radiator remove JEEP GRAND CHEROKEE 2002 WJ / 2.G Owner's Guide

OPERATION
The battery tray provides a secure mounting loca-
tion and supports the battery. On some vehicles, the
battery tray also provides the anchor point/s for the
battery holddown hardware. The battery tray and
the battery holddown hardware combine to secure
and stabilize the battery in the engine compartment,
which prevents battery movement during vehicle
operation. Unrestrained battery movement during
vehicle operation could result in damage to the vehi-
cle, the battery, or both.
REMOVAL
(1) Remove the battery from the battery tray
(Refer to 8 - ELECTRICAL/BATTERY SYSTEM/BAT-
TERY - REMOVAL).
(2) Remove the Power Distribution Center (PDC)
from the stanchions on the outboard side of the bat-
tery tray and support unit. Refer toPower Distri-
bution Centerin the Power Distribution section of
this service manual for PDC removal procedure.
(3) Remove the one screw that secures the front of
the battery tray and support unit to the bracket on
the right side of the radiator support (Fig. 26).
(4) Remove the one screw that secures the out-
board side of the battery tray and support unit to the
right fender side cowl reinforcement.
(5) Remove the one nut that secures the rear of
the battery tray and support unit to the stud on the
right fender front wheelhouse inner panel.
(6) Remove the battery temperature sensor from
the battery tray. Refer toBattery Temperature
Sensorin the Charging section of this service man-
ual for battery temperature sensor removal proce-
dure.
(7) Remove the battery tray and support unit from
the right front corner of the engine compartment.
Fig. 25 Battery Tray and Support
1 - SCREW
2 - HOLD DOWN BRACKET
3 - BATTERY SUPPORT
4 - ACCUMULATOR
5 - NUT
6 - U-NUT
7 - STUD
8 - RADIATOR SUPPORT BRACKET
9 - U-NUT
10 - SCREW
11 - BATTERY TEMPERATURE SENSOR
12 - BATTERYFig. 26 Battery Tray and Support Remove/Install
1 - BATTERY TRAY AND SUPPORT
2 - NUT (1)
3 - STUD
4 - U-NUT (1)
5 - RADIATOR SUPPORT BRACKET
6 - SCREW (1)
7 - SCREW (1)
8F - 22 BATTERY SYSTEMWJ
BATTERY TRAY (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
HORN SOUNDS
CONTINUOUSLY1. Faulty horn relay. 1. Refer to Horn Relay for the proper horn relay
diagnosis and testing procedures. Replace the
horn relay or repair the shorted horn relay control
circuit, if required.
2. Faulty horn switch. 2. Refer to Horn Switch for the proper horn switch
diagnosis and testing procedures. Replace the
horn switch or repair the shorted horn switch
circuit, if required.
HORN
DESCRIPTION
The dual electromagnetic diaphragm-type horns
are standard equipment on this model. Both horns
are secured to a mounting bracket. The mounting
bracket is secured with a screw to the back side of
the right extension of the radiator closure assembly,
just ahead of the right front wheel house and below
the front wheel house extension. The two horns are
connected in parallel. Each horn is grounded through
its wire harness connector and circuit to an eyelet
secured to the right inner fender shield near the bat-
tery, and receives battery feed through the closed
contacts of the horn relay.
The horns cannot be repaired or adjusted and, if
faulty or damaged, they must be individually
replaced.
OPERATION
Within the two halves of the molded plastic horn
housing are a flexible diaphragm, a plunger, an elec-
tromagnetic coil and a set of contact points. The dia-
phragm is secured in suspension around its
perimeter by the mating surfaces of the horn hous-
ing. The plunger is secured to the center of the dia-
phragm and extends into the center of the
electromagnet. The contact points control the current
flow through the electromagnet.
When the horn is energized, electrical current
flows through the closed contact points to the electro-
magnet. The resulting electromagnetic field draws
the plunger and diaphragm toward it until that
movement mechanically opens the contact points.
When the contact points open, the electromagnetic
field collapses allowing the plunger and diaphragm to
return to their relaxed positions and closing the con-
tact points again. This cycle continues repeating at a
very rapid rate producing the vibration and move-
ment of air that creates the sound that is directed
through the horn outlet.
DIAGNOSIS AND TESTING - HORN
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, details of wire
harness routing and retention, connector pin-out
information and location views for the various wire
harness connectors, splices and grounds.
(1) Disconnect the wire harness connector(s) from
the horn connector receptacle(s). Measure the resis-
tance between the ground circuit cavity of the horn(s)
wire harness connector(s) and a good ground. There
should be no measurable resistance. If OK, go to Step
2. If not OK, repair the open ground circuit to ground
as required.
(2) Check for battery voltage at the horn relay out-
put circuit cavity of the horn(s) wire harness connec-
tor(s). There should be zero volts. If OK, go to Step 3.
If not OK, repair the shorted horn relay output cir-
cuit or replace the faulty horn relay as required.
(3) Depress the horn switch. There should now be
battery voltage at the horn relay output circuit cavity
of the horn(s) wire harness connector(s). If OK,
replace the faulty horns. If not OK, repair the open
horn relay output circuit to the horn relay as
required.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Raise and support the vehicle.
(3) Remove the lower front half of the inner liner
from the right front fender wheel house. (Refer to 23
- BODY/EXTERIOR/FRONT FENDER - REMOVAL).
(4) Reach through the front of the right front
fender wheel house opening to access and disconnect
the two right headlamp and dash wire harness con-
nectors from the horn connector receptacles (Fig. 1).
Be certain to disengage the connector lock tabs
before disconnecting them from the horn connector
receptacles.
(5) Remove the screw that secures the horn
mounting bracket to the right extension of the radi-
ator closure assembly.
WJHORN 8H - 3
HORN SYSTEM (Continued)

(6) Remove both horns and the mounting bracket
from the right extension of the radiator closure
assembly as a unit.
INSTALLATION
(1) Position both horns and the mounting bracket
onto the right extension of the radiator closure
assembly as a unit.
(2) Install and tighten the screw that secures the
horn mounting bracket to the right extension of the
radiator closure assembly. Tighten the screw to 11.3
N´m (100 in. lbs.).
(3) Reconnect the two right headlamp and dash
wire harness connectors to the horn connector recep-
tacles. Be certain to engage the connector lock tabs
after reconnecting them to the horn connector recep-
tacles.
(4) Install the lower front half of the inner liner to
the right front fender wheel house. (Refer to 23 -
BODY/EXTERIOR/FRONT FENDER - INSTALLA-
TION) for the procedure.
(5) Lower the vehicle.
(6) Reconnect the battery negative cable.
HORN RELAY
DESCRIPTION
The horn relay is a electromechanical device that
switches battery current to the horn when the horn
switch grounds the relay coil. The horn relay is
located in the Power Distribution Center (PDC) inthe engine compartment. If a problem is encountered
with a continuously sounding horn, it can usually be
quickly resolved by removing the horn relay from the
PDC until further diagnosis is completed. See the
fuse and relay layout label affixed to the inside sur-
face of the PDC cover for horn relay identification
and location.
The horn relay is a International Standards Orga-
nization (ISO) micro-relay. Relays conforming to the
ISO specifications have common physical dimensions,
current capacities, terminal patterns, and terminal
functions. The ISO micro-relay terminal functions
are the same as a conventional ISO relay. However,
the ISO micro-relay terminal pattern (or footprint) is
different, the current capacity is lower, and the phys-
ical dimensions are smaller than those of the conven-
tional ISO relay.
The horn relay cannot be repaired or adjusted and,
if faulty or damaged, it must be replaced.
OPERATION
The ISO relay consists of an electromagnetic coil, a
resistor or diode, and three (two fixed and one mov-
able) electrical contacts. The movable (common feed)
relay contact is held against one of the fixed contacts
(normally closed) by spring pressure. When the elec-
tromagnetic coil is energized, it draws the movable
contact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact.
When the electromagnetic coil is de-energized,
spring pressure returns the movable contact to the
normally closed position. The resistor or diode is con-
nected in parallel with the electromagnetic coil in the
relay, and helps to dissipate voltage spikes that are
produced when the coil is de-energized.
DIAGNOSIS AND TESTING - HORN RELAY
The horn relay (Fig. 2) is located in the Power Dis-
tribution Center (PDC) between the battery and the
right inner fender shield on the passenger side of the
engine compartment. If a problem is encountered
with a continuously sounding horn, it can usually be
quickly resolved by removing the horn relay from the
PDC until further diagnosis is completed. See the
fuse and relay layout label affixed to the inside sur-
face of the PDC cover for horn relay identification
and location. For complete circuit diagrams, refer to
the appropriate wiring information. The wiring infor-
mation includes wiring diagrams, proper wire and
connector repair procedures, details of wire harness
routing and retention, connector pin-out information
and location views for the various wire harness con-
nectors, splices and grounds.
Fig. 1 Horns Remove/Install
1 - RADIATOR CLOSURE ASSEMBLY
2 - HORNS AND MOUNTING BRACKET
3 - RIGHT HEADLAMP AND DASH WIRE HARNESS
CONNECTORS
8H - 4 HORNWJ
HORN (Continued)

AMBIENT TEMP SENSOR
DESCRIPTION
Ambient air temperature is monitored by the Elec-
tronic Vehicle Information Center (EVIC) through
ambient temperature messages received from the
Body Control Module (BCM) over the Programmable
Communications Interface (PCI) data bus network.
The BCM receives a hard wired input from the ambi-
ent temperature sensor. The ambient temperature
sensor is a variable resistor mounted to a bracket
that is secured with a screw to the right side of the
headlamp mounting module grille opening, behind
the radiator grille and in front of the engine compart-
ment.
Refer toBody Control Modulein Electronic Con-
trol Modules. For complete circuit diagrams, refer to
the appropriate wiring information. The ambient
temperature sensor cannot be adjusted or repaired
and, if faulty or damaged, it must be replaced.
OPERATION
The ambient temperature sensor is a variable
resistor that operates on a five-volt reference signal
sent to it by the BCM. The resistance in the sensor
changes as temperature changes, changing the tem-
perature sensor signal circuit voltage to the BCM.
Based upon the resistance in the sensor, the BCM
senses a specific voltage on the temperature sensor
signal circuit, which it is programmed to correspond
to a specific temperature. The BCM then sends the
proper ambient temperature messages to the EVIC
over the PCI data bus.
The temperature function is supported by the
ambient temperature sensor, a wiring circuit, the
Body Control Module (BCM), the Programmable
Communications Interface (PCI) data bus, and a por-
tion of the Electronic Vehicle Information Center
(EVIC) module. If any portion of the ambient temper-
ature sensor circuit fails, the BCM will self-diagnose
the circuit. A temperature reading of 130É F will
appear in the EVIC display in place of the tempera-
ture when the sensor circuit is shorted. A tempera-
ture reading of ±40É F will appear in the EVIC
display in place of the temperature when the sensor
circuit is open.
The ambient temperature sensor circuit can also be
diagnosed by referring toDiagnosis and Testing -
Ambient Temperature Sensor, and Diagnosis
and Testing - Ambient Temperature Sensor Cir-
cuit. If the temperature sensor and circuit are con-
firmed to be OK, but the temperature display is
inoperative or incorrect, refer toDiagnosis and
Testing - Electronic Vehicle Information Center
in this group. For complete circuit diagrams, refer to
the appropriate wiring information.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - AMBIENT
TEMPERATURE SENSOR
(1) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the ambient temperature sensor wire har-
ness connector.
(2) Measure the resistance of the ambient temper-
ature sensor. At ±40É C (±40É F), the sensor resis-
tance is 336.6 kilohms. At 60É C (140É F), the sensor
resistance is 2.49 kilohms. The sensor resistance
should read between these two values. If OK, refer to
Diagnosis and Testing - Ambient Temperature
Sensor Circuitin this group. If not OK, replace the
faulty ambient temperature sensor.
DIAGNOSIS AND TESTING - AMBIENT
TEMPERATURE SENSOR CIRCUIT
(1) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the 2-way ambient temperature sensor
wire harness connector and the 22-way Body Control
Module (BCM) wire harness connector.
(2) Connect a jumper wire between the two termi-
nals in the body half of the 2-way ambient tempera-
ture sensor wire harness connector.
(3) Check for continuity between the sensor return
circuit and the ambient temperature sensor signal
circuit cavities of the 22-way BCM wire harness con-
nector. There should be continuity. If OK, go to Step
4. If not OK, repair the open sensor return circuit or
ambient temperature sensor signal circuit to the
ambient temperature sensor as required.
(4) Remove the jumper wire from the body half of
the 2-way ambient temperature sensor wire harness
connector. Check for continuity between the sensor
return circuit cavity of the 22-way BCM wire harness
connector and a good ground. There should be no
continuity. If OK, go to Step 5. If not OK, repair the
shorted sensor return circuit as required.
(5) Check for continuity between the ambient tem-
perature sensor signal circuit cavity of the 22-way
BCM wire harness connector and a good ground.
There should be no continuity. If OK, refer toDiag-
nosis and Testing - Electronic Vehicle Informa-
tion Centerin this group. If not OK, repair the
shorted ambient temperature sensor signal circuit as
required.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
8M - 12 MESSAGE SYSTEMSWJ

(2) Locate the ambient temperature sensor, on the
right side of the radiator opening in the headlamp
mounting module, behind the grille (Fig. 6).(3) Remove the radiator grille fascia and insert
from the headlamp mounting module. Refer to Body
for the procedures.
(4) Disconnect the wire harness connector from the
ambient temperature sensor connector receptacle.
(5) Remove the one screw that secures the ambient
temperature sensor bracket to the headlamp mount-
ing module.
(6) Remove the ambient temperature sensor from
the headlamp mounting module.
INSTALLATION
(1) Position the ambient temperature sensor onto
the headlamp mounting module.
(2) Install and tighten the one screw that secures
the ambient temperature sensor bracket to the head-
lamp mounting module. Tighten the screw to 2.2 N´m
(20 in. lbs.).
(3) Reconnect the wire harness connector to the
ambient temperature sensor connector receptacle.
(4) Install the radiator grille fascia and insert onto
the headlamp mounting module. Refer to the Body
section of this manual for the procedures.
(5) Reconnect the battery negative cable.
Fig. 6 AMBIENT TEMPERATURE SENSOR
1 - AMBIENT TEMPERATURE SENSOR
2 - WIRE HARNESS CONNECTOR
3 - HEADLAMP MOUNTING MODULE
WJMESSAGE SYSTEMS 8M - 13
AMBIENT TEMP SENSOR (Continued)

OPERATION
The front impact sensors are electronic accelerom-
eters that sense the rate of vehicle deceleration,
which provides verification of the direction and sever-
ity of an impact. Each sensor also contains an elec-
tronic communication chip that allows the unit to
communicate the sensor status as well as sensor
fault information to the microprocessor in the Airbag
Control Module (ACM). The ACM microprocessor con-
tinuously monitors all of the passive restraint system
electrical circuits to determine the system readiness.
If the ACM detects a monitored system fault, it sets
a Diagnostic Trouble Code (DTC) and controls the
airbag indicator operation accordingly.
The impact sensors each receive battery current
and ground through dedicated left and right sensor
plus and minus circuits from the ACM. The impact
sensors and the ACM communicate by modulating
the voltage in the sensor plus circuit. The hard wired
circuits between the front impact sensors and the
ACM may be diagnosed and tested using conven-
tional diagnostic tools and procedures. However, con-
ventional diagnostic methods will not prove
conclusive in the diagnosis of the ACM or the impact
sensors. The most reliable, efficient, and accurate
means to diagnose the impact sensors, the ACM, and
the electronic message communication between the
sensors and the ACM requires the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
REMOVAL
The front and side impact sensors are interchange-
able except that the front impact sensors are serviced
with a right or left mounting bracket, while the side
impact sensors use no mounting bracket. If a front
impact sensor is faulty, but not damaged, the sensor
may be removed from the sensor mounting bracket
and replaced with a side impact sensor. If the front
impact sensor or the sensor mounting bracket are
damaged in any way, or if proper tightening torque of
the screws that secure the sensor to the bracket can-
not be achieved, the front impact sensor and bracket
must be replaced as a unit.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, FRONT IMPACT SENSOR,
SIDE IMPACT SENSOR, SIDE CURTAIN AIRBAG, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. DISCONNECT AND ISOLATE THE BAT-
TERY NEGATIVE (GROUND) CABLE, THEN WAIT
TWO MINUTES FOR THE SYSTEM CAPACITOR TO
DISCHARGE BEFORE PERFORMING FURTHERDIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
WARNING: THE FRONT IMPACT SENSOR ENABLES
THE SYSTEM TO DEPLOY THE FRONT SUPPLE-
MENTAL RESTRAINTS. NEVER STRIKE OR DROP
THE FRONT IMPACT SENSOR, AS IT CAN DAMAGE
THE IMPACT SENSOR OR AFFECT ITS CALIBRA-
TION. IF AN IMPACT SENSOR IS ACCIDENTALLY
DROPPED DURING SERVICE, THE SENSOR MUST
BE SCRAPPED AND REPLACED WITH A NEW UNIT.
FAILURE TO OBSERVE THIS WARNING COULD
RESULT IN ACCIDENTAL, INCOMPLETE, OR
IMPROPER FRONT SUPPLEMENTAL RESTRAINT
DEPLOYMENT AND POSSIBLE OCCUPANT INJU-
RIES.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) From the engine compartment, disconnect the
right or left headlamp and dash wire harness connec-
tor for the front impact sensor from the sensor con-
nector receptacle (Fig. 25).
Fig. 25 Front Impact Sensor Remove/Install (Right
Side Shown, Left Side Similar)
1 - BRACKET
2 - IMPACT SENSOR
3 - RADIATOR SUPPORT
4 - WIRE HARNESS CONNECTOR
5 - SCREW (2)
8O - 24 RESTRAINTSWJ
FRONT IMPACT SENSOR (Continued)

(3) From the engine compartment, remove the two
screws that secure the right or left front impact sen-
sor to the sensor mounting bracket on the right or
left radiator support vertical member.
(4) Remove the front impact sensor from the sen-
sor mounting bracket.
INSTALLATION
The front and side impact sensors are interchange-
able except that the front impact sensors are serviced
with a right or left mounting bracket, while the side
impact sensors use no mounting bracket. If a front
impact sensor is faulty, but not damaged, the sensor
may be removed from the sensor mounting bracket
and replaced with a side impact sensor. If the front
impact sensor or the sensor mounting bracket are
damaged in any way, or if proper tightening torque of
the screws that secure the sensor to the bracket can-
not be achieved, the front impact sensor and bracket
must be replaced as a unit.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, FRONT IMPACT SENSOR,
SIDE IMPACT SENSOR, SIDE CURTAIN AIRBAG, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. DISCONNECT AND ISOLATE THE BAT-
TERY NEGATIVE (GROUND) CABLE, THEN WAIT
TWO MINUTES FOR THE SYSTEM CAPACITOR TO
DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
WARNING: THE FRONT IMPACT SENSOR ENABLES
THE SYSTEM TO DEPLOY THE FRONT SUPPLE-
MENTAL RESTRAINTS. NEVER STRIKE OR DROP
THE FRONT IMPACT SENSOR, AS IT CAN DAMAGE
THE IMPACT SENSOR OR AFFECT ITS CALIBRA-
TION. IF AN IMPACT SENSOR IS ACCIDENTALLY
DROPPED DURING SERVICE, THE SENSOR MUST
BE SCRAPPED AND REPLACED WITH A NEW UNIT.
FAILURE TO OBSERVE THIS WARNING COULD
RESULT IN ACCIDENTAL, INCOMPLETE, OR
IMPROPER FRONT SUPPLEMENTAL RESTRAINT
DEPLOYMENT AND POSSIBLE OCCUPANT INJU-
RIES.(1) Position the right or left front impact sensor to
the sensor mounting bracket on the right or left radi-
ator support vertical member in the engine compart-
ment (Fig. 25).
(2) Install and tighten the two screws that secure
the right or left front impact sensor to the sensor
mounting bracket. Tighten the screws to 10 N´m (85
in. lbs.).
(3) Reconnect the right or left headlamp and dash
wire harness connector for the front impact sensor to
the sensor connector receptacle.
(4) Do not reconnect the battery negative cable at
this time. The supplemental restraint system verifi-
cation test procedure should be performed following
service of any supplemental restraint system compo-
nent. (Refer to 8 - ELECTRICAL/RESTRAINTS -
STANDARD PROCEDURE - VERIFICATION TEST).
FRONT IMPACT SENSOR &
BRACKET
REMOVAL
The front and side impact sensors are interchange-
able except that the front impact sensors are serviced
with a right or left mounting bracket, while the side
impact sensors use no mounting bracket. If a front
impact sensor is faulty, but not damaged, the sensor
may be removed from the sensor mounting bracket
and replaced with a side impact sensor. If the front
impact sensor or the sensor mounting bracket are
damaged in any way, or if proper tightening torque of
the screws that secure the sensor to the bracket can-
not be achieved, the front impact sensor and bracket
must be replaced as a unit.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, FRONT IMPACT SENSOR,
SIDE IMPACT SENSOR, SIDE CURTAIN AIRBAG, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. DISCONNECT AND ISOLATE THE BAT-
TERY NEGATIVE (GROUND) CABLE, THEN WAIT
TWO MINUTES FOR THE SYSTEM CAPACITOR TO
DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
WJRESTRAINTS 8O - 25
FRONT IMPACT SENSOR (Continued)

WARNING: THE FRONT IMPACT SENSOR ENABLES
THE SYSTEM TO DEPLOY THE FRONT SUPPLE-
MENTAL RESTRAINTS. NEVER STRIKE OR DROP
THE FRONT IMPACT SENSOR, AS IT CAN DAMAGE
THE IMPACT SENSOR OR AFFECT ITS CALIBRA-
TION. IF AN IMPACT SENSOR IS ACCIDENTALLY
DROPPED DURING SERVICE, THE SENSOR MUST
BE SCRAPPED AND REPLACED WITH A NEW UNIT.
FAILURE TO OBSERVE THIS WARNING COULD
RESULT IN ACCIDENTAL, INCOMPLETE, OR
IMPROPER FRONT SUPPLEMENTAL RESTRAINT
DEPLOYMENT AND POSSIBLE OCCUPANT INJU-
RIES.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) Remove the headlamp mounting module from
the front of the vehicle. (Refer to 23 - BODY/EXTE-
RIOR/HEADLAMP MOUNTING MODULE -
REMOVAL).
(3) Disconnect the right or left headlamp and dash
wire harness connector for the front impact sensor
from the sensor connector receptacle.
(4) Remove the three screws that secure the right
or left front impact sensor and bracket unit to the
right or left radiator support vertical member (Fig.
26).
(5) Remove the right or left front impact sensor
and bracket unit from the front of the vehicle.INSTALLATION
The front and side impact sensors are interchange-
able except that the front impact sensors are serviced
with a right or left mounting bracket, while the side
impact sensors use no mounting bracket. If a front
impact sensor is faulty, but not damaged, the sensor
may be removed from the sensor mounting bracket
and replaced with a side impact sensor. If the front
impact sensor or the sensor mounting bracket are
damaged in any way, or if proper tightening torque of
the screws that secure the sensor to the bracket can-
not be achieved, the front impact sensor and bracket
must be replaced as a unit.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, FRONT IMPACT SENSOR,
SIDE IMPACT SENSOR, SIDE CURTAIN AIRBAG, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. DISCONNECT AND ISOLATE THE BAT-
TERY NEGATIVE (GROUND) CABLE, THEN WAIT
TWO MINUTES FOR THE SYSTEM CAPACITOR TO
DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
WARNING: THE FRONT IMPACT SENSOR ENABLES
THE SYSTEM TO DEPLOY THE FRONT SUPPLE-
MENTAL RESTRAINTS. NEVER STRIKE OR DROP
THE FRONT IMPACT SENSOR, AS IT CAN DAMAGE
THE IMPACT SENSOR OR AFFECT ITS CALIBRA-
TION. IF AN IMPACT SENSOR IS ACCIDENTALLY
DROPPED DURING SERVICE, THE SENSOR MUST
BE SCRAPPED AND REPLACED WITH A NEW UNIT.
FAILURE TO OBSERVE THIS WARNING COULD
RESULT IN ACCIDENTAL, INCOMPLETE, OR
IMPROPER FRONT SUPPLEMENTAL RESTRAINT
DEPLOYMENT AND POSSIBLE OCCUPANT INJU-
RIES.
(1) Position the right or left front impact sensor
and bracket unit to the front of the vehicle (Fig. 26).
(2) Position the right or left front impact sensor
and bracket unit to the right or left radiator support
vertical member.
(3) Loosely install the three screws that secure the
right or left front impact sensor and bracket unit
right or left radiator support vertical member.
Fig. 26 Front Impact Sensor & B Remove/Install
1 - RADIATOR SUPPORT
2 - SCREW (3)
3 - BRACKET
4 - WIRE HARNESS CONNECTOR
5 - IMPACT SENSOR
8O - 26 RESTRAINTSWJ
FRONT IMPACT SENSOR & BRACKET (Continued)

(4) For the right impact sensor and bracket unit,
the tightening sequence for the three screws that
secure it to the right radiator support vertical mem-
ber is from top to bottom. For the left impact sensor
and bracket unit, the tightening sequence for the
three screws that secure it to the left radiator sup-
port vertical member is from bottom to top. Tighten
the screws to 12 N´m (105 in. lbs.).
(5) Reconnect the right or left headlamp and dash
wire harness connector for the front impact sensor to
the sensor connector receptacle.
(6) Reinstall the headlamp mounting module to
the front of the vehicle. (Refer to 23 - BODY/EXTE-
RIOR/HEADLAMP MOUNTING MODULE -
INSTALLATION).
(7) Do not reconnect the battery negative cable at
this time. The supplemental restraint system verifi-
cation test procedure should be performed following
service of any supplemental restraint system compo-
nent. (Refer to 8 - ELECTRICAL/RESTRAINTS -
STANDARD PROCEDURE - VERIFICATION TEST).
FRONT SEAT BELT &
RETRACTOR
REMOVAL
WARNING: DURING AND FOLLOWING ANY SEAT
BELT SERVICE, CAREFULLY INSPECT ALL SEAT
BELTS, BUCKLES, MOUNTING HARDWARE, AND
RETRACTORS FOR PROPER INSTALLATION,
OPERATION, OR DAMAGE. REPLACE ANY BELT
THAT IS CUT, FRAYED, OR TORN. STRAIGHTEN
ANY BELT THAT IS TWISTED. TIGHTEN ANY
LOOSE FASTENERS. REPLACE ANY BELT THAT
HAS A DAMAGED OR INOPERATIVE BUCKLE OR
RETRACTOR. REPLACE ANY BELT THAT HAS A
BENT OR DAMAGED LATCH PLATE OR ANCHOR
PLATE. NEVER ATTEMPT TO REPAIR A SEAT BELT
COMPONENT. ALWAYS REPLACE DAMAGED OR
FAULTY SEAT BELT COMPONENTS WITH THE COR-
RECT, NEW AND UNUSED REPLACEMENT PARTS
LISTED IN THE MOPAR PARTS CATALOG.
(1) Adjust the front seat to its most forward posi-
tion for easiest access to the front seat belt lower
anchor and the B-pillar trim.
(2) Disconnect and isolate the battery negative
cable.
(3) Lift the front seat belt lower anchor cover far
enough to access the screw that secures it to the
lower B-pillar (Fig. 27).
(4) Remove the screw that secures the lower
anchor to the B-pillar.(5) Using a trim stick or another suitable wide
flat-bladed tool, gently pry the top of the turning loop
trim cover to unsnap it from the height adjuster and
access the screw that secures the front seat belt turn-
ing loop to the adjuster on the upper B-pillar (Fig.
28).
Fig. 27 Front Seat Belt & Retractor Remove/Install
1 - ADJUSTER
2 - TURNING LOOP
3 - SCREW
4 - LOWER ANCHOR
5 - SCREW
6 - RETRACTOR
Fig. 28 Turning Loop Cover Remove/Install
1 - PILLAR
2 - TRIM COVER
3 - ADJUSTER
WJRESTRAINTS 8O - 27
FRONT IMPACT SENSOR & BRACKET (Continued)

DIAGNOSIS AND TESTINGÐCYLINDER
COMPRESSION PRESSURE
The results of a cylinder compression pressure test
can be utilized to diagnose several engine malfunc-
tions.
Ensure the battery is completely charged and the
engine starter motor is in good operating condition.
Otherwise, the indicated compression pressures may
not be valid for diagnosis purposes.
(1) Clean the spark plug recesses with compressed
air.
(2) Remove the spark plugs (Refer to 8 - ELEC-
TRICAL/IGNITION CONTROL/SPARK PLUG -
REMOVAL).
(3) Secure the throttle in the wide-open position.
(4) Disconnect the ignition coil.
(5) Insert a compression pressure gauge and rotate
the engine with the engine starter motor for three
revolutions.
(6) Record the compression pressure on the third
revolution. Continue the test for the remaining cylin-
ders.
(Refer to 9 - ENGINE - SPECIFICATIONS) for the
correct engine compression pressures.
DIAGNOSIS AND TESTING - CYLINDER
COMBUSTION PRESSURE LEAKAGE
The combustion pressure leakage test provides an
accurate means for determining engine condition.
Combustion pressure leakage testing will detect:
²Exhaust and intake valve leaks (improper seat-
ing)
²Leaks between adjacent cylinders or into water
jacket²Any causes for combustion/compression pressure
loss
WARNING: DO NOT REMOVE THE RADIATOR CAP
WITH THE SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM HOT COOLANT CAN
OCCUR.
Check the coolant level and fill as required. DO
NOT install the radiator cap.
Start and operate the engine until it attains nor-
mal operating temperature, then turn OFF the
engine.
Remove the spark plugs.
Remove the oil filler cap.
Remove the air cleaner.
Calibrate the tester according to the manufactur-
er's instructions. The shop air source for testing
should maintain 483 kPa (70 psi) minimum, 1,379
kPa (200 psi) maximum and 552 kPa (80 psi) recom-
mended.
Perform the test procedure on each cylinder accord-
ing to the tester manufacturer's instructions. While
testing, listen for pressurized air escaping through
the throttle body, tailpipe or oil filler cap opening.
Check for bubbles in the radiator coolant.
All gauge pressure indications should be equal,
with no more than 25% leakage.
FOR EXAMPLE:At 552 kPa (80 psi) input pres-
sure, a minimum of 414 kPa (60 psi) should be main-
tained in the cylinder CYLINDER COMBUSTION
PRESSURE LEAKAGE DIAGNOSIS CHART .
CYLINDER COMBUSTION PRESSURE LEAKAGE DIAGNOSIS CHART
CONDITION POSSIBLE CAUSE CORRECTION
AIR ESCAPES THROUGH
THROTTLE BODYIntake valve bent, burnt, or not
seated properlyInspect valve and valve seat.
Reface or replace, as necessary
AIR ESCAPES THROUGH
TAILPIPEExhaust valve bent, burnt, or not
seated properlyInspect valve and valve seat.
Reface or replace, as necessary
AIR ESCAPES THROUGH
RADIATORHead gasket leaking or cracked
cylinder head or blockRemove cylinder head and inspect.
Replace defective part
MORE THAN 50% LEAKAGE
FROM ADJACENT CYLINDERSHead gasket leaking or crack in
cylinder head or block between
adjacent cylindersRemove cylinder head and inspect.
Replace gasket, head, or block as
necessary
MORE THAN 25% LEAKAGE AND
AIR ESCAPES THROUGH OIL
FILLER CAP OPENING ONLYStuck or broken piston rings;
cracked piston; worn rings and/or
cylinder wallInspect for broken rings or piston.
Measure ring gap and cylinder
diameter, taper and out-of-round.
Replace defective part as necessary
9 - 8 ENGINE - 4.0LWJ
ENGINE - 4.0L (Continued)