2002 JEEP LIBERTY main power fuse

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)

three consecutive messages from the PCM indicating
that the engine oil pressure is about 4 kPa or lower
(about 0.6 psi or lower), the low oil pressure indicator
is illuminated. The indicator remains illuminated
until the cluster receives a single message from the
PCM indicating that the engine oil pressure is about
76 kPa or higher (about 11 psi or higher), or until the
ignition switch is turned to the Off position, which-
ever occurs first. Once the cluster monitors and
engine speed of greater than 450 rpm, the cluster
logic will ignore engine speed in determining low oil
pressure indicator operation for the remainder of the
current ignition cycle.
²Actuator Test- Each time the cluster is put
through the actuator test, the low oil pressure indi-
cator will be turned on, then off again during the
bulb check portion of the test to confirm the function-
ality of the LED and the cluster control circuitry.
The PCM continually monitors the engine oil pres-
sure sensor to determine the engine oil pressure. The
PCM then sends the proper engine oil pressure mes-
sages to the instrument cluster. For further diagnosis
of the low oil pressure indicator or the instrument
cluster circuitry that controls the LED, (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNO-
SIS AND TESTING). If the instrument cluster turns
on the indicator after the bulb test, it may indicate
that the engine or the engine oiling system requires
service. For proper diagnosis of the engine oil pres-
sure sensor, the PCM, the PCI data bus, or the elec-
tronic message inputs to the instrument cluster that
control the low oil pressure indicator, a DRBIIItscan
tool is required. Refer to the appropriate diagnostic
information.
MALFUNCTION INDICATOR
LAMP (MIL)
DESCRIPTION
A Malfunction Indicator Lamp (MIL) is standard
equipment on all instrument clusters. The MIL is
located above the coolant temperature gauge and to
the right of the speedometer in the instrument clus-
ter. The MIL consists of a stencil-like cutout of the
International Control and Display Symbol icon for
ªEngineº in the opaque layer of the instrument clus-
ter overlay. The dark outer layer of the overlay pre-
vents 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 sol-
dered onto the instrument cluster electronic circuitboard. The MIL is serviced as a unit with the instru-
ment cluster.
OPERATION
The Malfunction Indicator Lamp (MIL) gives an
indication to the vehicle operator when the Power-
train Control Module (PCM) has recorded a Diagnos-
tic Trouble Code (DTC) for an On-Board Diagnostics
II (OBDII) emissions-related circuit or component
malfunction. This indicator is controlled by a transis-
tor on the instrument cluster electronic circuit board
based upon cluster programming and electronic mes-
sages received by the cluster from the PCM over the
Programmable Communications Interface (PCI) data
bus. The MIL Light Emitting Diode (LED) is com-
pletely controlled by the instrument cluster logic cir-
cuit, 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 MIL for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the MIL is illuminated for
about seven seconds as a bulb test.
²PCM Lamp-On Message- Each time the clus-
ter receives a malfunction indicator lamp-on message
from the PCM, the indicator will be illuminated. The
indicator can be flashed on and off, or illuminated
solid, as dictated by the PCM message. For some
DTC's, if a problem does not recur, the PCM will
send a lamp-off message automatically. Other DTC's
may require that a fault be repaired and the PCM be
reset before a 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 malfunction indicator lamp-on or lamp-off mes-
sage from the PCM for twenty consecutive seconds,
the MIL is illuminated by the instrument cluster.
The indicator remains controlled and illuminated by
the cluster until a valid malfunction indicator
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,
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 each of the many
fuel and emissions system circuits and sensors to
decide whether the system is in good operating con-
8J - 24 INSTRUMENT CLUSTERKJ
LOW OIL PRESSURE INDICATOR (Continued)

indicator lights when the transfer case is engaged in
the4X4Part Time position. This indicator is con-
trolled by a transistor on the instrument cluster elec-
tronic circuit board based upon the cluster
programming and electronic messages received by
the cluster from the Powertrain Control Module
(PCM) over the Programmable Communications
Interface (PCI) data bus. The instrument cluster
must be configured for the type of transfer case in
the vehicle using a DRBIIItscan tool in order to pro-
vide proper operation of the part time indicator. The
part time 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 part time indicator for the following rea-
sons:
²Part Time Lamp-On Message- Each time the
cluster receives a part time lamp-on message from
the PCM indicating that a four-wheel drive part time
position of the transfer case has been selected, the
part time indicator will be illuminated. The indicator
remains illuminated until the cluster receives a part
time lamp-off message from the PCM or until the
ignition switch is turned to the Off position, which-
ever occurs first.
²Actuator Test- Each time the cluster is put
through the actuator test, the part time 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 transfer case
switch to determine the driveline operating mode.
The PCM then sends the proper part time lamp-on
and lamp-off messages to the instrument cluster. For
further diagnosis of the part time 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 transfer case switch, the
PCM, the PCI data bus, or the electronic message
inputs to the instrument cluster that control the part
time indicator, a DRBIIItscan tool is required. Refer
to the appropriate diagnostic information.
OPERATION - FULL TIME INDICATOR
The full time indicator gives an indication to the
vehicle operator that a four-wheel drive full time
operating mode of the transfer case is selected. On
vehicles equipped with the optional Selec-Trac four-wheel drive system, the full time indicator lights
when the transfer case is engaged in the4X4Full
Time position. This indicator is controlled by a tran-
sistor 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
instrument cluster must be configured for the type of
transfer case in the vehicle using a DRBIIItscan
tool in order to provide proper operation of the full
time indicator. The full time indicator Light Emitting
Diode (LED) 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 LED 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 full time indicator for the fol-
lowing reasons:
²Full Time Lamp-On Message- Each time the
cluster receives a full time lamp-on message from the
PCM indicating that a four-wheel drive full time
position of the transfer case has been selected, the
full time indicator will be illuminated. The indicator
remains illuminated until the cluster receives a full
time lamp-off message from the PCM or until the
ignition switch is turned to the Off position, which-
ever occurs first.
²Actuator Test- Each time the cluster is put
through the actuator test, the full time 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 transfer case
switch to determine the driveline operating mode.
The PCM then sends the proper full time lamp-on
and lamp-off messages to the instrument cluster. For
further diagnosis of the full time 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 transfer case switch, the
PCM, the PCI data bus, or the electronic message
inputs to the instrument cluster that control the full
time indicator, a DRBIIItscan tool is required. Refer
to the appropriate diagnostic information.
OPERATION - FOUR LOW MODE INDICATOR
The four low mode indicator gives an indication to
the vehicle operator that a four-wheel drive low oper-
ating mode of the transfer case is selected. On vehi-
cles equipped with the standard Command-Trac four-
8J - 30 INSTRUMENT CLUSTERKJ
SHIFT INDICATOR (TRANSFER CASE) (Continued)

wheel drive system, the four low mode indicator
lights when the transfer case is engaged in the 4L
position. On vehicles equipped with the optional
Selec-Trac four-wheel drive system, the four low
mode indicator lights when the transfer case is
engaged in the 4 Lo position. This indicator is con-
trolled by a transistor on the instrument cluster elec-
tronic circuit board based upon the cluster
programming and electronic messages received by
the cluster from the Powertrain Control Module
(PCM) over the Programmable Communications
Interface (PCI) data bus. The instrument cluster
must be configured for the type of transfer case in
the vehicle using a DRBIIItscan tool in order to pro-
vide proper operation of the four low mode indicator.
The four low mode 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 LED
will always be off when the ignition switch is in any
position except On or Start. 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 four low mode indicator for the fol-
lowing reasons:
²Four Low Mode Lamp-On Message- Each
time the cluster receives a four low mode lamp-on
message from the PCM indicating that a four-wheel
drive low position of the transfer case has been
selected, the four low mode indicator will be illumi-
nated. The indicator remains illuminated until the
cluster receives a four low mode 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 four low mode indica-
tor 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 transfer case
switch to determine the driveline operating mode.
The PCM then sends the proper four low mode
lamp-on and lamp-off messages to the instrument
cluster. For further diagnosis of the four low mode
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 transfer case
switch, the PCM, the PCI data bus, or the electronic
message inputs to the instrument cluster that control
the four low mode indicator, a DRBIIItscan tool is
required. Refer to the appropriate diagnostic infor-
mation.SKIS INDICATOR
DESCRIPTION
A Sentry Key Immobilizer System (SKIS) indicator
is standard equipment on all instrument clusters, but
is only operational on vehicles equipped with the
optional SKIS. The SKIS indicator is located above
the fuel gauge and to the left of the tachometer in
the instrument cluster. The SKIS indicator consists
of a stencil-like cutout of a graphical representation
or icon of a key that is circled and crossed-out 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
indicator 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. The SKIS
indicator is serviced as a unit with the instrument
cluster.
OPERATION
The Sentry Key Immobilizer System (SKIS) indica-
tor gives an indication to the vehicle operator of the
status of the SKIS. 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 Sen-
try Key Immobilizer Module (SKIM) over the
Programmable Communications Interface (PCI) data
bus. The SKIS indicator Light Emitting Diode (LED)
is completely controlled by the instrument cluster
logic circuit, and that logic will only allow this indi-
cator to operate when the instrument cluster receives
a battery current input on the fused ignition switch
output (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 switched to ground by the instrument clus-
ter transistor. The instrument cluster will turn on
the SKIS indicator for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position, the SKIM tells the cluster
to illuminate the SKIS indicator for about three sec-
onds as a bulb test.
²SKIS Lamp-On Message- Each time the clus-
ter receives a SKIS lamp-on message from the SKIM,
the SKIS indicator will be illuminated. The indicator
can be flashed on and off, or illuminated solid, as dic-
tated by the SKIM message. For more information on
the SKIS and the SKIS indicator control parameters,
(Refer to 8 - ELECTRICAL/VEHICLE THEFT SECU-
RITY - OPERATION). The indicator remains illumi-
nated until the cluster receives a SKIS lamp-off
KJINSTRUMENT CLUSTER 8J - 31
SHIFT INDICATOR (TRANSFER CASE) (Continued)

message from the SKIM or until the ignition switch
is turned to the Off position, whichever occurs first.
²Communication Error- If the cluster receives
no SKIS lamp-on or lamp-off messages from the
SKIM for twenty consecutive seconds, the SKIS indi-
cator is illuminated by the instrument cluster. The
indicator remains controlled and illuminated by the
cluster until a valid SKIS lamp-on or lamp-off mes-
sage is received from the SKIM.
²Actuator Test- Each time the cluster is put
through the actuator test, the SKIS indicator will be
turned on, then off again during the bulb check por-
tion of the test to confirm the functionality of the
LED and the cluster control circuitry.
The SKIM performs a self-test each time the igni-
tion switch is turned to the On position to decide
whether the system is in good operating condition
and whether a valid key is present in the ignition
lock cylinder. The SKIM then sends the proper SKIS
lamp-on or lamp-off messages to the instrument clus-
ter. For further diagnosis of the SKIS indicator or the
instrument cluster circuitry that controls the indica-
tor, (Refer to 8 - ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND TESTING). If the
instrument cluster flashes the SKIS indicator upon
ignition On, or turns on the SKIS indicator solid
after the bulb test, it indicates that a SKIS malfunc-
tion has occurred or that the SKIS is inoperative. For
proper diagnosis of the SKIS, the PCI data bus, or
the electronic message inputs to the instrument clus-
ter that control the SKIS indicator, a DRBIIItscan
tool is required. Refer to the appropriate diagnostic
information.
SPEEDOMETER
DESCRIPTION
A speedometer is standard equipment on all instru-
ment clusters. The speedometer is located to the
right of the tachometer in the instrument cluster.
The speedometer consists of a movable gauge needle
or pointer controlled by the instrument cluster cir-
cuitry, and a fixed 255 degree primary scale on the
gauge dial face that reads left-to-right either from 0
to 120 mph, or from 0 to 240 km/h, depending upon
the market for which the vehicle is manufactured.
Most models also have a smaller secondary inner
scale on the gauge dial face that provides the equiv-
alent opposite measurement units from the primary
scale. Text appearing on the cluster overlay just
below the hub of the speedometer needle abbreviates
the unit of measure for the primary scale first (i.e.:
MPH or km/h), followed by the unit of measure for
the secondary scale (i.e.: MPH or km/h). The speed-
ometer graphics are dark blue (primary scale) andlight blue (secondary scale) against a beige field,
making them clearly visible within the instrument
cluster in daylight. When illuminated from behind by
the panel lamps dimmer controlled cluster illumina-
tion lighting with the exterior lamps turned On, both
the dark blue and light blue graphics retain their
blue colors. 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 speedometer is serviced as a unit with the
instrument cluster.
OPERATION
The speedometer gives an indication to the vehicle
operator of the vehicle road speed. This gauge is con-
trolled by 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
speedometer is an air core magnetic unit that
receives battery current on the instrument cluster
electronic circuit board through the fused ignition
switch output (run-start) circuit whenever the igni-
tion switch is in the On or Start positions. The clus-
ter is programmed to move the gauge needle back to
the low end of the scale after the ignition switch is
turned to the Off position. The instrument cluster
circuitry controls the gauge needle position and pro-
vides the following features:
²Vehicle Speed Message- Each time the clus-
ter receives a vehicle speed message from the PCM it
will calculate the correct vehicle speed reading and
position the gauge needle at that speed position on
the gauge scale. The cluster will receive a new vehi-
cle speed message and reposition the gauge pointer
accordingly about every 86 milliseconds. The gauge
needle will continue to be positioned at the actual
vehicle speed position on the gauge scale until the
ignition switch is turned to the Off position.
²Communication Error- If the cluster fails to
receive a speedometer message, it will hold the gauge
needle at the last indication for about six seconds, or
until the ignition switch is turned to the Off position,
whichever occurs first. If a new speed message is not
received after about six seconds, the gauge needle
will return to the far left (low) end of the scale.
²Actuator Test- Each time the cluster is put
through the actuator test, the gauge needle will be
swept to several calibration points on the gauge scale
in sequence in order to confirm the functionality of
the gauge and the cluster control circuitry.
The PCM continually monitors the vehicle speed
information received from the Body Control Module
(BCM) to determine the vehicle road speed, then
8J - 32 INSTRUMENT CLUSTERKJ
SKIS INDICATOR (Continued)

ible when it is not illuminated. An amber Light
Emitting Diode (LED) behind the cutout in the
opaque layer of the overlay causes the ªTRANS
TEMPº text to appear in amber through the translu-
cent outer layer of the overlay when the indicator is
illuminated from behind by the LED, which is sol-
dered onto the instrument cluster electronic circuit
board. The transmission over-temperature indicator
is serviced as a unit with the instrument cluster.
OPERATION
The transmission over-temperature indicator gives
an indication to the vehicle operator when the trans-
mission fluid temperature is excessive, which may
lead to accelerated transmission component wear or
failure. This indicator is controlled by a transistor on
the instrument cluster electronic circuit board based
upon the 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 transmis-
sion over-temperature 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 LED
will always be off when the ignition switch is in any
position except On or Start. 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 transmission over-temperature indi-
cator for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the transmission over-tem-
perature indicator is illuminated for about three sec-
onds as a bulb test.
²Trans Over-Temp Lamp-On Message- Each
time the cluster receives a trans over-temp lamp-on
message from the PCM indicating that the transmis-
sion fluid temperature is 135É C (275É F) or higher,
the indicator will be illuminated. The indicator
remains illuminated until the cluster receives a trans
over-temp 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 trans over-temp indi-
cator will be turned on, then off again during the
bulb check portion of the test to confirm the function-
ality of the LED and the cluster control circuitry.
The PCM continually monitors the transmission
temperature sensor to determine the transmission
operating condition. The PCM then sends the proper
trans over-temp lamp-on and lamp-off messages to
the instrument cluster. If the instrument clusterturns on the transmission over-temperature indicator
due to a high transmission oil temperature condition,
it may indicate that the transmission and/or the
transmission cooling system are being overloaded or
that they require service. For further diagnosis of the
transmission over-temperature 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 transmission temperature
sensor, the PCM, the PCI data bus, or the electronic
message inputs to the instrument cluster that control
the transmission over-temperature indicator, a
DRBIIItscan tool is required. Refer to the appropri-
ate diagnostic information.
TURN SIGNAL INDICATOR
DESCRIPTION
Two turn signal indicators, one right and one left,
are standard equipment on all instrument clusters.
The turn signal indicators are located near the upper
edge of the instrument cluster, between the speedom-
eter and the tachometer. Each turn signal indicator
consists of a stencil-like cutout of the International
Control and Display Symbol icon for ªTurn Warningº
in the opaque layer of the instrument cluster overlay.
The dark outer layer of the overlay prevents these
icons from being clearly visible when they are not
illuminated. A green Light-Emitting Diode (LED)
behind each cutout in the opaque layer of the cluster
overlay causes the indicator to appear in green
through the translucent outer layer of the overlay
when it is illuminated from behind by the LED,
which is soldered onto the instrument cluster elec-
tronic circuit board. The turn signal indicators are
serviced as a unit with the instrument cluster.
OPERATION
The turn signal indicators give an indication to the
vehicle operator that the turn signal (left or right
indicator flashing) or hazard warning (both left and
right indicators flashing) have been selected and are
operating. These indicators are controlled by two
individual hard wired inputs from the combination
flasher circuitry within the hazard switch to the
instrument cluster electronic circuit board. Each turn
signal indicator Light Emitting Diode (LED) is
grounded on the instrument cluster electronic circuit
board at all times; therefore, these indicators remain
functional regardless of the ignition switch position.
Each LED will only illuminate when it is provided
battery current by the combination flasher circuitry
of the hazard switch.
8J - 34 INSTRUMENT CLUSTERKJ
TRANS TEMP INDICATOR (Continued)

The turn signal indicators are connected in parallel
with the other turn signal circuits. This arrangement
allows the turn signal indicators to remain func-
tional, regardless of the condition of the other cir-
cuits in the turn signal and hazard warning systems.
The combination flasher outputs of the hazard switch
to the instrument cluster turn signal indicator inputs
can be diagnosed using conventional diagnostic tools
and methods. (Refer to 8 - ELECTRICAL/LAMPS/
LIGHTING - EXTERIOR/HAZARD SWITCH -
DESCRIPTION) for more information on the combi-
nation flasher and hazard switch operation.
WAIT-TO-START INDICATOR
DESCRIPTION
A wait-to-start indicator is only found in the
instrument clusters of vehicles equipped with an
optional diesel engine. The wait-to-start indicator is
located above the fuel gauge and to the left of the
tachometer in the instrument cluster. The wait-to-
start indicator consists of a stencil-like cutout of the
International Control and Display Symbol icon for
ªDiesel Preheatº in the opaque layer of the instru-
ment cluster overlay. The dark outer layer of the
overlay prevents the indicator from being clearly vis-
ible 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 cluster
electronic circuit board. The wait-to-start indicator is
serviced as a unit with the instrument cluster.
OPERATION
The wait-to-start indicator gives an indication to
the vehicle operator when the diesel engine glow
plugs are energized in their pre-heat operating mode.
This indicator is controlled by a transistor on the
instrument cluster electronic circuit board based
upon the 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 wait-to-
start 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 willturn on the wait-to-start indicator for the following
reasons:
²Wait-To-Start Lamp-On Message- Each time
the cluster receives a wait-to-start lamp-on message
from the PCM indicating the glow plugs are heating
and the driver must wait to start the engine, the
wait-to-start indicator will be illuminated. The indi-
cator remains illuminated until the cluster receives a
wait-to-start lamp-off message, or until the ignition
switch is turned to the Off position, whichever occurs
first.
²Actuator Test- Each time the cluster is put
through the actuator test, the wait-to-start indicator
will be turned on, 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 ambient tem-
perature and the glow plug pre-heater circuits to
determine how long the glow plugs must be heated in
the pre-heat operating mode. The PCM then sends
the proper wait-to-start lamp-on and lamp-off mes-
sages to the instrument cluster. For further diagnosis
of the wait-to-start indicator or the instrument clus-
ter circuitry that controls the indicator, (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNO-
SIS AND TESTING). For proper diagnosis of the
glow plug pre-heater control circuits, the PCM, the
PCI data bus, or the electronic message inputs to the
instrument cluster that control the wait-to-start indi-
cator, a DRBIIItscan tool is required. Refer to the
appropriate diagnostic information.
WASHER FLUID INDICATOR
DESCRIPTION
A washer fluid indicator is standard equipment on
all instrument clusters. The washer fluid indicator
consists of the text ªlowashº, which appears in place
of the odometer/trip odometer information in the Vac-
uum-Fluorescent Display (VFD) of the instrument
cluster. The VFD is part of the cluster electronic cir-
cuit 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
overlay prevents the VFD from being clearly visible
when it is not illuminated. The text message
ªlowashº 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 circuit board. The washer fluid
indicator is serviced as a unit with the instrument
cluster.
KJINSTRUMENT CLUSTER 8J - 35
TURN SIGNAL INDICATOR (Continued)