2002 JEEP GRAND CHEROKEE Lamps

(5) Pull the upper mounting tabs of the instrument
cluster downward, then pull the instrument cluster
rearward far enough to access the instrument panel
wire harness connector for the instrument cluster
(Fig. 3).
(6) Disconnect the instrument panel wire harness
connector for the instrument cluster from the connec-
tor receptacle on the back of the instrument cluster
housing.
(7) Remove the instrument cluster from the instru-
ment panel.
DISASSEMBLY
Some of the components for the instrument cluster
used in this vehicle are serviced individually. The
serviced components include: the incandescent
instrument cluster indicator and illumination lamp
bulbs (including the integral bulb holders), the clus-
ter lens, hood and mask unit, and the cluster housing
rear cover. Following are the procedures for disas-
sembling these components from the instrument clus-
ter unit.
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.
CLUSTER BULB
This procedure applies to each of the incandescent
cluster illumination lamp or indicator bulb and bulb
holder units. However, the illumination lamps and
the indicators use different bulb and bulb holder unit
sizes. They must never be interchanged. Be certain
that any bulb holder removed from the electronic cir-
cuit board is reinstalled in the correct position.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the instrument cluster from the instru-
ment panel. (Refer to 8 - ELECTRICAL/INSTRU-
MENT CLUSTER - REMOVAL).
(3) Turn the bulb holder counterclockwise about
sixty degrees on the cluster electronic circuit board
(Fig. 4).
(4) Pull the bulb and bulb holder straight back to
remove it from the bulb mounting hole in the cluster
electronic circuit board.
CLUSTER LENS, HOOD AND MASK
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the instrument cluster from the instru-
ment panel. (Refer to 8 - ELECTRICAL/INSTRU-
MENT CLUSTER - REMOVAL).
(3) Work around the perimeter of the cluster hous-
ing to disengage each of the eight latches that secure
the cluster lens, hood and mask unit to the cluster
housing (Fig. 5).
(4) Gently pull the cluster lens, hood and mask
unit away from the cluster housing.
CLUSTER HOUSING REAR COVER
(1) Disconnect and isolate the battery negative
cable.
Fig. 3 Instrument Cluster Remove/Install
1 - INSTRUMENT PANEL WIRE HARNESS CONNECTOR
2 - INSTRUMENT CLUSTER
8J - 10 INSTRUMENT CLUSTERWJ
INSTRUMENT CLUSTER (Continued)

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.
CLUSTER BULB
This procedure applies to each of the incandescent
cluster illumination lamp or indicator bulb and bulb
holder units. However, the illumination lamps and
the indicators use different bulb and bulb holder unit
sizes. They must never be interchanged.
CAUTION: Be certain that any bulb and bulb holder
unit removed from the cluster electronic circuit
board is reinstalled in the correct position. Always
use the correct bulb size and type for replacement.
An incorrect bulb size or type may overheat and
cause damage to the instrument cluster, the elec-
tronic circuit board and/or the gauges.
(1) Insert the bulb and bulb holder straight into
the correct bulb mounting hole in the cluster elec-
tronic circuit board (Fig. 4).
(2) With the bulb holder fully seated against the
cluster electronic circuit board, turn the bulb holder
clockwise about sixty degrees to lock it into place.
(3) Reinstall the instrument cluster onto the
instrument panel. (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - INSTALLATION).
(4) Reconnect the battery negative cable.
CLUSTER LENS, HOOD AND MASK
(1) Position the cluster lens, hood and mask unit
over the face of the instrument cluster (Fig. 5). Be
certain that the odometer/trip odometer switch but-
ton is inserted through the proper clearance holes in
the mask and the lens.
(2) Press firmly and evenly on the cluster lens,
hood and mask unit to install it onto the cluster
housing.
(3) Work around the perimeter of the cluster hous-
ing to be certain that each of the eight latches that
secure the cluster lens, hood and mask unit to the
cluster housing is fully engaged.
(4) Reinstall the instrument cluster into the
instrument panel. (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - INSTALLATION).
(5) Reconnect the battery negative cable.CLUSTER HOUSING REAR COVER
(1) Position the rear cover onto the back of the
cluster housing (Fig. 6).
(2) Press firmly and evenly on the rear cover until
each of the eight latches (four on top, four on the bot-
tom) that secure the upper and lower edges of the
rear cover to the top and bottom of the cluster hous-
ing are fully engaged.
(3) Install and tighten the seven screws that
secure the rear cover to the back of the cluster hous-
ing. Tighten the screws to 2 N´m (20 in. lbs.).
(4) On models with a premium cluster only, recon-
nect the electro-luminescent illumination lamp pig-
tail wire connector to the receptacle on the cluster
electronic circuit board and engage the pigtail wire
under the integral routing clip on the rear cover.
(5) Reinstall the instrument cluster onto the
instrument panel. (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - INSTALLATION).
(6) Reconnect the battery negative cable.
INSTALLATION
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) Position the instrument cluster to the instru-
ment panel.
8J - 12 INSTRUMENT CLUSTERWJ
INSTRUMENT CLUSTER (Continued)

exterior lighting is turned On, the illumination inten-
sity of the coolant low indicator is dimmable, which
is adjusted using the panel lamps dimmer control
ring on the control stalk of the left multi-function
switch. The coolant low indicator lens is serviced as a
unit with the instrument cluster lens, hood and mask
unit.
OPERATION
The coolant low indicator gives an indication to the
vehicle operator when the diesel engine coolant level
is low. This indicator is controlled by a transistor on
the instrument cluster circuit board based upon clus-
ter programming and electronic messages received by
the cluster from the Body Control Module (BCM)
over the Programmable Communications Interface
(PCI) data bus. The coolant low indicator bulb 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 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 bulb only illuminates
when it is provided a path to ground by the instru-
ment cluster transistor. The instrument cluster will
turn on the coolant low indicator for the following
reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the coolant low indicator is
illuminated for about three seconds as a bulb test.
²Coolant Low Indicator Lamp-On Message-
Each time the cluster receives a coolant low indicator
lamp-on message from the BCM indicating the
engine coolant is below the minimum level in the
coolant reservoir, the coolant low indicator will be
illuminated. The indicator remains illuminated until
the cluster receives a coolant low indicator lamp-off
message from the BCM indicating that the engine
coolant level is above the minimum level.
²Actuator Test- Each time the cluster is put
through the actuator test, the coolant low 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 input from the
coolant level switch, then sends the proper coolant
low indicator lamp-on and lamp-off messages to the
instrument cluster. If the coolant low indicator fails
to light during the bulb test, replace the bulb with a
known good unit. For further diagnosis of the coolant
low indicator or the instrument cluster circuitry that
controls the indicator, (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - DIAGNOSIS AND TEST-
ING). For proper diagnosis of the coolant level
switch, the BCM, the PCI data bus, or the electronicmessage inputs to the instrument cluster that control
the coolant low indicator, a DRBIIItscan tool is
required. Refer to the appropriate diagnostic infor-
mation.
CRUISE INDICATOR
DESCRIPTION
A cruise indicator is standard equipment on all
instrument clusters, but is only functional on vehi-
cles equipped with the optional speed control system.
The cruise indicator is located on the right edge of
the instrument cluster, to the right of the speedome-
ter. The cruise indicator consists of the word
ªCRUISEº imprinted on a blue/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 ªCRUISEº text
appears silhouetted against a blue/green field
through the translucent outer layer of the overlay
when the indicator is illuminated from behind by a
replaceable bulb and bulb holder unit located on the
instrument cluster electronic circuit board. When the
exterior lighting is turned On, the illumination inten-
sity of the cruise indicator is dimmable, which is
adjusted using the panel lamps dimmer control ring
on the control stalk of the left multi-function switch.
The cruise indicator lens is serviced as a unit with
the instrument cluster lens, hood and mask unit.
OPERATION
The cruise indicator gives an indication to the vehi-
cle operator when the speed control system is turned
On, regardless of whether the speed control is
engaged. This indicator is controlled by a transistor
on the instrument cluster electronic 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 cruise
indicator bulb is completely controlled by the instru-
ment 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 indicator will always be off when the ignition
switch is in any position except On or Start. The bulb
only illuminates when it is provided a path to ground
by the instrument cluster transistor. The instrument
cluster will turn on the cruise indicator for the fol-
lowing reasons:
²Cruise Indicator Lamp-On Message- Each
time the cluster receives a cruise indicator lamp-on
message from the PCM indicating the speed control
8J - 18 INSTRUMENT CLUSTERWJ
COOLANT LOW INDICATOR (Continued)

system has been turned On, the cruise indicator is
illuminated. The indicator remains illuminated until
the cluster receives a cruise indicator lamp-off mes-
sage from the PCM 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 cruise indicator will be
turned on for the duration of the test to confirm the
functionality of the bulb and the cluster control cir-
cuitry.
The PCM continually monitors the speed control
switches to determine the proper outputs to the
speed control servo. The PCM then sends the proper
cruise indicator lamp-on and lamp-off messages to
the instrument cluster. If the cruise indicator fails to
light during the actuator test, replace the bulb with a
known good unit. For further diagnosis of the cruise
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 speed control
switches, the PCM, the PCI data bus, or the elec-
tronic message inputs to the instrument cluster that
control the cruise indicator, a DRBIIItscan tool is
required. Refer to the appropriate diagnostic infor-
mation.
ENGINE TEMPERATURE
GAUGE
DESCRIPTION
An engine coolant temperature gauge is standard
equipment on all instrument clusters. The engine
coolant temperature gauge is located in the lower
right corner of the instrument cluster, to the right of
the speedometer. The engine coolant temperature
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 40É C to 125É C, or from 100É
F to 260É F, depending upon the market for which
the vehicle is manufactured. An International Con-
trol and Display Symbol icon for ªEngine Coolant
Temperatureº is located on the gauge dial face.
The engine coolant temperature 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 visible within the instrument cluster in
daylight. When illuminated from behind by the panel
lamps dimmer controlled cluster illumination lighting
with the exterior lamps turned On, the base cluster
white gauge graphics appear blue-green and the
orange graphics still appear orange, while the pre-
mium cluster taupe gauge dial face appears blue-green with the black graphics silhouetted against the
illuminated background and the red graphics still
appear red. The gray gauge graphics for both ver-
sions 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 pre-
mium 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
engine coolant temperature gauge is serviced as a
unit with the instrument cluster.
OPERATION
The engine coolant temperature gauge gives an
indication to the vehicle operator of the engine cool-
ant temperature. This gauge is controlled by 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 engine coolant temper-
ature gauge is an air core magnetic unit that is com-
pletely controlled by the instrument cluster electronic
circuit board. The cluster 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 nee-
dle position and provides the following features:
²Engine Temperature Normal Message- Each
time the cluster receives a message from the PCM
indicating the engine coolant temperature is within
the normal operating range [up to about 124É C (255É
F) for gasoline engines, and 115É C (239É F) for diesel
engines], the gauge needle is moved to the relative
temperature position of the gauge scale.
²Engine Temperature High Message- Each
time the cluster receives a message from the PCM
indicating the engine coolant temperature is high
[above about 127É C (260É F) for gasoline engines
except Gulf Coast Country (GCC), 129É C (264É F) for
GCC gasoline engines, and 118É C (244É F) for diesel
engines], the gauge needle is moved to the center of
the red warning zone on the gauge scale.
²Engine Temperature Critical Message-
Each time the cluster receives a message from the
PCM indicating the engine coolant temperature is
critical [about 132É C (270É F) or higher for all gaso-
line engines, and 126É C (259É F) for all diesel
engines], the gauge needle is moved to the high end
of the red warning zone on the gauge scale.
²Communication Error- If the cluster fails to
receive an engine temperature message, it will hold
WJINSTRUMENT CLUSTER 8J - 19
CRUISE 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)

FUEL GAUGE
DESCRIPTION
A fuel gauge is standard equipment on all instru-
ment clusters. The fuel gauge is located in the lower
left corner of the instrument cluster, to the left of the
tachometer. The fuel 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 E (or
Empty) to F (or Full). An International Control and
Display Symbol icon for ªFuelº is located on the
gauge dial face. An arrowhead pointed to the left side
of the vehicle is imprinted next to the ªFuelº icon on
the fuel gauge dial face to provide the driver with a
reminder as to the location of the fuel filler access.
The fuel gauge graphics are either white, gray and
orange against a black gauge dial face (base cluster)
or black and gray against a taupe gauge dial face
(premium cluster), making them clearly visible
within the instrument cluster in daylight. When illu-
minated 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. The gray gauge graphics for both versions of
the cluster are not illuminated. The orange gauge
needle in the base cluster gauge is internally illumi-
nated, 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
fuel gauge is serviced as a unit with the instrument
cluster.
OPERATION
The fuel gauge gives an indication to the vehicle
operator of the level of fuel in the fuel tank. 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
fuel gauge is an air core magnetic unit that receives
battery current on the instrument cluster electronic
circuit board through the fused ignition switch out-
put (run-start) circuit whenever the ignition switch is
in the On or Start positions. The cluster is pro-
grammed to move the gauge needle back to the lowend of the scale after the ignition switch is turned to
the Off position. The instrument cluster circuitry
controls the gauge needle position and provides the
following features:
²Percent Tank Full Message- Each time the
cluster receives a message from the PCM indicating
the percent tank full, the cluster moves the gauge
needle to the relative fuel level position on the gauge
scale. The PCM applies an algorithm to the input
from the fuel tank sender to dampen gauge needle
movement against the negative effect that fuel slosh-
ing within the fuel tank can have on accurate inputs
to the PCM.
²Less Than 12.5 Percent Tank Full Message-
Each time the cluster receives messages from the
PCM indicating the percent tank full is less than
12.5 (one-eighth), the gauge needle is moved to the
proper position on the gauge scale and the low fuel
indicator is illuminated. The low fuel indicator
remains illuminated until the cluster receives mes-
sages from the PCM indicating that the percent tank
full is greater than 12.5 (one-eighth), or until the
ignition switch is turned to the Off position, which-
ever occurs first.
²Less Than Empty Percent Tank Full Mes-
sage- Each time the cluster receives a message from
the PCM indicating the percent tank full is less than
empty, the gauge needle is moved to the far left (low)
end of the gauge scale and the low fuel indicator is
illuminated immediately. This message would indi-
cate that the fuel tank sender input to the PCM is a
short circuit.
²More Than Full Percent Tank Full Message
- Each time the cluster receives a message from the
PCM indicating the percent tank full is more than
full, the gauge needle is moved to the far left (low)
end of the gauge scale and the low fuel indicator is
illuminated immediately. This message would indi-
cate that the fuel tank sender input to the PCM is an
open circuit.
²Communication Error- If the cluster fails to
receive a percent tank full 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 in order
to confirm the functionality of the gauge and the
cluster control circuitry.
The PCM continually monitors the fuel tank
sender to determine the fuel level. The PCM then
applies an algorithm to the input and sends the
WJINSTRUMENT CLUSTER 8J - 21

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)

instrument cluster logic circuit, and that logic will
only allow this indicator to operate when the instru-
ment cluster receives a battery current 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 bulb only illuminates when it is provided a path
to ground by the instrument cluster transistor. The
instrument cluster will turn on the MIL for the fol-
lowing reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the MIL is illuminated for
about three seconds as a bulb test.
²MIL Lamp-On Message- Each time the clus-
ter receives a MIL lamp-on message from the PCM,
the indicator will be illuminated. The indicator can
be flashed on and off, or illuminated solid, as dic-
tated by the PCM message. For some DTC's, if a
problem does not recur, the PCM will send a MIL
lamp-off message automatically. Other DTC's may
require that a fault be repaired and the PCM be
reset before a MIL lamp-off message will be sent. For
more information on the PCM and the DTC set and
reset parameters, (Refer to 25 - EMISSIONS CON-
TROL - OPERATION).
²Communication Error- If the cluster receives
no MIL lamp-on or lamp-off messages from the PCM
for twenty consecutive seconds, the MIL is illumi-
nated by the instrument cluster. The indicator
remains controlled and illuminated by the cluster
until a valid MIL lamp-on or lamp-off message is
received from the PCM.
²Actuator Test- Each time the cluster is put
through the actuator test, the MIL will be turned on
for the duration of the test to confirm the functional-
ity of the bulb and the cluster control circuitry.
The PCM continually monitors each of the many
fuel and emissions system circuits and sensors to
decide whether the system is in good operating con-
dition. The PCM then sends the proper MIL lamp-on
or lamp-off messages to the instrument cluster. If the
MIL fails to light during the bulb test, replace the
bulb with a known good unit. For further diagnosis of
the MIL or the instrument cluster circuitry that con-
trols the indicator, (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - DIAGNOSIS AND
TESTING). If the instrument cluster turns on the
MIL after the bulb test, it may indicate that a mal-
function has occurred and that the fuel and emis-
sions system may require service. For proper
diagnosis of the fuel and emissions systems, the
PCM, the PCI data bus, or the electronic message
inputs to the instrument cluster that control the
MIL, a DRBIIItscan tool is required. Refer to the
appropriate diagnostic information.ODOMETER
DESCRIPTION
An odometer and trip odometer are standard
equipment in all instrument clusters. The odometer
and trip odometer information are displayed in a
common electronic, blue-green Vacuum-Fluorescent
Display (VFD), which is located in the lower edge of
the speedometer dial face in the instrument cluster
and, when illuminated, is visible through a small
window cutout in the gauge overlay. However, the
odometer and trip odometer information are not dis-
played simultaneously. The trip odometer reset
switch on the instrument cluster electronic circuit
board toggles the display between odometer and trip
odometer modes by depressing the odometer/trip
odometer switch button that extends through the
lower edge of the cluster lens to the right of the
speedometer.
All odometer and trip odometer distance informa-
tion is stored in the instrument cluster memory. This
distance information can be increased when the
proper inputs are provided to the instrument cluster,
but the distance information cannot be decreased.
The odometer can display values up to 999,999 kilo-
meters (999,999 miles). The odometer will not roll
over, but will latch at the maximum value. The trip
odometer can display values up to 999.9 kilometers
(999.9 miles) before it rolls over to zero. The odome-
ter display does not have a decimal point and will
not show values less than a full unit (kilometer or
mile), the trip odometer display does have a decimal
point and will show tenths of a unit (kilometer or
mile).
The unit of measure for the odometer and trip
odometer display is not shown in the VFD. The unit
of measure for the odometer/trip odometer is selected
at the time that the instrument cluster is manufac-
tured, and cannot be changed. If the instrument clus-
ter has a kilometers-per-hour primary speedometer
scale, the odometer/trip odometer registers kilome-
ters; and, if the cluster features a miles-per-hour pri-
mary speedometer scale, the odometer/trip odometer
registers miles.
During daylight hours (exterior lamps Off) the
VFD is illuminated at full brightness for clear visibil-
ity. At night (exterior lamps are On) the instrument
cluster converts an electronic dimming level message
received from the Body Control Module (BCM) over
the Programmable Communications Interface (PCI)
data bus to a digital dimming level signal for control-
ling the lighting level of the VFD. However, a
ªParadeº mode position of the panel lamps dimmer
control ring on the control stalk of the left (lighting)
multi-function switch allows the VFD to be illumi-
8J - 24 INSTRUMENT CLUSTERWJ
MALFUNCTION INDICATOR LAMP (MIL) (Continued)