2003 JEEP GRAND CHEROKEE Information

an input from the auto headlamp light sensor to
determine the ambient light levels. If the BCM
decides that the exterior lighting is turned on in the
daylight, it overrides the selected panel dimmer
switch signal by sending a message over the PCI
data bus to illuminate all vacuum fluorescent dis-
plays at full brightness for improved visibility in day-
time light levels. The automatic parade mode has no
effect on the incandescent bulb illumination intensity.
The hard wired cluster illumination circuits
between the left (lighting) multi-function switch and
the BCM may be diagnosed using conventional diag-
nostic tools and methods. The electro-luminescent
lamp is diagnosed using the EMIC self-diagnostic
actuator test. (Refer to 8 - ELECTRICAL/INSTRU-
MENT CLUSTER - DIAGNOSIS AND TESTING).
However, proper testing of the EMIC and the elec-
tronic dimming level messages sent by the BCM over
the PCI data bus requires the use of a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
CHIME SERVICE
The EMIC is programmed to request chime service
from the Body Control Module (BCM) when certain
indicators are illuminated. The EMIC chime request
for illumination of the low fuel indicator is a cus-
tomer programmable feature. When the programmed
conditions are met, the EMIC generates an electronic
chime request message and sends it over the PCI
data bus to the BCM. Upon receiving the proper
chime request, the BCM activates an integral chime
tone generator to provide the audible chime tone to
the vehicle operator. (Refer to 8 - ELECTRICAL/
CHIME WARNING SYSTEM - OPERATION). Proper
testing of the PCI data bus and the electronic chime
request message outputs from the EMIC requires the
use of a DRBIIItscan tool. Refer to the appropriate
diagnostic information.
DIAGNOSIS AND TESTING - INSTRUMENT
CLUSTER
If all of the instrument cluster gauges and/or indi-
cators are inoperative, refer to PRELIMINARY
DIAGNOSIS . If an individual gauge or Programma-
ble Communications Interface (PCI) data bus mes-
sage-controlled indicator is inoperative, refer to
ACTUATOR TEST . If an individual hard wired indi-
cator is inoperative, refer to the diagnosis and testing
information for that specific indicator. If the base
instrument cluster incandescent illumination lighting
is inoperative, refer to CLUSTER ILLUMINATION
DIAGNOSIS . If the premium instrument cluster
electro-luminescent illumination lighting is inopera-
tive, refer to ACTUATOR TEST . Refer to the appro-
priate wiring information. The wiring information
includes wiring diagrams, proper wire and connectorrepair 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.
NOTE: Occasionally, a condition may be encoun-
tered where the gauge pointer for the speedometer
or the tachometer becomes caught on the wrong
side of the pointer stop. To correct this condition,
the technician should use a DRBIIITscan tool and
the appropriate diagnostic information to perform
the instrument cluster self-diagnostic actuator test
procedure. When performed, the actuator test pro-
cedure will automatically return the pointer to the
correct side of the pointer stop.
PRELIMINARY DIAGNOSIS
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.
WARNING: ON VEHICLES EQUIPPED WITH THE
PREMIUM INSTRUMENT CLUSTER, THE CLUSTER
CIRCUITRY PROVIDES AN ALTERNATING CURRENT
TO SUPPLY POWER TO THE ELECTRO-LUMINES-
CENT ILLUMINATION LAMP THROUGH A PIGTAIL
WIRE AND CONNECTOR THAT IS ACCESSIBLE AT
THE BACK OF THE CLUSTER HOUSING. USE
PROPER PRECAUTIONS WHEN HANDLING THIS
UNIT DURING DIAGNOSIS OR SERVICE TO AVOID
ELECTRICAL SHOCK AND POSSIBLE PERSONAL
INJURY.
(1) Check the fused B(+) fuse (Fuse 17 - 10
ampere) in the Junction Block (JB). If OK, go to Step
2. If not OK, repair the shorted circuit or component
as required and replace the faulty fuse.
(2) Check for battery voltage at the fused B(+) fuse
(Fuse 17 - 10 ampere) in the JB. If OK, go to Step 3.
If not OK, repair the open fused B(+) circuit between
WJINSTRUMENT CLUSTER 8J - 7
INSTRUMENT CLUSTER (Continued)

the JB and the Power Distribution Center (PDC) as
required.
(3) Check the fused ignition switch output (run-
start) fuse (Fuse 22 - 10 ampere) in the JB. If OK, go
to Step 4. If not OK, repair the shorted circuit or
component as required and replace the faulty fuse.
(4) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run-start) fuse (Fuse 22 - 10 ampere) in the
JB. If OK, go to Step 5. If not OK, repair the open
fused ignition switch output (run-start) circuit
between the JB and the ignition switch as required.
(5) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the instrument cluster. Reconnect the bat-
tery negative cable. Check for battery voltage at the
fused B(+) circuit cavity of the instrument panel wire
harness connector for the instrument cluster. If OK,
go to Step 6. If not OK, repair the open fused B(+)
circuit between the instrument cluster and the JB as
required.
(6) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run-start) circuit cavity of the instrument
panel wire harness connector for the instrument clus-
ter. If OK, go to Step 7. If not OK, repair the open
fused ignition switch output (run-start) circuit
between the instrument cluster and the JB as
required.
(7) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Check for continuity between each of the ground cir-
cuit cavities of the instrument panel wire harness
connector for the instrument cluster and a good
ground. There should be continuity. If OK, refer to
the ACTUATOR TEST . If not OK, repair the open
ground circuit(s) between the instrument cluster and
ground (G200) as required.
ACTUATOR TEST
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.
WARNING: ON VEHICLES EQUIPPED WITH THE
PREMIUM INSTRUMENT CLUSTER, THE CLUSTER
CIRCUITRY PROVIDES AN ALTERNATING CURRENT
TO SUPPLY POWER TO THE ELECTRO-LUMINES-
CENT ILLUMINATION LAMP THROUGH A PIGTAIL
WIRE AND CONNECTOR THAT IS ACCESSIBLE AT
THE BACK OF THE CLUSTER HOUSING. USE
PROPER PRECAUTIONS WHEN HANDLING THIS
UNIT DURING DIAGNOSIS OR SERVICE TO AVOID
ELECTRICAL SHOCK AND POSSIBLE PERSONAL
INJURY.
The instrument cluster actuator test will put the
instrument cluster into its self-diagnostic mode. In
this mode the instrument cluster can perform a self-
diagnostic test that will confirm that the instrument
cluster circuitry, the gauges, the PCI data bus mes-
sage controlled indicators, and the electro-lumines-
cent illumination lamp (if equipped) are capable of
operating as designed. During the actuator test the
instrument cluster circuitry will sweep each of the
gauge needles across the gauge faces, illuminate each
of the segments in the Vacuum-Fluorescent Display
(VFD), turn all of the PCI data bus message-con-
trolled indicators on and off again, and turn the elec-
tro-luminescent illumination lamp (if equipped) on
and off again.
Successful completion of the actuator test will con-
firm that the instrument cluster is operational. How-
ever, there may still be a problem with the PCI data
bus, the Powertrain Control Module, the Airbag Con-
trol Module (ACM), the Body Control Module (BCM),
the Controller Anti-lock Brake (CAB), the Sentry Key
Immobilizer Module (SKIM), or the inputs to one of
these electronic control modules. Use a DRBIIItscan
tool to diagnose these components. Refer to the
appropriate diagnostic information.
If an individual indicator lamp or the electro-lumi-
nescent illumination lamp do not illuminate during
the actuator test, the instrument cluster should be
removed. However, check that the incandescent lamp
bulb is not faulty, that the bulb holder is properly
installed on the instrument cluster electronic circuit
board, or that the electro-luminescent lamp pigtail
wire connector is properly connected to the instru-
ment cluster electronic circuit board before consider-
ing instrument cluster replacement. If the bulb and
bulb holder, or the electro-luminescent lamp connec-
tion check OK, replace the faulty instrument cluster
unit.
(1) Begin the test with the ignition switch in the
Off position.
(2) Depress the odometer/trip odometer switch but-
ton.
8J - 8 INSTRUMENT CLUSTERWJ
INSTRUMENT CLUSTER (Continued)

(3) While still holding the odometer/trip odometer
switch button depressed, turn the ignition switch to
the On position, but do not start the engine.
(4) Release the odometer/trip odometer switch but-
ton.
(5) The instrument cluster will automatically
begin the actuator test sequence, as follows:
(a) The cluster will turn on, then off again each
of the PCI data bus message controlled indicators
(except Airbag) to confirm the functionality of the
indicator and the cluster control circuitry:
(b) The cluster will sweep the needles for each of
the gauges from minimum to maximum and back
to minimum to confirm the functionality of the
gauge and the cluster control circuitry:
(c) Only on models with a premium version of
the cluster, the cluster will illuminate the electro-
luminescent lamp and turn it off again to confirm
the functionality of the lamp and the cluster con-
trol circuitry.
(d) The cluster will sequentially step the odome-
ter/trip odometer VFD display from all zeros
(000000) through all nines (999999) to confirm the
functionality of all VFD segments and their control
circuitry, then display the software version number,
followed by ªDONEº.
(6) The actuator test is now completed. The instru-
ment cluster will automatically exit the self-diagnos-
tic mode and return to normal operation at the
completion of the test, if the ignition switch is turned
to the Off position during the test, or if a vehicle
speed message indicating that the vehicle is moving
is received from the PCM over the PCI data bus dur-
ing the test.
(7) Go back to Step 1 to repeat the test, if
required.
CLUSTER ILLUMINATION DIAGNOSIS
On models equipped with a base version of the
instrument cluster, the EMIC has several incandes-
cent illumination lamps that are illuminated when-
ever the exterior lighting is turned On. If the
problem being diagnosed is a single inoperative illu-
mination lamp, be certain that the bulb and bulb
holder unit are properly installed in the instrument
cluster electronic circuit board. If no installation
problems are found replace the faulty bulb and bulb
holder unit. If all of the cluster illumination lamps
are inoperative, the most reliable, efficient, and accu-
rate means to diagnose the cluster illumination func-tion of the instrument cluster requires the use of a
DRBIIItscan tool. Refer to the appropriate diagnos-
tic information.
REMOVAL
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.
WARNING: ON VEHICLES EQUIPPED WITH THE
PREMIUM INSTRUMENT CLUSTER, THE CLUSTER
CIRCUITRY PROVIDES AN ALTERNATING CURRENT
TO SUPPLY POWER TO THE ELECTRO-LUMINES-
CENT ILLUMINATION LAMP THROUGH A PIGTAIL
WIRE AND CONNECTOR THAT IS ACCESSIBLE AT
THE BACK OF THE CLUSTER HOUSING. USE
PROPER PRECAUTIONS WHEN HANDLING THIS
UNIT DURING DIAGNOSIS OR SERVICE TO AVOID
ELECTRICAL SHOCK AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cluster bezel from the instrument
panel. (Refer to 23 - BODY/INSTRUMENT PANEL/
CLUSTER BEZEL - REMOVAL).
(3) Remove the two screws that secure the upper
mounting tabs of the instrument cluster to the
underside of the instrument cluster hood formation of
the instrument panel top pad.
(4) Remove the two screws that secure the lower
mounting tabs of the instrument cluster to the
instrument panel structural duct.
WJINSTRUMENT CLUSTER 8J - 9
INSTRUMENT CLUSTER (Continued)

Diagnostic Trouble Code (DTC) for any malfunction it
detects. Each time the airbag indicator fails to illu-
minate due to an open or short in the cluster airbag
indicator circuit, the cluster sends a message notify-
ing the ACM of the condition, then the instrument
cluster and the ACM will each store a DTC. For
proper diagnosis of the airbag system, the ACM, the
PCI data bus, or the electronic message inputs to the
instrument cluster that control the airbag indicator,
a DRBIIItscan tool is required. Refer to the appro-
priate diagnostic information.
BRAKE/PARK BRAKE
INDICATOR
DESCRIPTION
A brake indicator is standard equipment on all
instrument clusters. The brake indicator is located
near the left edge of the instrument cluster, to the
left of the tachometer. There are two versions of the
brake indicator. The version used depends upon the
market for which the vehicle is manufactured. The
version of the brake indicator used for vehicles man-
ufactured for the United States consists of the word
ªBRAKEº imprinted on a red lens. The Rest-Of-World
(ROW) market version of this indicator has two
International Control and Display Symbol icons
imprinted on the red lens; one is the icon for ªBrake
Failureº, and the other is the icon for ªParking
Brakeº. In either case, 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 indicator from being clearly visible when it is not
illuminated. The ªBRAKEº text or the two icons
appear silhouetted against a red field through the
translucent outer layer of the overlay when the indi-
cator is illuminated from behind by a Light Emitting
Diode (LED), which is soldered onto the instrument
cluster electronic circuit board. The brake indicator
lens is serviced as a unit with the instrument cluster
lens, hood and mask unit.
OPERATION
The brake indicator gives an indication to the vehi-
cle operator when the parking brake is applied, when
the fluid level of the brake hydraulic system is low,
or if there are certain malfunctions of the Anti-lock
Brake System (ABS). This indicator is controlled by a
transistor on the instrument cluster electronic circuit
board based upon cluster programming, electronic
messages received by the cluster from the Controller
Anti-lock Brake (CAB) over the Programmable Com-
munications Interface (PCI) data bus, and a hard
wired input to the cluster from the park brake
switch. The brake indicator Light Emitting Diode(LED) is completely controlled by the instrument
cluster 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 LED only illu-
minates when it is provided a path to ground by the
instrument cluster transistor. The instrument cluster
will turn on the brake indicator for the following rea-
sons:
²Bulb Test- Each time the ignition switch is
turned to the On position the brake indicator is illu-
minated by the instrument cluster for about three
seconds as a bulb test.
²Brake Indicator Lamp-On Message- Each
time the cluster receives a brake indicator lamp-on
message from the CAB, the brake indicator will be
illuminated. The indicator remains illuminated until
the cluster receives a brake indicator lamp-off mes-
sage from the CAB.
²Park Brake Switch Input- Each time the
cluster logic circuit detects ground on the park brake
switch sense circuit (park brake switch closed = park
brake applied or not fully released) the brake indica-
tor is illuminated. The indicator remains illuminated
until the park brake switch sense input to the cluster
is an open circuit (park brake switch open = park
brake fully released), or until the ignition switch is
turned to the Off position, whichever occurs first.
²Communication Error- If the cluster receives
no brake indicator lamp-on or lamp-off messages
from the CAB for six consecutive seconds, the brake
indicator is illuminated. The indicator remains illu-
minated until the cluster receives a single valid
brake indicator lamp-off message from the CAB.
²Actuator Test- Each time the cluster is put
through the actuator test, the brake indicator will be
turned on for the duration of the test to confirm the
functionality of the LED and the cluster control cir-
cuitry.
The park brake switch on the park brake pedal
mechanism provides a hard wired ground input to
the instrument cluster circuitry through the red
brake warning indicator driver circuit whenever the
park brake is applied or not fully released. The CAB
continually monitors the input from the brake fluid
level switch and the circuits of the anti-lock brake
system, then sends the proper brake indicator
lamp-on or lamp-off messages to the instrument clus-
ter. If the CAB sends a brake indicator lamp-on mes-
sage after the bulb test, it indicates that the CAB
has detected a brake hydraulic system malfunction
and/or that the ABS system has become inoperative.
The CAB will store a Diagnostic Trouble Code (DTC)
for any malfunction it detects.
WJINSTRUMENT CLUSTER 8J - 15
AIRBAG INDICATOR (Continued)

For further diagnosis of the brake indicator or the
instrument cluster circuitry that controls the indica-
tor, (Refer to 8 - ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND TESTING). The park
brake switch input to the instrument cluster can be
diagnosed using conventional diagnostic tools and
methods. For proper diagnosis of the brake fluid level
switch input to the CAB, the anti-lock brake system,
the CAB, the PCI data bus, or the electronic message
inputs to the instrument cluster that control the
brake indicator, a DRBIIItscan tool is required.
Refer to the appropriate diagnostic information.
DIAGNOSIS AND TESTING - BRAKE INDICATOR
The diagnosis found here addresses an inoperative
park brake indicator condition. If there are problems
with several indicators in the instrument cluster,
(Refer to 8 - ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING). If the brake
indicator stays on with the ignition switch in the On
position and the park brake released, or comes on
while driving, (Refer to 5 - BRAKES - DIAGNOSIS
AND TESTING). If no brake system problem is
found, the following procedures will help to locate a
shorted or open circuit, or a faulty park brake switch
input. Refer to the appropriate wiring information.
The wiring information includes wiring diagrams,
proper wire and connector repair procedures, details
of wire harness routing and retention, connector pin-
out information and location views for the various
wire harness connectors, splices and grounds.
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.
INDICATOR ILLUMINATES DURING BULB TEST, BUT DOES
NOT WHEN PARK BRAKE APPLIED
(1) Disconnect and isolate the battery negative
cable. Disconnect the instrument panel wire harness
connector for the park brake switch from the switch
terminal. Apply the parking brake. Check for conti-nuity between the park brake switch terminal and a
good ground. There should be continuity. If OK, go to
Step 2. If not OK, replace the faulty park brake
switch.
(2) Disconnect the instrument panel wire harness
connector for the instrument cluster from the cluster
connector receptacle. Check for continuity between
the red brake warning indicator driver circuit cavi-
ties of the instrument panel wire harness connector
for the park brake switch and the instrument panel
wire harness connector for the instrument cluster.
There should be continuity. If not OK, repair the
open red brake warning indicator driver circuit
between the park brake switch and the instrument
cluster as required.
INDICATOR REMAINS ILLUMINATED - BRAKE SYSTEM
CHECKS OK
(1) Disconnect and isolate the battery negative
cable. Disconnect the instrument panel wire harness
connector for the park brake switch from the park
brake switch terminal. Check for continuity between
the terminal of the park brake switch and a good
ground. There should be no continuity with the park
brake released, and continuity with the park brake
applied. If OK, go to Step 2. If not OK, replace the
faulty park brake switch.
(2) Disconnect the instrument panel wire harness
connector for the instrument cluster from the cluster
connector receptacle. Check for continuity between
the red brake warning indicator driver circuit cavity
of the instrument panel wire harness connector for
the park brake switch and a good ground. There
should be no continuity. If not OK, repair the shorted
red brake warning indicator driver circuit between
the park brake switch and the instrument cluster as
required.
CHECK GAUGES INDICATOR
DESCRIPTION
A check gauges indicator is standard equipment on
all instrument clusters. The check gauges indicator is
located on the right edge of the instrument cluster, to
the right of the speedometer. The check gauges indi-
cator consists of the words ªCHECK GAGESº
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 indicator from being clearly visible when it is not
illuminated. The ªCHECK GAGESº text appears sil-
houetted against a red field through the translucent
outer layer of the overlay when the indicator is illu-
minated from behind by a Light Emitting Diode
(LED), which is soldered onto the instrument cluster
electronic circuit board. The check gauges indicator
8J - 16 INSTRUMENT CLUSTERWJ
BRAKE/PARK BRAKE INDICATOR (Continued)

lens is serviced as a unit with the instrument cluster
lens, hood and mask unit.
OPERATION
The check gauges indicator gives an indication to
the vehicle operator when certain instrument cluster
gauge readings reflect a condition requiring immedi-
ate attention. This indicator is controlled by a tran-
sistor 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 Communica-
tions Interface (PCI) data bus. The check gauges
indicator Light Emitting Diode (LED) is completely
controlled by the instrument cluster logic circuit, and
that logic will only allow this indicator to operate
when the instrument cluster receives a battery cur-
rent input on the fused ignition switch output (run-
start) circuit. Therefore, the indicator will always be
off when the ignition switch is in any position except
On or Start. The LED only illuminates when it is
provided a path to ground by the instrument cluster
transistor. The instrument cluster will turn on the
check gauges indicator for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the check gauges indicator
is illuminated for about three seconds as a bulb test.
²Engine Temperature High/Critical Message
- Each time the cluster receives a message from the
PCM indicating the engine coolant temperature is
high or critical [above about 127É C (261É F) for gas-
oline engines except Gulf Coast Country (GCC), 129É
C (264É F) for GCC gasoline engines, and 118É C
(244É F) for diesel engines], the check gauges indica-
tor is illuminated. The indicator remains illuminated
until the cluster receives a message indicating the
engine coolant temperature is not high or critical
[about 125É C (255É F) or below for all gasoline
engines, or 115É C (239É F) for all diesel engines].
²Engine Oil Pressure Low Message- Each
time the cluster receives a message from the PCM
indicating the engine oil pressure is about 0.28
kg/cm or lower (about 4 psi or lower), the check
gauges indicator is illuminated. The indicator
remains illuminated until the cluster receives a mes-
sage from the PCM indicating that the engine oil
pressure is about 0.56 kg/cm or higher (about 8 psi
or higher). The cluster will only turn the indicator on
in response to an engine oil pressure low message if
the ignition switch is in the On position and the
engine speed is 300 rpm or greater.
²System Voltage Low Message- Each time the
cluster receives a message from the PCM indicating
a low system voltage condition (system voltage is
about eleven volts or lower), the check gauges indica-
tor is illuminated. The indicator remains illuminateduntil the cluster receives a message from the PCM
indicating 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-
ing a high system voltage condition (system voltage
is about sixteen volts or higher), the check gauges
indicator is illuminated. The indicator remains illu-
minated until the cluster receives a message from
the PCM indicating there is no high system voltage
condition (system voltage is below about sixteen
volts, but higher than about eleven volts).
²Actuator Test- Each time the cluster is put
through the actuator test, the check gauges 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 engine temper-
ature, oil pressure, and electrical system voltage,
then sends the proper messages to the instrument
cluster. For further diagnosis of the check gauges
indicator or the instrument cluster circuitry that con-
trols the indicator, (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - DIAGNOSIS AND
TESTING). For proper diagnosis of the PCM, the PCI
data bus, or the electronic message inputs to the
instrument cluster that control the check gauges
indicator, a DRBIIItscan tool is required. Refer to
the appropriate diagnostic information.
COOLANT LOW INDICATOR
DESCRIPTION
A coolant low indicator is only found in the instru-
ment clusters of vehicles equipped with an optional
diesel engine. The coolant low indicator should not be
confused with the coolant level low indication pro-
vided by the Electronic Vehicle Information Center
(EVIC) of vehicles equipped with a gasoline engine,
although they do perform the same function. The
coolant low indicator is located in the lower left cor-
ner of the instrument cluster, to the left of the
tachometer. The coolant low indicator consists of an
International Control and Display Symbol icon for
ªLow Coolantº imprinted on an amber 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 indicator from being clearly
visible when it is not illuminated. The icon appears
silhouetted against an amber field through the trans-
lucent outer layer of the overlay when the indicator
is illuminated from behind by a replaceable incandes-
cent bulb and bulb holder unit located on the instru-
ment cluster electronic circuit board. When the
WJINSTRUMENT CLUSTER 8J - 17
CHECK GAUGES INDICATOR (Continued)

the gauge needle at the last indication for about
twelve seconds or until a new engine temperature
message is received, whichever occurs first. After
twelve seconds, the cluster will return the gauge nee-
dle 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 in order
to confirm the functionality of the gauge and the
cluster control circuitry.
The PCM continually monitors the engine coolant
temperature sensor to determine the engine operat-
ing temperature. The PCM then sends the proper
engine coolant temperature messages to the instru-
ment cluster. For further diagnosis of the engine cool-
ant temperature gauge or the instrument cluster
circuitry that controls the gauge, (Refer to 8 - ELEC-
TRICAL/INSTRUMENT CLUSTER - DIAGNOSIS
AND TESTING). If the instrument cluster moves the
engine coolant temperature gauge needle to indicate
a high or critical engine temperature, it may indicate
that the engine or the engine cooling system requires
service. For proper diagnosis of the engine coolant
temperature sensor, the PCM, the PCI data bus, or
the electronic message inputs to the instrument clus-
ter that control the engine coolant temperature
gauge, a DRBIIItscan tool is required. Refer to the
appropriate diagnostic information.
FRONT FOG LAMP INDICATOR
DESCRIPTION
A front fog lamp indicator is standard equipment
on all instrument clusters, but is only functional on
vehicles equipped with the optional front fog lamps.
The front fog lamp indicator is located on the left
edge of the instrument cluster, to the left of the
tachometer. The front fog lamp indicator consists of
an International Control and Display Symbol icon for
ªFront Fog Lightº imprinted on a green 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 indicator from being
clearly visible when it is not illuminated. The icon
appears silhouetted against a green field through the
translucent outer layer of the overlay when the indi-
cator is illuminated from behind by a replaceable
incandescent bulb and bulb holder unit located on
the instrument cluster electronic circuit board. When
the exterior lighting is turned On, the illumination
intensity of the front fog lamp indicator is dimmable,
which is adjusted using the panel lamps dimmer con-
trol ring on the control stalk of the left multi-func-
tion switch. The front fog lamp indicator lens isserviced as a unit with the instrument cluster lens,
hood and mask unit.
OPERATION
The front fog lamp indicator gives an indication to
the vehicle operator whenever the front fog lamps
are illuminated. 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 Body Control
Module (BCM) over the Programmable Communica-
tions Interface (PCI) data bus. The front fog lamp
indicator bulb is completely controlled by the instru-
ment cluster logic circuit, and that logic will allow
this indicator to operate whenever the instrument
cluster receives a battery current input on the fused
B(+) circuit. Therefore, the indicator can be illumi-
nated regardless of the ignition switch position. The
bulb only illuminates when it is provided a path to
ground by the instrument cluster transistor. The
instrument cluster will turn on the front fog lamp
indicator for the following reasons:
²Front Fog Lamp Indicator Lamp-On Mes-
sage- Each time the cluster receives a front fog
lamp indicator lamp-on message from the BCM indi-
cating that the front fog lamps are turned On, the
front fog lamp indicator will be illuminated. The indi-
cator remains illuminated until the cluster receives a
front fog lamp indicator lamp-off message from the
BCM.
²Actuator Test- Each time the cluster is put
through the actuator test, the front fog lamp indica-
tor will be turned on for the duration of the test to
confirm the functionality of the bulb and the cluster
control circuitry.
The BCM continually monitors the exterior light-
ing (left multi-function) switch to determine the
proper outputs to the front fog lamp relay. The BCM
then sends the proper front fog lamp indicator
lamp-on and lamp-off messages to the instrument
cluster. If the front fog lamp indicator fails to light
during the actuator test, replace the bulb with a
known good unit. For further diagnosis of the front
fog lamp indicator or the instrument cluster circuitry
that controls the indicator, (Refer to 8 - ELECTRI-
CAL/INSTRUMENT CLUSTER - DIAGNOSIS AND
TESTING). For proper diagnosis of the front fog
lamp system, the BCM, the PCI data bus, or the elec-
tronic message inputs to the instrument cluster that
control the front fog lamp indicator, a DRBIIItscan
tool is required. Refer to the appropriate diagnostic
information.
8J - 20 INSTRUMENT CLUSTERWJ
ENGINE TEMPERATURE GAUGE (Continued)

proper percent tank full messages to the instrument
cluster. For further diagnosis of the fuel gauge or the
instrument cluster circuitry that controls the gauge,
(Refer to 8 - ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING). For proper
diagnosis of the fuel tank sender, the PCM, the PCI
data bus, or the electronic message inputs to the
instrument cluster that control the fuel gauge, a
DRBIIItscan tool is required. Refer to the appropri-
ate diagnostic information.
HIGH BEAM INDICATOR
DESCRIPTION
A high beam indicator is standard equipment on
all instrument clusters. The high beam indicator is
located near the upper edge of the instrument clus-
ter, between the tachometer and the speedometer.
The high beam indicator consists of an International
Control and Display Symbol icon for ªHigh Beamº
imprinted on a blue 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 indicator from being clearly visible when it is not
illuminated. The icon appears silhouetted against a
blue 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 elec-
tronic circuit board. When the exterior lighting is
turned On, the illumination intensity of the high
beam indicator is dimmable, which is adjusted using
the panel lamps dimmer control ring on the control
stalk of the left multi-function switch. The high beam
indicator lens is serviced as a unit with the instru-
ment cluster lens, hood and mask unit.
OPERATION
The high beam indicator gives an indication to the
vehicle operator whenever the headlamp high beams
are illuminated. This indicator is controlled by a
transistor on the instrument cluster electronic circuit
board based upon cluster programming and elec-
tronic messages received by the cluster from the
Body Control Module (BCM) over the Programmable
Communications Interface (PCI) data bus. The high
beam indicator bulb is completely controlled by the
instrument cluster logic circuit, and that logic will
allow this indicator to operate whenever the instru-
ment cluster receives a battery current input on the
fused B(+) circuit. Therefore, the indicator can be
illuminated regardless of the ignition switch position.
The LED only illuminates when it is provided a path
to ground by the instrument cluster transistor. Theinstrument cluster will turn on the high beam indi-
cator for the following reasons:
²High Beam Indicator Lamp-On Message-
Each time the cluster receives a high beam indicator
lamp-on message from the BCM indicating that the
headlamp high beams are turned On, the high beam
indicator will be illuminated. The indicator remains
illuminated until the cluster receives a high beam
indicator lamp-off message from the BCM.
²Actuator Test- Each time the cluster is put
through the actuator test, the high beam 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 BCM continually monitors the exterior light-
ing (left multi-function) switch to determine the
proper outputs to the headlamp low beam and high
beam relays. The BCM then sends the proper high
beam indicator lamp-on and lamp-off messages to the
instrument cluster. If the high beam indicator fails to
light during the actuator test, replace the bulb with a
known good unit. For further diagnosis of the high
beam indicator or the instrument cluster circuitry
that controls the indicator, (Refer to 8 - ELECTRI-
CAL/INSTRUMENT CLUSTER - DIAGNOSIS AND
TESTING). For proper diagnosis of the headlamp
system, the BCM, the PCI data bus, or the electronic
message inputs to the instrument cluster that control
the high beam indicator, a DRBIIItscan tool is
required. Refer to the appropriate diagnostic infor-
mation.
LOW FUEL INDICATOR
DESCRIPTION
A low fuel indicator is standard equipment on all
instrument clusters. The low fuel indicator is located
near the left edge of the instrument cluster, to the left
of the tachometer. The low fuel indicator consists of an
International Control and Display Symbol icon for
ªFuelº imprinted on an amber 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 silhou-
etted against an amber field through the translucent
outer layer of the overlay when the indicator is illumi-
nated from behind by a replaceable incandescent bulb
and bulb holder unit located on the instrument cluster
electronic circuit board. When the exterior lighting is
turned On, the illumination intensity of the low fuel
indicator is dimmable, which is adjusted using the
panel lamps dimmer control ring on the control stalk
of the left multi-function switch. The low fuel indica-
8J - 22 INSTRUMENT CLUSTERWJ
FUEL GAUGE (Continued)