2002 JEEP GRAND CHEROKEE Electric plug ins

INSTALLATION
(1) Position relay to body and install 2 bolts.
Tighten bolts to 3 N´m (25 in. lbs.) torque.
(2) Connect electrical connector to relay.
(3) Connect vacuum hose to reservoir.
(4) Install reservoir and tighten 2 bolts to 3 N´m
(25 in. lbs.) torque.
(5) Install front bumper and grill assembly.
RADIATOR - 4.7L
DESCRIPTION
All vehicles are equipped with a cross flow type
radiator with plastic side tanks (Fig. 31).
Plastic tanks, while stronger than brass, are sub-
ject to damage by impact, such as from tools or
wrenches. Handle radiator with care.
REMOVAL
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR. REFER TO COOLING SYSTEM DRAIN-
ING.Do not waste reusable coolant. If the solution is
clean, drain the coolant into a clean container for
reuse.
WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER
6094) (Fig. 32). SNAP-ON CLAMP TOOL (NUMBER
HPC-20) MAY BE USED FOR LARGER CLAMPS.
ALWAYS WEAR SAFETY GLASSES WHEN SERVIC-
ING CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps (Fig. 33). If
replacement is necessary, use only an original
equipment clamp with matching number or letter.
CAUTION: When removing the radiator or A/C con-
denser for any reason, note the location of all radi-
ator-to-body and radiator-to-A/C condenser rubber
air seals (Fig. 34). These are used at the top, bot-
tom and sides of the radiator and A/C condenser.
To prevent overheating, these seals must be
installed to their original positions.
(1) Disconnect the negative battery cable at bat-
tery.
(2) Drain coolant from radiator (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(3) Remove the front grill (Refer to 23 - BODY/EX-
TERIOR/GRILLE - REMOVAL).
Fig. 30 Radiator Cooling Fan Relay Removal/
Installation
1 - ELECTRICAL CONNECTOR
2 - RADIATOR FAN RELAY
3 - MOUNTING BOLTS (2)
Fig. 31 Cross Flow Radiator - Typical
1 - RADIATOR
7 - 42 ENGINEWJ
PWM FAN CONTROL MODULE - 4.0L (Continued)

the radiator to flush the radiator and/or A/C con-
denser of debris.
INSPECTION
The radiator cooling fins should be checked for
damage or deterioration. Inspect cooling fins to make
sure they are not bent or crushed, these areas result
in reduced heat exchange causing the cooling system
to operate at higher temperatures. Inspect the plastic
end tanks for cracks, damage or leaks.
Inspect the radiator neck for damage or distortion.
INSTALLATION
CAUTION: Before installing the radiator or A/C con-
denser, be sure the radiator-to-body and radiator-to-
A/C condenser rubber air seals (Fig. 39) are
properly fastened to their original positions. These
are used at the top, bottom and sides of the radia-
tor and A/C condenser. To prevent overheating,
these seals must be installed to their original posi-
tions.
(1) Equipped with air conditioning: Gently lower
the radiator and fan shroud into the vehicle. Guide
the two radiator alignment dowels through the holes
in the rubber air seals first and then through the A/C
support brackets (Fig. 40). Continue to guide thealignment dowels into the rubber grommets located
in lower radiator crossmember. The holes in the
L-shaped brackets (located on bottom of A/C con-
denser) must be positioned between bottom of rubber
air seals and top of rubber grommets.
(2) Connect the radiator upper and lower hoses
and hose clamps to radiator.
CAUTION: The tangs on the hose clamps must be
positioned straight down.
(3) Install coolant reserve/overflow tank hose at
radiator.
(4) Connect both transmission cooler lines at the
radiator.
(5) Install both radiator mounting bolts.
(6) Install air inlet duct at grill.
(7) Attach electric connector for hydraulic fan con-
trol solenoid.
(8) Install the grill (Refer to 23 - BODY/EXTERI-
OR/GRILLE - INSTALLATION).
(9) Connect the two high pressure lines to the
hydraulic fan drive. Tighten
1¤2in. pressure line fit-
ting to 49 N´m (36 ft. lbs.). and the 3/8 in. pressure
line fitting to 29 N´m (21.5 ft. lbs.).
(10) Connect the low pressure hose to the hydrau-
lic fan drive. Position the spring clamp.
(11) Connect the power steering filter hoses to the
filter. Install new hose clamps.
(12) Rotate the fan blades (by hand) and check for
interference at fan shroud.
(13) Refill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(14) Refill the power steering reservoir and bleed
air from system (Refer to 19 - STEERING/PUMP -
STANDARD PROCEDURE).
(15) Connect battery cable at battery.
(16) Start and warm engine. Check for leaks.
RADIATOR - 4.0L
DESCRIPTION
All vehicles are equipped with a cross flow type
radiator with plastic side tanks (Fig. 36).
Plastic tanks, while stronger than brass, are sub-
ject to damage by impact, such as from tools or
wrenches. Handle radiator with care.
REMOVAL
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR. REFER TO COOLING SYSTEM DRAIN-
ING.
Fig. 35 Radiator Alignment Dowels - Typical
1 - RADIATOR
2 - ALIGNMENT DOWEL
3 - RADIATOR LOWER ISOLATOR
4 - RADIATOR LOWER CROSSMEMBER
7 - 44 ENGINEWJ
RADIATOR - 4.7L (Continued)

(2) If equipped, remove Transmission Control Mod-
ule (TCM).
(3) Remove coolant reserve/overflow tank.
(4) Remove cover over electrical connectors. Cover
snaps onto PCM.
(5) Carefully unplug three 32±way connectors at
PCM.
(6) Remove three PCM bracket-to-body mounting
nuts (Fig. 13).
(7) Remove PCM/PCM bracket assembly from
vehicle.
(8) Remove 3 PCM-to-PCM bracket bolts (screws)
(Fig. 14).
INSTALLATION
USE THE DRBIIItSCAN TOOL TO REPRO-
GRAM THE NEW POWERTRAIN CONTROL
MODULE (PCM) WITH THE VEHICLES ORIGI-
NAL IDENTIFICATION NUMBER (VIN) AND
THE VEHICLES ORIGINAL MILEAGE. IF THIS
STEP IS NOT DONE, A DIAGNOSTIC TROUBLE
CODE (DTC) MAY BE SET.
The PCM is located on the cowl panel in right/rear
side of engine compartment (Fig. 12).
(1) Check pins in three 32±way electrical connec-
tors for damage. Repair as necessary.
(2) Install PCM to its mounting bracket. Tighten
three mounting bolts to 3 N´m (25 in. lbs.) torque.
(3) Install PCM/PCM bracket to body. Install 3
nuts and tighten 9 N´m (80 in. lbs.) torque.
(4) Install three 32±way connectors.(5) Install cover over electrical connectors. Cover
snaps onto PCM.
(6) Install coolant reserve/overflow tank.
(7) If equipped, install Transmission Control Mod-
ule (TCM).
(8) Connect negative cable to battery.
(9) Use the DRBIIItscan tool to reprogram new
PCM with vehicles original Identification Number
(VIN) and original vehicle mileage.
SENTRY KEY IMMOBILIZER
MODULE
DESCRIPTION
The Sentry Key Immobilizer Module (SKIM) is the
primary component of the Sentry Key Immobilizer
System (SKIS) (Fig. 15). The SKIM is located in the
steering column, below the ignition lock cylinder
housing. The SKIM has an integral halo-like antenna
ring that extends from one side.
The SKIM cannot be adjusted or repaired. If faulty
or damaged, the entire SKIM unit must be replaced.
OPERATION
The Sentry Key Immobilizer Module (SKIM) con-
tains a Radio Frequency (RF) transceiver and a
microprocessor. The SKIM transmits RF signals to,
and receives RF signals from the Sentry Key tran-
Fig. 14 Powertrain Control Module (PCM) Mounting
Bracket
1 - PCM BRACKET
2 - PCM
3 - PCM-TO-BRACKET SCREWS (3)
Fig. 15 Sentry Key Immobilizer Module
1 - STEERING COLUMN
2 - SKIM
3 - MOUNTING SCREW
WJELECTRONIC CONTROL MODULES 8E - 17
POWERTRAIN CONTROL MODULE (Continued)

IGNITION CONTROL
TABLE OF CONTENTS
page page
IGNITION CONTROL
DESCRIPTION..........................1
OPERATION............................1
SPECIFICATIONS
ENGINE FIRING ORDER - 4.0L 6-CYLINDER
ENGINE..............................2
ENGINE FIRING ORDERÐ4.7L V-8 ENGINE . . 2
IGNITION COIL RESISTANCE - 4.0L ENGINE . 2
IGNITION COIL RESISTANCEÐ4.7L V-8
ENGINE..............................2
IGNITION TIMING......................2
SPARK PLUGS........................3
TORQUE - IGNITION SYSTEM............3
AUTO SHUT DOWN RELAY
DESCRIPTION - PCM OUTPUT.............3
OPERATION
OPERATION - PCM OUTPUT.............3
OPERATION - ASD SENSE - PCM INPUT....4
REMOVAL.............................4
INSTALLATION..........................4
CAMSHAFT POSITION SENSOR
DESCRIPTION
DESCRIPTION - 4.0L....................4
DESCRIPTION - 4.7L....................5
OPERATION
OPERATION - 4.0L.....................5
OPERATION - 4.7L.....................5
REMOVAL
REMOVAL - 4.0L.......................6
REMOVAL - 4.7L.......................7INSTALLATION
INSTALLATION - 4.0L...................8
INSTALLATION - 4.7L...................9
COIL RAIL
DESCRIPTION..........................9
OPERATION...........................10
REMOVAL.............................10
INSTALLATION.........................11
IGNITION COIL
DESCRIPTION.........................11
OPERATION...........................12
REMOVAL.............................12
INSTALLATION.........................12
IGNITION COIL CAPACITOR
DESCRIPTION.........................13
OPERATION...........................13
REMOVAL.............................13
INSTALLATION.........................13
KNOCK SENSOR
DESCRIPTION.........................13
OPERATION...........................13
REMOVAL.............................14
INSTALLATION.........................15
SPARK PLUG
DESCRIPTION.........................15
DIAGNOSIS AND TESTING - SPARK PLUG
CONDITIONS.........................15
REMOVAL.............................18
CLEANING............................18
INSTALLATION.........................18
IGNITION CONTROL
DESCRIPTION
Two different ignition systems are used. One type
of system is for the 4.0L 6±cylinder engine. The other
is for the 4.7L V-8 engine.
OPERATION
The 4.0L 6±cylinder engine uses a one-piece coil
rail containing three independent coils. Although cyl-
inder firing order is the same as 4.0L engines of pre-
vious 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 compressionstroke), 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.
The 4.7L V-8 engine uses 8 dedicated and individ-
ually fired coil for each spark plug. Each coil is
mounted directly to the top of each spark plug. A sep-
arate electrical connector is used for each coil.
Because of coil design, spark plug cables (second-
ary cables) are not used on either engine. Adistrib-
utor is not usedwith either the 4.0L or 4.7L
engines.
WJIGNITION CONTROL 8I - 1

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)

(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 0É 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
on ignition timing. All ignition timing values are con-
trolled by powertrain control module (PCM).
(15) Tighten hold-down clamp bolt to 23 N´m (17
ft. lbs.) torque.
INSTALLATION - 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).
(1) Clean out machined hole in cylinder head.
(2) Apply a small amount of engine oil to sensor
o-ring.
(3) Install sensor into cylinder head with a slight
rocking action. Do not twist sensor into position as
damage to o-ring may result.
CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to cylinder head.
If sensor is not flush, damage to sensor mounting
tang may result.
(4) Install mounting bolt and tighten to 12 N´m
(106 in. lbs.) torque.
(5) Connect electrical connector to sensor.
(6) Lower vehicle.
COIL RAIL
DESCRIPTION
A one-piece coil rail assembly containing three
individual coils is used on the 4.0L 6±cylinder engine
(Fig. 11). The coil rail must be replaced as one
assembly. The bottom of the coil is equipped with 6
individual rubber boots (Fig. 11) 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. 12). One electrical connector (located at rear of
coil) is used for all three coils.
Fig. 11 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. 12 Coil LocationÐ4.0L Engine
1 - COIL RAIL
2 - COIL MOUNTING BOLTS (4)
3 - COIL
4 - COIL ELECTRICAL CONNECTION
WJIGNITION CONTROL 8I - 9
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)