2003 JEEP GRAND CHEROKEE lamp

the engine compartment. This relay can be energized
by the BCM to sound the horns as an audible alert
for the RKE panic function and, if the Sound Horn
on Lock programmable feature is enabled, as an
audible verification for the RKE lock event. (Refer to
8 - ELECTRICAL/HORN/HORN RELAY - DESCRIP-
TION).
LOW BEAM HEADLAMP RELAY
The low beam headlamp relay is a electromechan-
ical device that switches battery current to the head-
lamp low beams when the BCM grounds the relay
coil. The low beam headlamp relay is located in the
junction block in the passenger compartment. This
relay can be energized by the BCM to flash the head-
lamp low beams as an optical alert for the RKE panic
function. (Refer to 8 - ELECTRICAL/LAMPS/LIGHT-
ING - EXTERIOR/HEADLAMP - DESCRIPTION).
DESCRIPTION - LIFTGATE FLIP-UP GLASS
POWER RELEASE SYSTEM
A power operated liftgate flip-up glass release sys-
tem is standard factory installed equipment on this
model. The liftgate flip-up glass power release system
allows the flip-up glass latch to be released electri-
cally by depressing a switch located on the bottom of
the liftgate license plate lamp housing unit, above
the license plate on the outside of the liftgate.
The liftgate flip-up glass release system operates
on non-switched battery current supplied through a
fuse in the junction block so that the system remains
functional, regardless of the ignition switch position.
However, a limit switch that is integral to the liftgate
latch actuator unit opens to prevent the flip-up glass
latch from being actuated when the liftgate latch is
locked.
The liftgate flip-up glass power release system
includes the following components:
²Liftgate Flip-Up Glass Limit Switch- The
liftgate flip-up glass limit switch is integral to the
liftgate latch unit. (Refer to 23 - BODY/DECKLID/
HATCH/LIFTGATE/TAILGATE/LATCH - REMOVAL)
and (Refer to 23 - BODY/DECKLID/HATCH/LIFT-
GATE/TAILGATE/LATCH - INSTALLATION).
²Liftgate Flip-Up Glass Release Motor- The
liftgate flip-up glass release motor is integral to the
liftgate flip-up glass latch unit. (Refer to 23 - BODY/
DECKLID/HATCH/LIFTGATE/TAILGATE/FLIP-UP
GLASS LATCH - REMOVAL) and (Refer to 23 -
BODY/DECKLID/HATCH/LIFTGATE/TAILGATE/
FLIP-UP GLASS LATCH - INSTALLATION).
²Liftgate Flip-Up Glass Release Switch- The
liftgate flip-up glass release switch is integral to the
liftgate license plate lamp housing. (Refer to 23 -
BODY/DECKLID/HATCH/LIFTGATE/TAILGATE/
FLIP-UP GLASS SWITCH - REMOVAL) and (Referto 23 - BODY/DECKLID/HATCH/LIFTGATE/TAIL-
GATE/FLIP-UP GLASS SWITCH - INSTALLATION).
Hard wired circuitry connects the liftgate flip-up
glass power release system components to the electri-
cal system of the vehicle. 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
liftgate flip-up glass power release system compo-
nents through the use of a combination of soldered
splices, splice block connectors, and many different
types of wire harness terminal connectors and insu-
lators. Refer to the appropriate wiring information.
The wiring information 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
OPERATION - POWER LOCK SYSTEM
The Passenger Door Module (PDM) contains the
power door lock control logic and a power lock switch.
The Driver Door Module (DDM) contains a power
lock switch and controls the output to the driver side
front door power lock motor, while the PDM controls
the output to the power lock motors for the remain-
ing doors and the liftgate.
When the power lock switch on the DDM is used to
lock or unlock the doors, the DDM sends a control
output to the driver side front door power lock motor
and sends lock or unlock request messages to the
PDM over the Programmable Communications Inter-
face (PCI) data bus. The PDM responds to these mes-
sages by sending control outputs to the power lock
motors of the remaining doors and the liftgate. When
the power lock switch on the PDM is used to lock or
unlock the doors, the PDM sends control outputs to
the power lock motors in the passenger side front
door, both rear doors and the liftgate, then sends lock
or unlock request messages to the DDM over the Pro-
grammable Communications Interface (PCI) data
bus. The DDM responds to these messages by send-
ing control outputs to the power lock motor of the
driver side front door.
In order to support the auto door locks and unlock
on exit features, if enabled, the power lock system
logic in the PDM needs to know the door ajar switch
status, vehicle speed, and transmission gear selector
lever position. The passenger side front door ajar
switch is the only hard wired input to the PDM. The
PDM obtains the remaining information from mes-
sages it receives from other electronic modules over
the PCI data bus network.
8N - 4 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)

DIAGNOSIS AND TESTING - POWER LOCK
MOTOR
Remember, the Driver Door Module (DDM) cir-
cuitry controls the output to the driver side front
door power lock motor. The Passenger Door Module
(PDM) circuitry controls the output to the power lock
motors for the remaining doors and the liftgate.
Refer to the appropriate wiring information. The wir-
ing 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.
(1) Check each power lock motor for correct opera-
tion while moving the power lock switch to both the
Lock and Unlock positions. If all of the power lock
motors are inoperative, go to Step 2. If one power
lock motor is inoperative, go to Step 3.
(2) If all of the power lock motors except the driver
side front door are inoperative, the problem may be
caused by one shorted motor. Disconnecting a shorted
power lock motor from the power lock circuit will
allow the good power lock motors to operate. Discon-
nect the wire harness connector from each PDM-con-
trolled power lock motor, one at a time, and recheck
both the lock and unlock functions by operating the
power lock switch. If all of the PDM-controlled power
lock motors are still inoperative after the above test,
check for a short or open circuit between the power
lock motors and the PDM. If disconnecting one power
lock motor causes the other motors to become func-
tional, go to Step 3 to test the power lock motor that
was last disconnected.
(3) Once it is determined which power lock motor
is inoperative, that motor can be tested as follows.
Disconnect the door or liftgate wire harness connec-
tor from the inoperative power lock motor. Apply 12
volts to the lock and unlock driver circuit cavities of
the power lock motor connector to check its operation
in one direction. Reverse the polarity to check the
motor operation in the opposite direction. If OK,
repair the shorted or open circuits between the lock
motor and the DDM or PDM as required. If not OK,
replace the faulty power lock motor.
POWER LOCK SWITCH
DESCRIPTION
The power lock motors are controlled by a two-way
momentary switch mounted on the trim panel of each
front door. Each power lock switch is illuminated by
a Light-Emitting Diode (LED) that is integral to the
switch paddle.
The driver side front door power lock switch is
integral to the Driver Door Module (DDM), and the
passenger side front door power lock switch is inte-
gral to the Passenger Door Module (PDM). The
power lock switches and their lamps cannot be
adjusted or repaired and, if faulty or damaged, the
entire DDM or PDM unit must be replaced. (Refer to
8 - ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/DOOR MODULE - DESCRIPTION).
OPERATION
The front door power lock switches provide a lock
and unlock signal to the door module circuitry. The
Driver Door Module (DDM) circuitry controls the out-
put to the driver side front door power lock motor,
while the Passenger Door Module (PDM) circuitry
controls the output to the passenger side front door,
both rear door and the liftgate power lock motors.
When the DDM-integrated power lock switch is
actuated, the DDM circuitry sends control outputs to
the driver side front door power lock motor and sends
a message to the PDM over the Programmable Com-
munications Interface (PCI) data bus to control the
output to the passenger side front door, both rear
door and the liftgate power lock motors. When the
PDM-integrated power lock switch is actuated, the
PDM circuitry sends control outputs to the passenger
side front door, both rear door and the liftgate power
lock motors and sends a message to the DDM over
the Programmable Communications Interface (PCI)
data bus to control the output to the driver side front
door power lock motor.
Each power lock switch is illuminated by a Light-
Emitting Diode (LED) when the ignition switch is
turned to the On position. See the owner's manual in
the vehicle glove box for more information on the fea-
tures, use and operation of the power lock switches.
8N - 8 POWER LOCKSWJ
POWER LOCK MOTOR (Continued)

DESCRIPTION - OUTSIDE REAR VIEW MIRROR
An automatic dimming outside rear view mirror is
an available factory-installed option for the driver
side of the vehicle, if the vehicle is also equipped
with the automatic day/night inside rear view mirror.
The automatic dimming outside mirror is completely
controlled by the circuitry of the automatic day/night
inside rear view mirror. The automatic dimming out-
side mirror will automatically change the reflectance
of the driver side outside rear view mirror to protect
the driver from the unwanted headlight glare of
trailing vehicles while driving at night. The auto-
matic dimming outside mirror will only operate when
the ignition switch is in the On position.
The automatic dimming outside mirror sensitivity
cannot be repaired or adjusted. If any component of
this unit is faulty or damaged, the entire automatic
dimming outside mirror unit must be replaced. (Refer
to 8 - ELECTRICAL/POWER MIRRORS/SIDEVIEW
MIRROR - DIAGNOSIS AND TESTING). Refer to
the appropriate wiring information. The wiring infor-
mation 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 con-
nectors, splices and grounds.
OPERATION
OPERATION - REAR VIEW MIRROR
The automatic day/night mirror switch allows the
driver a manual control of whether the automatic
dimming feature is operational. This switch is a
momentary rocker-type switch located on the lower
rear-facing surface of the mirror housing. When Auto
is selected, a Light-Emitting Diode (LED) on the mir-
ror housing just to the right of the switch illuminates
to indicate that automatic day/night mirror is turned
on. When Off is selected, the LED is turned off. The
mirror also senses the backup lamp circuit, and will
automatically disable its self-dimming feature when-
ever the transmission gear selector is in the Reverse
position.
A thin layer of electrochromatic material between
two pieces of conductive glass make up the face of
the mirror. Two photocell sensors are used to monitor
light levels and adjust the reflectance of the mirror.
The ambient photocell sensor faces forward, to detect
the outside light levels. The headlamp sensor is
located on the mirror housing just to the left of the
switch and facing rearward, to detect the light level
received at the rear window side of the mirror. When
the difference between the two light levels becomes
too great (the light level received at the rear of themirror is much higher than that at the front of the
mirror), the mirror begins to darken.
On models with an optional driver side automatic
dimming outside mirror, the signal to control the
dimming of that mirror is generated by the auto-
matic day/night inside rear view mirror circuitry.
That signal is then delivered to the driver side out-
side rear view mirror on a hard wired circuit.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the automatic day/night mirror system.
OPERATION - OUTSIDE REAR VIEW MIRROR
The automatic dimming outside mirror is operated
by the same controls and circuitry as the automatic
day/night mirror. When the automatic day/night mir-
ror is turned on or off, the automatic dimming out-
side mirror is likewise turned on or off. Like in the
automatic day/night mirror, a thin layer of electro-
chromatic material between two pieces of conductive
glass make up the face of the automatic dimming
outside mirror. However, the signal to control the
dimming of the outside mirror is generated by the
automatic day/night inside rear view mirror circuitry.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the automatic dimming outside mirror.
DIAGNOSIS AND TESTING - AUTOMATIC DAY /
NIGHT MIRROR
For complete circuit diagrams, refer to the appro-
priate 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 connec-
tors, splices and grounds.
(1) Check the fused ignition switch output (run/
start) fuse in the junction block. If OK, go to Step 2.
If not OK, repair the shorted circuit or component as
required and replace the faulty fuse.
(2) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run/start) fuse in the junction block. If OK,
go to Step 3. If not OK, repair the open fused ignition
switch output (run/start) circuit to the ignition switch
as required.
(3) Disconnect the overhead wire harness connec-
tor from the automatic day/night mirror connector
receptacle. Check for battery voltage at the fused
ignition switch output (run/start) circuit cavity of the
overhead wire harness connector for the automatic
day/night mirror. If OK, go to Step 4. If not OK,
repair the open fused ignition switch output (run/
start) circuit to the fuse in the junction block as
required.
WJPOWER MIRRORS 8N - 13
AUTOMATIC DAY/NIGHT MIRROR (Continued)

(4) Turn the ignition switch to the Off position.
Check for continuity between the ground circuit cav-
ity of the overhead wire harness connector for the
automatic day/night mirror and a good ground. There
should be continuity. If OK, go to Step 5. If not OK,
repair the open ground circuit to ground as required.
(5) Turn the ignition switch to the On position. Set
the parking brake. Place the transmission gear selec-
tor lever in the Reverse position. Check for battery
voltage at the backup lamp switch output circuit cav-
ity of the overhead wire harness connector for the
automatic day/night mirror. If OK, reconnect the
overhead wire harness connector to the automatic
day/night mirror connector receptacle and go to Step
6. If not OK, repair the open backup lamp switch
output circuit as required.
(6) Place the transmission gear selector lever in
the Neutral position. Place the automatic day/night
mirror switch in the Auto (LED next to the switch is
lighted) position (Fig. 1). Cover the forward facing
ambient photocell sensor to keep out any ambient
light.
NOTE: The ambient photocell sensor must be cov-
ered completely, so that no light reaches the sen-
sor. Use a finger pressed tightly against the sensor,
or cover the sensor completely with electrical tape.
(7) Shine a light into the rearward facing head-
lamp photocell sensor. The automatic day/night mir-
ror should darken. If OK, go to Step 8. If not OK,
replace the faulty automatic day/night mirror unit.
(8) With the mirror darkened, place the transmis-
sion gear selector lever in the Reverse position. The
automatic day/night mirror should return to its nor-
mal reflectance. If not OK, replace the faulty auto-
matic day/night mirror unit.POWER FOLD-AWAY MIRROR -
EXPORT
DESCRIPTION
Some vehicles are equipped with Power Fold-Away
Side View Mirrors. This feature allows both the
driver and passenger side view mirrors to fold
inward (retract) on demand. This feature is con-
trolled by an additional switch located on the power
mirror switch.
The fold-away side view mirror is attached to the
vehicle's door in the same manner as mirrors without
the fold-away option. The fold-away mirrors unique
option is the internal motor which allows the mirrors
to fold inward on demand. the fold-away mirror
motor is not serviceable separately, and if a motor is
found to be faulty the entire side view mirror must
be replaced.
OPERATION
When the mirror retract switch is depressed, both
of the side view mirrors will fold inward, thus mak-
ing the overall width of the vehicle the smallest pos-
sible. This can be very helpful where parking space is
an absolute minimum.
DIAGNOSIS AND TESTING - POWER
FOLD-AWAY MIRROR - EXPORT
The most reliable, efficient and accurate means to
diagnose the power mirror system requires the use of
a DRB scan tool and the proper Diagnostic Proce-
dures manual. The DRB scan tool can provide confir-
mation that the PCI data bus is functional, that all
of the electronic modules are sending and receiving
the proper messages on the PCI data bus, that the
power mirror motors are being sent the proper hard
wired outputs, and that the mirror position potenti-
ometers are returning the proper outputs to the door
modules for them to perform their power mirror sys-
tem functions.
REMOVAL
The fold-away mirror motor is not serviceable sep-
arately, and if a motor is found to be faulty the entire
side view mirror must be replaced. (Refer to 8 -
ELECTRICAL/POWER MIRRORS/SIDEVIEW MIR-
ROR - REMOVAL).
Fig. 1 Automatic Day/Night Mirror
1 - LED INDICATOR
2 - SWITCH
3 - HEADLAMP SENSOR
8N - 14 POWER MIRRORSWJ
AUTOMATIC DAY/NIGHT MIRROR (Continued)

POWER MIRROR SWITCH
DESCRIPTION
Both the right and left power outside mirrors are
controlled by a single multi-function switch unit
located on the driver side front door trim panel. The
power mirror switch unit includes a three-position
rocker selector switch and four momentary direc-
tional push button switches.
The power mirror switch unit is integral to the
Driver Door Module (DDM). The power mirror switch
cannot be repaired or adjusted and, if faulty or dam-
aged, the entire DDM unit must be replaced. (Refer
to 8 - ELECTRICAL/ELECTRONIC CONTROL
MODULES/DRIVER DOOR MODULE - REMOVAL)
for the DDM service procedures.
OPERATION
The power mirror selector switch is moved right
(right mirror control), left (left mirror control), or
center to turn the power outside mirror system off.
When the selector switch is in the right mirror con-
trol or left mirror control position, one of the four
directional control buttons is depressed to control
movement of the selected mirror up, down, right, or
left. When the selector switch is in the Off position,
depressing any of the directional switches will not
change either mirror position.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the power mirror switches.
SIDEVIEW MIRROR
DESCRIPTION
Mechanically folding, power operated outside rear
view mirrors are standard equipment on this model.
Each power mirror housing contains two electric
motors, two drive mechanisms, an electric heating
grid, the mirror glass case and the mirror glass. One
motor and drive controls mirror up-and-down (verti-
cal) movement, and the other controls right-and-left
(horizontal) movement. If the vehicle is equipped
with the optional memory system, each mirror head
also contains two position potentiometers. One posi-
tion potentiometer monitors the vertical mirror
motor, and the other monitors the horizontal mirror
motor.
An optional driver side automatic dimming mirror
is able to automatically change its reflectance level.
This mirror is controlled by the circuitry of the auto-
matic day/night inside rear view mirror. A thin layer
of electrochromic material between two pieces of con-
ductive glass make up the face of the mirror. (Refer
to 8 - ELECTRICAL/POWER MIRRORS/AUTO-MATIC DAY / NIGHT MIRROR - DESCRIPTION) for
more information on this feature.
The power mirror unit cannot be repaired. Only
the mirror glass and glass case are serviced sepa-
rately. The replacement mirror glass is supplied with
an instruction sheet that details the recommended
replacement procedure. If any other component of the
power mirror unit is faulty or damaged, the entire
power mirror unit must be replaced.
OPERATION
Each of the two outside power mirrors includes two
reversible electric motors that are secured within the
power mirror housing. Each motor moves the mirror
case and glass through an integral drive unit. When
a power mirror motor is supplied with battery cur-
rent and ground, it moves the mirror case and glass
through its drive unit in one direction. When the bat-
tery current and ground feeds to the motor are
reversed, it moves the mirror case and glass in the
opposite direction.
The power mirrors are equipped with a standard
equipment electric heating grid that is applied to the
back of each outside rear view mirror glass. When an
electrical current is passed through the resistor wire
of the heating grid, it warms the mirror glass. (Refer
to 8 - ELECTRICAL/HEATED MIRRORS -
DESCRIPTION) for more information on the opera-
tion of the heated mirrors and the rear window
defogger system.
If the driver side mirror is equipped with the auto-
matic dimming outside mirror option, two photocell
sensors on the inside rear view mirror are used to
monitor light levels and adjust the reflectance of both
the inside and driver side outside mirrors. This
change in reflectance helps to reduce the glare of
headlamps approaching the vehicle from the rear.
(Refer to 8 - ELECTRICAL/POWER MIRRORS/AU-
TOMATIC DAY / NIGHT MIRROR - OPERATION)
for more information on this feature.
If the vehicle is equipped with the optional mem-
ory system, the Driver Door Module (DDM) and the
Passenger Door Module (PDM) store the mirror posi-
tion information as monitored through the mirror
motor position potentiometers. When the memory
system requests a recall of the stored mirror position,
the DDM and the PDM are able to duplicate the
stored mirror positions by moving the mirror motors
until the potentiometer readings match the stored
values.
WJPOWER MIRRORS 8N - 15

mirror position potentiometers. Refer toPower Seat
TrackandPower Seat Reclinerin the Power Seat
System section of this group for more information on
the driver side power seat position potentiometers.
Refer toPower Seatin Wiring Diagrams for com-
plete circuit diagrams. Following are general descrip-
tions of the remaining major components in the
factory-installed memory system.
OPERATION
OPERATION - POWER SEAT SYSTEM
The power seat system allows the driver and/or
front passenger seating positions to be adjusted elec-
trically and independently using the separate power
seat switches found on the outboard seat cushion
side shield of each front seat. See the owner's manual
in the vehicle glove box for more information on the
features, use and operation of the power seat system.
OPERATION - MEMORY SYSTEM
See the owner's manual in the vehicle glove box for
more information on the features, use and operation of
the memory system. For diagnosis of the MSM, the PCI
data bus, or the other electronic modules on the PCI
data bus that provide inputs and outputs for the mem-
ory system, the use of a DRBtscan tool and the proper
Diagnostic Procedures manual are recommended.
DRIVER AND PASSENGER DOOR MODULES
The Driver Door Module (DDM) monitors the mem-
ory switch through a hard wired circuit. It also mon-
itors the unlock messages from the Remote Keyless
Entry (RKE) receiver in the Passenger Door Module
(PDM) sent over the Programmable Communications
Interface (PCI) data bus. The DDM is programmed to
send memory recall messages and memory system
status messages over the PCI data bus to the other
electronic modules when it detects a memory recall
request.
Refer toDoor Modulein Electronic Control Mod-
ules for more information on the DDM and PDM.
ELECTRONIC VEHICLE INFORMATION CENTER
The Electronic Vehicle Information Center (EVIC)
serves as the user interface for the memory system. It
displays memory system status messages and provides
the user with the means for enabling and disabling
the many customer programmable features available
on the vehicle, including those for the memory system.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the EVIC. Refer toElectronic Vehicle Informa-
tion Centerin Overhead Console Systems for more
information on the EVIC.
DIAGNOSIS AND TESTING
DIAGNOSIS & TESTING - POWER SEAT
SYSTEM
Following are tests that will help to diagnose the
hard wired components and circuits of the power seat
system. However, if the vehicle is also equipped with
the optional memory system, these tests may not
prove conclusive in the diagnosis of the driver side
power seat. In order to obtain conclusive testing of
the driver side power seat with the memory system
option, the Programmable Communications Interface
(PCI) data bus network and all of the electronic mod-
ules that provide inputs to, or receive outputs from
the memory system components must be checked.
The most reliable, efficient, and accurate means to
diagnose the driver side power seat with the memory
system option requires the use of a DRBtscan tool
and the proper Diagnostic Procedures manual. The
DRBtscan tool can provide confirmation that the
PCI data bus is functional, that all of the electronic
modules are sending and receiving the proper mes-
sages on the PCI data bus, and that the memory sys-
tem is receiving the proper hard wired inputs and
relaying the proper hard wired outputs to perform its
driver side power seat functions.
Before any testing of the power seat system is
attempted, the battery should be fully-charged and
all of the power seat system wire harness connections
and pins cleaned and tightened to ensure proper cir-
cuit continuity and ground paths. For complete cir-
cuit diagrams, refer toPower Seatin Wiring
Diagrams.
With the dome lamp on, apply the power seat
switch in the direction of the failure. If the dome
lamp dims, the seat may be jamming. Check under
and behind the seat for binding or obstructions. If
the dome lamp does not dim, proceed with testing of
the individual components and circuits.
DIAGNOSIS & TESTING - MEMORY SYSTEM
Following are tests that will help to diagnose the
components and circuits that provide hard wired
inputs to the memory system. However, these tests
may not prove conclusive in the diagnosis of this sys-
tem. In order to obtain conclusive testing of the
memory system, the Programmable Communications
Interface (PCI) data bus network and all of the elec-
tronic modules that provide inputs to, or receive out-
puts from the memory system components must be
checked.
The most reliable, efficient, and accurate means to
diagnose the memory system requires the use of a
DRBtscan tool and the proper Diagnostic Proce-
dures manual. The DRBtscan tool can provide con-
firmation that the PCI data bus is functional, that all
8N - 20 POWER SEAT SYSTEMWJ
POWER SEAT SYSTEM (Continued)

OPERATION
The power window system includes the Driver
Door Module (DDM) and Passenger Door Module
(PDM), which are mounted in their respective front
door, the rear door power window switches mounted
on the rear doors, and the power window motors
mounted to the window regulator in each door. The
DDM houses four master power window switches, the
power window lockout switch and the control logic for
the driver side front and rear door power windows.
The PDM houses the passenger side front door power
window switch and the control logic for the passenger
side front and rear door power windows.
When a master power window switch on the DDM
is used to operate a passenger side power window,
the DDM sends the window switch actuation mes-
sage to the PDM over the Programmable Communi-
cations Interface (PCI) data bus. The PDM responds
to these messages by sending control outputs to move
the passenger side power window motors. In addi-
tion, when the power window lockout switch in the
DDM is actuated to disable power window operation,
a lockout message is sent to the PDM over the PCI
data bus.
The Body Control Module (BCM) also supports and
controls certain features of the power window sys-
tem. The BCM receives a hard wired input from the
ignition switch. The programming in the BCM allows
it to process the information from this input and
send ignition switch status messages to the DDM
and the PDM over the PCI data bus. The DDM and
PDM use this information and hard wired inputs
from the front door ajar switches to control the light-
ing of the power window switch lamps, and to control
the operation of the power window after ignition-off
feature.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the power window system.
DIAGNOSIS AND TESTING - POWER
WINDOWS
Following are tests that will help to diagnose the
hard wired components and circuits of the power
window system. However, these tests may not prove
conclusive in the diagnosis of this system. In order to
obtain conclusive testing of the power window sys-
tem, the Programmable Communications Interface
(PCI) data bus network and all of the electronic mod-
ules that provide inputs to, or receive outputs from
the power window system components must be
checked.The most reliable, efficient, and accurate means to
diagnose the power window system requires the use
of a DRB scan tool and the proper Diagnostic Proce-
dures manual. The DRB scan tool can provide confir-
mation that the PCI data bus is functional, that all
of the electronic modules are sending and receiving
the proper messages on the PCI data bus, and that
the power window motors are being sent the proper
hard wired outputs by the door modules for them to
perform their power window system functions.
For complete circuit diagrams, refer to the appro-
priate 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 connec-
tors, splices and grounds.
ALL WINDOWS INOPERATIVE
(1) Check the operation of the power lock switch
on the driver side front door. If all of the doors lock
and unlock, but none of the power windows operate,
use a DRB scan tool and the proper Diagnostic Pro-
cedures manual to check the Body Control Module
(BCM), the Driver Door Module (DDM) and the PCI
data bus for proper operation. If not OK, go to Step
2.
(2) Check the operation of the power lock switch
on the passenger side front door. If the passenger
doors lock and unlock, but the driver side front door
does not, go to Step 5. If all of the power locks and
power windows are inoperative from both front doors,
go to Step 3.
(3) Check the fused B(+) fuse in the Power Distri-
bution Center (PDC). If OK, go to Step 4. If not OK,
repair the shorted circuit or component as required
and replace the faulty fuse.
(4) Check for battery voltage at the fused B(+) fuse
in the PDC. If OK, go to Step 5. If not OK, repair the
open fused B(+) circuit to the battery as required.
(5) Disconnect and isolate the battery negative
cable. Remove the trim panel from the driver side
front door. Disconnect the 15-way door wire harness
connector from the DDM connector receptacle. Check
for continuity between the ground circuit cavity of
the 15-way door wire harness connector for the DDM
and a good ground. There should be continuity. If
OK, go to Step 6. If not OK, repair the open ground
circuit to ground as required.
(6) Reconnect the battery negative cable. Check for
battery voltage at the fused B(+) circuit cavity of the
15-way door wire harness connector for the DDM. If
OK, replace the faulty DDM. If not OK, repair the
open fused B(+) circuit to the fuse in the PDC as
required.
8N - 34 POWER WINDOWSWJ
POWER WINDOWS (Continued)