2002 JEEP GRAND CHEROKEE Security light circuit

Programmable Communications Interface (PCI) data
bus. The SKIS indicator bulb is completely controlled
by the instrument cluster logic circuit, and that logic
will only allow this indicator to operate when the
instrument cluster receives a battery current input
on the fused ignition switch output (run-start) cir-
cuit. Therefore, the indicator will always be off when
the ignition switch is in any position except On or
Start. The bulb only illuminates when it is switched
to ground by the instrument cluster 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 Indicator Lamp-On Message- Each
time the cluster receives a SKIS indicator lamp-on
message from the SKIM, the SKIS indicator will be
illuminated. The indicator can be flashed on and off,
or illuminated solid, as dictated by the SKIM mes-
sage. For more information on the SKIS and the
SKIS indicator control parameters, (Refer to 8 -
ELECTRICAL/VEHICLE THEFT SECURITY -
OPERATION). The indicator remains illuminated
until the cluster receives a SKIS indicator lamp-off
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 indicator lamp-on or lamp-off messages from
the SKIM for twenty consecutive seconds, the SKIS
indicator is illuminated by the instrument cluster.
The indicator remains controlled and illuminated by
the cluster until a valid SKIS indicator lamp-on or
lamp-off message is received from the SKIM.
²Actuator Test- Each time the cluster is put
through the actuator test, the SKIS indicator will be
turned on for the duration of the test to confirm the
functionality of the bulb and the cluster control cir-
cuitry.
The 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
indicator lamp-on or lamp-off messages to the instru-
ment cluster. If the SKIS indicator fails to light dur-
ing the bulb test, replace the bulb with a known good
unit. For further diagnosis of the SKIS indicator or
the instrument cluster circuitry that controls the
indicator, (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. Forproper 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, from 0 to 200 km/h, or from 0 to 220
km/h, depending upon the market for which the vehi-
cle is manufactured. Most models also have a smaller
secondary inner scale on the gauge dial face that pro-
vides the equivalent opposite measurement units
from the primary scale. Text appearing in the center
of the gauge dial face just beneath the hub of the
speedometer needle abbreviates the unit of measure
for the primary scale in all upper case letters (i.e.:
MPH or KM/H). On models with a secondary scale,
the abbreviation for that scale follows the abbrevia-
tion for the primary scale in all lower case letters
(i.e.: mph or km/h).
The speedometer graphics are either white, gray
and orange against a black gauge dial face (base
cluster) or black and gray against a taupe gauge dial
face (premium cluster), making them clearly visible
within the instrument cluster in daylight. When illu-
minated from behind by the panel lamps dimmer
controlled cluster illumination lighting with the exte-
rior lamps turned On, the base cluster white gauge
graphics appear blue-green and the orange graphics
still appear orange, while the premium cluster taupe
gauge dial face appears blue-green with the black
graphics silhouetted against the illuminated back-
ground. The gray gauge graphics for both versions of
the cluster are not illuminated. The orange gauge
needle in the base cluster gauge is internally illumi-
nated, while the black gauge needle in the premium
cluster gauge is not.
Base cluster gauge illumination is provided by
replaceable incandescent bulb and bulb holder units
located on the instrument cluster electronic circuit
board. Premium cluster gauge illumination is pro-
vided by an integral electro-luminescent lamp that is
serviced as a unit with the instrument cluster. The
speedometer is serviced as a unit with the instru-
ment cluster.
8J - 30 INSTRUMENT CLUSTERWJ
SKIS INDICATOR (Continued)

LICENSE PLATE LAMP UNIT
REMOVAL.............................18
INSTALLATION.........................19
LEFT MULTI-FUNCTION SWITCH
DESCRIPTION.........................19
OPERATION...........................19
DIAGNOSIS AND TESTING - LEFT MULTI -
FUNCTION SWITCH...................20
REMOVAL
REMOVAL - LEFT MULTI-FUNCTION
SWITCH............................22
REMOVAL - MULTI-FUNCTION SWITCH
MOUNTING HOUSING..................22
INSTALLATION
INSTALLATION - LEFT MULTI-FUNCTION
SWITCH............................23
INSTALLATION - MULTI-FUNCTION SWITCH
MOUNTING HOUSING..................24
PARK/TURN SIGNAL LAMP
REMOVAL - BULBS.....................25INSTALLATION - BULBS..................25
TAIL LAMP
DESCRIPTION.........................25
OPERATION...........................25
REMOVAL
REMOVAL - BULBS....................25
REMOVAL - LAMP.....................25
INSTALLATION
INSTALLATION - BULBS................26
INSTALLATION - LAMP.................26
TURN SIGNAL CANCEL CAM
DESCRIPTION.........................26
OPERATION...........................26
UNDERHOOD LAMP
REMOVAL
REMOVAL - BULB.....................27
REMOVAL - LAMP.....................27
INSTALLATION
INSTALLATION - BULB.................27
INSTALLATION - LAMP.................27
LAMPS/LIGHTING - EXTERIOR
DESCRIPTION - TURN SIGNAL & HAZARD
WARNING SYSTEM
The turn signal and hazard warning system
includes the following major components, which are
described in further detail elsewhere in this service
information:
²Combination Flasher
²Front Side Marker Lamps
²Hazard Warning Switch
²Turn Signal Cancel Cam
²Turn Signal Indicators
²Turn Signal Lamps
²Turn Signal Switch
The turn signal and hazard warning systems also
provide the following features:
²Flash Lights with Lock- This customer pro-
grammable feature flashes the hazard warning lamps
to provide optical verification that the Remote Key-
less Entry (RKE) System has received a valid Lock or
Unlock request from an RKE transmitter. (Refer to 8
- ELECTRICAL/POWER LOCKS - DESCRIPTION -
REMOTE KEYLESS ENTRY SYSTEM).
²Panic Mode Optical Alert- This feature
flashes the hazard warning lamps to provide an opti-
cal alert when the Remote Keyless Entry (RKE) Sys-
tem panic mode is activated by depressing the Panic
button on an RKE transmitter. (Refer to 8 - ELEC-
TRICAL/POWER LOCKS - DESCRIPTION -
REMOTE KEYLESS ENTRY SYSTEM).
²Turn Signal On Warning- This feature pro-
vides the vehicle operator with both visual and audi-
ble reminders when a turn signal has been left
turned on for an extended period. (Refer to 8 - ELEC-TRICAL/OVERHEAD CONSOLE/ELECTRONIC
VEHICLE INFO CENTER - DESCRIPTION).
²Vehicle Theft Security System (VTSS) Opti-
cal Alarm- This feature flashes the hazard warning
lamps to provide an optical alarm when the VTSS is
armed and activated by an unauthorized entry into
the vehicle. (Refer to 8 - ELECTRICAL/VEHICLE
THEFT SECURITY - DESCRIPTION - VEHICLE
THEFT SECURITY SYSTEM).
OPERATION - TURN SIGNAL & HAZARD
WARNING SYSTEM
The turn signal system operates on battery current
received on a fused ignition switch output (run) cir-
cuit so that the turn signals will only operate with
the ignition switch in the On position. The hazard
warning system operates on non-switched battery
current received on a fused B(+) circuit so that the
hazard warning remains operational regardless of
the ignition switch position. When the turn signal
system is activated, the circuitry of the turn signal
switch and the combination flasher will cause the
selected (right or left) turn signal indicator, front
park/turn signal lamp, front side marker lamp and
rear tail/stop/turn signal lamp to flash on and off.
When the hazard warning system is activated, the
circuitry of the hazard warning switch and the com-
bination flasher will cause both the right side and
the left side turn signal indicators, front park/turn
signal lamps, front side marker lamps and rear tail/
stop/turn signal lamps to flash on and off.
The Body Control Module (BCM) can also activate
the hazard warning system lamps by energizing the
combination flasher through a single hard wired con-
nection to the hazard warning switch sense circuit.
The BCM grounds the circuit to energize and de-en-
8L - 2 LAMPS/LIGHTING - EXTERIORWJ

wired between a body ground, the Body Control Mod-
ule (BCM) and the rear wiper motor module through
the liftgate and body wire harnesses.
The liftgate flip-up glass ajar switch cannot be
adjusted or repaired and, if faulty or damaged, the
liftgate flip-up glass latch unit must be replaced.
(Refer to 23 - BODY/DECKLID/HATCH/LIFTGATE/
TAILGATE/FLIP-UP GLASS LATCH - REMOVAL)
for the service procedures. For complete circuit dia-
grams, refer to the appropriate wiring information.
DESCRIPTION - LIFTGATE AJAR SWITCH
The two liftgate ajar switches are integral to the
two liftgate latch mechanisms. The two liftgate ajar
switches are actuated by the liftgate latch mecha-
nisms, and are hard wired with each other between a
body ground and the Body Control Module (BCM)
through the liftgate and body wire harnesses.
The liftgate ajar switches cannot be adjusted or
repaired and, if faulty or damaged, the liftgate latch
unit must be replaced. (Refer to 23 - BODY/DECK-
LID/HATCH/LIFTGATE/TAILGATE/LATCH -
REMOVAL) for the service procedures. For complete
circuit diagrams, refer to the appropriate wiring
information.
OPERATION
OPERATION - DOOR AJAR SWITCH
The front door ajar switches close a path to ground
for the DDM or the PDM when a front door is
opened, and opens the ground path when a front door
is closed. The rear door ajar switches close a path to
ground for the BCM when a rear door is opened, and
opens the ground path when a rear door is closed.
The DDM, PDM, or BCM read the switch status then
send the proper switch status messages to other
modules over the Programmable Communications
Interface (PCI) data bus network. The door ajar
switch status message is used by the BCM as an
input for Vehicle Theft Security System (VTSS) oper-
ation.
OPERATION - FLIP UP GLASS AJAR SWITCH
The liftgate flip-up glass ajar switch can close a
path to ground for the BCM and the rear wiper
motor module when the liftgate flip-up glass is
opened, and opens the ground path when the liftgate
flip-up glass is closed. The rear wiper motor module
uses the liftgate flip-up glass ajar switch input to
control the rear wiper operation, and will park the
rear wiper blade if this input indicates that the lift-
gate flip-up glass is ajar. The BCM reads the switch
status then sends the proper switch status message
to other modules over the Programmable Communi-cations Interface (PCI) data bus network. The liftgate
flip-up glass ajar switch status message is used by
the BCM as an input for Vehicle Theft Security Sys-
tem (VTSS) operation.
OPERATION - LIFTGATE AJAR SWITCH
Each of the liftgate ajar switches can close a path
to ground for the BCM when the liftgate is opened,
and opens the ground path when the liftgate is
closed. The BCM reads the switch status then sends
the proper switch status message to other modules
over the Programmable Communications Interface
(PCI) data bus network. The liftgate ajar switch sta-
tus message is used by the BCM as an input for
Vehicle Theft Security System (VTSS) operation.
DIAGNOSIS AND TESTING - DOOR AJAR
SWITCH
The following diagnosis and testing is only
for the chime functions. For interior lamp diag-
nosis, refer to the appropriate wiring informa-
tion.The driver door ajar switch is hard wired to the
Driver Door Module (DDM). The DDM communicates
the switch status to the other modules in the vehicle
on the Programmable Communications Interface
(PCI) data bus network. The following test will diag-
nose a faulty driver door ajar switch and circuits. For
complete circuit diagrams, refer to the appropriate
wiring information.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO ELECTRICAL, RESTRAINTS
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
(1) Check that the interior lighting switch on the
control stalk of the left multi-function switch is not
in the dome lamp disable position. Open the driver
side front door and note whether the interior lamps
light. They should light. If OK, refer to Key-In Igni-
tion Switch in the Diagnosis and Testing section of
this group for further diagnosis of the chime warning
system. If not OK, go to Step 2.
(2) Disconnect and isolate the battery negative
cable. Remove the trim panel from the driver front
door and disconnect the 4-way door wire harness con-
nector from the front door latch connector. Check for
continuity between the ground circuit of the 4-way
door wire harness connector and a good ground.
There should be continuity. If OK, go to Step 3. If not
OK, repair the ground circuit.
8L - 30 LAMPS/LIGHTING - INTERIORWJ
DOOR AJAR SWITCH (Continued)

NOTE: If the vehicle is equipped with the Tire Pres-
sure Monitoring (TPM) System, and the overhead
console electronics module is removed or replaced,
the TPM system will need to be retrained. Refer to
the Tires/Wheels section of this manual for the pro-
cedure.
UNIVERSAL TRANSMITTER
DESCRIPTION
The Grand Cherokee Limited model has a Univer-
sal Garage Door Opener (UGDO) transceiver as stan-
dard factory-installed equipment. The UGDO is
optional on Laredo models. The UGDO transceiver is
integral to the Electronic Vehicle Information Center
(EVIC), which is located in the overhead console. The
only visible component of the UGDO are the three
transmitter push buttons centered between the four
EVIC push buttons located just rearward of the
EVIC display screen in the overhead console. The
three UGDO transmitter push buttons are identified
with one, two or three dots so that they be easily
identified by sight.
Each of the three UGDO transmitter push buttons
controls an independent radio transmitter channel.
Each of these three channels can be trained to trans-
mit a different radio frequency signal for the remoteoperation of garage door openers, motorized gate
openers, home or office lighting, security systems or
just about any other device that can be equipped
with a radio receiver in the 288 to 410 MegaHertz
(MHz) frequency range for remote operation. The
UGDO is capable of operating systems using either
rolling code or non-rolling code technology.
The EVIC module displays messages and a small
house-shaped icon with one, two or three dots corre-
sponding to the three transmitter buttons to indicate
the status of the UGDO. The EVIC messages are:
²Cleared Channels- Indicates that all of the
transmitter codes stored in the UGDO have been suc-
cessfully cleared.
²Training- Indicates that the UGDO is in its
transmitter learning mode.
²Trained- Indicates that the UGDO has success-
fully acquired a new transmitter code.
²Transmit- Indicates that a trained UGDO
transmitter button has been depressed and that the
UGDO is transmitting.
The UGDO cannot be repaired, and is available for
service only as a unit with the EVIC module. This
unit includes the push button switches and the plas-
tic module. If any of these components are faulty or
damaged, the complete EVIC module must be
replaced.
OPERATION
The universal transmitter operates on a non-
switched source of battery current so the unit will
remain functional, regardless of the ignition switch
position. For more information on the features, pro-
gramming procedures and operation of the universal
transmitter, see the owner's manual in the vehicle
glove box.
DIAGNOSIS AND TESTING - UNIVERSAL
TRANSMITTER
If the Universal Transmitter is inoperative, but the
Electronic Vehicle Information Center (EVIC) is oper-
ating normally, see the owner's manual in the vehicle
glove box for instructions on training the Transmit-
ter. Retrain the Transmitter with a known good
transmitter as instructed in the owner's manual and
test the Transmitter operation again. If the unit is
still inoperative, replace the faulty Transmitter and
EVIC module as a unit. If both the Transmitter and
the EVIC module are inoperative, refer toElec-
tronic Vehicle Information Center Diagnosis
and Testingin this group for further diagnosis. For
complete circuit diagrams, refer toWiring Dia-
grams.
Fig. 5 Top of Overhead Console
1 - OVERHEAD CONSOLE HOUSING
2 - EVIC MODULE
3 - ILLUMINATION LAMPS
4 - SCREWS (4)
WJMESSAGE SYSTEMS 8M - 11
ELECTRONIC VEHICLE INFO CENTER (Continued)

This vehicle also offers several customer program-
mable features, which allows the selection of several
optional electronic features to suit individual prefer-
ences. (Refer to 8 - ELECTRICAL/OVERHEAD CON-
SOLE/ELECTRONIC VEHICLE INFO CENTER -
DESCRIPTION). Customer programmable feature
options affecting the power door lock system include:
²Auto Door Locks- Automatically locks all of
the vehicle doors and the liftgate when the vehicle
reaches a speed of about 24 kilometers-per-hour (15
miles-per-hour) with 10% throttle tip-in.
²Auto Unlock on Exit- Automatically unlocks
all of the vehicle doors and the liftgate when the
driver side front door is opened, if the vehicle is
stopped and the transmission gear selector is in the
Park or Neutral positions. This feature is linked to
the Auto Door Locks feature, and will only occur one
time following each Auto Door Lock event.
The power lock system for this vehicle can also be
operated remotely using the standard equipment
Remote Keyless Entry (RKE) system radio frequency
transmitters. (Refer to 8 - ELECTRICAL/POWER
LOCKS - DESCRIPTION - REMOTE KEYLESS
ENTRY SYSTEM).
The components of the power lock system include:
²Driver Door Module (DDM)
²Passenger Door Module (PDM)
²PCI Bus Messages
²Power Lock Motors
Certain functions and features of the power lock
system rely upon resources shared with other elec-
tronic modules in the vehicle over the Programmable
Communications Interface (PCI) data bus network.
The PCI data bus network allows the sharing of sen-
sor information. This helps to reduce wire harness
complexity, internal controller hardware, and compo-
nent sensor current loads. At the same time, this sys-
tem provides increased reliability, enhanced
diagnostics, and allows the addition of many new fea-
ture capabilities. For proper diagnosis of these elec-
tronic modules or of the PCI data bus network, the
use of a DRBIIItscan tool and the appropriate diag-
nostic information are required.
The other electronic modules that may affect power
lock system operation are as follows:
²Body Control Module (BCM)- (Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/BODY CONTROL/CENTRAL TIMER MOD-
ULE - DESCRIPTION).
²Electronic Vehicle Information Center
(EVIC)- (Refer to 8 - ELECTRICAL/OVERHEAD
CONSOLE/ELECTRONIC VEHICLE INFO CENTER
- DESCRIPTION).
²Powertrain Control Module (PCM)- (Refer
to 8 - ELECTRICAL/ELECTRONIC CONTROLMODULES/POWERTRAIN CONTROL MODULE -
DESCRIPTION).
Hard wired circuitry connects the power lock sys-
tem components to the electrical system of the vehi-
cle. These hard wired circuits are integral to several
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 power lock sys-
tem 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.
DESCRIPTION - REMOTE KEYLESS ENTRY
SYSTEM
A Radio Frequency (RF) type Remote Keyless
Entry (RKE) system is standard factory-installed
equipment on this model. The RKE system allows
the use of a remote battery-powered radio transmit-
ter to control the power lock system. The RKE
receiver operates on non-switched battery current
through a fuse in the Power Distribution Center
(PDC), so that the system remains operational,
regardless of the ignition switch position.
In addition to Lock and Unlock buttons, the RKE
transmitters are also equipped with a Panic button.
If the Panic button on the RKE transmitter is
depressed, the horn will sound and the exterior lights
will flash on the vehicle for about three minutes, or
until the Panic button is depressed a second time, if
ignition is in the Off position. A vehicle speed of
about 24 kilometers-per-hour (15 miles-per-hour) will
also cancel the panic event.
The RKE system can also perform other functions
on this vehicle. If the vehicle is equipped with the
optional Vehicle Theft Security System (VTSS), the
RKE transmitter will arm the VTSS when the Lock
button is depressed, and disarm the VTSS when the
Unlock button is depressed. (Refer to 8 - ELECTRI-
CAL/VEHICLE THEFT SECURITY - DESCRIPTION
- VEHICLE THEFT SECURITY SYSTEM). If the
vehicle is equipped with the optional Memory Sys-
tem, each of the two numbered and color-coded RKE
transmitters can be used to recall the stored driver
side front seat position, both outside power rear view
mirror positions, and the radio station presets for the
two assigned drivers. (Refer to 8 - ELECTRICAL/
POWER SEATS - DESCRIPTION - MEMORY SYS-
TEM).
8N - 2 POWER LOCKSWJ
POWER LOCKS (Continued)

See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the power lock system.
OPERATION - REMOTE KEYLESS ENTRY
SYSTEM
The Passenger Door Module (PDM) contains the
RKE system control logic and the RKE receiver.
When the RKE receiver recognizes a Lock, Unlock or
Panic message from a valid RKE transmitter, the
RKE receiver provides that input to the PDM. The
PDM circuitry and programming responds by sending
the proper messages to the other electronic modules
over the Programmable Communications Interface
(PCI) data bus.
When an RKE lock message is received, the doors
and the liftgate lock, the interior lighting fades to off,
the horn chirps (if this feature is enabled), the exte-
rior lamps flash (if this feature is enabled) and, if the
vehicle is so equipped, the Vehicle Theft Security
System (VTSS) is armed. When an RKE unlock mes-
sage is received, the driver side front door (or all
doors and the liftgate if this feature is enabled)
unlock, the interior lighting is turned on and, if the
vehicle is so equipped, the VTSS is disarmed. If the
vehicle is equipped with the Memory System and the
RKE Linked to Memory feature is enabled, the RKE
unlock message also recalls the driver seat, outside
mirror and radio settings assigned to the RKE trans-
mitter that sent the unlock signal.
When an RKE panic message is received, it causes
the exterior lamps (including the headlights) to flash,
and the horn to pulse for about three minutes, or
until a second panic message is received. A vehicle
speed of about 24 kilometers-per-hour (15 miles-per-
hour) will also cancel the panic event.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the RKE system.
OPERATION - LIFTGATE FLIP-UP GLASS
POWER RELEASE SYSTEM
When the liftgate mounted flip-up glass release
switch is depressed, battery current is directed to the
electric release motor that is integral to the flip-up
glass latch located inside the liftgate. When the
release motor is energized the latch releases and the
flip-up glass can be opened. A liftgate flip-up glass
limit switch is integral to the liftgate latch actuator
mechanism. The limit switch automatically enables
or disables the liftgate flip-up glass power release cir-
cuitry, depending upon the position of the liftgate
latch lock mechanism. When the liftgate latch is
unlocked, the limit switch closes and battery current
is available at the release switch. When the liftgatelatch is locked , the limit switch opens, and the
release switch is disabled.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the liftgate flip-up glass power release system.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - POWER LOCK
SYSTEM
Following are tests that will help to diagnose the
hard wired components and circuits of the power lock
system. However, these tests may not prove conclu-
sive in the diagnosis of this system. In order to
obtain conclusive testing of the power lock system,
the Programmable Communications Interface (PCI)
data bus network and all of the electronic modules
that provide inputs to, or receive outputs from the
power lock system components must be checked.
The most reliable, efficient, and accurate means to
diagnose the power lock system requires the use of a
DRBIIItscan tool and the proper Diagnostic Proce-
dures manual. The DRBIIItscan tool can provide
confirmation that the PCI data bus is functional, that
all of the electronic modules are sending and receiv-
ing the proper messages on the PCI data bus, and
that the power lock motors are being sent the proper
hard wired outputs by the door modules for them to
perform their power lock system functions.
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, details of wire
harness routing and retention, connector pin-out
information and location views for the various wire
harness connectors, splices and grounds.
PRELIMINARY DIAGNOSIS
As a preliminary diagnosis for the power lock sys-
tem, note the system operation while you actuate
both the Lock and Unlock functions with the power
lock switches and with the Remote Keyless Entry
(RKE) transmitter. Then, proceed as follows:
²If the entire power lock system fails to function
with either the power lock switches or the RKE
transmitter, check the fused B(+) fuse in the Power
Distribution Center. If the fuse is OK, proceed to
diagnosis of the door modules. (Refer to 8 - ELEC-
TRICAL/ELECTRONIC CONTROL MODULES/
DOOR MODULE - DIAGNOSIS AND TESTING).
²If the power lock system functions with both
power lock switches, but not with the RKE transmit-
ter, proceed to diagnosis of the Remote Keyless Entry
(RKE) system. (Refer to 8 - ELECTRICAL/POWER
LOCKS - DIAGNOSIS AND TESTING - REMOTE
KEYLESS ENTRY SYSTEM).
WJPOWER LOCKS 8N - 5
POWER LOCKS (Continued)

If not OK, replace the faulty liftgate latch actuator
(brainplate) unit.
(5) Disconnect the liftgate wire harness connector
for the liftgate flip-up glass release switch from the
switch connector receptacle. With the liftgate latch
unlocked, check for battery voltage at the liftgate
flip-up glass limit switch output circuit cavity of the
liftgate wire harness connector for the release switch.
If OK, go to Step 6. If not OK, repair the open lift-
gate flip-up glass limit switch output circuit between
the release switch and the limit switch as required.
(6) Check for continuity between the two terminals
of the liftgate flip-up glass release switch. There
should be no continuity. Depress the switch, there
should now be continuity. If OK, go to Step 7. If not
OK, replace the faulty liftgate flip-up glass release
switch.
(7) Disconnect the liftgate wire harness connector
for the liftgate flip-up glass latch motor from the
motor connector receptacle. Check for continuity
between the ground circuit cavity of the liftgate wire
harness connector for the latch motor and a good
ground. There should be continuity. If OK, go to Step
8. If not OK, repair the open ground circuit to ground
as required.
(8) With the liftgate latch unlocked and the flip-up
glass release switch depressed, check for battery volt-
age at the liftgate flip-up glass release switch output
circuit cavity of the liftgate wire harness connector
for the latch motor. If OK, replace the faulty liftgate
flip-up glass latch unit. If not OK, repair the open
liftgate flip-up glass release switch output circuit
between the latch motor and the release switch as
required.
DOOR CYLINDER LOCK
SWITCH
DESCRIPTION
The driver cylinder lock switch is integral to the
key lock cylinder inside the driver side front door.
The driver cylinder lock switch is a resistive multi-
plexed switch that is hard wired between a body
ground and the Driver Door Module (DDM) through
the front door wire harness. It maintains a path to
ground, and changes voltages through an internal
resistor when the lock cylinder is rotated to the lock
or unlock position.
The driver cylinder lock switch cannot be adjusted
or repaired and, if faulty or damaged, the driver side
front door lock cylinder unit must be replaced. (Refer
to 23 - BODY/DOOR - FRONT/LOCK CYLINDER -
REMOVAL) and (Refer to 23 - BODY/DOOR -
FRONT/LOCK CYLINDER - INSTALLATION). Refer
to the appropriate wiring information. The wiringinformation includes wiring diagrams, proper wire
and connector repair procedures, further details on
wire harness routing and retention, as well as pin-
out and location views for the various wire harness
connectors, splices and grounds.
OPERATION
The driver cylinder lock switch is actuated by the
key lock cylinder when the key is inserted in the lock
cylinder and turned to the unlock position. The
driver cylinder lock switch maintains a path to
ground and changes voltages through an internal
resistor for the DDM when the driver door key lock
cylinder is in the lock or unlock position. The DDM
reads the switch status through an internal pull-up,
then sends the proper switch status messages to
other electronic modules over the Programmable
Communications Interface (PCI) data bus network.
The driver cylinder lock switch unlock status mes-
sage is used by the BCM as an input for Vehicle
Theft Security System (VTSS) operation and interior
lighting.
POWER LOCK MOTOR
DESCRIPTION
Power operated front door, rear door, and liftgate
locking mechanisms are standard equipment on this
model. The lock mechanisms are actuated by a
reversible electric motor mounted within each door
and the liftgate. The power lock motors for the doors
are integral to the door latch units. The liftgate
power lock motor is a separate unit secured to the
latch brainplate near the center of the liftgate and
operates the liftgate latch lock mechanism through a
connecting linkage rod.
The power lock motors for the four doors cannot be
adjusted or repaired and, if faulty or damaged, the
entire door latch unit must be replaced. The liftgate
power lock motor cannot be adjusted or repaired and,
if faulty or damaged, the entire liftgate latch actua-
tor (brainplate) unit must be replaced.
OPERATION
The driver side front door power lock motor is con-
trolled by the Driver Door Module (DDM). The
remaining power door lock motors and the liftgate
power lock motor are controlled by the Passenger
Door Module (PDM). A positive and negative battery
connection to the two motor terminals will cause the
power lock motor plunger to move in one direction.
Reversing the current through these same two con-
nections will cause the power lock motor plunger to
move in the opposite direction.
WJPOWER LOCKS 8N - 7
POWER LOCKS (Continued)

CONTROL/CENTRAL TIMER MODULE -
DESCRIPTION).
²Combination Flasher (Refer to 8 - ELECTRI-
CAL/LAMPS/LIGHTING - EXTERIOR/COMBINA-
TION FLASHER - DESCRIPTION).
²Door Ajar Switch (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - INTERIOR/DOOR AJAR
SWITCH - DESCRIPTION - DOOR AJAR SWITCH).
²Driver Cylinder Lock Switch (Refer to 8 - ELEC-
TRICAL/POWER LOCKS/DOOR CYLINDER LOCK/
UNLOCK SWITCH - DESCRIPTION).
²Hood Ajar Switch(Refer to 8 - ELECTRICAL/VE-
HICLE THEFT SECURITY/HOOD AJAR SWITCH -
DESCRIPTION).
²Horn Relay (Refer to 8 - ELECTRICAL/HORN/
HORN RELAY - DESCRIPTION).
²Liftgate Ajar Switch (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - INTERIOR/DOOR AJAR
SWITCH - DESCRIPTION - LIFTGATE AJAR
SWITCH).
²Liftgate Flip-Up Glass Ajar Switch(Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - INTERIOR/
DOOR AJAR SWITCH - DESCRIPTION - LIFTGATE
FLIP-UP GLASS AJAR SWITCH).
²Low Beam Headlamp Relay
²VTSS Indicator (Refer to 8 - ELECTRICAL/VE-
HICLE THEFT SECURITY/VTSS INDICATOR -
DESCRIPTION).
Certain functions and features of the VTSS rely
upon resources shared with or controlled by other
modules in the vehicle over the Programmable Com-
munications Interface (PCI) data bus network. The
other modules that may affect VTSS operation are:
²Driver Door Module (Refer to 8 - ELECTRICAL/
ELECTRONIC CONTROL MODULES/DOOR MOD-
ULE - DESCRIPTION).
²Passenger Door Module (Refer to 8 - ELECTRI-
CAL/ELECTRONIC CONTROL MODULES/DOOR
MODULE - DESCRIPTION).
DESCRIPTION - SENTRY KEY IMMOBILIZER
SYSTEM
Vehicles equipped with the Sentry Key Immobilizer
System (SKIS) can be identified by the presence of
an amber SKIS indicator in the instrument cluster
that will illuminate for about three seconds each
time the ignition switch is turned to the On position,
or by a gray molded rubber cap on the head of the
ignition key. Models not equipped with SKIS still
have a SKIS indicator in the cluster, but it will not
illuminate. Also, models not equipped with the SKIS
have a black molded rubber cap on the head of the
ignition key.
The SKIS includes the following major components,
which are described in further detail elsewhere in
this service manual:²Powertrain Control Module
²Sentry Key Immobilizer Module
²Sentry Key Transponder
²SKIS Indicator
Except for the Sentry Key transponders, which rely
upon Radio Frequency (RF) communication, hard
wired circuitry connects the SKIS components to the
electrical system of the vehicle.Refer to the appropri-
ate wiring information.
OPERATION
OPERATION - VEHICLE THEFT SECURITY
SYSTEM
The Vehicle Theft Security System (VTSS) is
divided into two basic subsystems: Vehicle Theft
Alarm (VTA) and Sentry Key Immobilizer System
(SKIS). The following are paragraphs that briefly
describe the operation of each of those two sub-
systems.
A Body Control Module (BCM) is used to control
and integrate many of the functions and features
included in the Vehicle Theft Security System
(VTSS). In the VTSS, the BCM receives inputs indi-
cating the status of the door ajar switches, the driver
cylinder lock switch, the ignition switch, the liftgate
ajar switches, the liftgate flip-up glass ajar switch,
the power lock switches and, in vehicles so equipped,
the hood ajar switch. The programming in the BCM
allows it to process the information from all of these
inputs and send control outputs to energize or de-en-
ergize the combination flasher, the horn relay (except
vehicles with the premium version of the VTA), and
the VTSS indicator. In addition, in vehicles built for
certain markets where premium versions of the VTA
is required, the BCM also exchanges messages with
the Intrusion Transceiver Module (ITM) over the Pro-
grammable Communications Interface (PCI) data
buss network to provide the features found in this
version of the VTA. The control of these inputs and
outputs are what constitute all of the features of the
VTSS. Following is information on the operation of
each of the VTSS features.
ENABLING
The BCM must have the VTSS function enabled in
order for the VTSS to perform as designed. The logic
in the BCM keeps its VTSS function dormant until it
is enabled using a DRBIIItscan tool. Refer to the
appropriate diagnostic information.
PRE-ARMING
The VTA has a pre-arming sequence. Pre-arming
occurs when a door, the tailgate, or the flip-up glass
is open when the vehicle is locked using a power lock
8Q - 2 VEHICLE THEFT SECURITYWJ
VEHICLE THEFT SECURITY (Continued)