2002 JEEP LIBERTY Powertrain control

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 the cluster programming and electronic
messages received by the cluster from the Powertrain
Control Module (PCM) over the Programmable Com-
munications Interface (PCI) data bus. The cruise
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 LED will always be off
when the ignition switch is in any position except On
or Start. The LED only illuminates when it is pro-
vided a path to ground by the instrument cluster
transistor. The instrument cluster will turn on the
cruise indicator for the following reasons:
²Cruise Lamp-On Message- Each time the
cluster receives a cruise lamp-on message from the
PCM indicating the speed control system has been
turned On, the cruise indicator is illuminated. The
indicator remains illuminated until the cluster
receives a cruise lamp-off message 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, then off again during the bulb check por-
tion of the test in order to confirm the functionality
of the LED and the cluster control circuitry.
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. For further diagnosis of the
cruise 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 speed control
system, the PCM, the PCI data bus, or the electronic
message inputs to the instrument cluster that control
the cruise indicator, a DRBIIItscan tool is required.
Refer to the appropriate diagnostic information.
DOOR AJAR INDICATOR
DESCRIPTION
A door ajar indicator is standard equipment on all
instrument clusters. The door ajar indicator consists
of the word ªdoorº, which appears in place of the
odometer/trip odometer information in the Vacuum-Fluorescent Display (VFD) of the instrument cluster.
The VFD is part of the cluster electronic circuit
board, and is visible through a cutout located near
the lower edge of the speedometer dial face in the
instrument cluster. The dark outer layer of the over-
lay prevents the VFD from being clearly visible when
it is not illuminated. The word ªdoorº appears in the
same blue-green color and at the same lighting level
as the odometer/trip odometer information through
the translucent outer layer of the overlay when it is
illuminated by the instrument cluster electronic cir-
cuit board. The door ajar indicator is serviced as a
unit with the instrument cluster.
OPERATION
The door ajar indicator gives an indication to the
vehicle operator that one or more of the passenger
compartment doors may be open or not completely
latched. This indicator is controlled by the instru-
ment cluster electronic 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 door ajar indicator function of
the Vacuum Fluorescent Display (VFD) 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 VFD door ajar indication
will always be off when the ignition switch is in any
position except On or Start. The instrument cluster
will turn on the door ajar indicator for the following
reasons:
²Door Ajar Lamp-On Message- Each time the
cluster receives a door ajar lamp-on message from
the BCM indicating that a door is open or not com-
pletely latched, the door ajar indicator will be illumi-
nated. If the vehicle is not moving when the door
ajar lamp-on message is received, the VFD will
repeatedly and sequentially cycle its indication in
two second intervals with the odometer/trip odometer
information, the door ajar warning, and any other
active warnings including: gate ajar, glass ajar, and
low washer fluid. If the vehicle is moving, or once the
cluster of a non-moving vehicle receives an electronic
vehicle speed message from the Powertrain Control
Module (PCM) indicating a speed greater than zero,
the warning sequence will consist of three complete
display cycles, then revert to only the odometer/trip
odometer display until the door ajar switch is cycled.
The door ajar indicator will also be extinguished
when the cluster receives a door ajar lamp-off mes-
sage from the BCM, or if the ignition switch is
turned to the Off position, whichever occurs first.
KJINSTRUMENT CLUSTER 8J - 17
CRUISE INDICATOR (Continued)

The BCM continually monitors the door ajar
switches that are integral to each door latch to deter-
mine the status of the doors. The BCM then sends
the proper door ajar lamp-on and lamp-off messages
to the instrument cluster. For further diagnosis of
the door ajar indicator or the instrument cluster cir-
cuitry that controls the indicator, (Refer to 8 - ELEC-
TRICAL/INSTRUMENT CLUSTER - DIAGNOSIS
AND TESTING). For proper diagnosis of the door
ajar switches and circuits, the BCM, the PCI data
bus, or the electronic message inputs to the instru-
ment cluster that control the door ajar indicator, a
DRBIIItscan tool is required. Refer to the appropri-
ate diagnostic information.
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 right
lower 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 cluster overlay that
reads left-to-right from ªCº (or Cold) to ªHº (or Hot)
for all engines. An International Control and Display
Symbol icon for ªEngine Coolant Temperatureº is
located on the cluster overlay, in the center of the
gauge directly above the hub of the gauge needle.
The engine coolant temperature gauge graphics are
dark blue and black against a beige field, except for a
single light blue graduation at the far left (Cold) end
of the gauge scale and a single red graduation at the
far right (Hot) end of the gauge scale, making them
clearly visible within the instrument cluster in day-
light. When illuminated from behind by the panel
lamps dimmer controlled cluster illumination lighting
with the exterior lamps turned On, the blue graphics
appear blue and the red graphics appear red. The
orange gauge needle is internally illuminated. Gauge
illumination is provided by replaceable incandescent
bulb and bulb holder units located on the instrument
cluster electronic circuit board. 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 bythe 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 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 low
end of the scale after the ignition switch is turned to
the Off position. The instrument cluster circuitry
controls the gauge needle position and 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, or about 110É C (230É F) for
diesel engines], the gauge needle is moved to the rel-
ative 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, or
112É C (233É F) for diesel engines], the gauge needle
is moved into 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 [above about 132É C (269É F) for gasoline
engines, or 115É C (239É F) for diesel engines], the
gauge needle is moved to the high end of the red
warning zone on the gauge scale.
²Actuator Test- Each time the cluster is put
through the actuator test, the gauge needle will be
swept to the gauge calibration points on the gauge
scale in sequence in order to confirm the functional-
ity 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
8J - 18 INSTRUMENT CLUSTERKJ
DOOR AJAR INDICATOR (Continued)

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 low
end of the scale after the ignition switch is turned to
the Off position. The instrument cluster circuitry
controls the gauge needle position and 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.
²Actuator Test- Each time the cluster is put
through the actuator test, the gauge needle will beswept to the gauge calibration points on the gauge
scale in sequence in order to confirm the functional-
ity of the gauge and the cluster control circuitry.
The PCM continually monitors the fuel tank
sender input to determine the fuel level. The PCM
then applies an algorithm to the input and sends the
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.
GATE AJAR INDICATOR
DESCRIPTION
A gate ajar indicator is standard equipment on all
instrument clusters. The gate ajar indicator consists
of the word ªgateº, which appears in place of the
odometer/trip odometer information in the Vacuum-
Fluorescent Display (VFD) of the instrument cluster.
The VFD is part of the cluster electronic circuit
board, and is visible through a cutout located near
the lower edge of the speedometer dial face in the
instrument cluster. The dark outer layer of the over-
lay prevents the VFD from being clearly visible when
it is not illuminated. The word ªgateº appears in the
same blue-green color and at the same lighting level
as the odometer/trip odometer information through
the translucent outer layer of the overlay when it is
illuminated by the instrument cluster electronic cir-
cuit board. The gate ajar indicator is serviced as a
unit with the instrument cluster.
OPERATION
The gate ajar indicator gives an indication to the
vehicle operator that the rear tailgate may be open
or not completely latched. This indicator is controlled
by the instrument cluster electronic 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 gate ajar indica-
tor function of the Vacuum Fluorescent Display
(VFD) 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 VFD
gate ajar indicator will always be off when the igni-
tion switch is in any position except On or Start. The
8J - 20 INSTRUMENT CLUSTERKJ
FUEL GAUGE (Continued)

instrument cluster will turn on the gate ajar indica-
tor for the following reasons:
²Gate Ajar Lamp-On Message- Each time the
cluster receives a gate ajar lamp-on message from
the BCM indicating that the rear tailgate is open or
not completely latched, the gate ajar indicator will be
illuminated. If the vehicle is not moving when the
gate ajar lamp-on message is received, the VFD will
repeatedly and sequentially cycle its indication in
two second intervals with the odometer/trip odometer
information, the gate ajar warning, and any other
active warnings including: door ajar, glass ajar, and
low washer fluid. If the vehicle is moving, or once the
cluster of a non-moving vehicle receives an electronic
vehicle speed message from the Powertrain Control
Module (PCM) indicating a speed greater than zero,
the warning sequence will consist of three complete
display cycles, then revert to only the odometer/trip
odometer display until the tailgate ajar switch is
cycled. The gate ajar indicator will also be extin-
guished when the cluster receives a gate ajar lamp-
off message from the BCM, or if the ignition switch is
turned to the Off position, whichever occurs first.
The BCM continually monitors the tailgate ajar
switch that is integral to the tailgate latch to deter-
mine the status of the rear tailgate. The BCM then
sends the proper gate ajar lamp-on and lamp-off mes-
sages to the instrument cluster. For further diagnosis
of the gate ajar indicator or the instrument cluster
circuitry that controls the indicator, (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNO-
SIS AND TESTING). For proper diagnosis of the tail-
gate ajar switch and circuit, the BCM, the PCI data
bus, or the electronic message inputs to the instru-
ment cluster that control the gate ajar indicator, a
DRBIIItscan tool is required. Refer to the appropri-
ate diagnostic information.
GLASS AJAR INDICATOR
DESCRIPTION
A glass ajar indicator is standard equipment on all
instrument clusters. The glass ajar indicator consists
of the word ªglassº, which appears in place of the
odometer/trip odometer information in the Vacuum-
Fluorescent Display (VFD) of the instrument cluster.
The VFD is part of the cluster electronic circuit
board, and is visible through a cutout located near
the lower edge of the speedometer dial face in the
instrument cluster. The dark outer layer of the over-
lay prevents the VFD from being clearly visible when
it is not illuminated. The word ªglassº appears in the
same blue-green color and at the same lighting level
as the odometer/trip odometer information through
the translucent outer layer of the overlay when it isilluminated by the instrument cluster electronic cir-
cuit board. The glass ajar indicator is serviced as a
unit with the instrument cluster.
OPERATION
The glass ajar indicator gives an indication to the
vehicle operator that the rear flip-up glass may be
open or not completely latched. This indicator is con-
trolled by 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 glass
ajar indicator function of the Vacuum Fluorescent
Display (VFD) 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 VFD glass ajar indicator will always be off when
the ignition switch is in any position except On or
Start. The instrument cluster will turn on the glass
ajar indicator for the following reasons:
²Glass Ajar Lamp-On Message- Each time the
cluster receives a glass ajar lamp-on message from
the BCM indicating that the rear flip-up glass is
open or not completely latched, the glass ajar indica-
tor will be illuminated. If the vehicle is not moving
when the glass ajar lamp-on message is received, the
VFD will repeatedly and sequentially cycle its indica-
tion in two second intervals with the odometer/trip
odometer information, the glass ajar warning, and
any other active warnings including: door ajar, gate
ajar, and low washer fluid. If the vehicle is moving,
or once the cluster of a non-moving vehicle receives
an electronic vehicle speed message from the Power-
train Control Module (PCM) indicating a speed
greater than zero, the warning sequence will consist
of three complete display cycles, then revert to only
the odometer/trip odometer display until the glass
ajar switch is cycled. The glass ajar indicator will
also be extinguished when the cluster receives a
glass ajar lamp-off message from the BCM, or if the
ignition switch is turned to the Off position, which-
ever occurs first.
The BCM continually monitors the glass ajar
switch that is integral to the flip-up glass latch to
determine the status of the rear flip-up glass. The
BCM then sends the proper glass ajar lamp-on and
lamp-off messages to the instrument cluster. For fur-
ther diagnosis of the glass ajar indicator or the
instrument cluster circuitry that controls the indica-
tor, (Refer to 8 - ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND TESTING). For
proper diagnosis of the glass ajar switch and circuit,
the BCM, the PCI data bus, or the electronic mes-
KJINSTRUMENT CLUSTER 8J - 21
GATE AJAR INDICATOR (Continued)

sage inputs to the instrument cluster that control the
glass ajar indicator, a DRBIIItscan tool is required.
Refer to the appropriate diagnostic information.
HIGH BEAM INDICATOR
DESCRIPTION
A high beam indicator lamp is standard equipment
on all instrument clusters. The high beam indicator
is located near the upper edge of the instrument clus-
ter overlay, between the tachometer and the speed-
ometer. The high beam indicator consists of a stencil-
like cutout of the International Control and Display
Symbol icon for ªHigh Beamº in the opaque layer of
the instrument cluster overlay. The dark outer layer
of the overlay prevents the indicator from being
clearly visible when the it is not illuminated. A blue
Light Emitting Diode (LED) behind the cutout in the
opaque layer of the overlay causes the icon to appear
in blue through the translucent outer layer of the
overlay when it is illuminated from behind by the
LED, which is soldered onto the instrument cluster
electronic circuit board. The high beam indicator is
serviced as a unit with the instrument cluster.
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 the 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 Light Emitting Diode (LED) is com-
pletely controlled by the instrument cluster logic cir-
cuit, 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 LED can be illuminated regardless of
the ignition switch position. The LED only illumi-
nates when it is provided a path to ground by the
instrument cluster transistor. The instrument cluster
will turn on the high beam indicator for the following
reasons:
²High Beam Headlamps-On Message- Each
time the cluster receives a high beam headlamps-on
message from the BCM indicating 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 headlamps-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, then off again during the bulbcheck portion of the test to confirm the functionality
of the LED and the cluster control circuitry.
The BCM continually monitors the exterior light-
ing (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. 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
above the fuel gauge and to the left of the tachometer
in the instrument cluster. The low fuel indicator con-
sists of a stencil-like cutout of the International Con-
trol and Display Symbol icon for ªFuelº 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. An
amber Light Emitting Diode (LED) behind the cutout
in the opaque layer of the overlay causes the icon to
appear in amber through the translucent outer layer
of the overlay when it is illuminated from behind by
the LED, which is soldered onto the instrument clus-
ter electronic circuit board. The low fuel indicator is
serviced as a unit with the instrument cluster.
OPERATION
The low fuel indicator gives an indication to the
vehicle operator when the level of fuel in the fuel
tank becomes low. 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
Powertrain Control Module (PCM) over the Program-
mable Communications Interface (PCI) data bus. The
low fuel 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 bat-
tery current input on the fused ignition switch out-
put (run-start) circuit. Therefore, the LED will
always be off when the ignition switch is in any posi-
tion except On or Start. The LED only illuminates
8J - 22 INSTRUMENT CLUSTERKJ
GLASS AJAR INDICATOR (Continued)

when it is provided a path to ground by the instru-
ment cluster transistor. The instrument cluster will
turn on the low fuel indicator for the following rea-
sons:
²Bulb Test- Each time the ignition switch is
turned to the On position the low fuel indicator is
illuminated for about three seconds as a bulb test.
²Less Than 12.5 Percent Tank Full Message-
Each time the cluster receives a message from the
PCM indicating that the percent tank full is less
than 12.5 (one-eighth), the low fuel indicator is illu-
minated. The indicator remains illuminated until the
cluster receives messages from the PCM indicating
that the percent tank full has increased to greater
than 12.5 (one-eighth). The PCM applies an algo-
rithm to the input from the fuel tank sender to
dampen the illumination of the low fuel indicator
against the negative effect that fuel sloshing within
the fuel tank can have on accurate inputs to the
PCM.
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 low fuel indicator is illuminated immedi-
ately. This message would indicate 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 low fuel indicator is illuminated immedi-
ately. This message would indicate 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 for more than
about twelve seconds, the cluster control circuitry
will illuminate the low fuel indicator until a new per-
cent tank full message is received, or until the igni-
tion switch is turned to the Off position, whichever
occurs first.
²Actuator Test- Each time the cluster is put
through the actuator test, the low fuel indicator will
be turned on, then off again during the bulb check
portion of the test to confirm the functionality of the
LED and the cluster control circuitry.
The PCM continually monitors the fuel tank
sender input to determine the fuel level. The PCM
then applies an algorithm to the input and sends the
proper percent tank full messages to the instrument
cluster. For further diagnosis of the low fuel indicator
or the instrument cluster circuitry that controls the
LED, (Refer to 8 - ELECTRICAL/INSTRUMENT
CLUSTER - 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 low fuel indi-cator, a DRBIIItscan tool is required. Refer to the
appropriate diagnostic information.
LOW OIL PRESSURE
INDICATOR
DESCRIPTION
A low oil pressure indicator is standard equipment
on all instrument clusters. The low oil pressure indi-
cator is located near the lower edge of the instrument
cluster, between the tachometer and the speedometer.
The low oil pressure indicator consists of a stencil-
like cutout of the International Control and Display
Symbol icon for ªEngine Oilº 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. A red Light
Emitting Diode (LED) behind the cutout in the
opaque layer of the overlay causes the icon to appear
in red through the translucent outer layer of the
overlay when it is illuminated from behind by the
LED, which is soldered onto the instrument cluster
electronic circuit board. The low oil pressure indica-
tor is serviced as a unit with the instrument cluster.
OPERATION
The low oil pressure indicator gives an indication
to the vehicle operator when the engine oil pressure
is low. This indicator is controlled by a transistor on
the instrument cluster electronic 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 low oil pressure
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 LED will always be off
when the ignition switch is in any position except On
or Start. The LED only illuminates when it is pro-
vided a path to ground by the instrument cluster
transistor. The instrument cluster will turn on the
low oil pressure indicator for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the low oil pressure indica-
tor is illuminated as a bulb test. The indicator will
remain illuminated until the engine is started
(engine speed is greater than 450 rpm), or until the
ignition switch is turned to the Off position, which-
ever occurs first.
²Engine Oil Pressure Low Message- Once the
engine has been started (engine speed has been
greater than 450 rpm), each time the cluster receives
KJINSTRUMENT CLUSTER 8J - 23
LOW FUEL INDICATOR (Continued)

dition. The PCM then sends the proper malfunction
indicator lamp-on or lamp-off messages to the instru-
ment cluster. For further diagnosis of the MIL or the
instrument cluster circuitry that controls the LED,
(Refer to 8 - ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING). If the instru-
ment cluster turns on the MIL after the bulb test, it
may indicate that a malfunction has occurred and
that the fuel and emissions system may require ser-
vice. For proper diagnosis of the fuel and emissions
systems, the PCM, the PCI data bus, or the elec-
tronic 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 cluster 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 knob that extends through the lower
edge of the cluster lens, just right of the odometer
VFD. Both the odometer and trip odometer informa-
tion is stored in the instrument cluster memory.
All odometer and trip odometer distance informa-
tion is stored in the instrument cluster. This distance
information can be increased when the proper inputs
are provided to the instrument cluster, but the dis-
tance information cannot be decreased. The odometer
can display values up to 864,004 kilometers (536,870
miles). The odometer will not roll over, but will latch
at the maximum value. The trip odometer can dis-
play values up to 9999.9 kilometers (9999.9 miles)
before it rolls over to zero. The odometer 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). When the
trip odometer is active, the word ªTRIPº will also
illuminate near the bottom of the VFD. The unit of
measure for the odometer and trip odometer display
is not shown in the VFD. If the instrument cluster
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. In this instrument cluster, the odom-
eter/trip odometer VFD is also used to display certain
warning messages and diagnostic information.
The odometer/trip odometer has a ªRental Carº
mode, which will illuminate the odometer informa-
tion in the VFD whenever the driver side front door
is opened with the ignition switch in the Off or
Accessory positions. During daylight hours (exterior
lamps Off) the VFD is illuminated at full brightness
for clear visibility. At night (exterior lamps are On)
the instrument cluster converts an electronic dim-
ming level message received from the Body Control
Module (BCM) over the Programmable Communica-
tions Interface (PCI) data bus to a digital dimming
level signal for controlling the lighting level of the
VFD. However, a ªParadeº mode position of the panel
lamps dimmer control ring on the multi-function
switch left control stalk allows the VFD to be illumi-
nated at full brightness if the exterior lamps are
turned On during daylight hours.
The VFD, the trip odometer switch, and the trip
odometer switch button are serviced as a unit with
the instrument cluster.
OPERATION
The odometer and trip odometer give an indication
to the vehicle operator of the distance the vehicle has
traveled. This gauge is controlled by the instrument
cluster electronic circuitry based upon cluster pro-
gramming and electronic messages received by the
cluster from the Powertrain Control Module (PCM)
over the Programmable Communications Interface
(PCI) data bus. The odometer and trip odometer
information is displayed by the instrument cluster
Vacuum Fluorescent Display (VFD). The VFD will
display the odometer information whenever the
driver side front door is opened with the ignition
switch in the Off or Accessory positions, and will dis-
play the last previously selected odometer or trip
odometer information when the ignition switch is in
the On or Start positions. The instrument cluster cir-
cuitry controls the VFD and provides the following
features:
²Odometer/Trip Odometer Display Toggling-
Actuating the trip odometer reset switch momen-
tarily with the VFD illuminated will toggle the dis-
play between the odometer and trip odometer
information. Each time the VFD is illuminated with
the ignition switch in the On or Start positions, the
display will automatically return to the last mode
previously selected (odometer or trip odometer).
²Trip Odometer Reset- When the trip odome-
ter reset switch is pressed and held for longer than
about two seconds with the ignitions switch in the
KJINSTRUMENT CLUSTER 8J - 25
MALFUNCTION INDICATOR LAMP (MIL) (Continued)

On or Start positions, the trip odometer will be reset
to 0.0 kilometers (miles). The VFD must be display-
ing the trip odometer information in order for the
trip odometer information to be reset.
²Warning Display- The odometer or trip odom-
eter information will be toggled at two second inter-
vals with a warning display when certain monitored
conditions are active. If multiple conditions are
active, the VFD will toggle each active warning and
the odometer/trip odometer information at two sec-
ond intervals. Once the vehicle is moving and a vehi-
cle speed input is received by the instrument cluster,
each active warning will be displayed for three two-
second intervals before the VFD reverts to displaying
only the selected odometer or trip odometer informa-
tion. The warnings and monitored conditions include:
²ªdoorº- A door is open or not fully latched.
²ªgateº- The tailgate is open or not fully
latched.
²ªglassº- The rear flip-up glass is open or not
fully latched.
²ªlowashº- The fluid level in the washer reser-
voir is low.
²ªno busº- The instrument cluster can detect no
PCI bus communication. This message is illuminated
solid when there is no PCI bus communication, and
will override the display of all other active warning
displays.
²Communication Error- If the cluster fails to
receive a distance message during normal operation,
it will hold and display the last data received until
the ignition switch is turned to the Off position. If
the cluster does not receive a distance message
within one second after the ignition switch is turned
to the On position, it will display the last distance
message stored in the cluster memory. If the cluster
is unable to display distance information due to an
error internal to the cluster, ªerrorº will be displayed
in the VFD.
²Actuator Test- Each time the cluster is put
through the actuator test, the VFD will step sequen-
tially through a display of ª111111 ºthrough ª999999º,
then display the cluster software version number to
confirm the functionality of the VFD and the cluster
control circuitry.
The PCM continually monitors the vehicle speed
pulse information received from the Body Control
Module (BCM), then sends the proper distance mes-
sages to the instrument cluster. For further diagnosis
of the odometer/trip odometer or the instrument clus-
ter circuitry that controls these functions, (Refer to 8
- ELECTRICAL/INSTRUMENT CLUSTER - DIAG-
NOSIS AND TESTING). For proper diagnosis of the
vehicle speed sensor, the BCM, the PCM, the PCI
data bus, or the electronic message inputs to the
instrument cluster that control the odometer/tripodometer, a DRBIIItscan tool is required. Refer to
the appropriate diagnostic information.
OVERDRIVE OFF INDICATOR
DESCRIPTION
An overdrive off indicator is standard equipment
on all instrument clusters, but is only functional on
vehicles equipped with the optional overdrive auto-
matic transmission. The overdrive off indicator is
located above the fuel gauge and to the left of the
tachometer in the instrument cluster. The overdrive
off indicator consists of a stencil-like cutout of the
text ªO/D OFFº 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. An amber Light Emitting
Diode (LED) behind the cutout in the opaque layer of
the overlay causes the ªO/D OFFº text to appear in
amber through the translucent outer layer of the
overlay when it is illuminated from behind by the
LED, which is soldered onto the instrument cluster
electronic circuit board. When the exterior lighting is
turned On, the illumination intensity of the overdrive
off indicator is dimmable, which is adjusted using the
panel lamps dimmer control ring on the left control
stalk of the multi-function switch. The overdrive off
indicator is serviced as a unit with the instrument
cluster.
OPERATION
The overdrive off indicator gives an indication to
the vehicle operator when the Off position of the
overdrive off switch has been selected, disabling the
electronically controlled overdrive feature of the auto-
matic transmission. This indicator is controlled by a
transistor on the instrument cluster electronic circuit
board based upon the 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
overdrive off 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 bat-
tery current input on the fused ignition switch out-
put (run-start) circuit. Therefore, the LED 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 overdrive off indicator for the following
reasons:
²Overdrive Off Lamp-On Message- Each time
the cluster receives an overdrive off lamp-on message
8J - 26 INSTRUMENT CLUSTERKJ
ODOMETER (Continued)