2002 JEEP GRAND CHEROKEE Trim

DIAGNOSIS AND TESTING - HEATED SEAT
ELEMENT
RESISTOR WIRE ELEMENT
(1) Disconnect and isolate the battery negative
cable. The power seat wire harness connectors for the
seat cushion and seat back heating elements are
secured to a bracket located under the rear edge of
the seat cushion frame. Refer toWiringfor complete
circuit schematics and connector locations.
(2) Disconnect the Heated Seat Module (HSM) or
Memory Heated Seat Module (MHSM) C2 connector.
Check for continuity between the SEAT HEATER
B(+) DRIVER circuit cavity of the C2 connector and
the seat cushion frame. There should be NO continu-
ity. If OK, go to Step 3. If not OK, repair the shorted
seat heater B(+) driver circuit as required.
NOTE: WHEN CHECKING HEATED SEAT ELE-
MENTS FOR CONTINUITY, BE CERTAIN TO MOVE
THE HEATING ELEMENT BEING CHECKED. MOV-
ING THE ELEMENT, SUCH AS SITTING IN THE SEAT
WILL ELIMINATE THE POSSIBILITY OF AN INTER-
MITTENT OPEN IN THE ELEMENT WHICH WOULD
ONLY BE EVIDENT IF THE ELEMENT WAS MOVED
IN A CERTAIN DIRECTION. FAILURE TO CHECK
THE ELEMENT IN VARIOUS POSITIONS COULD
RESULT IN AN INCOMPLETE TEST.
(3) Check for continuity between the SEAT
HEATER B(+) DRIVER circuit cavity of the C2 con-
nector and the ground circuit cavity. There should be
continuity at all times (even upon moving or sitting
in the seat). If OK, proceed with testing the other
components in the heated seat system. If not OK,
replace the open heating element. Refer to the proce-
dure in this section of the manual.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the appropriate seat cushion or seat
back trim cover. Refer to the Body section of the ser-
vice manual for the procedures.
(3) Disconnect the inoperative heated seat cushion
or seat back element electrical connectors.
(4) Gently peel-off defective heater element from
foam cushion.
INSTALLATION
(1) Peel off the adhesive backing on the back of the
replacement heating element and install on cushion
pad in the same location as the original (Fig. 6).
CAUTION: During the installation of the replace-
ment heating element, be very careful not to fold or
crease the element assembly. Folds or creases will
cause premature failure.
(2) Connect the new heating element electrical
connectors (Fig. 6).
(3) Connect the negative battery cable.
(4) Verify heated seat system operation.
(5) Install the appropriate seat cushion or seat
back trim cover. Make certain the seat wire harness
is correctly routed through the seat and seat back.
The excess wire between the cushion and back ele-
ments should be securely tucked between the rear of
the cushion foam and the rear carpet flap of the trim
cover.
Fig. 6 HEATING ELEMENT INSTALLED
1 - SEAT BACK WIRE HARNESS
2 - HEATED SEAT WIRE HARNESS CONNECTOR
3 - HEATED SEAT CUSHION ELEMENT
8G - 14 HEATED SEAT SYSTEMWJ
HEATED SEAT ELEMENT (Continued)

connector pin-out information and location views for
the various wire harness connectors, splices and
grounds. Following are general descriptions of the
remaining major components in the horn system.
OPERATION
The horn system is activated by a horn switch con-
cealed beneath the driver side airbag module trim
cover in the center of the steering wheel. Depressing
the center of the driver side airbag module trim cover
closes the horn switch. Closing the horn switch acti-
vates the horn relay. The activated horn relay then
switches the battery current needed to energize the
horns.
The BCM can also activate the horn system by
energizing the horn relay through a single hard
wired output circuit. The BCM energizes and de-en-
ergizes the horn relay in response to internal pro-
gramming as well as message inputs received over
the Programmable Communications Interface (PCI)
data bus network. The BCM can energize the horn
relay for a single chirp (RKE lock request), or for
extended operation (RKE panic mode and VTSS
alarm mode).
Refer to the owner's manual in the vehicle glove
box for more information on the features, use and
operation of the horn system.
DIAGNOSIS AND TESTING - HORN SYSTEM
In most cases, any problem involving continually
sounding horns can be quickly alleviated by removing
the horn relay from the Power Distribution Center
(PDC). Refer to Horn Relay for the proper removal
procedure. Refer to the appropriate wiring informa-
tion. The wiring information includes wiring dia-
grams, proper wire and connector repair procedures,
further details on wire harness routing and reten-
tion, as well as pin-out and location views for the
various wire harness connectors, splices and grounds.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
HORN SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
BOTH HORNS
INOPERATIVE1. Faulty fuse. 1. Check the fuses in the Power Distribution
Center (PDC) and the Junction Block (JB).
Replace the fuse and repair the shorted circuit or
component, if required.
2. Faulty horn relay. 2. Refer to Horn Relay for the proper horn relay
diagnosis and testing procedures. Replace the
horn relay or repair the open horn relay circuit, if
required.
3. Faulty horn switch. 3. Refer to Horn Switch for the proper horn switch
diagnosis and testing procedures. Replace the
horn switch or repair the open horn switch circuit,
if required.
4. Faulty horns. 4. Refer to Horn for the proper horn diagnosis
and testing procedures. Replace the horns or
repair the open horn circuit, if required.
ONE HORN INOPERATIVE 1. Faulty horn. 1. Refer to Horn for the proper horn diagnosis
and testing procedures. Replace the horn or
repair the open horn circuit, if required.
8H - 2 HORNWJ
HORN SYSTEM (Continued)

HORN SWITCH
DESCRIPTION
A center-blow, normally open, resistive membrane-
type horn switch is secured in a plastic tray that is
inserted in a pocket sewn on the front of the driver
side airbag retainer strap. The horn switch is con-
cealed behind the driver side airbag module trim
cover in the center of the steering wheel. The switch
consists of two plastic membranes, one that is flat
and one that is slightly convex. These two mem-
branes are secured to each other around the perime-
ter. Inside the switch, the centers of the facing
surfaces of these membranes each has a grid made
with an electrically conductive material applied to it.
One of the grids is connected to a circuit that pro-
vides it with continuity to ground at all times. The
grid of the other membrane is connected to the horn
relay control circuit.
The steering wheel and steering column must be
properly grounded in order for the horn switch to
function properly. The horn switch and plastic tray
are serviced as a unit. If the horn switch is damaged
or faulty, or if the driver side airbag is deployed, the
horn switch and tray must be replaced as a unit.
OPERATION
When the center area of the driver side airbag trim
cover is depressed, the electrically conductive grids
on the facing surfaces of the horn switch membranes
contact each other, closing the switch circuit. The
completed horn switch circuit provides a ground for
the control coil side of the horn relay, which activates
the relay. When the horn switch is released, the
resistive tension of the convex membrane separates
the two electrically conductive grids and opens the
switch circuit.
DIAGNOSIS AND TESTING - HORN SWITCH
For complete circuit diagrams, refer to the appro-
priate 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 connec-
tors, splices and grounds.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO ELECTRICAL, RESTRAINTS
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
(1) Disconnect and isolate the battery negative
cable. Remove the steering column opening cover
from the instrument panel.
(2) Check for continuity between the metal steer-
ing column jacket and a good ground. There should
be continuity. If OK, go to Step 3. If not OK, refer to
Steering, Column for proper installation of the steer-
ing column.
(3) Remove the driver side airbag module from the
steering wheel. Disconnect the horn switch wire har-
ness connectors from the driver side airbag module.
(4) Remove the horn relay from the Power Distri-
bution Center (PDC). Check for continuity between
the steering column half of the horn switch feed wire
harness connector and a good ground. There should
be no continuity. If OK, go to Step 5. If not OK,
repair the shorted horn relay control circuit to the
horn relay in the PDC as required.
(5) Check for continuity between the steering col-
umn half of the horn switch feed wire harness con-
nector and the horn relay control circuit cavity for
the horn relay in the PDC. There should be continu-
ity. If OK, go to Step 6. If not OK, repair the open
horn relay control circuit to the horn relay in the
PDC as required.
Fig. 3 Power Distribution Center
1 - RIGHT FENDER
2 - BATTERY
3 - POWER DISTRIBUTION CENTER
4 - COVER
8H - 6 HORNWJ
HORN RELAY (Continued)

(6) Check for continuity between the horn switch
feed wire and the horn switch ground wire on the
driver side airbag module. There should be no conti-
nuity. If OK, go to Step 7. If not OK, replace the
faulty horn switch.
(7) Depress the center of the driver side airbag
module trim cover and check for continuity between
the horn switch feed wire and the horn switch
ground wire on the driver side airbag module. There
should now be continuity. If not OK, replace the
faulty horn switch.
REMOVAL
WARNING:
²ON VEHICLES EQUIPPED WITH AIRBAGS,
REFER TO ELECTRICAL, RESTRAINTS BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
²THE HORN SWITCH IS INTEGRAL TO THE
DRIVER SIDE AIRBAG MODULE. SERVICE OF THIS
COMPONENT SHOULD BE PERFORMED ONLY BY
CHRYSLER-TRAINED AND AUTHORIZED DEALER
SERVICE TECHNICIANS. FAILURE TO TAKE THE
PROPER PRECAUTIONS OR TO FOLLOW THE
PROPER PROCEDURES COULD RESULT IN ACCI-
DENTAL, INCOMPLETE, OR IMPROPER AIRBAG
DEPLOYMENT AND POSSIBLE OCCUPANT INJU-
RIES.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the trim cover from the driver side air-
bag module. (Refer to 8 - ELECTRICAL/RE-
STRAINTS/DRIVER AIRBAG - REMOVAL) for the
procedure.
(3) Remove the horn switch and tray as a unit
from the pouch on the retaining strap of the driver
side airbag module (Fig. 4).
INSTALLATION
WARNING:
²ON VEHICLES EQUIPPED WITH AIRBAGS,
REFER TO ELECTRICAL, RESTRAINTS BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.²THE HORN SWITCH IS INTEGRAL TO THE
DRIVER SIDE AIRBAG MODULE. SERVICE OF THIS
COMPONENT SHOULD BE PERFORMED ONLY BY
CHRYSLER-TRAINED AND AUTHORIZED DEALER
SERVICE TECHNICIANS. FAILURE TO TAKE THE
PROPER PRECAUTIONS OR TO FOLLOW THE
PROPER PROCEDURES COULD RESULT IN ACCI-
DENTAL, INCOMPLETE, OR IMPROPER AIRBAG
DEPLOYMENT AND POSSIBLE OCCUPANT INJU-
RIES.
(1) Install the horn switch and tray as a unit into
the pouch on the retaining strap of the driver side
airbag module. Be certain that the tray is facing the
airbag module, that the horn switch is facing the
trim cover, that the horn switch feed wire is on the
left, and that the horn switch ground wire is on the
right.
(2) Install the trim cover onto the driver side air-
bag module. (Refer to 8 - ELECTRICAL/RE-
STRAINTS/DRIVER AIRBAG - INSTALLATION) for
the procedure.
(3) Reconnect the battery negative cable.
Fig. 4 Horn Switch Remove/Install
1 - HORN SWITCH GROUND WIRE EYELET
2 - HORN SWITCH
3 - AIRBAG RETAINING STRAP
4 - POUCH
5 - DRIVER SIDE AIRBAG MODULE (TRIM COVER REMOVED)
6 - TRAY
7 - HORN SWITCH FEED WIRE CONNECTOR
WJHORN 8H - 7
HORN SWITCH (Continued)

INSTRUMENT CLUSTER
DESCRIPTION
The instrument cluster for this model is an Elec-
troMechanical Instrument Cluster (EMIC) module
that is located in the instrument panel above the
steering column opening, directly in front of the
driver (Fig. 1). The remainder of the EMIC, including
the mounts and the electrical connections, are con-
cealed behind the cluster bezel. The EMIC gauges
and indicators are protected by an integral clear
plastic cluster lens, and are visible through a dedi-
cated hooded opening in the instrument panel top
pad. Just behind and integral to the cluster lens are
the cluster hood and cluster mask, which are con-
structed of molded black plastic. Two cluster masks
are used: A base version features a black matte face
and no trim ring around the perimeter of each gauge
opening, while a premium version features a black
matte face and a raised trim ring around the perim-
eter of each gauge opening. The cluster hood serves
as a visor and shields the face of the cluster from
ambient light and reflections to reduce glare, while
the cluster mask serves to separate and define the
individual gauges of the EMIC. On the lower edge of
the cluster lens just right of the speedometer, the
black plastic odometer/trip odometer switch button
protrudes through dedicated holes in the cluster
mask and the cluster lens. The molded plastic EMIC
lens, hood and mask unit has four integral mounting
tabs, two tabs extend down vertically from the lower
edge of the unit and two tabs extend horizontally
rearward from the upper surface of the hood. The
two lower mounting tabs are used to secure theEMIC to the molded plastic instrument panel cluster
carrier with two screws, while the two upper tabs are
secured to the underside of the hood formation of the
instrument panel top pad with two screws. A single
molded connector receptacle located on the EMIC
electronic circuit board is accessed from the back of
the cluster housing and is connected to the vehicle
electrical system through a single dedicated take out
and connector of the instrument panel wire harness.
The cluster mask features two large round open-
ings near its center through which the two major
gauges are visible, and two smaller round openings
stacked at the outboard side of each of the large
openings through which the four minor gauges are
visible. The cluster mask and the dial faces of the
gauges are laminated plastic units. The dark, visible
surface of the mask and the gauge dial faces are the
outer layer or overlay, which is translucent. The
darkness of this outer layer prevents the cluster from
appearing too cluttered or busy by concealing the
cluster indicators that are not illuminated, while the
translucence of this layer allows those indicators and
icons that are illuminated to be readily visible. The
underlying layer of the cluster mask overlay is
opaque and allows light from the various indicators
behind it to be visible through the outer layer of the
mask and gauge dial faces only through predeter-
mined cutouts. On the base instrument clusters the
graphics, increments, and numerals on the gauge
faces are also translucent and illuminated from
behind, while the orange gauge pointers are illumi-
nated internally. On the premium instrument clus-
ters the graphics, increments, numerals and gauge
needles are opaque while the remainder of the gauge
faces are translucent and illuminated from behind by
an electro-luminescent lamp. The EMIC electronic
circuitry is protected by a molded plastic rear cover
that features several round access holes for service of
the incandescent cluster indicator and illumination
lighting lamps and a large rectangular access hole
for the EMIC connector receptacle. The EMIC rear
cover is secured to the cluster housing with screws,
while the cluster lens, hood, and mask unit is
secured to the cluster housing with several integral
plastic latch features.
Twelve versions of the EMIC module are offered on
this model, two base and ten premium. These ver-
sions accommodate all of the variations of optional
equipment and regulatory requirements for the vari-
ous markets in which the vehicle will be offered. This
module utilizes integrated circuitry and information
carried on the Programmable Communications Inter-
face (PCI) data bus network for control of all gauges
and many of the indicators. (Refer to 8 - ELECTRI-
CAL/ELECTRONIC CONTROL MODULES/COM-
MUNICATION - DESCRIPTION - PCI BUS). The
Fig. 1 Instrument Cluster
1 - INSTRUMENT PANEL TOP PAD HOOD FORMATION
2 - INSTRUMENT CLUSTER
3 - CLUSTER BEZEL
8J - 2 INSTRUMENT CLUSTERWJ

BRAKE LAMP SWITCH
DESCRIPTION
The brake lamp switch is mounted on a bracket
attached to the brake pedal support. The switch is
adjustable.
OPERATION
The brake lamp switch is used for the brake lamp,
speed control and brake sensor circuits.
DIAGNOSIS AND TESTING Ð BRAKE LAMP
SWITCH
Brake lamp switch operation can be tested with an
ohmmeter. The ohmmeter is used to check continuity
between the pin terminals at different plunger posi-
tions (Fig. 2).
SWITCH CIRCUIT IDENTIFICATION
²Terminals 1 and 2: brake sensor circuit
²Terminals 3 and 4: speed control circuit
²Terminals 5 and 6: brake lamp circuit
SWITCH CONTINUITY TEST
NOTE: Disconnect switch harness before testing
continuity.
With the switch plunger retracted, attach the test
leads to terminal pins 1 and 2. Replace switch if
meter indicates no continuity.
With the switch plunger retracted, attach the test
leads to terminal pins 3 and 4. Replace switch if
meter indicates no continuity.With the switch plunger extended, attach the test
leads to terminal pins 5 and 6. Replace switch if
meter indicates no continuity.
REMOVAL
(1) Remove the steering column cover and lower
trim panel.
(2) Press the brake pedal downward to fully
applied position.
(3) Rotate the switch approximately 30É in coun-
terclockwise direction to unlock the switch retainer.
Pull switch rearward and out of bracket.
(4) Disconnect switch harness and remove switch
from vehicle (Fig. 3).
INSTALLATION
(1) Pull the switch plunger all the way out to fully
extended position.
(2) Connect the harness wires to switch.
(3) Press and hold brake pedal in applied position.
(4) Install the switch as follows: Align the tab on
the switch with the notch in the switch bracket.
Insert the switch in the bracket and turn it clockwise
about 30É to lock it in place.
(5) Release the brake pedal. Then pull the pedal
lightly rearward. The pedal will set the plunger to
the correct position as the pedal pushes the plunger
into switch body. The switch will make ratcheting
sound as it self adjusts.
CAUTION: Booster damage may occur if the pedal
pull exceeds 20 lbs.
Fig. 1 Auto Headlamp Sensor
1 - AUTO HEADLAMP SENSOR
2 - I/P ASSEMBLY
3 - CONNECTOR
Fig. 2 Brake Lamp Switch Terminal Identification
1 - TERMINAL PINS
2 - PLUNGER TEST POSITIONS
WJLAMPS/LIGHTING - EXTERIOR 8L - 5
AUTO HEADLAMP SENSOR (Continued)

REMOVAL - LAMP
(1) Remove the screws attaching lamp assembly to
liftgate. (Fig. 20).
(2) Pull the lamp assembly away from the sheet-
metal at extreme outboard edges to disengage the
push pins.
(3) Separate lamp assembly harness wiring con-
nector.
(4) Remove lamp.
INSTALLATION
INSTALLATION - BULB
(1) Install bulb in socket.
(2) Install socket and bulb assembly in lamp hous-
ing.
(3) Install lamp assembly in liftgate lamp module.
INSTALLATION - LAMP
(1) Connect bulb harness to lamp assembly.
(2) Position lamp assembly on liftgate and press
outboard fasteners in place.
(3) Install screws in lamp assembly.
LICENSE PLATE LAMP UNIT
REMOVAL
(1) Remove the screws retaining the lamp housing/
trim panel to the liftgate (Fig. 21).
(2) Disconnect the wire harness for the license
plate lamps and the flip up glass switch, if equipped.
(3) Remove the license plate lamps and the flip up
glass switch, if equipped.
(4) Remove the license plate lamp housing.
Fig. 17 Low Beam Pattern
1 - LOW BEAM INTENSITY PATTERN (ISO-CANDELA CURVE)
Fig. 18 Headlamp Beam Adjustment Screw
1 - ADJUSTMENT SCREW LOCATION
Fig. 19 Headlamp Beam Adjustment
Fig. 20 License Plate Lamp Housing
1 - LICENSE PLATE LAMP
2 - CONNECTOR
3 - LIFTGATE
8L - 18 LAMPS/LIGHTING - EXTERIORWJ
LICENSE PLATE LAMP (Continued)

INSTALLATION
(1) Install the license plate lamps, and the flip up
glass switch, if equipped.
(2) Connect the wire harnesses for the license
plate lamps and the flip up glass switch.
(3) Install the lamp housing/trim panel on the lift-
gate.
LEFT MULTI-FUNCTION
SWITCH
DESCRIPTION
The left multi-function switch, its mounting provi-
sions, and its electrical connections are all concealed
beneath the steering column shrouds, just below the
steering wheel (Fig. 22).
A single connector with eleven terminal pins is
located on the back of the switch housing and con-
nects the switch to the vehicle electrical system. The
left multi-function switch supports the following exte-
rior lighting functions:
²Auto Headlamps
²Front Fog Lamps
²Hazard Warning Control
²Headlamps
²Headlamp Beam Selection
²Headlamp Optical Horn
²Park Lamps
²Rear Fog Lamps
²Turn Signal Control
The left multi-function switch also supports the fol-
lowing interior lighting functions:
²Panel Lamps Dimming
²Interior Lamps Defeat²Interior Lamps On
²Parade Mode
The left multi-function switch cannot be adjusted
or repaired. If any function of the switch is faulty, or
if the switch is damaged, the entire switch unit must
be replaced.
OPERATION
The left multi-function switch uses a combination
of resistor multiplexed and conventionally switched
outputs to control the many functions and features it
provides using a minimal number of hard wired cir-
cuits. The switch is grounded to the chassis beneath
the center floor console, just forward of the Airbag
Control Module (ACM). Following are descriptions of
the how the left multi-function switch operates to
control the many exterior lighting functions and fea-
tures it provides:
²Auto Headlamps- The automatic headlamps
feature is provided by the Body Control Module
(BCM), which monitors an input from a photodiode
sensor located on the top of the instrument panel to
detect ambient light levels whenever the ignition
switch is in the On position. Based upon the multi-
plexed input from the left multi-function switch and
the input of the photodiode sensor, the BCM controls
outputs to the park lamp and headlamp relays to
illuminate or extinguish all exterior lighting.
²Front Fog Lamps- The Body Control Module
(BCM) monitors the left multi-function switch then,
based upon that switched ground input, controls an
output to the front fog lamp relay to illuminate or
extinguish the front fog lamps.
Fig. 21 License Plate Lamp Housing
1 - LICENSE PLATE LAMP
2 - CONNECTOR
3 - LIFTGATE
Fig. 22 Left (Lighting) Multi-Function Switch
1 - EXTERIOR LIGHTING CONTROL
2 - INTERIOR LIGHTING CONTROL
3 - CONTROL STALK
4 - HAZARD WARNING BUTTON
5 - CANCEL ACTUATOR
6 - LEFT (LIGHTING) MULTI-FUNCTION SWITCH
WJLAMPS/LIGHTING - EXTERIOR 8L - 19
LICENSE PLATE LAMP UNIT (Continued)