2002 JEEP GRAND CHEROKEE turn signal bulb

WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SIDE CURTAIN AIRBAG,
FRONT IMPACT SENSOR, SIDE IMPACT SENSOR,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER 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.
(1) Disconnect and isolate the battery negative
cable. Remove the instrument cluster from the
instrument panel and disconnect the instrument
panel wire harness for the instrument cluster from
the cluster connector receptacle.
(2) Reconnect the battery negative cable. Activate
the hazard warning system by moving the hazard
warning switch button to the On position. Check for
battery voltage at the inoperative (right or left) turn
signal circuit cavity of the instrument panel wire
harness connector for the instrument cluster. There
should be a switching (on and off) battery voltage sig-
nal present. If OK, replace the faulty (right or left)
turn signal indicator bulb. If not OK, repair the open
(right or left) turn signal circuit between the instru-
ment cluster and the combination flasher in the
Junction Block (JB) as required.
VOLTAGE GAUGE
DESCRIPTION
A voltage gauge is standard equipment on all
instrument clusters. The voltage gauge is located in
the upper left corner of the instrument cluster, to the
left of the tachometer. The voltage gauge consists of a
movable gauge needle or pointer controlled by the
instrument cluster circuitry and a fixed 90 degree
scale on the gauge dial face that reads left-to-right
from 9 volts to 19 volts. An International Control and
Display Symbol icon for ªBattery Charging Condi-
tionº is located on the gauge dial face.
The voltage gauge graphics are either white, gray
and orange against a black gauge dial face (base
cluster) or black, gray and red against a taupe gauge
dial face (premium cluster), making them clearly vis-
ible within the instrument cluster in daylight. When
illuminated from behind by the panel lamps dimmer
controlled cluster illumination lighting with the exte-rior lamps turned On, the base cluster white gauge
graphics appear blue-green and the orange graphics
still appear orange, while the premium cluster taupe
gauge dial face appears blue-green with the black
graphics silhouetted against the illuminated back-
ground and the red graphics still appear red. The
gray gauge graphics for both versions of the cluster
are not illuminated. The orange gauge needle in the
base cluster gauge is internally illuminated, while
the black gauge needle in the premium cluster gauge
is not.
Base cluster gauge illumination is provided by
replaceable incandescent bulb and bulb holder units
located on the instrument cluster electronic circuit
board. Premium cluster gauge illumination is pro-
vided by an integral electro-luminescent lamp that is
serviced as a unit with the instrument cluster. The
voltage gauge is serviced as a unit with the instru-
ment cluster.
OPERATION
The voltage gauge gives an indication to the vehi-
cle operator of the electrical system voltage. This
gauge is controlled by the instrument cluster circuit
board based upon cluster programming and elec-
tronic messages received by the cluster from the
Powertrain Control Module (PCM) over the Program-
mable Communications Interface (PCI) data bus. The
voltage gauge is an air core magnetic unit that
receives battery current on the instrument cluster
electronic circuit board through the fused ignition
switch output (run-start) circuit whenever the igni-
tion switch is in the On or Start positions. The clus-
ter is programmed to move the gauge needle back to
the low end of the scale after the ignition switch is
turned to the Off position. The instrument cluster
circuitry controls the gauge needle position and pro-
vides the following features:
²System Voltage Message- Each time the clus-
ter receives a message from the PCM indicating the
system voltage, the cluster moves the gauge needle to
the relative voltage level position on the gauge scale.
²System Voltage Low Message- Each time the
cluster receives a message from the PCM indicating
the system voltage is low (system voltage is about
eleven volts or lower), the gauge needle is moved to
the relative voltage position in the red zone of the
gauge scale and the check gauges indicator is illumi-
nated. The gauge needle remains in the red zone and
the check gauges indicator remains illuminated until
the cluster receives a message from the PCM indicat-
ing there is no low system voltage condition (system
voltage is above about eleven volts, but lower than
about sixteen volts).
²System Voltage High Message- Each time
the cluster receives a message from the PCM indicat-
8J - 34 INSTRUMENT CLUSTERWJ
TURN SIGNAL INDICATOR (Continued)

LAMPS
TABLE OF CONTENTS
page page
LAMPS/LIGHTING - EXTERIOR............... 1LAMPS/LIGHTING - INTERIOR............... 28
LAMPS/LIGHTING - EXTERIOR
TABLE OF CONTENTS
page page
LAMPS/LIGHTING - EXTERIOR
DESCRIPTION - TURN SIGNAL & HAZARD
WARNING SYSTEM.....................2
OPERATION - TURN SIGNAL & HAZARD
WARNING SYSTEM.....................2
DIAGNOSIS AND TESTING - TURN SIGNAL &
HAZARD WARNING SYSTEMS............3
SPECIFICATIONS
EXTERIOR LAMPS.....................4
AUTO HEADLAMP SENSOR
DIAGNOSIS AND TESTING - AUTO
HEADLAMP SENSOR (AHL)..............4
REMOVAL.............................4
INSTALLATION..........................4
BRAKE LAMP SWITCH
DESCRIPTION..........................5
OPERATION............................5
DIAGNOSIS AND TESTING Ð BRAKE LAMP
SWITCH.............................5
REMOVAL.............................5
INSTALLATION..........................5
ADJUSTMENTS
ADJUSTMENT.........................6
CENTER HIGH MOUNTED STOP LAMP
REMOVAL
REMOVAL - BULB......................6
REMOVAL - CHMSL....................6
INSTALLATION
INSTALLATION - BULB..................6
INSTALLATION - CHMSL.................7
COMBINATION FLASHER
DESCRIPTION..........................7
OPERATION............................7
REMOVAL.............................9
INSTALLATION..........................9
DAYTIME RUNNING LAMP MODULE
DESCRIPTION..........................9OPERATION............................9
REMOVAL.............................9
INSTALLATION..........................9
FOG LAMP
REMOVAL.............................10
INSTALLATION.........................10
FOG LAMP UNIT
REMOVAL.............................10
INSTALLATION.........................10
ADJUSTMENTS
FOG LAMP ADJUSTMENT...............10
HEADLAMP
DESCRIPTION.........................11
OPERATION...........................11
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING Ð HEADLAMP
SYSTEM............................12
DIAGNOSIS AND TESTING Ð HEADLAMP . . 14
REMOVAL - BULB.......................14
INSTALLATION - BULB...................15
HEADLAMP SWITCH
DESCRIPTION.........................15
OPERATION...........................15
DIAGNOSIS AND TESTING Ð HEADLAMP
SWITCH............................15
HEADLAMP UNIT
REMOVAL.............................16
INSTALLATION.........................16
ADJUSTMENTS........................16
LICENSE PLATE LAMP
REMOVAL
REMOVAL - BULB.....................17
REMOVAL - LAMP.....................18
INSTALLATION
INSTALLATION - BULB.................18
INSTALLATION - LAMP.................18
WJLAMPS 8L - 1

LICENSE PLATE LAMP UNIT
REMOVAL.............................18
INSTALLATION.........................19
LEFT MULTI-FUNCTION SWITCH
DESCRIPTION.........................19
OPERATION...........................19
DIAGNOSIS AND TESTING - LEFT MULTI -
FUNCTION SWITCH...................20
REMOVAL
REMOVAL - LEFT MULTI-FUNCTION
SWITCH............................22
REMOVAL - MULTI-FUNCTION SWITCH
MOUNTING HOUSING..................22
INSTALLATION
INSTALLATION - LEFT MULTI-FUNCTION
SWITCH............................23
INSTALLATION - MULTI-FUNCTION SWITCH
MOUNTING HOUSING..................24
PARK/TURN SIGNAL LAMP
REMOVAL - BULBS.....................25INSTALLATION - BULBS..................25
TAIL LAMP
DESCRIPTION.........................25
OPERATION...........................25
REMOVAL
REMOVAL - BULBS....................25
REMOVAL - LAMP.....................25
INSTALLATION
INSTALLATION - BULBS................26
INSTALLATION - LAMP.................26
TURN SIGNAL CANCEL CAM
DESCRIPTION.........................26
OPERATION...........................26
UNDERHOOD LAMP
REMOVAL
REMOVAL - BULB.....................27
REMOVAL - LAMP.....................27
INSTALLATION
INSTALLATION - BULB.................27
INSTALLATION - LAMP.................27
LAMPS/LIGHTING - EXTERIOR
DESCRIPTION - TURN SIGNAL & HAZARD
WARNING SYSTEM
The turn signal and hazard warning system
includes the following major components, which are
described in further detail elsewhere in this service
information:
²Combination Flasher
²Front Side Marker Lamps
²Hazard Warning Switch
²Turn Signal Cancel Cam
²Turn Signal Indicators
²Turn Signal Lamps
²Turn Signal Switch
The turn signal and hazard warning systems also
provide the following features:
²Flash Lights with Lock- This customer pro-
grammable feature flashes the hazard warning lamps
to provide optical verification that the Remote Key-
less Entry (RKE) System has received a valid Lock or
Unlock request from an RKE transmitter. (Refer to 8
- ELECTRICAL/POWER LOCKS - DESCRIPTION -
REMOTE KEYLESS ENTRY SYSTEM).
²Panic Mode Optical Alert- This feature
flashes the hazard warning lamps to provide an opti-
cal alert when the Remote Keyless Entry (RKE) Sys-
tem panic mode is activated by depressing the Panic
button on an RKE transmitter. (Refer to 8 - ELEC-
TRICAL/POWER LOCKS - DESCRIPTION -
REMOTE KEYLESS ENTRY SYSTEM).
²Turn Signal On Warning- This feature pro-
vides the vehicle operator with both visual and audi-
ble reminders when a turn signal has been left
turned on for an extended period. (Refer to 8 - ELEC-TRICAL/OVERHEAD CONSOLE/ELECTRONIC
VEHICLE INFO CENTER - DESCRIPTION).
²Vehicle Theft Security System (VTSS) Opti-
cal Alarm- This feature flashes the hazard warning
lamps to provide an optical alarm when the VTSS is
armed and activated by an unauthorized entry into
the vehicle. (Refer to 8 - ELECTRICAL/VEHICLE
THEFT SECURITY - DESCRIPTION - VEHICLE
THEFT SECURITY SYSTEM).
OPERATION - TURN SIGNAL & HAZARD
WARNING SYSTEM
The turn signal system operates on battery current
received on a fused ignition switch output (run) cir-
cuit so that the turn signals will only operate with
the ignition switch in the On position. The hazard
warning system operates on non-switched battery
current received on a fused B(+) circuit so that the
hazard warning remains operational regardless of
the ignition switch position. When the turn signal
system is activated, the circuitry of the turn signal
switch and the combination flasher will cause the
selected (right or left) turn signal indicator, front
park/turn signal lamp, front side marker lamp and
rear tail/stop/turn signal lamp to flash on and off.
When the hazard warning system is activated, the
circuitry of the hazard warning switch and the com-
bination flasher will cause both the right side and
the left side turn signal indicators, front park/turn
signal lamps, front side marker lamps and rear tail/
stop/turn signal lamps to flash on and off.
The Body Control Module (BCM) can also activate
the hazard warning system lamps by energizing the
combination flasher through a single hard wired con-
nection to the hazard warning switch sense circuit.
The BCM grounds the circuit to energize and de-en-
8L - 2 LAMPS/LIGHTING - EXTERIORWJ

ergize the combination flasher in response to mes-
sage inputs received over the Programmable
Communications Interface (PCI) data bus network.
The BCM can energize the combination flasher when
the VTSS is requested.
Vehicles equipped with the optional Electronic
Vehicle Information Center (EVIC) use turn signal
status messages received from the Electro-Mechani-
cal Instrument Cluster (EMIC) and distance mes-
sages received from the Powertrain Control Module
(PCM) over the PCI data bus to determine when the
Turn Signal On warning should be activated. The
EMIC receives hard wired inputs from the combina-
tion flasher to operate the turn signal indicators,
then sends the proper turn signal status message to
the EVIC. If a turn signal is left on for more than
about 1.6 kilometers (1 mile) of driving distance, the
EVIC will display a visual ªTurn Signal Onº message
and will send a request to the BCM over the PCI
data bus to notify the vehicle operator.
During both the turn signal and the hazard warn-
ing operation, if the exterior lamps are turned Off,
the front park/turn signal lamps and the front side
marker lamps will flash in unison. If the exterior
lamps are turned On, the front park/turn signal
lamps and the front side marker lamps will flash
alternately. Refer to the owner's manual.
DIAGNOSIS AND TESTING - TURN SIGNAL &
HAZARD WARNING SYSTEMS
When diagnosing the turn signal and hazard warn-
ing circuits, remember that high generator output
can burn out bulbs rapidly and repeatedly. If this is a
concern on the vehicle being diagnosed, test the
charging system as required.
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) Turn the ignition switch to the On position.
Actuate the turn signal switch or the hazard warning
switch. Observe the turn signal indicator lamp(s) in
the instrument cluster. If the flash rate is very high,
check for a turn signal bulb that is not lit or is verydimly lit. Repair the circuits to that lamp or replace
the faulty bulb, as required. If the turn signal indi-
cator(s) fail to light, go to Step 2.
(2) Turn the ignition switch to the Off position.
Check the ignition run fuse and the flasher fuse in
the Junction Block (JB). If OK, go to Step 3. If not
OK, repair the shorted circuit or component as
required and replace the faulty fuse(s).
(3) Check for battery voltage at the flasher fuse in
the JB. If OK, go to Step 4. If not OK, repair the
open fused B(+) circuit between the JB and the
Power Distribution Center (PDC).
(4) Turn the ignition switch to the On position.
Check for battery voltage at the ignition run fuse in
the JB. If OK, go to Step 5. If not OK, repair the
open fused ignition switch output (run) circuit
between the JB and the ignition switch.
(5) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the combination flasher from the JB and
replace it with a known good unit. Reconnect the bat-
tery negative cable. Test the operation of the turn
signal and hazard warning systems. If OK, discard
the faulty combination flasher. If not OK, remove the
test flasher and go to Step 6.
(6) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run) circuit cavity in the JB for the combina-
tion flasher. If OK, go to Step 7. If not OK, repair the
open fused ignition switch output (run) circuit
between the combination flasher and the ignition run
fuse in the JB.
(7) Turn the ignition switch to the Off position.
Check for battery voltage at the B(+) circuit of the JB
for the combination flasher. If OK, go to Step 8. If
not OK, repair the open B(+) circuit between the
combination flasher and the flasher fuse in the JB.
(8) Disconnect and isolate the battery negative
cable. Disconnect the instrument panel wire harness
connector for the turn signal and hazard warning
switches from the multi-function switch connector.
Check for continuity between the ground circuit of
the instrument panel wire harness connector for the
left multi-function switch and a good ground. There
should be continuity. If OK, go to Step 9. If not OK,
repair the open ground circuit.
(9) Check for continuity between the hazard switch
sense 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 10. If not OK, repair the shorted hazard switch
sense circuit between the multi-function switch and
the combination flasher.
(10) Check for continuity between the hazard
switch sense circuit of the JB for the combination
flasher and the instrument panel wire harness con-
WJLAMPS/LIGHTING - EXTERIOR 8L - 3
LAMPS/LIGHTING - EXTERIOR (Continued)

nector for the multi-function switch. There should be
continuity. If OK, go to Step 11. If not OK, repair the
open hazard switch sense circuit between the multi-
function switch and the combination flasher.
(11) Check for continuity between the turn switch
sense 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 12. If not OK, repair the shorted left turn
switch sense circuit between the multi-function
switch and the combination flasher.
(12) Check for continuity between the left turn
switch sense circuit of the JB for the combination
flasher and the instrument panel wire harness con-
nector for the multi-function switch. There should be
continuity. If OK, go to Step 13. If not OK, repair the
open left turn switch sense circuit between the multi-
function switch and the combination flasher.
(13) Check for continuity between the right turn
switch sense circuit of the instrument panel wire
harness connector for the left multi-function switch
and a good ground. There should be no continuity. If
OK, go to Step 14. If not OK, repair the shorted right
turn switch sense circuit between the left multi-func-
tion switch and the combination flasher.
(14) Check for continuity between the right turn
switch sense circuit of the JB for the combination
flasher and the instrument panel wire harness con-
nector for the multi-function switch. There should be
continuity. If OK, test the left multi-function switch.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
EXTERIOR/LEFT MULTI-FUNCTION SWITCH -
DIAGNOSIS AND TESTING). If not OK, repair the
open right turn switch sense circuit between the
multi-function switch and the combination flasher as
required.
SPECIFICATIONS
EXTERIOR LAMPS
CAUTION: Do not use bulbs other than the bulbs
listed in the Bulb Application Table. Damage to
lamp can result. Do not touch halogen bulbs with
fingers or other oily surfaces. Bulb life will be
reduced.
LAMP BULB TYPE
BACK-UP 3157
CENTER HIGH
MOUNTED STOP LAMP921
FOG LAMP 9005
FRONT SIDE MARKER 194/194NA
LAMP BULB TYPE
FRONT TURN SIGNAL 3157/3157NA
HIGH BEAM 9005XS
LOW BEAM 9006XS
LICENSE PLATE 168
TAIL/BRAKE 3157
REAR TURN SIGNAL 3157
UNDERHOOD LAMP 561
AUTO HEADLAMP SENSOR
DIAGNOSIS AND TESTING - AUTO HEADLAMP
SENSOR (AHL)
The auto headlamp sensor needs real sunlight to
properly register the light level. When auto head-
lamps are enabled indoors, the headlamps may be
turned on. The sensor is located in the center of the
defroster grille at the base of the windshield. There
are no faults set in the Body Control Module (BCM)
for a inoperative or missing AHL Sensor. Symptom of
a missing sensor or unconnected sensor would be
that the Headlamps and Parklamps turn on when
the vehicle is started and there is a high level of
ambient light present (ie. daytime). Auto headlamps
should not function in the presence of daylight.
REMOVAL
(1) Remove the instrument panel top cover. (Refer
to 23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL TOP COVER - REMOVAL) for service proce-
dures.
(2) Remove the screw attaching auto headlamp
sensor to instrument panel (Fig. 1).
(3) Disengage the harness connector from auto
headlamp sensor.
(4) Separate the auto headlamp sensor from
instrument panel.
INSTALLATION
(1) Position the auto headlamp sensor on instru-
ment panel.
(2) Engage the harness connector to auto head-
lamp sensor.
(3) Install the screw attaching auto headlamp sen-
sor to instrument panel.
(4) Install the instrument panel top cover. (Refer
to 23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL TOP COVER - INSTALLATION) for service
procedures.
8L - 4 LAMPS/LIGHTING - EXTERIORWJ
LAMPS/LIGHTING - EXTERIOR (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)

HEADLAMP
DESCRIPTION
The headlamps are modular in design.The head-
lamp module contains five bulbs; a dual filament
headlamp low beam bulb, a single filament high
beam bulb, two turnsignal/park bulbs, and a side
marker bulb.
OPERATION
All headlamp, turnsignal, park lamp, and high
beam operations are controlled by the left multifunc-
tion switch. Exterior lamps and bulbs are serviceable
separately.
Fig. 11 Fog Lamp AlignmentÐTypical
1 - VEHICLE CENTERLINE
2 - CENTER OF VEHICLE TO CENTER OF FOG LAMP LENS
3 - HIGH-INTENSITY AREA
4 - FLOOR TO CENTER OF FOG LAMP LENS5 - 100 mm (4 in.)
6 - 7.62 METERS (25 FEET)
7 - FRONT OF FOG LAMP
Fig. 12 Fog Lamp Adjustment
1 - ADJUSTMENT SCREW
2 - FOG LAMP
WJLAMPS/LIGHTING - EXTERIOR 8L - 11
FOG LAMP UNIT (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)