCESSORY position, the lever mechanism may be
defective. This mechanism is not serviceable. If
repair is necessary, the steering column assembly
must be replaced. Refer to Group 19, Steering for
procedures.

On other models, the ignition key cylinder must be
depressed to allow it to be rotated into the LOCK or
ACCESSORY position. If it is difficult to rotate the
key to the LOCK or ACCESSORY position, the lock
mechanism within the steering column may be defec­tive. This mechanism is not serviceable. If repair is
necessary, the steering column assembly must be
replaced. Refer to Group 19, Steering for procedures.

DIAGNOSIS AND TESTING

DISTRIBUTOR CAP-2.5L ENGINE

Remove the distributor cap and wipe it clean with
a dry lint free cloth. Visually inspect the cap for
cracks, carbon paths, broken towers or damaged
rotor button (Fig. 8) or (Fig. 9). Also check for white
deposits on the inside (caused by condensation enter­ing the cap through cracks). Replace any cap that
displays charred or eroded terminals. The machined
surface of a terminal end (faces toward rotor) will
indicate some evidence of erosion from normal oper­ation. Examine the terminal ends for evidence of
mechanical interference with the rotor tip.

Fig. 8 Cap Inspection—External—Typical

1 – BROKEN TOWER
2 – DISTRIBUTOR CAP
3 – CARBON PATH
4 – CRACK

DISTRIBUTOR ROTOR-2.5L ENGINE

Visually inspect the rotor (Fig. 10) for cracks, evi­dence of corrosion or the effects of arcing on the
metal tip. Also check for evidence of mechanical
interference with the cap. Some charring is normal
on the end of the metal tip. The silicone-dielectric­varnish-compound applied to the rotor tip for radio
interference noise suppression, will appear charred.
This is normal. Do not remove the charred com-
pound. Test the spring for insufficient tension.
Replace a rotor that displays any of these adverse
conditions.

XJ IGNITION SYSTEM 8D - 7

DIAGNOSIS AND TESTING (Continued)

Clean high voltage ignition cables with a cloth
moistened with a non-flammable solvent. Wipe the
cables dry. Check for brittle or cracked insulation.

When testing secondary cables for damage with an
oscilloscope, follow the instructions of the equipment
manufacturer.

If an oscilloscope is not available, spark plug cables
may be tested as follows:

CAUTION: Do not leave any one spark plug cable
disconnected for longer than necessary during test­ing. This may cause possible heat damage to the
catalytic converter. Total test time must not exceed
ten minutes.

With the engine running, remove spark plug cable

Fig. 9 Cap Inspection—Internal—Typical

1 – CHARRED OR ERODED TERMINALS
2 – WORN OR DAMAGED ROTOR BUTTON
3 – CARBON PATH

from spark plug (one at a time) and hold next to a
good engine ground. If the cable and spark plug are
in good condition, the engine rpm should drop and
the engine will run poorly. If engine rpm does not
drop, the cable and/or spark plug may not be operat­ing properly and should be replaced. Also check
engine cylinder compression.

With the engine not running, connect one end of a
test probe to a good ground. Start the engine and run
the other end of the test probe along the entire
length of all spark plug cables. If cables are cracked
or punctured, there will be a noticeable spark jump
from the damaged area to the test probe. The cable
running from the ignition coil to the distributor cap
can be checked in the same manner. Cracked, dam­aged or faulty cables should be replaced with resis­tance type cable. This can be identified by the words
ELECTRONIC SUPPRESSION printed on the cable
jacket.

Use an ohmmeter to test for open circuits, excessive
resistance or loose terminals. Remove the distributor
cap from the distributor. Do not remove cables from

cap.

Remove cable from spark plug. Connect ohmme-

ter to spark plug terminal end of cable and to corre-

Fig. 10 Rotor Inspection—Typical

1 – INSUFFICIENT SPRING TENSION
2 – CRACKS
3 – EVIDENCE OF PHYSICAL CONTACT WITH CAP
4 – ROTOR TIP CORRODED

sponding electrode in distributor cap. Resistance
should be 250 to 1000 Ohms per inch of cable. If not,
remove cable from distributor cap tower and connect
ohmmeter to the terminal ends of cable. If resistance
is not within specifications as found in the SPARK
PLUG CABLE RESISTANCE chart, replace the

SPARK PLUG CABLES

cable. Test all spark plug cables in this manner.

SPARK PLUG CABLE RESISTANCE

TESTING

Check the spark plug cable connections for good
contact at the coil(s), distributor cap towers, and
spark plugs. Terminals should be fully seated. The
insulators should be in good condition and should fit
tightly on the coil, distributor and spark plugs. Spark
plug cables with insulators that are cracked or torn
must be replaced.

remove the cable from the cap. Connect ohmmeter to
rotor button (center contact) of distributor cap and

MINIMUM MAXIMUM

250 Ohms Per Inch 1000 Ohms Per Inch

3000 Ohms Per Foot 12,000 Ohms Per Foot

To test ignition coil-to-distributor cap cable, do not

8D - 8 IGNITION SYSTEM XJ

DIAGNOSIS AND TESTING (Continued)

terminal at ignition coil end of cable. If resistance is
not within specifications as found in the Spark Plug
Cable Resistance chart, remove the cable from the
distributor cap. Connect the ohmmeter to the termi­nal ends of the cable. If resistance is not within spec­ifications as found in the Spark Plug Cable
Resistance chart, replace the cable. Inspect the igni­tion coil tower for cracks, burns or corrosion.

SPARK PLUG CONDITIONS

NORMAL OPERATING

The few deposits present on the spark plug will
probably be light tan or slightly gray in color. This is
evident with most grades of commercial gasoline
(Fig. 11). There will not be evidence of electrode
burning. Gap growth will not average more than
approximately 0.025 mm (.001 in) per 3200 km (2000
miles) of operation. Spark plugs that have normal
wear can usually be cleaned, have the electrodes
filed, have the gap set and then be installed.

two plugs in a set may be caused by sticking valves
or defective spark plug cables. Cold (carbon) fouling
of the entire set of spark plugs may be caused by a
clogged air cleaner element or repeated short operat­ing times (short trips).

WET FOULING OR GAS FOULING

A spark plug coated with excessive wet fuel or oil
is wet fouled. In older engines, worn piston rings,
leaking valve guide seals or excessive cylinder wear
can cause wet fouling. In new or recently overhauled
engines, wet fouling may occur before break-in (nor­mal oil control) is achieved. This condition can usu­ally be resolved by cleaning and reinstalling the
fouled plugs.

OIL OR ASH ENCRUSTED

If one or more spark plugs are oil or oil ash
encrusted (Fig. 12), evaluate engine condition for the
cause of oil entry into that particular combustion
chamber.

Fig. 11 Normal Operation and Cold (Carbon) Fouling

1 – NORMAL
2 – DRY BLACK DEPOSITS
3 – COLD (CARBON) FOULING

Some fuel refiners in several areas of the United
States have introduced a manganese additive (MMT)
for unleaded fuel. During combustion, fuel with MMT
causes the entire tip of the spark plug to be coated
with a rust colored deposit. This rust color can be
misdiagnosed as being caused by coolant in the com­bustion chamber. Spark plug performance may be
affected by MMT deposits.

COLD FOULING/CARBON FOULING

Cold fouling is sometimes referred to as carbon
fouling. The deposits that cause cold fouling are basi­cally carbon (Fig. 11). A dry, black deposit on one or

Fig. 12 Oil or Ash Encrusted

ELECTRODE GAP BRIDGING

Electrode gap bridging may be traced to loose
deposits in the combustion chamber. These deposits
accumulate on the spark plugs during continuous
stop-and-go driving. When the engine is suddenly
subjected to a high torque load, deposits partially liq­uefy and bridge the gap between electrodes (Fig. 13).
This short circuits the electrodes. Spark plugs with
electrode gap bridging can be cleaned using standard
procedures.

XJ IGNITION SYSTEM 8D - 9

DIAGNOSIS AND TESTING (Continued)

severe detonation can also separate the insulator
from the center electrode (Fig. 15). Spark plugs with
this condition must be replaced.

Fig. 13 Electrode Gap Bridging

1 – GROUND ELECTRODE
2 – DEPOSITS
3 – CENTER ELECTRODE

SCAVENGER DEPOSITS

Fuel scavenger deposits may be either white or yel­low (Fig. 14). They may appear to be harmful, but this
is a normal condition caused by chemical additives in
certain fuels. These additives are designed to change
the chemical nature of deposits and decrease spark
plug misfire tendencies. Notice that accumulation on
the ground electrode and shell area may be heavy, but
the deposits are easily removed. Spark plugs with
scavenger deposits can be considered normal in condi­tion and can be cleaned using standard procedures.

1 – GROUND ELECTRODE
2 – CENTER ELECTRODE
3 – CHIPPED INSULATOR

PREIGNITION DAMAGE

Preignition damage is usually caused by excessive
combustion chamber temperature. The center elec­trode dissolves first and the ground electrode dis­solves somewhat latter (Fig. 16). Insulators appear
relatively deposit free. Determine if the spark plug
has the correct heat range rating for the engine.
Determine if ignition timing is over advanced or if
other operating conditions are causing engine over­heating. (The heat range rating refers to the operat­ing temperature of a particular type spark plug.
Spark plugs are designed to operate within specific
temperature ranges. This depends upon the thick­ness and length of the center electrodes porcelain
insulator.)

Fig. 15 Chipped Electrode Insulator

Fig. 14 Scavenger Deposits

1 – GROUND ELECTRODE COVERED WITH WHITE OR

YELLOW DEPOSITS

2 – CENTER ELECTRODE

CHIPPED ELECTRODE INSULATOR

A chipped electrode insulator usually results from
bending the center electrode while adjusting the
spark plug electrode gap. Under certain conditions,

SPARK PLUG OVERHEATING

Overheating is indicated by a white or gray center

electrode insulator that also appears blistered (Fig.

17). The increase in electrode gap will be consider­ably in excess of 0.001 inch per 2000 miles of opera­tion. This suggests that a plug with a cooler heat
range rating should be used. Over advanced ignition
timing, detonation and cooling system malfunctions
can also cause spark plug overheating.

IGNITION SWITCH AND KEY LOCK CYLINDER

ELECTRICAL DIAGNOSIS

For ignition switch electrical schematics, refer to

Ignition Switch in Group 8W, Wiring Diagrams.

8D - 10 IGNITION SYSTEM XJ

DIAGNOSIS AND TESTING (Continued)

Transmission Shift Interlock Cable Adjustment in
Group 21, Transmissions for adjustment procedures.

Vehicles equipped with an automatic trans-

mission and a steering column mounted shifter:

an interlock device is located within the steering col­umn. This interlock device is used to lock the trans­mission shifter in the PARK position when the key
lock cylinder is in the LOCKED or ACCESSORY
position. If it is difficult to rotate the key to or from
the LOCK or ACCESSORY position, the interlock
device within the steering column may be defective.
This device is not serviceable. If repair is necessary,
the steering column assembly must be replaced.
Refer to Group 19, Steering for procedures.

Fig. 16 Preignition Damage

1 – GROUND ELECTRODE STARTING TO DISSOLVE
2 – CENTER ELECTRODE DISSOLVED

Fig. 17 Spark Plug Overheating

1 – BLISTERED WHITE OR GRAY COLORED INSULATOR

Vehicles equipped with a manual transmis-

sion and a floor mounted shifter: on certain mod-

els, a lever is located on the steering column behind
the ignition key lock cylinder. The lever must be
manually operated to allow rotation of the ignition
key lock cylinder to the LOCK or ACCESSORY posi­tion. If it is difficult to rotate the key to the LOCK or
ACCESSORY position, the lever mechanism may be
defective. This mechanism is not serviceable. If
repair is necessary, the steering column assembly
must be replaced. Refer to Group 19, Steering for
procedures.

On other models, the ignition key cylinder must be
depressed to allow it to be rotated into the LOCK or
ACCESSORY position. If it is difficult to rotate the
key to the LOCK or ACCESSORY position, the lock
mechanism within the steering column may be defec­tive. This mechanism is not serviceable. If repair is
necessary, the steering column assembly must be
replaced. Refer to Group 19, Steering for procedures.

REMOVAL AND INSTALLATION

MECHANICAL DIAGNOSIS (KEY DIFFICULT TO ROTATE)

Vehicles equipped with an automatic trans-

mission and a floor mounted shifter: a cable is

used to connect the interlock device in the steering
column assembly, to the transmission floor shift
lever. This interlock device is used to lock the trans­mission shifter in the PARK position when the key
lock cylinder is rotated to the LOCKED or ACCES­SORY position. The interlock device within the steer­ing column is not serviceable. If repair is necessary,
the steering column assembly must be replaced.
Refer to Group 19, Steering for procedures.

If the ignition key is difficult to rotate to or from
the LOCK or ACCESSORY position, it may not be
the fault of the key cylinder or the steering column
components. The brake transmission shift interlock
cable may be out of adjustment. Refer to Brake

SPARK PLUG CABLES

REMOVAL

CAUTION: When disconnecting a high voltage
cable from a spark plug or from the distributor cap,
twist the rubber boot slightly (1/2 turn) to break it
loose (Fig. 18). Grasp the boot (not the cable) and
pull it off with a steady, even force.

INSTALLATION

Push the cable firmly onto the sparkplug.

SPARK PLUGS

PLUG REMOVAL

On the 4.0L 6–cylinder engine the spark plugs are

located below the coil rail assembly. To gain access to

XJ IGNITION SYSTEM 8D - 11

REMOVAL AND INSTALLATION (Continued)

Fig. 18 Cable Removal

1 – SPARK PLUG CABLE AND BOOT
2 – SPARK PLUG BOOT PULLER
3 – TWIST AND PULL
4 – SPARK PLUG

any/all spark plug(s), refer to Ignition Coil-4.0L
Engine Removal/Installation.

(1) 2.5L 4–Cylinder Engine: Always remove spark
plug or ignition coil cables by grasping at the cable
boot (Fig. 18). Turn the cable boot 1/2 turn and pull
straight back in a steady motion. Never pull directly
on the cable. Internal damage to cable will result.

(2) Prior to removing the spark plug, spray com­pressed air around the spark plug hole and the area
around the spark plug. This will help prevent foreign
material from entering the combustion chamber.

(3) Remove the spark plug using a quality socket
with a rubber or foam insert.

(4) Inspect the spark plug condition. Refer to
Spark Plugs Conditions.

PLUG CLEANING

The plugs may be cleaned using commercially
available spark plug cleaning equipment. After clean­ing, file the center electrode flat with a small point
file or jewelers file before adjusting gap.

CAUTION: Never use a motorized wire wheel brush
to clean the spark plugs. Metallic deposits will
remain on the spark plug insulator and will cause
plug misfire.

PLUG GAP ADJUSTMENT

Check the spark plug gap with a gap gauge tool. If
the gap is not correct, adjust it by bending the
ground electrode (Fig. 19). Never attempt to adjust

the gap by bending the center electrode.

Fig. 19 Setting Spark Plug Gap—Typical

1 – GAUGE
2 – SPARK PLUG

SPARK PLUG GAP

• 2.5L 4-Cylinder Engine Spark Plug Gap:.89 mm

(.035 in).

• 4.0L 6-Cylinder Engine Spark Plug Gap:.89 mm

(.035 in).

PLUG INSTALLATION

Always tighten spark plugs to the specified torque.
Over tightening can cause distortion. This may result
in a change in the spark plug gap, or a cracked por­celain insulator.

When replacing the spark plug and ignition coil
cables, route the cables correctly and secure them in
the appropriate retainers. Failure to route the cables
properly can cause the radio to reproduce ignition
noise. It could cause cross ignition of the spark plugs,
or short circuit the cables to ground.

(1) Start the spark plug into the cylinder head by
hand to avoid cross threading.

(2) Tighten the spark plugs to 35-41 N·m (26-30 ft.
lbs.) torque.

(3) 2.5L 4–Cylinder Engine: Install spark plug
cables over spark plugs.

(4) 4.0L 6–Cylinder Engine: Install coil rail. Refer
to Ignition Coil-4.0L Engine Removal/Installation.

8D - 12 IGNITION SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

IGNITION COIL—2.5L ENGINE

REMOVAL

The ignition coil is an epoxy filled type. If the coil

is replaced, it must be replaced with the same type.

On the 2.5L 4-cylinder engine, the ignition coil is
mounted to a bracket on side of engine (to rear of
distributor) (Fig. 20).

ber boots (Fig. 21) to seal the 6 spark plugs to the
coil. Inside each rubber boot is a spring. The spring
is used for an electrical contact between the coil and
the top of the spark plug. These rubber boots and
springs are a permanent part of the coil and are not
serviced separately.

(1) Disconnect negative battery cable at battery.
(2) The coil is bolted directly to the cylinder head.

Remove 4 coil mounting bolts (Fig. 22).

(3) Carefully pry up coil assembly from spark
plugs. Do this by prying alternately at each end of
coil until rubber boots have disengaged from all
spark plugs. If boots will not release from spark
plugs, use a commercially available spark plug boot
removal tool. Twist and loosen a few boots from a few
spark plugs to help remove coil.

(4) After coil has cleared spark plugs, position coil
for access to primary electrical connector. Disconnect
connector from coil by pushing slide tab outwards to
right side of vehicle (Fig. 23). After slide tab has been
positioned outwards, push in on secondary release
lock (Fig. 23) on side of connector and pull connector
from coil.

(5) Remove coil from vehicle.

Fig. 20 Ignition Coil—2.5L Engine

1 – IGNITION COIL
2 – ELECTRICAL CONNECTOR
3 – MOUNTING BOLTS (2)
4 – SECONDARY CABLE

(1) Disconnect ignition coil secondary cable from

ignition coil.

(2) Disconnect engine harness connector from igni-

tion coil.

(3) Remove ignition coil mounting bolts (nuts are

used on back side of bracket on some coils).

(4) Remove coil from vehicle.

INSTALLATION

(1) Install ignition coil to bracket on cylinder block
with mounting bolts (and nuts if equipped). If
equipped with nuts and bolts, tighten to 11 N·m (100
in. lbs.) torque. If equipped with bolts only, tighten to
5 N·m (50 in. lbs.) torque.

(2) Connect engine harness connector to coil.

(3) Connect ignition coil cable to ignition coil.

IGNITION COIL—4.0L ENGINE

REMOVAL

A one-piece coil rail assembly containing three
individual coils is used on the 4.0L engine (Fig. 21).
The coil rail must be replaced as one assembly. The
bottom of the coil is equipped with 6 individual rub-

Fig. 21 Ignition Coil Assembly—4.0L 6–Cylinder

Engine

1 – CYL. #6
2 – CYL. #5
3 – CYL. #4
4 – CYL. #3
5 – CYL. #2
6 – CYL. #1
7 – COILS (3)
8 – MOUNTING BOLTS (4)
9 – BOLT BASES (4)
10 – RUBBER BOOTS (6)

XJ IGNITION SYSTEM 8D - 13

REMOVAL AND INSTALLATION (Continued)

INSTALLATION

(1) Position ignition coil rubber boots to all spark
plugs. Push down on coil assembly until bolt bases
have contacted cylinder head

(2) Install 4 coil mounting bolts. Loosely tighten 4
bolts just enough to allow bolt bases to contact cylin­der head. Do a final tightening of each bolt in steps
down to 29 N·m (250 in. lbs.) torque. Do not apply
full torque to any bolt first.

(3) Connect engine harness connector to coil by
snapping into position. Move slide tab towards
engine (Fig. 23) for a positive lock.

(4) Connect negative battery cable to battery.

CRANKSHAFT POSITION (CKP) SENSOR

Fig. 22 Ignition Coil Rail Location—4.0L 6–Cylinder

Engine

1 – COIL RAIL
2 – COIL MOUNTING BOLTS (4)
3 – COIL
4 – COIL ELECTRICAL CONNECTION

REMOVAL

The crankshaft position (CKP) sensor is mounted
to the transmission bellhousing at the left/rear side
of the engine block.

The sensor may be mounted to the transmission
with one of the following three different configura­tions:

• with one bolt (Fig. 24). If sensor is equipped

with one mounting bolt, it is adjustable..

• with two nuts (Fig. 25).

• with two bolts (Fig. 26).

Fig. 23 Ignition Coil Electrical Connector—4.0L

6–Cylinder Engine

1 – REAR OF VALVE COVER
2 – COIL RAIL
3 – SLIDE TAB
4 – RELEASE LOCK
5 – COIL CONNECTOR

Fig. 24 Crankshaft Position Sensor—One-Bolt

Mounting

1 – SENSOR PIGTAIL
2 – CRANKSHAFT POSITION SENSOR
3 – MOUNTING BOLT
4 – TRANSMISSION HOUSING
5 – PAPER SPACER
6 – SLOTTED HOLE

8D - 14 IGNITION SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

Fig. 25 Crankshaft Position Sensor—Two-Nut

Mounting

1 – TRANSMISSION BELLHOUSING
2 – MOUNTING NUTS (2)
3 – CRANKSHAFT POSITION SENSOR
4 – MOUNTING STUDS (2)
5 – RUBBER GROMMET
6 – SENSOR PIGTAIL

(1) Near left-rear side of engine, disconnect sensor
pigtail harness (electrical connector) from main elec­trical harness connector. These connectors are
attached to a bracket which is attached to the left­front side of the transmission.

(2) Depending upon application, remove either sen­sor mounting bolt(s) or nuts.

(3) Remove sensor from engine.

INSTALLATION

Sensor With 2–Bolt Mounting:

(1) Install sensor flush against opening in trans­mission housing.

(2) Install and tighten two sensor mounting bolts
to 19 N·m (14 ft. lbs.) torque. The two sensor mount­ing bolts are specially machined to correctly space
unit to flywheel. Do not attempt to install any other
bolts.

Sensor With 2–Nut Mounting:

(3) Install and tighten two sensor mounting nuts
to 19 N·m (14 ft. lbs.) torque.

Sensor With One-Bolt Mounting:

New replacement sensors will be equipped with a
paper spacer glued to bottom of sensor. If installing
(returning) a used sensor to vehicle, a new paper
spacer must be installed to bottom of sensor. This

Fig. 26 Crankshaft Position Sensor—Two-Bolt

Mounting

1 – TRANSMISSION BELLHOUSING
2 – MOUNTING BOLTS (2)
3 – CRANKSHAFT POSITION SENSOR
4 – RUBBER GROMMET
5 – SENSOR PIGTAIL

spacer will be ground off the first time engine is
started. If spacer is not used, sensor will be broken
the first time engine is started.

(4) New Sensors: Be sure paper spacer is installed
to bottom of sensor. If not, obtain spacer
PN05252229.

(5) Used Sensors: Clean bottom of sensor and
install spacer PN05252229.

(6) Install sensor into transmission bellhousing
hole.

(7) Push sensor against flywheel/drive plate. With
sensor pushed against flywheel/drive plate, tighten
mounting bolt to 7 N·m (60 in. lbs.) torque.

(8) Connect sensor pigtail harness electrical con­nector to main wiring harness connector.

CAMSHAFT POSITION SENSOR—2.5L ENGINE

On 2.5L engines, the camshaft position sensor is
located in the distributor (Fig. 27).

REMOVAL

Distributor removal is not necessary to remove
camshaft position sensor.

(1) Disconnect negative battery cable at battery.

(2) Remove distributor cap from distributor (two
screws).

(3) Disconnect camshaft position sensor wiring
harness from main engine wiring harness.

XJ IGNITION SYSTEM 8D - 15

REMOVAL AND INSTALLATION (Continued)

Fig. 27 Camshaft Position Sensor—2.5L Engine

1 – SYNC SIGNAL GENERATOR
2 – CAMSHAFT POSITION SENSOR
3 – PULSE RING
4 – DISTRIBUTOR ASSEMBLY

(4) Remove distributor rotor from distributor shaft.
(5) Lift camshaft position sensor assembly from

distributor housing (Fig. 27).

INSTALLATION

(1) Install camshaft position sensor to distributor.

Align sensor into notch on distributor housing.

(2) Connect wiring harness.
(3) Install rotor.
(4) Install distributor cap. Tighten mounting

screws.

CAMSHAFT POSITION SENSOR—4.0L ENGINE

The Camshaft Position Sensor (CMP) on the 4.0L
6–cylinder engine is bolted to the top of the oil pump
drive shaft assembly (Fig. 28). The sensor and drive
shaft assembly is located on the right side of the
engine near the oil filter (Fig. 29).

The rotational position of oil pump drive deter­mines fuel synchronization only. It does not deter­mine ignition timing.

NOTE: Do not attempt to rotate the oil pump drive
to modify ignition timing.

Two different procedures are needed for
removal and installation. The first procedure will
detail removal and installation of the sensor only.
The second procedure will detail removal and instal­lation of the sensor and oil pump drive shaft assem­bly. The second procedure is to be used if the engine
has been disassembled.

An internal oil seal is used in the drive shaft hous­ing that prevents engine oil at the bottom of the sen­sor. The seal is not serviceable.

Fig. 28 CMP and Oil Pump Drive Shaft—4.0L Engine

1 – CAMSHAFT POSITION SENSOR
2 – MOUNTING BOLTS (2)
3 – PULSE RING
4 – DRIVE GEAR (TO CAMSHAFT)
5 – OIL PUMP DRIVESHAFT
6 – SENSOR BASE (OIL PUMP DRIVESHAFT ASSEMBLY)

REMOVAL—SENSOR ONLY

(1) Disconnect electrical connector at CMP sensor

(Fig. 29).

(2) Remove 2 sensor mounting bolts (Fig. 28) or

(Fig. 29).

(3) Remove sensor from oil pump drive.

INSTALLATION—SENSOR ONLY

(1) Install sensor to oil pump drive.
(2) Install 2 sensor mounting bolts and tighten to

2 N·m (15 in. lbs.) torque.

(3) Connect electrical connector to CMP sensor.

REMOVAL—OIL PUMP DRIVE AND SENSOR

If the CMP and oil pump drive are to be
removed and installed, do not allow engine
crankshaft or camshaft to rotate. CMP sensor
relationship will be lost.

(1) Disconnect electrical connector at CMP sensor
(Fig. 29).

(2) Remove 2 sensor mounting bolts (Fig. 28) or
(Fig. 29).

(3) Remove sensor from oil pump drive.

8D - 16 IGNITION SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

Fig. 29 CMP Location—4.0L Engine

1 – OIL FILTER
2 – CAMSHAFT POSITION SENSOR
3 – CLAMP BOLT
4 – HOLD-DOWN CLAMP
5 – MOUNTING BOLTS (2)
6 – ELEC. CONNECTOR

Fig. 30 CMP Pulse Ring Alignment—4.0L Engine

1 – PULSE RING (SHUTTER)
2 – TOOTHPICK
3 – SENSOR BASE (OIL PUMP DRIVESHAFT ASSEMBLY)

Fig. 31 Align Timing Marks—4.0L Engine

1 – CRANKSHAFT VIBRATION DAMPER TIMING MARK

(4) Before proceeding to next step, mark and note
rotational position of oil pump drive in relationship
to engine block. After installation, the CMP sensor
should face rear of engine 0°.

(5) Remove hold-down bolt and clamp (Fig. 29).

(6) While pulling assembly from engine, note direc­tion and position of pulse ring (Fig. 28). After
removal, look down into top of oil pump and note
direction and position of slot at top of oil pump gear.

(7) Remove and discard old oil pump drive-to-en­gine block gasket.

INSTALLATION—OIL PUMP DRIVE AND SENSOR

(1) Clean oil pump drive mounting hole area of
engine block.

(2) Install new oil pump drive-to-engine block gas­ket.

(3) Temporarily install a toothpick or similar tool
through access hole at side of oil pump drive housing.
Align toothpick into mating hole on pulse ring (Fig.

30).

(4) Install oil pump drive into engine while align­ing into slot on oil pump. Rotate oil pump drive back
to its original position and install hold-down clamp
and bolt. Finger tighten bolt. Do not do a final tight­ening of bolt at this time.

(5) If engine crankshaft or camshaft has been
rotated, such as during engine tear-down, CMP sen­sor relationship must be reestablished.

(a) Remove ignition coil rail assembly. Refer to

Ignition Coil Removal/Installation.

XJ IGNITION SYSTEM 8D - 17

REMOVAL AND INSTALLATION (Continued)

(b) Remove cylinder number 1 spark plug.

(c) Hold a finger over the open spark plug hole.
Rotate engine at vibration dampener bolt until
compression (pressure) is felt.

(d) Slowly continue to rotate engine. Do this
until timing index mark on vibration damper pul­ley aligns with top dead center (TDC) mark (0
degree) on timing degree scale (Fig. 31). Always
rotate engine in direction of normal rotation. Do
not rotate engine backward to align timing marks.

(e) Install oil pump drive into engine while
aligning into slot on oil pump. If pump drive will
not drop down flush to engine block, the oil pump
slot is not aligned. Remove oil pump drive and
align slot in oil pump to shaft at bottom of drive.
Install into engine. Rotate oil pump drive back to
its original position and install hold-down clamp
and bolt. Finger tighten bolt. Do not do a final
tightening of bolt at this time.

(f) Remove toothpick from housing.
(6) Install sensor to oil pump drive. After installa-

tion, the CMP sensor should face rear of engine 0°.

(7) Install 2 sensor mounting bolts and tighten to

2 N·m (15 in. lbs.) torque.

(8) Connect electrical connector to CMP sensor.
(9) If removed, install spark plug and ignition coil

rail.

To verify correct rotational position of oil pump

drive, the DRB scan tool must be used.

on ignition timing. All ignition timing values are con­trolled by powertrain control module (PCM).

(15) Tighten hold-down clamp bolt to 23 N·m (17

ft. lbs.) torque.

DISTRIBUTOR—2.5L ENGINE

The distributor contains an internal oil seal that
prevents oil from entering the distributor housing.
The seal is not serviceable.

Factory replacement distributors are equipped with
a plastic alignment pin already installed. The pin is
located in an access hole on the bottom of the distrib­utor housing (Fig. 32). It is used to temporarily lock
the rotor to the cylinder number 1 position during
installation. The pin must be removed after install­ing the distributor.

WARNING: WHEN PERFORMING THE FOLLOWING
TEST, THE ENGINE WILL BE RUNNING. BE CARE­FUL NOT TO STAND IN LINE WITH THE FAN
BLADES OR FAN BELT. DO NOT WEAR LOOSE
CLOTHING.

(10) Connect DRB scan tool to data link connector.
The data link connector is located in passenger com­partment, below and to left of steering column.

(11) Gain access to SET SYNC screen on DRB.

(12) Follow directions on DRB screen and start
engine. Bring to operating temperature (engine must
be in “closed loop” mode).

(13) With engine running at idle speed, the words
IN RANGE should appear on screen along with 0°.
This indicates correct position of oil pump drive.

(14) If a plus (+) or a minus (-) is displayed next to
degree number, and/or the degree displayed is not
zero, loosen but do not remove hold-down clamp bolt.
Rotate oil pump drive until IN RANGE appears on
screen. Continue to rotate oil pump drive until
achieving as close to 0° as possible.

The degree scale on SET SYNC screen of DRB is
referring to fuel synchronization only. It is not
referring to ignition timing. Because of this, do
not attempt to adjust ignition timing using this
method. Rotating oil pump drive will have no effect

Fig. 32 Plastic Alignment Pin—2.5L Engine

1 – PLASTIC ALIGNMENT PIN

The camshaft position sensor is located in the dis­tributor (Fig. 33). For removal/installation proce­dures, refer to Camshaft Position Sensor. Distributor
removal is not necessary for sensor removal.

Refer to (Fig. 33) for an exploded view of the dis­tributor.

A fork with a slot is supplied on the bottom of the
distributor housing where the housing base seats
against the engine block (Fig. 33). The centerline of
the slot aligns with the distributor holddown bolt
hole in the engine block. Because of the fork, the dis­tributor cannot be rotated. Distributor rotation is not
necessary as all ignition timing requirements are
handled by the Powertrain Control Module (PCM).

The position of the distributor determines fuel syn­chronization only. It does not determine ignition tim­ing.

8D - 18 IGNITION SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

(7) Slowly continue to rotate engine. Do this until
timing index mark on vibration damper pulley aligns
with Top Dead Center (TDC) mark (0 degree) on tim­ing degree scale (Fig. 34). Always rotate engine in
direction of normal rotation. Do not rotate engine
backward to align timing marks.

(8) On models equipped with A/C, remove electri­cal cooling fan and shroud assembly from radiator.
Refer to Group 7, Cooling System for procedures.

(9) This will provide room to turn engine crank­shaft with a socket and ratchet using vibration
damper bolt.

Fig. 33 Distributor—2.5L Engine—Typical

1 – CAP
2 – CAMSHAFT POSITION SENSOR
3 – HOUSING
4 – FORK WITH SLOT
5 – DRIVE GEAR
6 – ROLL PIN
7 – WASHER
8 – GASKET
9 – HOLDDOWN CLAMP
10 – HOLDDOWN BOLT
11 – SHAFT
12 – PULSE RING
13 – ROTOR

NOTE: Do not attempt to modify this fork to attain
ignition timing.

REMOVAL

(1) Disconnect negative battery cable at battery.
(2) Disconnect coil secondary cable at coil.

(3) Remove distributor cap from distributor (2
screws). Do not remove cables from cap. Do not
remove rotor.

(4) Disconnect distributor wiring harness from
main engine harness.

(5) Remove cylinder number 1 spark plug.

(6) Hold a finger over open spark plug hole. Rotate
engine at vibration dampener bolt until compression
(pressure) is felt.

Fig. 34 Align Timing Marks—2.5L Engine

1 – CRANKSHAFT VIBRATION DAMPER TIMING MARK

(10) Remove distributor holddown bolt and clamp.
(11) Remove distributor from engine by slowly lift-

ing straight up.

(12) Note that rotor will rotate slightly in a coun­terclockwise direction while lifting up distributor.
The oil pump gear will also rotate slightly in a coun­terclockwise direction while lifting up distributor.
This is due to the helical cut gears on distributor and
camshaft.

(13) Note removed position of rotor during distrib­utor removal. During installation, this will be
referred to as the Pre-position.

(14) Observe slot in oil pump gear through hole on
side of engine. It should be slightly before (counter­clockwise of) 10 o’clock position (Fig. 35).

(15) Remove and discard the old distributor-to-en­gine block gasket.

XJ IGNITION SYSTEM 8D - 19

REMOVAL AND INSTALLATION (Continued)

Fig. 35 Slot At 10 O’clock Position—2.5L Engine

1 – 10 0’CLOCK POSITION
2 – OIL PUMP SLOT

INSTALLATION

(1) If engine crankshaft has been rotated after dis­tributor removal, cylinder number 1 must be
returned to its proper firing stroke. Refer to previous
REMOVAL Step 5 and Step 6. These steps must be
done before installing distributor.

(2) Check position of slot on oil pump gear. On the

2.5L engine, it should be just slightly before (counter­clockwise of) 10 o’clock position (Fig. 35). If not, place
a flat blade screwdriver into oil pump gear and
rotate it into proper position.

(3) Factory replacement distributors are equipped
with a plastic alignment pin already installed (Fig.

32). This pin is used to temporarily hold rotor to cyl­inder number 1 firing position during distributor
installation. If pin is in place, proceed to Step 8. If
not, proceed to next step.

(4) If original distributor is to be reinstalled, such
as during engine overhaul, the plastic pin will not be
available. A 3/16 inch drift pin punch tool may be
substituted for plastic pin.

(5) Remove camshaft position sensor from distrib­utor housing. Lift straight up.

(6) Four different alignment holes are provided on
plastic ring (Fig. 36). Note that 2.5L and 4.0L

engines have different alignment holes (Fig.

36).

(7) Rotate distributor shaft and install pin punch
tool through proper alignment hole in plastic ring
(Fig. 36) and into mating access hole in distributor
housing. This will prevent distributor shaft and rotor
from rotating.

(8) Clean distributor mounting hole area of engine
block.

(9) Install new distributor-to-engine block gasket
(Fig. 33).

Fig. 36 Pin Alignment Holes—2.5L Engine

1 – DISTRIBUTOR HOUSING (TOP VIEW)
2 – PULSE RING
3 – 4.0L 6–CYLINDER ENGINE ALIGN. HOLE
4 – 2.5L 4–CYLINDER ENGINE ALIGN. HOLE
5 – MATING ACCESS HOLE IN DISTRIBUTOR HOUSING
6 – PLASTIC RING

(10) Install rotor to distributor shaft.

(11) Pre-position distributor into engine while
holding centerline of base slot in 1 o’clock position
(Fig. 37). Continue to engage distributor into engine.
The rotor and distributor will rotate clockwise during
installation. This is due to the helical cut gears on
distributor and camshaft. When distributor is fully
seated to engine block, the centerline of base slot
should be aligned to clamp bolt mounting hole on
engine (Fig. 38). The rotor should also be pointed
slightly past (clockwise of) 3 o’clock position.

It may be necessary to rotate rotor and distributor
shaft (very slightly) to engage distributor shaft with
slot in oil pump gear. The same may have to be done
to engage distributor gear with camshaft gear.

8D - 20 IGNITION SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

The distributor is correctly installed when:

• rotor is pointed at 3 o’clock position.

• plastic alignment pin (or pin punch tool) is still

installed to distributor.

• number 1 cylinder piston is set at top dead cen-

ter (TDC) (compression stroke).

• centerline of slot at base of distributor is aligned
to centerline of distributor holddown bolt hole on
engine. In this position, the holddown bolt should
easily pass through slot and into engine.

No adjustments are necessary. Proceed to next

step.

(12) Install distributor holddown clamp and bolt.

Tighten bolt to 23 N·m (17 ft. lbs.) torque.

(13) Remove pin punch tool from distributor. Or, if
plastic alignment pin was used, remove it straight
down from bottom of distributor. Discard plastic pin.

(14) If removed, install camshaft position sensor to
distributor. Align wiring harness grommet to notch in
distributor housing.

(15) Install rotor.

Fig. 37 Distributor Pre-position—2.5L Engine

1 – 1 O’CLOCK POSITION
2 – BASE SLOT
3 – DISTRIBUTOR BASE

Fig. 38 Distributor Engaged Position—2.5L Engine

1 – DISTRIBUTOR BASE SLOT
2 – CLAMP BOLT MOUNTING HOLE (ON ENGINE)
3 – DISTRIBUTOR BASE

CAUTION: If the distributor cap is incorrectly posi­tioned on distributor housing, cap or rotor may be
damaged when engine is started.

(16) Install distributor cap. Tighten distributor cap
holddown screws to 3 N·m (26 in. lbs.) torque.

(17) If removed, install spark plug cables to dis­tributor cap. For proper firing order, refer to Engine
Firing Order.

(18) Connect distributor wiring harness to main
engine harness.

(19) Connect battery cable to battery.

IGNITION SWITCH AND KEY CYLINDER

The ignition key must be in the key cylinder for
cylinder removal. The key cylinder must be removed
first before removing ignition switch.

KEY CYLINDER REMOVAL

(1) Disconnect negative battery cable at battery.

(2) If equipped with an automatic transmission,
place shifter in PARK position.

(3) Rotate key to ON position.

(4) A release tang is located on bottom of key cyl­inder (Fig. 39).

(5) Position a small screwdriver or pin punch into
tang access hole on bottom of steering column lower
cover (Fig. 40).

(6) Push the pin punch up while pulling key cylin­der from steering column.

XJ IGNITION SYSTEM 8D - 21

REMOVAL AND INSTALLATION (Continued)

Fig. 39 Key Cylinder Release Tang

1 – KEY CYLINDER
2 – RELEASE TANG

Fig. 40 Key Cylinder and Cover Removal

1 – LOWER COVER
2 – ACCESS HOLE
3 – PIN PUNCH
4 – COVER SCREWS (3)

IGNITION SWITCH REMOVAL

(1) Remove key cylinder. Refer to previous steps.
(2) Remove lower steering column cover screws

and remove cover (Fig. 40).

(3) Remove ignition switch mounting screw (Fig.

43). Use tamper proof torx bit (Snap-Ont SDMTR10
or equivalent) to remove the screw.

Fig. 41 Ignition Switch Lock Tab

1 – LOCK TAB
2 – IGNITION SWITCH
3 – SCREWDRIVER

Fig. 42 Switch In ON Position

1 – IGNITION SWITCH
2 – ROTATE TO ON POSITION

(4) Using a small screwdriver, push on locking tab
(Fig. 41) and remove switch from steering column.

(5) Disconnect two electrical connectors at rear of
ignition switch (Fig. 43).

8D - 22 IGNITION SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

KEY CYLINDER INSTALLATION

(1) If equipped with an automatic transmission,
place shifter in PARK position.

(2) Position key cylinder into steering column as it
would normally be in the ON position.

(3) Press key cylinder into column until it snaps
into position.

(4) Check mechanical operation of switch. Auto-
matic Transmission: Be sure transmission lever is
locked in PARK position after key removal. If key is
difficult to rotate or is difficult to remove, the shift
lever-to-steering column cable may be out of adjust­ment or defective. Refer to Group 21, Transmission
for procedures. Manual Transmission: Be sure key
cannot be removed until release lever is operated. If
key can be removed, release lever mechanism may be
defective. Release lever mechanism is not serviced
separately. If repair is necessary, the steering column
must be replaced. Refer to Group 19, Steering for
procedures.

(5) Connect negative cable to battery.

Fig. 43 Ignition Switch Removal/Installation

1 – TAMPER PROOF SCREW
2 – IGNITION SWITCH
3 – ELECTRICAL CONNECTORS

IGNITION SWITCH INSTALLATION

(1) Before installing ignition switch, rotate the slot

in the switch to the ON position (Fig. 42).

(2) Connect two electrical connectors to rear of
ignition switch. Make sure that locking tabs are fully
seated into wiring connectors.

(3) Position switch to column and install tamper
proof screw. Tighten screw to 3 N·m (26 in. lbs.).

(4) Install steering column lower cover.

(6) Check electrical operation of switch.

SHIFTER/IGNITION INTERLOCK

REMOVAL/INSTALLATION

On models equipped with an automatic transmis­sion, a cable connects the ignition switch with the
floor shift lever. The shifter will be locked in the
PARK position when the ignition key is in the LOCK
or ACCESSORY positions. The cable can be adjusted
or replaced. Refer to Group 21, Transmissions for
procedures. The ignition interlock device within the
steering column is not serviceable. If service is nec­essary, the steering column must be replaced. Refer
to Group 19, Steering for procedures.

XJ IGNITION SYSTEM 8D - 23

SPECIFICATIONS

IGNITION TIMING

Ignition timing is not adjustable on any engine.

ENGINE FIRING ORDER—2.5L 4-CYLINDER
ENGINE

ENGINE FIRING ORDER—4.0L 6-CYLINDER
ENGINE

IGNITION COIL RESISTANCE—2.5L ENGINE

COIL

MANUFACTURER

Diamond 0.97 - 1.18 Ohms 11,300 - 15,300 Ohms

Toyodenso 0.95 - 1.20 Ohms 11,300 - 13,300 Ohms

PRIMARY RESISTANCE @

21-27°C (70-80°F)

IGNITION COIL RESISTANCE—4.0L ENGINE

SPARK PLUGS

ENGINE PLUG TYPE ELECTRODE GAP

2.5L RC12ECC 0.89 mm (0.035 in.)

4.0L RC12ECC 0.89 mm (0.035 in.)

SPARK PLUG CABLE RESISTANCE

MINIMUM MAXIMUM

250 Ohms Per Inch 1000 Ohms Per Inch

3000 Ohms Per Foot 12,000 Ohms Per Foot

SECONDARY RESISTANCE @ 21-27°C

(70-80°F)

PRIMARY RESISTANCE

21-27°C (70-80°F)

0.71 - 0.88 Ohms

8D - 24 IGNITION SYSTEM XJ

SPECIFICATIONS (Continued)

TORQUE CHART

DESCRIPTION TORQUE

Camshaft Position Sensor–to–base

bolts—4.0L .............. 28N·m(15in.lbs.)

Crankshaft Position Sensor Bolts

(sensor mounted with 2 bolts) ......... 19N·m

(14 ft. lbs.)

Crankshaft Position Sensor Nuts

(sensor mounted with 2 nuts) ......... 19N·m

(14 ft. lbs.)

Crankshaft Position Sensor Bolt

(sensor mounted with 1 bolt) . . 7 N·m (60 in. lbs.)

Distributor Hold Down Bolt—2.5L ....... 23N·m

(17 ft. lbs.)
Distributor Cap Screws—2.5L . . 3 N·m (26 in. lbs.)
Ignition Coil Mounting (if tapped

bolts are used)—2.5L ....... 5N·m(50in.lbs.)

Ignition Coil Mounting (if nuts/bolts

are used)—2.5L .......... 11N·m(100 in. lbs.)

Ignition Coil Rail Mounting Bolts—4.0L . . . 29 N·m

(250 in. lbs.)

Oil Pump Drive Hold-down Bolt—4.0L .... 23N·m

(17 ft. lbs.)

Spark Plugs (all engines) ..... 41N·m(30ft.lbs.)