2003 JEEP GRAND CHEROKEE Information

switch is turned to the Off position, whichever occurs
first.
²Actuator Test- Each time the cluster is put
through the actuator test, the transmission over-tem-
perature indicator will be turned on for the duration
of the test to confirm the functionality of the bulb
and the cluster control circuitry.
The PCM or TCM continually monitors the trans-
mission temperature sensor to determine the trans-
mission operating condition. The PCM or TCM then
sends the proper trans over-temp indicator lamp-on
or lamp-off messages to the instrument cluster. If the
transmission over-temperature indicator fails to light
during the bulb test, replace the bulb with a known
good unit. If the instrument cluster turns on the
transmission over-temperature indicator due to a
high transmission oil temperature condition, it may
indicate that the transmission or the transmission
cooling system are being overloaded or that they
require service. For further diagnosis of the trans-
mission over-temperature indicator or the instrument
cluster circuitry that controls the indicator, (Refer to
8 - ELECTRICAL/INSTRUMENT CLUSTER - DIAG-
NOSIS AND TESTING). For proper diagnosis of the
transmission temperature sensor, the PCM, the
TCM, the PCI data bus, or the electronic message
inputs to the instrument cluster that control the
transmission over-temperature indicator, a DRBIIIt
scan tool is required. Refer to the appropriate diag-
nostic information.
TURN SIGNAL INDICATOR
DESCRIPTION
Two turn signal indicators, one right and one left,
are standard equipment on all instrument clusters.
The turn signal indicators are located near the upper
edge of the instrument cluster, the left one is left of
the tachometer, and the right one is right of the
speedometer. Each turn signal indicator consists of
an International Control and Display Symbol icon for
ªTurn Warningº imprinted on a green lens. Each lens
is located behind a dedicated cutout in the opaque
layer of the instrument cluster overlay. The dark
outer layer of the overlay prevents these icons from
being clearly visible when they are not illuminated.
The icons appear silhouetted against a green field
through the translucent outer layer of the overlay
when the indicator is illuminated from behind by a
replaceable incandescent bulb and bulb holder unit
located on the instrument cluster electronic circuit
board. The turn signal indicator lenses are serviced
as a unit with the instrument cluster lens, hood and
mask unit.
OPERATION
The turn signal indicators give an indication to the
vehicle operator that the turn signal (left or right
indicator flashing) or hazard warning (both left and
right indicators flashing) have been selected and are
operating. These indicators are controlled by two
individual hard wired inputs from the combination
flasher circuitry to the instrument cluster electronic
circuit board. Each turn signal indicator bulb is
grounded on the instrument cluster electronic circuit
board at all times; therefore, these indicators remain
functional regardless of the ignition switch position.
Each indicator bulb will only illuminate when it is
provided with battery current by the combination
flasher in the Junction Block (JB).
The turn signal indicators are connected in parallel
with the other turn signal circuits. This arrangement
allows the turn signal indicators to remain func-
tional, regardless of the condition of the other cir-
cuits in the turn signal and hazard warning systems.
The combination flasher outputs to the instrument
cluster turn signal indicator inputs can be diagnosed
using conventional diagnostic tools and methods. For
more information on the turn signal and hazard
warning system, (Refer to 8 - ELECTRICAL/LAMPS/
LIGHTING - EXTERIOR - OPERATION - TURN
SIGNAL & HAZARD WARNING SYSTEM).
DIAGNOSIS AND TESTING - TURN SIGNAL
INDICATOR
The diagnosis found here addresses an inoperative
turn signal indicator condition. If the problem being
diagnosed is related to inoperative turn signal or
hazard warning lamps, be certain to repair the turn
signal and hazard warning system before attempting
to diagnose or repair the turn signal indicators.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
EXTERIOR - DIAGNOSIS AND TESTING - TURN
SIGNAL & HAZARD WARNING SYSTEM). If no
turn signal and hazard warning system problem is
found, the following procedure will help locate an
open in the turn signal indicator circuit. Refer to the
appropriate wiring information. The wiring informa-
tion includes wiring diagrams, proper wire and con-
nector 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.
WJINSTRUMENT CLUSTER 8J - 33
TRANS TEMP INDICATOR (Continued)

ing the system voltage is high (system voltage is
about sixteen volts or higher), the gauge needle is
moved to the relative voltage position in the red zone
of the gauge scale and the check gauges indicator is
illuminated. The gauge needle remains in the red
zone and the check gauges indicator remains illumi-
nated until the cluster receives a message from the
PCM indicating there is no high system voltage con-
dition (system voltage is below about sixteen volts,
but higher than about eleven volts).
²Communication Error- If the cluster fails to
receive a system voltage message, it will hold the
gauge needle at the last indication for about twelve
seconds, until a new message is received, or until the
ignition switch is turned to the Off position, which-
ever occurs first. After twelve seconds, the cluster
will return the gauge needle to the low end of the
gauge scale.
²Actuator Test- Each time the cluster is put
through the actuator test, the gauge needle will be
swept across the entire gauge scale and back to con-
firm the functionality of the gauge and the cluster
control circuitry.
The PCM continually monitors the system voltage
to control the generator output. The PCM then sends
the proper system voltage messages to the instru-
ment cluster. For further diagnosis of the voltage
gauge or the instrument cluster circuitry that con-
trols the gauge, (Refer to 8 - ELECTRICAL/INSTRU-
MENT CLUSTER - DIAGNOSIS AND TESTING). If
the instrument cluster turns on the check gauges
indicator due to a system voltage low or high condi-
tion, it may indicate that the charging system
requires service. For proper diagnosis of the charging
system, the PCI data bus, or the electronic message
inputs to the instrument cluster that control the volt-
age gauge, a DRBIIItscan tool is required. Refer to
the appropriate diagnostic information.
WAIT-TO-START INDICATOR
DESCRIPTION
A wait-to-start indicator is only found in the
instrument clusters of vehicles equipped with an
optional diesel engine. The wait-to-start indicator is
located near the lower edge of the tachometer gauge
dial face, to the right of center. The wait-to-start
indicator consists of an International Control and
Display Symbol icon for ªDiesel Preheatº imprinted
on an amber lens. The lens is located behind a cutout
in the opaque layer of the tachometer gauge dial face
overlay. The dark outer layer of the gauge dial face
overlay prevents the icon from being clearly visible
when the indicator is not illuminated. The icon
appears silhouetted against an amber field throughthe translucent outer layer of the gauge dial face
overlay when the indicator is illuminated from
behind by a replaceable incandescent bulb and bulb
holder unit located on the instrument cluster elec-
tronic circuit board. The wait-to-start indicator lens
is serviced as a unit with the instrument cluster.
OPERATION
The wait-to-start indicator gives an indication to
the vehicle operator when the diesel engine glow
plugs are energized in their preheat operating mode.
This indicator is controlled by a transistor on the
instrument cluster circuit board based upon cluster
programming and electronic messages received by
the cluster from the Powertrain Control Module
(PCM) over the Programmable Communications
Interface (PCI) data bus. The wait-to-start indicator
bulb is completely controlled by the instrument clus-
ter logic circuit, and that logic will only allow this
indicator to operate when the instrument cluster
receives a battery current input on the fused ignition
switch output (run-start) circuit. Therefore, the indi-
cator will always be off when the ignition switch is in
any position except On or Start. The bulb only illu-
minates when it is switched to ground by the instru-
ment cluster transistor. The instrument cluster will
turn on the wait-to-start indicator for the following
reasons:
²Wait-To-Start Indicator Lamp-On Message-
Each time the cluster receives a wait-to-start indica-
tor lamp-on message from the PCM indicating the
glow plugs are heating and the driver must wait to
start the engine, the wait-to-start indicator will be
illuminated. The indicator remains illuminated until
the cluster receives a wait-to-start indicator lamp-off
message, or until the ignition switch is turned to the
Off position, whichever occurs first.
²Actuator Test- Each time the cluster is put
through the actuator test, the wait-to-start indicator
will be turned on for the duration of the test to con-
firm the functionality of the bulb and the cluster con-
trol circuitry.
The PCM continually monitors the ambient tem-
perature and the glow plug pre-heater circuits to
determine how long the glow plugs must be heated in
the pre-heat operating mode. The PCM then sends
the proper wait-to-start indicator lamp-on and lamp-
off messages to the instrument cluster. If the wait-to-
start indicator fails to light during the actuator test,
replace the bulb with a known good unit. For further
diagnosis of the wait-to-start indicator or the instru-
ment cluster circuitry that controls the indicator,
(Refer to 8 - ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING). For proper
diagnosis of the glow plug pre-heater control circuits,
the PCM, the PCI data bus, or the electronic message
WJINSTRUMENT CLUSTER 8J - 35
VOLTAGE GAUGE (Continued)

inputs to the instrument cluster that control the
wait-to-start indicator, a DRBIIItscan tool is
required. Refer to the appropriate diagnostic infor-
mation.
WATER-IN-FUEL INDICATOR
DESCRIPTION
A water-in-fuel indicator is only found in the
instrument clusters of vehicles equipped with an
optional diesel engine. The water-in-fuel indicator is
located near the left edge of the instrument cluster,
to the left of the tachometer. The water-in-fuel indi-
cator consists of an International Control and Dis-
play Symbol icon for ªWater in Fuelº imprinted on a
red lens. The lens is located behind a cutout in the
opaque layer of the instrument cluster overlay. The
dark outer layer of the overlay prevents the icon
from being clearly visible when the indicator is not
illuminated. The icon appears silhouetted against a
red field through the translucent outer layer of the
overlay when the indicator is illuminated from
behind by a Light Emitting Diode (LED), which is
soldered onto the instrument cluster electronic circuit
board. The water-in-fuel indicator lens is serviced as
a unit with the instrument cluster lens, hood and
mask unit.
OPERATION
The water-in-fuel indicator gives an indication to
the vehicle operator when there is excessive water in
the fuel system. This indicator is controlled by a
transistor on the instrument cluster circuit board
based upon cluster programming and electronic mes-
sages received by the cluster from the Powertrain
Control Module (PCM) over the Programmable Com-
munications Interface (PCI) data bus. The water-in-
fuel indicator Light Emitting Diode (LED) is
completely controlled by the instrument cluster logic
circuit, and that logic will only allow this indicator tooperate when the instrument cluster receives a bat-
tery current input on the fused ignition switch out-
put (run-start) circuit. Therefore, the indicator will
always be off when the ignition switch is in any posi-
tion except On or Start. The LED only illuminates
when it is provided a path to ground by the instru-
ment cluster transistor. The instrument cluster will
turn on the water-in-fuel indicator for the following
reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the water-in-fuel indicator
is illuminated for about three seconds as a bulb test.
²Water-In-Fuel Indicator Lamp-On Message-
Each time the cluster receives a water-in-fuel indica-
tor lamp-on message from the PCM indicating there
is excessive water in the diesel fuel system, the
water-in-fuel indicator will be illuminated. The indi-
cator remains illuminated until the cluster receives a
water-in-fuel indicator lamp-off message, or until the
ignition switch is turned to the Off position, which-
ever occurs first.
²Actuator Test- Each time the cluster is put
through the actuator test, the water-in-fuel indicator
will be turned on for the duration of the test to con-
firm the functionality of the LED and the cluster con-
trol circuitry.
The PCM continually monitors the water-in-fuel
sensor to determine whether there is excessive water
in the diesel fuel. The PCM then sends the proper
water-in-fuel indicator lamp-on and lamp-off mes-
sages to the instrument cluster. For further diagnosis
of the water-in-fuel indicator or the instrument clus-
ter circuitry that controls the indicator, (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNO-
SIS AND TESTING). For proper diagnosis of the
water-in-fuel sensor, the PCM, the PCI data bus, or
the electronic message inputs to the instrument clus-
ter that control the water-in-fuel indicator, a
DRBIIItscan tool is required. Refer to the appropri-
ate diagnostic information.
8J - 36 INSTRUMENT CLUSTERWJ
WAIT-TO-START INDICATOR (Continued)

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)

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)

DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING Ð HEADLAMP
SYSTEM
HEADLAMPS
CONDITION POSSIBLE CAUSES CORRECTION
HEADLAMPS ARE DIM
WITH ENGINE IDLING1. Loose or corroded battery cables. 1. Clean and secure battery cable clamps
and posts.
OR IGNITION TURNED
OFF2. Loose or worn generator drive belt. 2. Adjust or replace generator drive belt.
3. Charging system output too low. 3. Test and repair charging system, refer
to Electrical, Charging
4. Battery has insufficient charge. 4. Test battery state-of -charge, refer to
Electrical, Battery System.
5. Battery is sulfated or shorted. 5. Load test battery, refer to
Electrical,Battery System.
6. Poor lighting circuit Z1-ground. 6. Test for voltage drop across Z1-ground
locations, refer to Electrical, Wiring Digram
Information.
7. Both headlamp bulbs defective. 7. Replace both headlamp bulbs.
HEADLAMP BULBS BURN
OUT1. Charging system output too high. 1. Test and repair charging system, refer
to Electrical, Charging.
FREQUENTLY 2. Loose or corroded terminals or
splices in circuit.2. Inspect and repair all connectors and
splices, refer to Electrical, Wiring
Information.
HEADLAMPS ARE DIM
WITH ENGINE RUNNING1. Charging system output too low. 1. Test and repair charging system, refer
to Electrical, Wiring Information.
ABOVE IDLE* 2. Poor lighting circuit Z1-ground. 2. Test for voltage drop across Z1-ground
locations, refer to Electrical, Wiring
Information.
3. High resistance in headlamp
circuit.3. Test amperage draw of headlamp
circuit.
4. Both headlamp bulbs defective. 4. Replace both headlamp bulbs.
HEADLAMPS FLASH
RANDOMLY1. Poor lighting circuit Z1-ground. 1. Test for voltage drop across Z1-ground
locations, refer to Electrical, Wiring
Information.
2. High resistance in headlamp
circuit.2. Test amperage draw of headlamp
circuit. Should not exceed 30 amps.
3. Loose or corroded terminals or
splices in circuit.3. Inspect and repair all connectors and
splices, refer to Electrical, Wiring
Information.
HEADLAMPS DO NOT
ILLUMINATE1. No voltage to headlamps. 1. Repair open headlamp circuit, refer to
Electrical, Wiring Information.
2. No Z1-ground at headlamps. 2. Repair circuit ground, refer to Electrical,
Wiring Information.
8L - 12 LAMPS/LIGHTING - EXTERIORWJ
HEADLAMP (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
3. Faulty headlamp switch. 3. Refer to BCM diagnostics.
4. Blown fuse for headlamps. 4. Replace fuse refer to Electrical, Wiring
Information.
5. Broken connector terminal or wire
splice in headlamp circuit.5. Repair connector terminal or wire splice.
6. Both headlamp bulbs defective. 6. Replace both headlamp bulbs.
*Canada vehicles must have lamps ON.
FOG LAMP
CONDITION POSSIBLE CAUSES CORRECTION
FOG LAMPS ARE DIM
WITH ENGINE IDLING
OR IGNITION TURNED
OFF.1. Loose or corroded battery cables. 1. Clean and secure battery cable clamps
and posts.
2. Loose or worn generator drive belt. 2. Adjust or replace generator drive belt.
3. Charging system output too low. 3. Test and repair charging system. Refer to
Electrical, Charging,
4. Battery has insufficient charge. 4. Test battery state-of -charge. Refer to
Electrical, Battery System.
5. Battery is sulfated or shorted. 5. Load test battery. Refer to Electrical,
Battery System.
6. Poor lighting circuit Z1-ground. 6. Test for voltage drop across Z1-ground
locations. Refer to Electrical, Wiring
Information.
FOG LAMP BULBS BURN
OUT FREQUENTLY1. Charging system output too high. 1. Test and repair charging system. Refer to
Electrical, Charging.
2. Loose or corroded terminals or
splices in circuit.2. Inspect and repair all connectors and
splices. Refer to Electrical, Wiring
Information.
FOG LAMPS ARE DIM
WITH ENGINE RUNNING
ABOVE IDLE1. Charging system output too low. 1. Test and repair charging system. Refer to
Electrical, Charging.
2. Poor lighting circuit Z1-ground. 2. Test for voltage drop across Z1-ground
locations. Refer to Electrical, Wiring
Information.
3. High resistance in fog lamp circuit. 3. Test amperage draw of fog lamp circuit.
FOG LAMPS FLASH
RANDOMLY1. Poor lighting circuit Z1-ground. 1. Test for voltage drop across Z1-ground
locations. Refer to Electrical, Wiring
Information.
2. High resistance in fog lamp circuit. 2. Test amperage draw of fog lamp circuit.
3. Faulty multifunction switch. 3. Refer to Electrical, Electronic Control
Modules.
4. Loose or corroded terminals or
splices in circuit.4. Inspect and repair all connectors and
splices. Refer to Electrical, Wiring
Information.
WJLAMPS/LIGHTING - EXTERIOR 8L - 13
HEADLAMP (Continued)