2003 JEEP GRAND CHEROKEE Lock cylinder

Repeat the test. If the reading is still above 0.2 volt,
replace the faulty battery positive cable.
(4) Connect the voltmeter to measure between the
battery negative terminal post and a good clean
ground on the engine block (Fig. 5). Rotate and hold
the ignition switch in the Start position. Observe the
voltmeter. If the reading is above 0.2 volt, clean and
tighten the battery negative cable attachment on the
engine block. Repeat the test. If the reading is still
above 0.2 volt, replace the faulty battery negative
cable.(5) Connect the positive lead of the voltmeter to
the starter housing. Connect the negative lead of the
voltmeter to the battery negative terminal post (Fig.
6). Rotate and hold the ignition switch in the Start
position. Observe the voltmeter. If the reading is
above 0.2 volt, correct the poor starter to engine
block ground contact.
If the resistance tests detect no feed circuit prob-
lems, refer toStarter Motorin the Diagnosis and
Testing section of this group.
CONTROL CIRCUIT TESTING
The starter control circuit components should be
tested in the order in which they are listed, as fol-
lows:
²Starter Relay- Refer toStarter Relayin the
Diagnosis and Testing section of this group for the
procedures.
²Starter Solenoid- Refer toStarter Motorin
the Diagnosis and Testing section of this group for
the procedures.
²Ignition Switch- Refer toIgnition Switch
and Key Lock Cylinderin the Diagnosis and Test-
ing section of Group 8D - Ignition System for the pro-
cedures.
²Park/Neutral Position Switch- Refer to
Park/Neutral Position Switchin the Diagnosis
and Testing section of Group 21 - Transmission for
the procedures.
²Wire harnesses and connections- Refer to
Starting Systemin the Contents of Group 8W -
Wiring Diagrams for complete circuit diagrams.
Fig. 4 Test Battery Positive Cable Resistance -
Typical
1 - BATTERY
2 - VOLTMETER
3 - STARTER MOTOR
Fig. 5 Test Ground Circuit
1 - VOLTMETER
2 - BATTERY
3 - ENGINE GROUND
Fig. 6 Test Starter Ground - Typical
1 - STARTER MOTOR
2 - BATTERY
3 - VOLTMETER
8F - 34 STARTINGWJ
STARTING (Continued)

(1) Remove the starter relay from the PDC. Refer
toStarter Relayin the Removal and Installation
section of this group for the procedures.
(2) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 3. If not OK, replace the faulty relay.
(3) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75   5 ohms. If OK, go to Step
4. If not OK, replace the faulty relay.
(4) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, perform the Relay Circuit Test that
follows. If not OK, replace the faulty relay.
RELAY CIRCUIT TEST
(1) The relay common feed terminal cavity (30) is
connected to battery voltage and should be hot at all
times. If OK, go to Step 2. If not OK, repair the open
circuit to the fuse in the PDC as required.
(2) The relay normally closed terminal (87A) is
connected to terminal 30 in the de-energized position,
but is not used for this application. Go to Step 3.
(3) The relay normally open terminal (87) is con-
nected to the common feed terminal (30) in the ener-
gized position. This terminal supplies battery voltage
to the starter solenoid field coils. There should be
continuity between the cavity for relay terminal 87
and the starter solenoid terminal at all times. If OK,
go to Step 4. If not OK, repair the open circuit to the
starter solenoid as required.
(4) The coil battery terminal (86) is connected to
the electromagnet in the relay. It is energized when
the ignition switch is held in the Start position.
Check for battery voltage at the cavity for relay ter-
minal 86 with the ignition switch in the Start posi-tion, and no voltage when the ignition switch is
released to the On position. If OK, go to Step 5. If
not OK, check for an open or short circuit to the igni-
tion switch and repair, if required. If the circuit to
the ignition switch is OK, refer toIgnition Switch
and Key Lock Cylinderin the Diagnosis and Test-
ing section of Group 8D - Ignition System for testing
of the ignition switch.
(5) The coil ground terminal (85) is connected to
the electromagnet in the relay. It is grounded
through the park/neutral position switch only when
the gearshift selector lever is in the Park or Neutral
positions. Check for continuity to ground at the cav-
ity for relay terminal 85. If not OK, check for an
open or short circuit to the park/neutral position
switch and repair, if required. If the circuit to the
park/neutral position switch is OK, refer toPark/
Neutral Position Switchin the Diagnosis and
Testing section of Group 21 - Transmission for testing
of the park/neutral position switch.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cover from the Power Distribution
Center (PDC) (Fig. 14) .
Fig. 13 Starter Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
Fig. 14 Power Distribution Center
1 - RIGHT FENDER
2 - BATTERY
3 - POWER DISTRIBUTION CENTER
4 - COVER
WJSTARTING 8F - 39
STARTER MOTOR RELAY (Continued)

DESCRIPTION - 4.7L
The Camshaft Position Sensor (CMP) on the 4.7L
V±8 engine is bolted to the front/top of the right cyl-
inder head (Fig. 4).
OPERATION
OPERATION - 4.0L
The CMP sensor contains a hall effect device called
a sync signal generator to generate a fuel sync sig-
nal. This sync signal generator detects a rotating
pulse ring (shutter) on the oil pump drive shaft (Fig.
2). The pulse ring rotates 180 degrees through the
sync signal generator. Its signal is used in conjunc-
tion with the crankshaft position sensor to differenti-
ate 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 approxi-
mately 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 sig-
nal voltage to switch low to 0 volts.
OPERATION - 4.7L
The CMP sensor contains a hall effect device called
a sync signal generator to generate a fuel sync sig-
nal. This sync signal generator detects notches
located on a tonewheel. The tonewheel is located at
the front of the camshaft for the right cylinder head
(Fig. 5). As the tonewheel rotates, the notches pass
through the sync signal generator. The pattern of the
notches (viewed counter-clockwise from front of
engine) is: 1 notch, 2 notches, 3 notches, 3 notches, 2
notches 1 notch, 3 notches and 1 notch. The signal
from the CMP sensor is used in conjunction with the
crankshaft position sensor to differentiate between
fuel injection and spark events. It is also used to syn-
chronize the fuel injectors with their respective cylin-
ders.
Fig. 3 CMP LocationÐ4.0L Engine
1 - OIL FILTER
2 - CAMSHAFT POSITION SENSOR
3 - CLAMP BOLT
4 - HOLD-DOWN CLAMP
5 - MOUNTING BOLTS (2)
6 - ELEC. CONNECTORFig. 4 CMP LocationÐ4.7L Engine
1 - RIGHT CYLINDER HEAD
2 - CAMSHAFT POSITION SENSOR
3 - MOUNTING BOLT
4 - ELEC. CONNECTOR
WJIGNITION CONTROL 8I - 5
CAMSHAFT POSITION SENSOR (Continued)

REMOVAL
REMOVAL - 4.0L
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).
The rotational position of oil pump drive deter-
mines fuel synchronization only. It does not deter-
mine ignition timing.
NOTE: Do not attempt to rotate the oil pump drive
to modify ignition timing.
Two different proceduresare used for removal
and installation. The first procedure will detail
removal and installation of the sensor only. The sec-
ond 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 hous-
ing that prevents engine oil at the bottom of the sen-
sor. The seal is not serviceable.
SENSOR ONLY - 4.0L
(1) Disconnect electrical connector at CMP sensor
(Fig. 7).
(2) Remove 2 sensor mounting bolts (Fig. 6) or
(Fig. 7).
(3) Remove sensor from oil pump drive.
OIL PUMP DRIVE AND SENSOR - 4.0L
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. 7).
(2) Remove 2 sensor mounting bolts (Fig. 6) or
(Fig. 7).
(3) Remove sensor from oil pump drive.
(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 0É.
(5) Remove hold-down bolt and clamp (Fig. 7).
Fig. 5 CMP Sensor and TonewheelÐ4.7L Engine
1 - NOTCHES
2 - RIGHT CYLINDER HEAD
3 - CAMSHAFT POSITION SENSOR
4 - TONEWHEEL
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)
8I - 6 IGNITION CONTROLWJ
CAMSHAFT POSITION SENSOR (Continued)

(6) While pulling assembly from engine, note direc-
tion and position of pulse ring (Fig. 6). 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-en-
gine block gasket.
REMOVAL - 4.7L
The Camshaft Position Sensor (CMP) on the 4.7L
V±8 engine is bolted to the front/top of the right cyl-
inder head (Fig. 10).
It is easier to remove/install sensor from under
vehicle.
(1) Raise and support vehicle.
(2) Disconnect electrical connector at CMP sensor
(Fig. 10).
(3) Remove sensor mounting bolt (Fig. 10).
(4) Carefully pry sensor from cylinder head in a
rocking action with two small screwdrivers.Some
4.7L engines are equipped with a sensor spacer
shim. If equipped, this shim will be located at
sensor bolt hole between cylinder head and
sensor mounting tang (TSB W08±18±00). Save
this shim for sensor installation.
(5) Check condition of sensor o-ring.
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
Fig. 8 CMP Pulse Ring Alignment - 4.0L Engine
1 - PULSE RING (SHUTTER)
2 - TOOTHPICK
3 - SENSOR BASE (OIL PUMP DRIVESHAFT ASSEMBLY)
Fig. 9 Align Timing Marks - 4.0L Engine
1 - CRANKSHAFT VIBRATION DAMPER TIMING MARK
WJIGNITION CONTROL 8I - 7
CAMSHAFT POSITION SENSOR (Continued)

INSTALLATION
INSTALLATION - 4.0L
SENSOR ONLY - 4.0L
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).
(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.
OIL PUMP DRIVE AND SENSOR - 4.0L
(1) Clean oil pump drive mounting hole area of
engine block.
(2) Install new oil pump drive-to-engine block gas-
ket.
(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.
8).(4) Install oil pump drive into engine while align-
ing 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 tight-
ening of bolt at this time.
(5) If engine crankshaft or camshaft has been
rotated, such as during engine tear-down, CMP sen-
sor relationship must be reestablished.
(a) Remove ignition coil rail assembly. Refer to
Ignition Coil Removal/Installation.
(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 pul-
ley aligns with top dead center (TDC) mark (0
degree) on timing degree scale (Fig. 9). 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 0É.
(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.
WARNING: WHEN PERFORMING THE FOLLOWING
TEST, THE ENGINE WILL BE RUNNING. BE CARE-
FUL 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 com-
partment, 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 ªclosed loopº mode).
(13) With engine running atidle speed, the words
IN RANGE should appear on screen along with 0É.
This indicates correct position of oil pump drive.
Fig. 10 CMP LocationÐ4.7L Engine
1 - RIGHT CYLINDER HEAD
2 - CAMSHAFT POSITION SENSOR
3 - MOUNTING BOLT
4 - ELEC. CONNECTOR
8I - 8 IGNITION CONTROLWJ
CAMSHAFT POSITION SENSOR (Continued)

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 con-
trolling 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 oper-
ating 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 (second-
ary cables) are not used. The cables are integral
within the coil rail.
REMOVAL
A one-piece coil rail assembly containing three
individual coils is used on the 4.0L engine (Fig. 13).
The coil rail must be replaced as one assembly. The
bottom of the coil is equipped with 6 individual rub-
ber boots (Fig. 13) 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. 14).
(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. 15). After slide tab has been
positioned outwards, push in on secondary release
lock (Fig. 15) on side of connector and pull connector
from coil.
(5) Remove coil from vehicle.
Fig. 13 Ignition Coil AssemblyÐ4.0L 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)
Fig. 14 Ignition Coil Rail LocationÐ4.0L 6±Cylinder
Engine
1 - COIL RAIL
2 - COIL MOUNTING BOLTS (4)
3 - COIL
4 - COIL ELECTRICAL CONNECTION
8I - 10 IGNITION CONTROLWJ
COIL RAIL (Continued)

INSTALLATION
(1) Connect engine harness connector to coil by
snapping into position. Move slide tab towards
engine (Fig. 15) for a positive lock.
(2) Position ignition coil rubber boots to all spark
plugs. Push down on coil assembly until bolt bases
have contacted cylinder head
(3) Install 4 coil mounting bolts. Loosely tighten 4
bolts just enough to allow bolt bases to contact cylin-
der 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.
(4) Connect negative battery cable to battery.
IGNITION COIL
DESCRIPTION
The 4.7L V±8 engine uses 8 dedicated, and individ-
ually fired coil (Fig. 16) for each spark plug. Each
coil is mounted directly to the top of each spark plug
(Fig. 17).
Fig. 15 Ignition Coil Electrical ConnectorÐ4.0L
6±Cylinder Engine
1 - REAR OF VALVE COVER
2 - COIL RAIL
3 - SLIDE TAB
4 - RELEASE LOCK
5 - COIL CONNECTOR
Fig. 16 Ignition CoilÐ4.7L Engine
1 - O-RING
2 - IGNITION COIL
3 - ELECTRICAL CONNECTOR
Fig. 17 Ignition Coil LocationÐ4.7L Engine
1 - IGNITION COIL
2 - COIL ELECTRICAL CONNECTOR
3 - COIL MOUNTING STUD/NUT
WJIGNITION CONTROL 8I - 11
COIL RAIL (Continued)