2003 JEEP GRAND CHEROKEE 23 Body

ADJUSTMENTS
ADJUSTMENT
(1) Press and hold brake pedal in applied position.
(2) Pull switch plunger all the way out to fully
extended position.
(3) Release brake pedal. Then pull pedal lightly
rearward. Pedal will set plunger to correct position
as pedal pushes plunger into switch body. Switch will
make ratcheting sound as it self adjusts.
CAUTION: Booster damage may occur if the pedal
pull exceeds 20 lbs.
CENTER HIGH MOUNTED
STOP LAMP
REMOVAL
REMOVAL - BULB
(1) Remove the screws attaching the lamp housing
to the liftgate.
(2) Rotate the bulb socket 1/4 turn and remove it
from the housing (Fig. 4).
(3) Remove the bulb from the socket.
REMOVAL - CHMSL
(1) Remove the screws attaching CHMSL to the
liftgate (Fig. 5).
(2) Disconnect the wire harness connector.
(3) Separate the CHMSL from the vehicle.
INSTALLATION
INSTALLATION - BULB
(1) Push the bulb into the socket.
(2) Position the socket in lamp and rotate 1/4 turn.
(3) Install the screws attaching the lamp housing
to liftgate.
Fig. 3 Brake Lamp
1 - SWITCH
2 - HARNESS CONNECTOR
Fig. 4 CHMSL Bulb
1 - CHMSL
2 - CHMSL BULB
Fig. 5 Center High Mounted Stop lamp
1 - PUSH-IN NUT
2 - CONNECTOR
3 - LIFTGATE
4 - CHSML
8L - 6 LAMPS/LIGHTING - EXTERIORWJ
BRAKE LAMP SWITCH (Continued)

INSTALLATION - CHMSL
(1) Connect the wire harness connector.
(2) Position the CHMSL on liftgate.
(3) Install the screws attaching the CHMSL to the
liftgate.
COMBINATION FLASHER
DESCRIPTION
The combination flasher is located in the Junction
Block (JB) (Fig. 6). The JB is located underneath the
driver side of the instrument panel outboard of the
steering column. The combination flasher is a smart
relay that functions as both the turn signal system
and the hazard warning system flasher. The combi-
nation flasher contains active electronic Integrated
Circuitry (IC) elements. This flasher is designed to
handle the current flow requirements of the factory-
installed lighting. If supplemental lighting is added
to the turn signal lamp circuits, such as when towing
a trailer with lights, the combination flasher will
automatically try to compensate to keep the flash
rate the same.The combination flasher has nine blade-type termi-
nals that connect it to the vehicle electrical system.
Refer to the appropriate wiring information.
Because of the active electronic elements within
the combination flasher, it cannot be tested with con-
ventional automotive electrical test equipment. If the
combination flasher is believed to be faulty, test the
turn signal system and hazard warning system cir-
cuits.(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING
- EXTERIOR - DIAGNOSIS AND TESTING - TURN
SIGNAL & HAZARD WARNING SYSTEM). The com-
bination flasher cannot be repaired or adjusted and,
if faulty or damaged, it must be replaced.
OPERATION
The combination flasher controls the following
inputs and outputs: B(+), fused ignition switch out-
put, left turn switch sense, right turn switch sense,
hazard switch sense, left front turn signal circuit,
right front turn signal circuit, left rear turn signal
circuit and right rear turn signal circuit. Constant
battery voltage is supplied to the flasher so that it
can perform the hazard warning function, and igni-
tion switched battery voltage is supplied for the turn
signal function. However, when the flasher is idle no
current is drawn through the module. The unit does
not become active until it is provided a signal ground
from the turn signal switch, hazard warning switch
or the Body Control Module (BCM).
The IC within the combination flasher (Fig. 7) con-
tains the logic that controls the flasher operation and
the flash rate. When a bulb is burnt out, or when a
circuit for a lamp is open, the turn signal flash rate
will increase. However, an open lamp circuit or burnt
out bulb does not change the hazard warning flash
rate.
Fig. 6 Combination Flasher
1 - COMBINATION FLASHER
2 - JUNCTION BLOCK
WJLAMPS/LIGHTING - EXTERIOR 8L - 7
CENTER HIGH MOUNTED STOP LAMP (Continued)

Turn signal inputs that actuate the combination
flasher are low current grounds, each drawing a
maximum of 300 milliamperes.The hazard warning
signal input is a low current ground drawing a max-
imum of 600 milliamperes.
REMOVAL
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.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the steering column cover. (Refer to 23
- BODY/INSTRUMENT PANEL/STEERING COL-
UMN OPENING COVER - REMOVAL).
(3) Remove the combination flasher from the Junc-
tion Block (JB) (Fig. 8).
INSTALLATION
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.
(1) Align the terminals of the combination flasher
with the terminal cavities in the JB. (Fig. 8)
(2) Push in firmly and evenly on the combination
flasher until the terminals are fully seated.
(3) Reinstall the steering column opening cover.
(Refer to 23 - BODY/INSTRUMENT PANEL/STEER-
ING COLUMN OPENING COVER - INSTALLA-
TION).
(4) Reconnect the battery negative cable.
DAYTIME RUNNING LAMP
MODULE
DESCRIPTION
The Daytime Running Lights (Headlamps) System
is installed on vehicles manufactured for sale in Can-
ada only. A separate module, mounted in the junction
block under the dash, controls the DRL.
OPERATION
The headlamps are illuminated at a reduced inten-
sity when the engine is running, headlamp switch
off, and the parking brake released.
REMOVAL
(1) Lower the junction block. (Refer to 8 - ELEC-
TRICAL/POWER DISTRIBUTION/JUNCTION
BLOCK - REMOVAL) for service procedures.
(2) Remove the module from the junction block.
INSTALLATION
(1) Position the module in the junction block and
press to secure.
(2) Install the junction block. (Refer to 8 - ELEC-
TRICAL/POWER DISTRIBUTION/JUNCTION
BLOCK - INSTALLATION) for service procedures.
Fig. 8 Combination Flasher
1 - COMBINATION FLASHER
2 - JUNCTION BLOCK
WJLAMPS/LIGHTING - EXTERIOR 8L - 9
COMBINATION FLASHER (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
FOG LAMPS DO NOT
ILLUMINATE1. Blown fuse for fog lamp. 1. Replace fuse. Refer to Electrical, Wiring
Information.
2. No Z1-ground at fog lamps. 2. Repair circuit ground. Refer to Electrical,
Wiring Information.
3. Faulty multifunction switch. 3. Refer to Electrical, Wiring Information.
4. Broken connector terminal or wire
splice in fog lamp circuit.4. Repair connector terminal or wire splice.
5. Defective or burned out bulb. 5. Replace bulb.
DAYTIME RUNNING LAMP
CONDITION POSSIBLE CAUSES CORRECTION
DAYTIME RUNNING LAMPS DO
NOT WORK1. Poor connection at DRL module. 1. Secure connector on DRL
module.
2. Parking brake engaged. 2. Disengage parking brake.
3. Parking brake circuit shorted to
ground.3. Check cluster telltale, refer to
Group 8W.
4. Headlamp circuit shorted to
ground.4. Refer to Group 8W.
5. Defective DRL relay. 5. Replace DRL relay.
6. Body controller not programed
with Canadian country code.6. Check country code.
7. DRL relay is missing. 7. Install DRL relay.
8. Blown fuse for DRL. 8. Replace fuse refer to Electrical,
Wiring Information.
Clicking or chattering when DRL is
on.1. Mechanical relay is installed in
the junction block.1. Ensure that the DRL relay is
installed in the proper socket in
junction block, and that no
mechanical relay exists in the low
beam socket.
DIAGNOSIS AND TESTING Ð HEADLAMP
WARNING: EYE PROTECTION SHOULD BE USED
WHEN SERVICING GLASS COMPONENTS. PER-
SONAL INJURY CAN RESULT.
CAUTION: Do not touch the glass of halogen bulbs
with fingers or other possibly oily surface, reduced
bulb life will result. Do not use bulbs other than
those indicated in the Bulb Application table. Dam-
age to lamp and/or Daytime Running Lamp Module
can result. Do not use fuses, circuit breakers or
relays having greater amperage value than indi-
cated on the fuse panel or in the Owners Manual.
Each vehicle is equipped with various lamp assem-
blies. A good power feed and ground are necessary forproper lighting operation. Grounding is provided by
the lamp socket when it comes in contact with the
metal body, or through a separate ground wire.
When changing lamp bulbs check the socket for
corrosion. If corrosion is present, clean it with a wire
brush and coat the inside of the socket lightly with
Mopar Multi-Purpose Grease or equivalent.
REMOVAL - BULB
(1) Remove the headlamp.
(2) Turn the bulb socket one quarter turn counter
clockwise.
(3) Remove the socket from lamp (Fig. 13).
(4) Remove the bulb from socket.
8L - 14 LAMPS/LIGHTING - EXTERIORWJ
HEADLAMP (Continued)

INSTALLATION - BULB
CAUTION: Do not touch the bulb glass with fingers
or other oily surfaces. Reduced bulb life will result.
(1) Position the bulb into socket and push into
place.
(2) Position the bulb socket in headlamp and turn
the bulb socket one quarter turn clockwise.
(3) Install the headlamp.
HEADLAMP SWITCH
DESCRIPTION
The headlamp switch is part of the left multi-func-
tion switch. A knob on the end of the multi-function
switch control stalk controls all of the exterior light-
ing switch functions. The exterior lighting switch is
hard wired to the Body Control Module (BCM).
The exterior lighting switch cannot be adjusted or
repaired and, if faulty or damaged, the entire left
multi-function switch unit must be replaced. (Refer
to 8 - ELECTRICAL/LAMPS/LIGHTING - EXTERI-
OR/TURN SIGNAL/HAZARD SWITCH - REMOVAL)
for the service procedures. (Refer to 8 - ELECTRI-
CAL/ELECTRONIC CONTROL MODULES/BODY
CONTROL/CENTRAL TIMER MODUL - DESCRIP-
TION) for more information on this component.
OPERATION
The exterior lighting switch uses a hard wired five
volt reference circuit from the BCM, resistor multi-
plexing and a hard wired switch output circuit to
provide the BCM with a zero to five volt signal thatindicates the status of all of the exterior lighting
switch settings. The BCM then uses control outputs
to energize the headlamp and park lamp relays that
activate the exterior lighting circuits.
The BCM monitors the exterior lighting switch sta-
tus, then sends the proper switch status messages to
other modules over the Programmable Communica-
tions Interface (PCI) data bus network. The exterior
lighting switch status is also used by the BCM as an
input for chime warning system operation.
DIAGNOSIS AND TESTING Ð HEADLAMP
SWITCH
Before testing the headlamp switch, turn on the
exterior lighting and open the driver side front door.
If the exterior lamps of the vehicle operate, but there
is no chime warning issued with the driver side front
door open, (Refer to 8 - ELECTRICAL/LAMPS/
LIGHTING - INTERIOR/DOOR AJAR SWITCH -
DIAGNOSIS AND TESTING). If the exterior lamps
of the vehicle are inoperative, but the chime warning
is issued, (Refer to 8 - ELECTRICAL/LAMPS/LIGHT-
ING - EXTERIOR - DIAGNOSIS AND TESTING).
If the exterior lamps and the chime warning are
both inoperative, test the left multi-function switch.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
EXTERIOR - DIAGNOSIS AND TESTING). If the
multi-function switch tests OK, proceed as follows.
The following tests will help to locate a short or open
in the hard wired circuits between the multi-function
switch and the Body Control Module (BCM). For
complete circuit diagrams, refer to the appropriate
wiring information.
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. Disconnect the instrument panel wire harness
connector from the left multi-function switch connec-
tor. Disconnect the instrument panel wire harness
connector from the Body Control Module (BCM).
Check for continuity between the headlamp switch
mux circuit of the instrument panel wire harness
connector for the multi-function switch and a good
ground. There should be no continuity. If OK, go to
Step 2. If not OK, repair the shorted headlamp
switch mux circuit.
(2) Check for continuity between the headlamp
switch mux circuit of the instrument panel wire har-
Fig. 13 Headlamp Bulb
1 - HIGH BEAM BULB
2 - LOW BEAM BULB
3 - MARKER BULB
4 - PARK/TURN SIGNAL BULB
WJLAMPS/LIGHTING - EXTERIOR 8L - 15
HEADLAMP (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)

²Hazard Warning Control- The hazard warn-
ing push button is pressed down to activate the haz-
ard warning system, and pressed down again to turn
the system off. The left multi-function switch pro-
vides a ground to the hazard warning sense input of
the combination flasher to control activation of the
hazard warning lamps.
²Headlamps- The Body Control Module (BCM)
monitors the left multi-function switch then, based
upon that multiplexed input, controls an output to
the headlamp low or high beam relays to illuminate
or extinguish the headlamps.
²Headlamp Beam Selection- The Body Control
Module (BCM) monitors the left multi-function
switch then, based upon that switched ground input,
controls an output to the headlamp low or high beam
relays to activate the selected headlamp beam.
²Headlamp Optical Horn- The Body Control
Module (BCM) monitors the left multi-function
switch then, based upon that switched ground input,
controls an output to the headlamp high beam relay
to activate the headlamp high beams.
²Park Lamps- The Body Control Module (BCM)
monitors the left multi-function switch then, based
upon that multiplexed input, controls an output to
the park lamp relay to illuminate or extinguish the
parking lamps.
²Rear Fog Lamps- The Body Control Module
(BCM) monitors the left multi-function switch then,
based upon that multiplexed input, controls an out-
put to the rear fog lamp relay to illuminate or extin-
guish the rear fog lamps.
²Turn Signal Control- The left multi-function
switch control stalk actuates the turn signal switch.
The Body Control Module (BCM) monitors the left
multi-function switch then, based upon that multi-
plexed input, provides a variable voltage output to
control the lighting of the turn signals.
Following are descriptions of the how the left
multi-function switch operates to control the many
interior lighting functions and features it provides:
²Panel Lamps Dimming- The Body Control
Module (BCM) monitors the left multi-function
switch then, based upon that multiplexed input, pro-
vides a variable voltage output through several panel
lamps driver circuits to control the lighting of many
incandescent panel lamps. The BCM also sends panel
lamps dimming messages over the Programmable
Communications Interface (PCI) data bus to other
modules to control Display lighting levels in those
modules.²Interior Lamps Defeat- The Body Control
Module (BCM) monitors the left multi-function
switch then, based upon that multiplexed input,
internally disables the function the BCM normally
provides to control the illumination of the interior
lamps.
²Interior Lamps On- The Body Control Module
(BCM) monitors the left multi-function switch then,
based upon that multiplexed input, provides a control
output to activate all of the interior lamp circuits.
²Parade Mode- The Body Control Module
(BCM) monitors the left multi-function switch then,
based upon that multiplexed input, provides a volt-
age output through several panel lamps driver cir-
cuits to control the lighting of many incandescent
panel lamps. The BCM also sends panel lamps dim-
ming messages over the Programmable Communica-
tions Interface (PCI) data bus to other modules on
the bus to control lighting levels in those modules.
DIAGNOSIS AND TESTING - LEFT MULTI -
FUNCTION SWITCH
Refer to the appropriate wiring information.
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.
(1) Disconnect and isolate the battery negative
cable. Disconnect the instrument panel wire harness
connector from the multi-function switch connector.
(2) Using an ohmmeter, perform the continuity
and resistance tests at the terminals in the multi-
function switch connector as shown in the Left Multi-
Function Switch Test chart (Fig. 23).
8L - 20 LAMPS/LIGHTING - EXTERIORWJ
LEFT MULTI-FUNCTION SWITCH (Continued)

MULTI-FUNCTION SWITCH - INSTALLATION -
LEFT MULTI-FUNCTION SWITCH).
(6) Reinstall the clockspring onto the multi-func-
tion switch housing. (Refer to 8 - ELECTRICAL/RE-
STRAINTS/CLOCKSPRING - INSTALLATION).
(7) Reconnect the battery negative cable.
PARK/TURN SIGNAL LAMP
REMOVAL - BULBS
(1) Remove the headlamp module.
(2) Rotate the turn signal bulb socket 1/4 turn
counter clockwise.
(3) Remove the bulb socket from module.
(4) Remove the bulb from socket.
INSTALLATION - BULBS
(1) Press the bulb into socket.
(2) Position the bulb socket in module.
(3) Rotate the turn signal bulb socket 1/4 turn
clockwise.
(4) Install the headlamp module.
TAIL LAMP
DESCRIPTION
The taillamp module contains a housing, lens, and
three bulbs. A dual filament bulb is used for tail and
stop functions. A single filament bulb is used for turn
signal operations. A separate bulb is used for back-up
illumination.
OPERATION
All exterior lighting function are controlled by the
multifunction switch. Stop lamp functions are con-
trolled by the stoplamp switch. The back-up lamps
are controlled by the back-up lamp switch.
REMOVAL
REMOVAL - BULBS
The brake, turn signal, back-up, and side marker
lamp bulbs are incorporated into the tail lamp.
(1) Remove the tail lamp.
(2) Rotate the bulb socket counterclockwise.
(3) Separate the socket from the lamp
(4) Remove the bulb from the socket (Fig. 32).
REMOVAL - LAMP
The brake, turn signal, back-up, and side marker
lamps are incorporated in the tail lamp.
(1) Remove the screws attaching the lamp to body
(Fig. 33).
(2) Disengage the lamp from the alignment pin.
(3) Disconnect lamp wire harness connector.
(4) Separate lamp from vehicle.
Fig. 31 Multi-Function Switch Mounting Housing
Screw Remove/Install
1 - CLOCK SPRING
2 - SCREW
3 - MULTI-FUNCTION SWITCH MOUNTING HOUSING
Fig. 32 Tail Lamp Bulbs
1 - TAIL/STOP BULB
2 - TAIL LAMP
3 - BACK-UP BULB
4 - TURN SIGNAL BULB
WJLAMPS/LIGHTING - EXTERIOR 8L - 25
LEFT MULTI-FUNCTION SWITCH (Continued)