2002 JEEP LIBERTY ECU

The dark outer layer of the overlay prevents the indi-
cator from being clearly visible when it is not illumi-
nated. 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 seat-
belt indicator is serviced as a unit with the instru-
ment cluster.
OPERATION
The seatbelt indicator gives an indication to the
vehicle operator of the status of the driver side front
seatbelt. 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 Airbag
Control Module (ACM) over the Programmable Com-
munications Interface (PCI) data bus. The seatbelt
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
seatbelt indicator for the following reasons:
²Seatbelt Reminder Function- Each time the
cluster receives a battery current input on the fused
ignition switch output (run-start) circuit, the indica-
tor will be illuminated as a seatbelt reminder for
about seven seconds, or until the ignition switch is
turned to the Off position, whichever occurs first.
This reminder function will occur regardless of the
status of the electronic seat belt lamp-on or lamp-off
messages received by the cluster from the ACM.
²Seat Belt Lamp-On Message- Following the
seatbelt reminder function, each time the cluster
receives a seat belt lamp-on message from the ACM
indicating the driver side front seat belt is not fas-
tened with the ignition switch in the Start or On
positions, the indicator will be illuminated. The seat-
belt indicator remains illuminated until the cluster
receives a seat belt lamp-off message, or until the
ignition switch is turned to the Off position, which-
ever occurs first.
²Actuator Test- Each time the cluster is put
through the actuator test, the seatbelt 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 ACM continually monitors the status of both
front seat belt switches to determine the proper air-
bag system response to a frontal impact of the vehi-
cle. The ACM then sends the proper seatbelt
indicator lamp-on and lamp-off messages to the
instrument cluster based upon the status of the
driver side front seat belt switch input. For further
diagnosis of the seatbelt indicator or the instrument
cluster circuitry that controls the indicator, (Refer to
8 - ELECTRICAL/INSTRUMENT CLUSTER - DIAG-
NOSIS AND TESTING). For proper diagnosis of the
seatbelt switches, the ACM, the PCI data bus, or the
electronic message inputs to the instrument cluster
that control the seatbelt indicator, a DRBIIItscan
tool is required. Refer to the appropriate diagnostic
information.
SECURITY INDICATOR
DESCRIPTION
A security indicator is standard equipment on all
instrument clusters, but is only functional on vehi-
cles equipped with the optional Vehicle Theft Secu-
rity System (VTSS). The security indicator is located
near the lower edge of the instrument cluster below
the tachometer and to the right of the fuel gauge.
The security indicator consists of a small stencil-like
round 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. A red Light Emitting
Diode (LED) behind the cutout in the opaque layer of
the overlay causes the indicator 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 elec-
tronic circuit board. The security indicator is serviced
as a unit with the instrument cluster.
OPERATION
The security indicator gives an indication to the
vehicle operator when the Vehicle Theft Alarm (VTA)
portion of the Vehicle Theft Security System (VTSS)
is arming or is armed. This indicator is controlled on
the instrument cluster circuit board based upon a
hard wired input to the cluster from the Body Con-
trol Module (BCM) on the VTSS indicator driver cir-
cuit. The security indicator Light Emitting Diode
(LED) receives battery current on the instrument
cluster electronic circuit board through the fused
B(+) circuit at all times; therefore, the LED will
remain functional regardless of the ignition switch
position. The LED only illuminates when it is pro-
vided a path to ground by the BCM. The security
8J - 28 INSTRUMENT CLUSTERKJ
SEATBELT INDICATOR (Continued)

indicator will be illuminated for the following rea-
sons:
²VTSS Indication- During the sixteen second
VTA pre-arming function, the BCM will flash the
security indicator on and off repeatedly at a steady,
fast rate to indicate that the VTA is in the process of
arming. Following successful VTA arming, the BCM
flashes the security indicator on and off continuously
at a slower rate to indicate that the VTA is armed.
The security indicator continues flashing at the
slower rate until the VTA is disarmed.
The BCM provides a hard wired ground input to
the instrument cluster circuitry through the VTSS
indicator driver circuit whenever the ignition switch
is in the Off position and the VTA is arming, armed,
or triggered. The VTSS indicator driver circuit
between the BCM and the instrument cluster can be
diagnosed using conventional diagnostic tools and
methods. However, for proper diagnosis of the VTA
and the BCM, or the hard wired inputs to the instru-
ment cluster that control the security indicator, a
DRBIIItscan tool is required. Refer to the appropri-
ate diagnostic information.
SHIFT INDICATOR (TRANSFER
CASE)
DESCRIPTION
DESCRIPTION - PART TIME INDICATOR
A part time indicator is standard equipment on all
instrument clusters. The part time indicator is
located near the lower edge of the tachometer dial
face in the instrument cluster. The part time indica-
tor consists of a stencil-like cutout of the words
ªPART TIMEº 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 ªPART TIMEº 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 part
time indicator is dimmable, which is adjusted using
the panel lamps dimmer control ring on the left con-
trol stalk of the multi-function switch. The part time
indicator is serviced as a unit with the instrument
cluster.
DESCRIPTION - FULL TIME INDICATOR
A full time indicator is standard equipment on all
instrument clusters, but is only functional on vehi-
cles equipped with the optional Selec-Trac four-wheel
drive system. The full time indicator is located near
the lower edge of the tachometer dial face in the
instrument cluster. The full time indicator consists of
a stencil-like cutout of the words ªFULL TIMEº in
the opaque layer of the instrument cluster overlay.
The dark outer layer of the overlay prevents the indi-
cator from being clearly visible when it is not illumi-
nated. A green Light Emitting Diode (LED) behind
the cutout in the opaque layer of the cluster overlay
causes the ªFULL TIMEº text 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. When the exterior lighting is
turned On, the illumination intensity of the full time
indicator is dimmable, which is adjusted using the
panel lamps dimmer control ring on the left control
stalk of the multi-function switch. The full time indi-
cator is serviced as a unit with the instrument clus-
ter.
DESCRIPTION - FOUR LOW MODE INDICATOR
A four low mode indicator is standard equipment
on all instrument clusters. The four low mode indica-
tor is located above the coolant temperature gauge
and to the right of the speedometer in the instru-
ment cluster. The four low mode indicator consists of
a stencil-like cutout of the words ª4 LO MODEº in
the opaque layer of the instrument cluster overlay.
The dark outer layer of the overlay prevents the indi-
cator from being clearly visible when it is not illumi-
nated. An amber Light Emitting Diode (LED) behind
the cutout in the opaque layer of the overlay causes
the ª4 LO MODEº text 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 circuit
board. The four low mode indicator is serviced as a
unit with the instrument cluster.
OPERATION
OPERATION - PART TIME INDICATOR
The part time indicator gives an indication to the
vehicle operator that a four-wheel drive part time
operating mode of the transfer case is selected. On
vehicles equipped with the standard Command-Trac
four-wheel drive system, the part time indicator
lights when the transfer case is engaged in the 4H or
4L positions. On vehicles equipped with the optional
Selec-Trac four-wheel drive system, the part time
KJINSTRUMENT CLUSTER 8J - 29
SECURITY INDICATOR (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)

HEADLAMP LEVELING MOTOR
DESCRIPTION.........................35
OPERATION...........................36
REMOVAL.............................36
INSTALLATION.........................36
HEADLAMP LEVELING SWITCH
DESCRIPTION.........................37
OPERATION...........................37
DIAGNOSIS AND TESTING - HEADLAMP
LEVELING SWITCH....................37
REMOVAL.............................38
INSTALLATION.........................38
HEADLAMP LOW BEAM RELAY
DESCRIPTION.........................39
OPERATION...........................39
DIAGNOSIS AND TESTING - HEADLAMP LOW
BEAM RELAY........................40
REMOVAL.............................40
INSTALLATION.........................41
HEADLAMP UNIT
REMOVAL.............................41
INSTALLATION.........................42
ADJUSTMENTS
ADJUSTMENT - HEADLAMP UNIT........42
LICENSE PLATE LAMP BULB
REMOVAL.............................44
INSTALLATION.........................45
LICENSE PLATE LAMP UNIT
REMOVAL.............................45
INSTALLATION.........................46
MULTI-FUNCTION SWITCH
DESCRIPTION.........................46
OPERATION...........................48
DIAGNOSIS AND TESTING - MULTI-
FUNCTION SWITCH...................50
REMOVAL.............................53
INSTALLATION.........................53
PARK LAMP RELAY
DESCRIPTION.........................54OPERATION...........................54
DIAGNOSIS AND TESTING - PARK LAMP
RELAY..............................55
REMOVAL.............................55
INSTALLATION.........................56
REAR FOG LAMP RELAY
DESCRIPTION.........................56
OPERATION...........................57
DIAGNOSIS AND TESTING - REAR FOG
LAMP RELAY.........................57
REMOVAL.............................58
INSTALLATION.........................58
REAR LAMP BULB
REMOVAL.............................58
INSTALLATION.........................59
REAR LAMP UNIT
REMOVAL.............................59
INSTALLATION.........................60
REPEATER LAMP BULB
REMOVAL.............................60
INSTALLATION.........................60
REPEATER LAMP UNIT
REMOVAL.............................60
INSTALLATION.........................61
TRAILER TOW CONNECTOR
REMOVAL.............................61
INSTALLATION.........................61
TRAILER TOW RELAY
DESCRIPTION.........................61
OPERATION...........................62
DIAGNOSIS AND TESTING - TRAILER TOW
RELAY..............................62
REMOVAL.............................63
INSTALLATION.........................64
TRAILER TOW WIRING
DESCRIPTION.........................64
LAMPS/LIGHTING - EXTERIOR
DESCRIPTION
The exterior lighting system for this model
includes the following exterior lamps (Fig. 1):
²Backup Lamps- The backup (or reverse) lamps
are integral to the rear lamp units mounted to the
back of the quarter panel on each side of the tailgate
at the rear of the vehicle.
²Brake Lamps- The brake (or stop) lamps
include a lamp that is integral to the rear lamp units
mounted to the back of the quarter panel on each
side of the tailgate, and the Center High Mounted
Stop Lamp (CHMSL) that is centered on the rear
edge of the roof panel above the flip-up glass opening
at the rear of the vehicle.²Daytime Running Lamps- Vehicles manufac-
tured for sale in Canada illuminate the high beam
filament in each headlamp bulb serves as the Day-
time Running Lamps (DRL).
²Front Fog Lamps- Optional front fog lamps
include a single round front fog lamp unit with an
adjustable reflector and a removable bulb that is
secured behind a dedicated opening on each forward-
facing end of the front bumper fascia.
²Hazard Warning Lamps- The hazard warning
lamps include all of the right and left turn signal
lamps.
²Headlamps- A single round headlamp housing
with a fixed lens, an adjustable reflector, and a single
removable halogen bulb is secured to the grille open-
ing panel on each side of the grille opening at the
8L - 2 LAMPS/LIGHTING - EXTERIORKJ

trols for both the exterior and interior lighting sys-
tems.
²Park Lamp Relay- A park lamp relay is
located in the Junction Block (JB) of all vehicles.
²Rear Fog Lamp Relay- Vehicles manufac-
tured for certain markets where rear fog lamps are
required equipment have a rear fog lamp relay
located in the Junction Block (JB).
²Trailer Tow Adapter- Vehicles equipped with
a factory-installed trailer towing package have an
adapter provided that adapts the factory-installed
heavy duty 7-way trailer tow connector to a conven-
tional 4-way light duty connector.
²Trailer Tow Connector- Vehicles equipped
with a factory-installed trailer towing package have a
heavy duty 7-way trailer tow connector installed in a
bracket on the trailer hitch receiver.
²Trailer Tow Relays- Vehicles equipped with a
factory-installed trailer towing package have a con-
nector bank containing four relays located behind the
right quarter trim panel and over the right rear
wheel housing. The four relays are used to supply
fused ignition switch output (run), brake lamps, right
turn signal, and left turn signal outputs to a trailer
through the trailer tow wiring and connectors.
Hard wired circuitry connects the exterior lighting
system components to the electrical system of the
vehicle. These hard wired circuits are integral to sev-
eral wire harnesses, which are routed throughout the
vehicle and retained by many different methods.
These circuits may be connected to each other, to the
vehicle electrical system and to the exterior lighting
system components through the use of a combination
of soldered splices, splice block connectors, and many
different types of wire harness terminal connectors
and insulators. Refer to the appropriate wiring infor-
mation. The wiring information includes wiring dia-
grams, proper wire and connector repair procedures,
further details on wire harness routing and reten-
tion, as well as pin-out and location views for the
various wire harness connectors, splices and grounds.
OPERATION
Following are paragraphs that briefly describe the
operation of each of the major exterior lighting sys-
tems. The hard wired circuits and components of the
exterior lighting systems may be diagnosed and
tested using conventional diagnostic tools and proce-
dures. However, conventional diagnostic methods
may not prove conclusive in the diagnosis of the Body
Control Module (BCM), the ElectroMechanical
Instrument Cluster (EMIC), the Powertrain Control
Module (PCM), or the Programmable Communica-
tions Interface (PCI) data bus network. The most
reliable, efficient, and accurate means to diagnose
the BCM, the EMIC, the PCM, and the PCI data busnetwork inputs and outputs related to the various
exterior lighting systems requires the use of a
DRBIIItscan tool. Refer to the appropriate diagnos-
tic information.
BACKUP LAMPS
The backup (or reverse) lamps have a path to
ground at all times through their connection to the
rear lighting wire harness from a take out of the rear
body wire harness with an eyelet terminal connector
that is secured by a ground screw to the base of the
right D-pillar behind the quarter trim panel. The
backup lamps receive battery current from a fused
ignition switch output (run) fuse in the Junction
Block (JB) on the back-up lamp feed circuit only
when the backup lamp switch (manual transmission),
or backup lamp switch circuit of the Transmission
Range Sensor (TRS - electronic automatic transmis-
sion) is closed by the gearshift mechanism within the
transmission.
BRAKE LAMPS
The brake (or stop) lamps have a path to ground at
all times through their connection to the rear light-
ing wire harness from a take out of the rear body
wire harness with an eyelet terminal connector that
is secured by a screw to the base of the right D-pillar
behind the quarter trim panel. The Center High
Mounted Stop Lamp (CHMSL) has a path to ground
at all times through its connection to the rear body
wire harness from a take out of the rear body wire
harness with an eyelet terminal connector that is
secured by a ground screw to the driver side D-pillar
(left side D-pillar for left-hand drive, right side D-pil-
lar for right-hand drive) behind the quarter trim
panel. The brake lamps and CHMSL receive battery
current from a fused B(+) fuse in the Junction Block
(JB) on the brake lamp switch output circuit only
when the brake lamp switch circuit of the brake
lamp switch is closed by the brake pedal arm.
DAYTIME RUNNING LAMPS
Vehicles manufactured for sale in Canada illumi-
nate the high beam filament at a reduced intensity
when the engine is running and the exterior lamps
are turned off. This feature is enabled by the Body
Control Module (BCM) and a solid state Daytime
Running Lamps (DRL) relay, which is installed in the
Junction Block (JB) and the high beam relay is omit-
ted. When the BCM monitors an engine speed signal
of greater than 450 RPM and the status of the exte-
rior lighting switch input from the multi-function
switch is Off, the BCM duty cycles the DRL relay to
produce illumination of the headlamp high beam fil-
aments at a reduced intensity. The BCM also pro-
vides normal headlamp high beam operation through
the DRL relay on vehicles so equipped. When the
KJLAMPS/LIGHTING - EXTERIOR 8L - 5
LAMPS/LIGHTING - EXTERIOR (Continued)

DRL relay is energized, it provides battery current
from a fused B(+) fuse in the JB to the headlamp
high beam filament through the DRL relay output
circuit.
FRONT FOG LAMPS
Vehicles equipped with optional front fog lamps
have a premium Body Control Module (BCM), a front
fog lamp relay installed in the Junction Block (JB),
and a front fog lamp switch integral to the left (light-
ing) control stalk of the multi-function switch. The
front fog lamps have a path to ground at all times
through their connection to the front fascia wire har-
ness from two take outs of the headlamp and dash
wire harness with eyelet terminal connectors that
are secured by ground screws to the left inner fender
shield in the engine compartment. The BCM controls
front fog lamp operation by monitoring the exterior
lighting switch input from the multi-function switch,
then energizing or de-energizing the front fog lamp
relay control coil; and, by sending the appropriate
electronic message to the instrument cluster over the
Programmable Communications Interface (PCI) data
bus to turn the front fog lamp indicator on or off.
When the front fog lamp relay is energized, it pro-
vides battery current from a fused B(+) fuse in the
JB to the front fog lamps through the front fog lamp
relay output circuit. The BCM provides a battery
saver (load shedding) feature for the front fog lamps,
which will turn these lamps off if they are left on for
more than about eight minutes with the ignition
switch in the Off position. In certain markets where
required, the front fog lamps are also turned off by
the BCM whenever the headlamp high beams are
selected. Each front fog lamp includes an integral
adjustment screw to be used for static aiming the fog
lamp beams.
HAZARD WARNING LAMPS
With the hazard switch in the On position, the
hazard warning system is activated causing the haz-
ard switch button illumination lamp, the right and
left turn signal indicators, and the right and left turn
signal lamps to flash on and off. When the hazard
warning system is activated, the circuitry within the
hazard switch and electronic combination flasher
unit will repeatedly energize and de-energize two
internal relays that switch battery current from a
fused B(+) fuse in the Junction Block (JB) to the
right side and left side turn signal indicators, and
turn signal lamps through the right and left turn sig-
nal circuits. The flashing of the hazard switch button
illumination lamp is performed internally by the haz-
ard switch and combination flasher unit circuit
board. The hazard warning lamps can also be ener-
gized by the Body Control Module (BCM) through ahazard lamp control circuit input to the hazard
switch and combination flasher unit.
HEADLAMPS
The headlamp system includes the Body Control
Module (BCM), a low beam relay installed in the
Junction Block (JB), a high beam relay installed in
the JB (except Canada), a solid state Daytime Run-
ning Lamps (DRL) relay installed in the JB (Canada
only), and the exterior lighting (headlamp and dim-
mer) switches integral to the left (lighting) control
stalk of the multi-function switch. The headlamp
bulbs have a path to ground at all times through
their connection to the grille opening reinforcement
wire harness from two take outs of the headlamp and
dash wire harness with eyelet terminal connectors
that are secured by ground screws to the left inner
fender shield in the engine compartment. The BCM
controls the headlamp operation by monitoring the
exterior lighting switch inputs from the multi-func-
tion switch, then energizing or de-energizing the con-
trol coils of the low beam relay, the high beam relay,
or the solid state circuitry of the DRL relay; and, by
sending the appropriate electronic message to the
instrument cluster over the Programmable Commu-
nications Interface (PCI) data bus to turn the high
beam indicator on or off. When each respective relay
is energized, it provides battery current from a fused
B(+) fuse in the Power Distribution Center (PDC)
through a relay (low beam, high beam, or DRL) out-
put circuit and four separate fuses in the JB through
individual fused right and left, low and high beam
output circuits to the appropriate headlamp bulb fil-
aments. The BCM provides a battery saver (load
shedding) feature for the headlamps, which will turn
these lamps off if they are left on for more than
about eight minutes with the ignition switch in the
Off position; and, a headlamp delay feature with a
DRBIIItscan tool programmable delay interval.
Each headlamp includes an integral adjustment
screw to be used for static aiming of the headlamp
beams.
HEADLAMP LEVELING
In certain markets where required, a headlamp
leveling system is provided on the vehicle. The head-
lamp leveling system includes unique headlamp units
equipped with a headlamp leveling actuator motor,
and a rotary thumbwheel actuated headlamp leveling
switch on the instrument panel. The headlamp level-
ing system allows the headlamp beams to be
adjusted to one of four vertical positions to compen-
sate for changes in inclination caused by the loading
of the vehicle suspension. The actuator motors are
mechanically connected through an integral pushrod
to an adjustable headlamp reflector. The headlamp
8L - 6 LAMPS/LIGHTING - EXTERIORKJ
LAMPS/LIGHTING - EXTERIOR (Continued)

leveling switch is a resistor multiplexed unit that
provides one of four voltage outputs to the headlamp
leveling motors. The headlamp leveling motors will
move the headlamps to the selected position based
upon the voltage input received from the switch. The
headlamp leveling motors and switch have a path to
ground at all times. The headlamp leveling compo-
nents operate on battery current received through
the fused park lamp relay output circuit so that the
system will only operate when the exterior lighting is
turned on.
PARK LAMPS
The park lamps system includes the Body Control
Module (BCM), a park lamp relay installed in the
Junction Block (JB), and the exterior lighting switch
integral to the left (lighting) control stalk of the
multi-function switch. The front park lamp and side
marker or, if equipped, the front position lamp bulbs
each have a path to ground at all times through their
connections to the grille opening reinforcement wire
harness from two take outs of the headlamp and
dash wire harness with eyelet terminal connectors
that are secured by ground screws to the left inner
fender shield in the engine compartment. The rear
park lamp bulbs and license plate lamp have a path
to ground at all times through their connection to the
rear lighting wire harness from a take out of the rear
body wire harness with an eyelet terminal connector
that is secured by a ground screw to the base of the
right D-pillar behind the quarter trim panel. The
BCM controls the park lamp operation by monitoring
the exterior lighting switch inputs from the multi-
function switch, then energizing or de-energizing the
control coil of the park lamp relay. When the park
lamp relay is energized, it provides battery current
from a fused B(+) fuse in the Power Distribution
Center (PDC) through a park lamp relay output cir-
cuit and a separate fuse in the JB through a fused
park lamp relay output circuit to the appropriate
lamp bulb filaments. The BCM provides a battery
saver (load shedding) feature for the park lamps,
which will turn these lamps off if they are left on for
more than about eight minutes with the ignition
switch in the Off position.
REAR FOG LAMPS
Rear fog lamps are installed on vehicles manufac-
tured for certain markets where they are required.
The rear fog lamp system includes a premium Body
Control Module (BCM), a rear fog lamp relay
installed in the Junction Block (JB), and a rear fog
lamp switch integral to the left (lighting) control
stalk of the multi-function switch. The rear fog lamps
have a path to ground at all times through their con-
nection to the rear lighting wire harness from a takeout of the rear body wire harness with an eyelet ter-
minal connector that is secured by a ground screw to
the base of the right D-pillar behind the quarter trim
panel. The BCM controls rear fog lamp operation by
monitoring the exterior lighting switch input from
the multi-function switch, then energizing or de-ener-
gizing the rear fog lamp relay control coil; and, by
sending the appropriate electronic message to the
instrument cluster over the Programmable Commu-
nications Interface (PCI) data bus to turn the rear
fog lamp indicator on or off. When the rear fog lamp
relay is energized, it provides battery current from a
fused B(+) fuse in the JB to the rear fog lamps
through the rear fog lamp relay output circuit. The
BCM provides a battery saver (load shedding) feature
for the rear fog lamps, which will turn these lamps
off if they are left on for more than about eight min-
utes with the ignition switch in the Off position.
TURN SIGNAL LAMPS
When the left control stalk of the multi-function
switch is moved up (right turn) or down (left turn),
the turn signal system is activated causing the
selected right or left turn signal indicator, and right
or left turn signal lamps to flash on and off. When
the turn signal system is activated, the circuitry
within the turn signal switch and the hazard switch/
electronic combination flasher unit will repeatedly
energize and de-energize one of two internal relays
that switch battery current from a fused ignition
switch output (run) fuse in the Junction Block (JB) to
the right side or left side turn signal indicators and
turn signal lamps through the right or left turn sig-
nal circuits. The ElectroMechanical Instrument Clus-
ter (EMIC) chime tone generator will generate an
audible turn signal cancel warning each time the
vehicle is driven for a distance of about 3.2 kilome-
ters (about two miles) with a turn signal indicator
flashing. The EMIC uses Programmable Communica-
tions Interface (PCI) data bus distance messages
from the Powertrain Control Module (PCM) and a
hard wired input from the turn signal switch cir-
cuitry of the multi-function switch to determine when
to sound the turn signal cancel warning.
DIAGNOSIS AND TESTING - LAMPS/LIGHTING
- EXTERIOR
The hard wired circuits and components of the
exterior lighting systems may be diagnosed and
tested using conventional diagnostic tools and proce-
dures. However, conventional diagnostic methods
may not prove conclusive in the diagnosis of the Body
Control Module (BCM), the ElectroMechanical
Instrument Cluster (EMIC), the Powertrain Control
Module (PCM), or the Programmable Communica-
tions Interface (PCI) data bus network. The most
KJLAMPS/LIGHTING - EXTERIOR 8L - 7
LAMPS/LIGHTING - EXTERIOR (Continued)