DDM JEEP GRAND CHEROKEE 2002 WJ / 2.G Workshop Manual

AUDIO
DESCRIPTION
An audio system is standard factory-installed
equipment on this model. The standard equipment
audio system includes an AM/FM/cassette (RBB sales
code) radio receiver, and speakers in six locations.
Several combinations of radio receivers and speaker
systems are offered as optional equipment on this
model. The audio system uses an ignition switched
control of battery current so that the system will only
operate when the ignition switch is in the On or
Accessory positions.
A Compact Disc (CD) changer with a ten disc mag-
azine, remote radio switches with six functions
mounted to the backs of the steering wheel spokes,
and a memory system that automatically stores and
recalls up to twenty radio station presets (ten AM
and ten FM) and the last station listened to for two
drivers are optional factory-installed equipment on
this model. Refer to Electrical, Power Seats for more
information on the memory system.
The audio system includes the following compo-
nents:
²Antenna
²Compact disc changer (available with RBP sales
code radio receivers only)
²Power amplifier (with premium speaker system
only)
²Radio noise suppression components
²Radio receiver
²Remote radio switches
²Speakers
Certain functions and features of the audio system
rely upon resources shared with other electronic
modules in the vehicle over the Programmable Com-
munications Interface (PCI) data bus network. The
PCI data bus network allows the sharing of sensor
information. This helps to reduce wire harness com-
plexity, internal controller hardware, and component
sensor current loads. At the same time, this system
provides increased reliability, enhanced diagnostics,
and allows the addition of many new feature capabil-
ities. For diagnosis of these electronic modules or of
the PCI data bus network, the use of a DRB scan
tool and the proper Diagnostic Procedures manual
are recommended.
The other electronic modules that may affect audio
system operation are as follows:
²Body Control Module (BCM)- (Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/BODY CONTROL/CENTRAL TIMER MODUL
- DESCRIPTION) for more information.
²Driver Door Module (DDM)(Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-ULES/DRIVER DOOR MODULE - DESCRIPTION)
for more information.
²Passenger Door Module (PDM)(Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/DRIVER DOOR MODULE - DESCRIPTION)
for more information.
The audio system includes the following major
components, which are described in further detail
elsewhere in this service information:
²Amplifier- On models equipped with the
optional premium speaker system, an audio power
amplifier is located on the rear floor panel under-
neath the right end of the rear seat cushion in the
passenger compartment.
²Antenna Body and Cable- The most visible
component of the antenna body and cable are the
antenna adapter and the antenna cap nut, which are
located on the top of the right front fender panel of
the vehicle, near the right end of the cowl plenum.
²Antenna Mast- The antenna mast is a metal
rod that extends upward from the antenna body and
cable on the top of the right front fender panel of the
vehicle, near the right end of the cowl plenum.
²Radio- The radio for this model is located in
the instrument panel center stack area, inboard of
the instrument cluster and above the heater and air
conditioner controls.
²Radio Noise Suppression Ground Strap-A
radio noise suppression ground strap is installed
between the rear of the engine cylinder head(s) and
the dash panel sheet metal in the engine compart-
ment.
²Speaker- The standard speaker system
includes six speakers in six locations, while the pre-
mium speaker system includes an amplifier for the
six speakers in six locations.
Hard wired circuitry connects the audio system
components to each other through the electrical sys-
tem of the vehicle. These hard wired circuits are
integral to several wire harnesses, which are routed
throughout the vehicle and retained by many differ-
ent methods. These circuits may be connected to each
other, to the vehicle electrical system and to the
audio system components through the use of a com-
bination of soldered splices, splice block connectors
and many different types of wire harness terminal
connectors and insulators. Refer to the appropriate
wiring information in this service manual for com-
plete standard and premium audio system circuit
diagrams. The wiring information includes 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 har-
ness connectors, splices, and grounds.
8A - 2 AUDIOWJ

OPERATION
The audio system components are designed to pro-
vide audio entertainment and information through
the reception, tuning and amplification of locally
broadcast radio signals in both the Amplitude Modu-
lating (AM) and Frequency Modulating (FM) com-
mercial frequency ranges. Electromagnetic radio
signals that are broadcast from a radio station
induce electrical modulations into the audio system
antenna mast. The antenna body and cable conduct
these weak signals from the antenna mast to the
radio. The radio then tunes and amplifies these weak
radio frequency signals into stronger electrical audio
signals that are required in order to operate the
audio system speakers. The speakers convert these
electrical signals into air movement, which repro-
duces the sounds being broadcast by the radio sta-
tion.
Some audio systems also offer the user the option
of selecting from and listening to prerecorded audio
cassette tapes, audio compact discs, or both. Regard-
less of the media type, the audio system components
provide the user with the ability to electronically
amplify and adjust the audio signals being repro-
duced by the speakers within the vehicle to suit the
preferences of the vehicle occupants.
The audio system components operate on battery
current received through a fuse in the Junction Block
(JB) on a fused ignition switch output (run-acc) cir-
cuit so that the system will only operate when the
ignition switch is in the On or Accessory positions.
On vehicles that are equipped with the optional
remote radio switches, the BCM receives hard wired
resistor multiplexed inputs from the remote radio
switches. The programming in the BCM allows it to
process those inputs and send the proper messages to
the radio receiver over the PCI data bus to control
the radio volume up or down, station seek up or
down, preset station advance, and mode advance
functions.On vehicles equipped with the optional memory
system, when the DDM receives a Driver 1 or Driver
2 memory recall input from the memory switch on
the driver side front door trim panel or a memory
recall message from the Remote Keyless Entry (RKE)
receiver in the PDM, the DDM sends a memory
recall message back to the radio receiver over the
PCI data bus to recall the radio station presets and
last station listened to information.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of each of the available audio systems.
DIAGNOSIS AND TESTING - AUDIO
Any diagnosis of the Audio system should
begin with the use of the DRB IIItdiagnostic
tool. For information on the use of the DRB
IIIt, refer to the appropriate Diagnostic Service
Manual.
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.
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, SEAT BELT TENSIONER, SIDE
AIRBAG, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
WJAUDIO 8A - 3
AUDIO (Continued)

The chime warning system provides an audible
indication to the vehicle operator under the following
conditions:
²Fasten Seat Belt Warning- The Body Control
Module (BCM) chime tone generator will generate
repetitive chimes to announce that an input from the
seat belt switch indicates the driver side front seat
belt is not fastened. Unless the driver side front seat
belt is fastened, the chimes will continue to sound for
a duration of about six seconds each time the ignition
switch is turned to the On position or until the driver
side front seat belt is fastened.
²Head/Park Lights-On Warning- The BCM
chime tone generator will generate repetitive chimes
at a fast rate to announce that a Programmable
Communications Interface (PCI) data bus driver door
ajar message, along with hard wired inputs from the
headlamp switch indicate that the exterior lamps are
turned On with the driver side front door opened.
The chime will continue to sound until the exterior
lamps are turned Off, the driver side front door is
closed, or the ignition switch is turned to the On
position.
²Key-In-Ignition Warning- The BCM chime
tone generator will generate repetitive chimes at a
fast rate to announce that a PCI data bus driver door
ajar message received from the Driver Door Module
(DDM), along with hard wired inputs from the key-
in-ignition warning switch indicate that the key is in
the ignition cylinder with the driver side front door
opened and the ignition switch in the Off position.
The chime will continue to sound until the key is
removed from the ignition lock cylinder, the driver
side front door is closed, or the ignition switch is
turned to the On position.
²Overspeed Warning- The BCM chime tone
generator will generate repetitive chimes at a slowrate to announce that a PCI data bus vehicle speed
message received from the Powertrain Control Mod-
ule (PCM) indicates that the vehicle speed is above
120 kilometers-per-hour (75 miles-per-hour). The
chimes will continue to sound until the vehicle speed
is below 120 kilometers-per-hour (75 miles-per-hour).
This feature is only enabled on a BCM that has been
programmed with a Middle East Gulf Coast Country
(GCC) country code.
²Tactile Beep Support- The BCM chime tone
generator will generate a single beep each time a
PCI data bus tactile beep request message is received
from the Electronic Vehicle Information Center
(EVIC) or the Sentry Key Immobilizer Module
(SKIM). This beep provides an audible confirmation
that an EVIC button was completely depressed, or
that the optional Sentry Key Immobilizer System
(SKIS) is in the ªCustomer Learnº mode.
²Warning Beep Support- The BCM chime tone
generator will generate a short series of beeps each
time a PCI data bus warning beep request message
is received from the EVIC or the Electro-Mechanical
Instrument Cluster (EMIC). These beeps provide an
audible alert to the vehicle operator, of certain visual
warning indications displayed by the EVIC and/or
the EMIC.
The BCM provides chime service for all available
features in the chime warning system. The BCM
relies upon message inputs received from other mod-
ules over the PCI data bus network to provide chime
service for all of the remaining chime warning sys-
tem features.
The internal programming of the BCM determines
the priority of each chime tone request input that is
received, as well as the rate and duration of each
chime tone that is to be generated.
8B - 2 CHIME/BUZZERWJ
CHIME WARNING SYSTEM (Continued)

BCM programming then performs those tasks and
provides features through both PCI data bus commu-
nication with other electronic modules and hard
wired outputs to a number of relays. These relays
provide the BCM with the ability to control numer-
ous high current accessory systems in the vehicle.
The BCM circuitry operates on battery current
received through fuses in the Junction Block (JB) on a
non-switched fused B(+) circuit, a fused ignition switch
output (start-run) circuit, and a fused ignition switch
output (run-accessory) circuit. This arrangement allows
the BCM to provide some features regardless of the
ignition switch position. The BCM circuitry is grounded
through the chassis beneath the center console.
The BCM monitors its own internal circuitry as
well as many of its input and output circuits, and
will store a Diagnostic Trouble Code (DTC) in elec-
tronic memory for any failure it detects. These DTCs
can be retrieved and diagnosed using a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
HARD WIRED INPUTS
The hard wired inputs to the BCM include the fol-
lowing:
²A/C switch signal
²Ambient temperature sensor signal
²Body control module flash enable
²Coolant level switch sense
²Door ajar switch sense (two circuits - one left
rear, and one right rear)
²Driver seat heater switch mux
²Fog lamp switch sense
²Fused B(+)
²Fused ignition switch output (run-acc)
²Fused ignition switch output (st-run)
²Ground (five circuits - two Z1, and three Z2)
²Hazard switch sense
²Headlamp switch mux
²High beam switch sense
²Hood ajar switch sense (export)
²Key-in ignition switch sense
²Liftgate ajar switch sense
²Liftgate courtesy disable
²Liftgate flip-up ajar switch sense
²Panel lamps dimmer signal
²Park lamp relay output
²Passenger seat heater switch mux
²PCI bus
²Radio control mux
²Rear window defogger switch sense
²Seat belt switch sense
²Ultralight sensor signal
²Washer fluid switch sense
²Washer pump switch sense
²Windshield wiper switch mux
²Wiper park switch sense
MESSAGING
The BCM uses the following messages received
from other electronic modules over the PCI data bus:
²Accessory Delay Control (DDM/PDM)
²Battery Temperature (PCM)
²Chime Request (EMIC, EVIC, SKIM)
²Cylinder Lock Switch Status (DDM)
²Door Ajar Status/Front Doors (DDM/PDM)
²Door Lock Status (DDM/PDM)
²Engine Model (PCM)
²Engine RPM (PCM)
²Engine Temperature (PCM)
²English/Metric Default (EMIC)
²Fuel Tank Level (PCM)
²Fuel Used/Injector Pulses (PCM)
²Panic Control (PDM)
²Programmable Features Preferences/Audible &
Optical Chirps/Headlamp Delay (EVIC)
²RKE Status (PDM)
²Vehicle Identification Number (PCM)
²Vehicle Speed (PCM)
The BCM provides the following messages to other
electronic modules over the PCI data bus:
²A/C Switch Status (PCM)
²Ambient Temperature Data (AZC/EVIC/PCM)
²Average/Instantaneous Fuel Economy (EVIC)
²Country Code (EMIC)
²Courtesy Lamp Status (DDM/PDM)
²Distance To Empty (EVIC)
²Elapsed Ignition On Timer (EVIC)
²English/Metric Status (EMIC)
²Front & Rear Door Ajar Status (EVIC)
²Front & Rear Fog Lamp Status (EMIC)
²Heated Seat Switch Status (HSM/MHSM)
²High Beam Status (EMIC)
²Ignition Off Timer (EVIC)
²Ignition Switch Position (DDM/PDM)
²Key-In Ignition Status (DDM/PDM)
²Low Beam Status (EMIC)
²Panel Lamp Status (AZC/EMIC/Radio)
²Rear Window Defogger Relay Status (DDM/
PDM)
²Remote Radio Switch Status (Radio)
²Seatbelt Status (EMIC/MHSM/MSM)
DIAGNOSIS AND TESTING - BODY CONTROL
MODULE
The hard wired inputs to and outputs from the
Body Control Module (BCM) may be diagnosed and
tested using conventional diagnostic tools and proce-
dures. Refer to the appropriate wiring information.
Conventional diagnostic methods may not prove
conclusive in the diagnosis of the BCM. In order to
obtain conclusive testing of the BCM, the Program-
mable Communications Interface (PCI) data bus net-
work and all of the electronic modules that provide
8E - 4 ELECTRONIC CONTROL MODULESWJ
BODY CONTROL MODULE (Continued)

faults arenoterased if the battery is disconnected.
(Fig. 4)
REMOVAL
(1) Remove negative battery cable from the bat-
tery.
(2) Remove air cleaner housing,(Refer to 9 -
ENGINE/AIR INTAKE SYSTEM/AIR CLEANER
HOUSING - REMOVAL) OR (Refer to 9 - ENGINE/
AIR INTAKE SYSTEM/AIR CLEANER HOUSING -
REMOVAL).
(3) Release CAB harness connector and remove
connector (Fig. 5).
(4) Remove pump motor connector.
(5) Remove CAB mounting bolts (Fig. 6) and
remove the CAB from the HCU.
INSTALLATION
(1) Install the CAB onto the HCU and tighten
mounting bolts to 1.8 N´m (16 in. lbs.).
(2) Install pump motor connector.
(3) Install CAB harness connector and push down
connector release.
(4) Install air cleaner housing,(Refer to 9 -
ENGINE/AIR INTAKE SYSTEM/AIR CLEANER
HOUSING - INSTALLATION) OR (Refer to 9 -
ENGINE/AIR INTAKE SYSTEM/AIR CLEANER
HOUSING - INSTALLATION).
(5) Install negative battery cable to the battery.
DATA LINK CONNECTOR
DESCRIPTION - DATA LINK CONNECTOR
The data link connector (DLC) is located at the
lower edge of the instrument panel near the steering
column.
OPERATION - DATA LINK CONNECTOR
The 16±way DLC links the DRBIIItscan tool or
the Mopar Diagnostic System (MDS) with the Power-
train Control Module (PCM).
DOOR MODULE
DESCRIPTION
A door module is concealed behind the trim panel
of each front door (Fig. 7).The module on the driver
side is referred to as the Driver Door Module (DDM),
while the module on the passenger side is the Pas-
senger Door Module (PDM). Each door module
houses both the front power lock and power window
switches. In addition to the power window and power
lock switches for its own door, the DDM also houses
individual switches for each passenger door power
window, a power window lockout switch, the power
mirror switch, and the power foldaway mirror switch
for export vehicles.
The DDM and PDM each utilize integrated cir-
cuitry and information carried on the Programmable
Communications Interface (PCI) data bus network
along with many hard wired inputs to monitor many
sensor and switch inputs throughout the vehicle. The
PDM also receives inputs through an integral Radio
Fig. 5 CAB Connector Release
1 - CONNECTOR RELEASE
2 - CAB
Fig. 6 CAB Mounting Bolts
1 - MOUNTING BOLTS
WJELECTRONIC CONTROL MODULES 8E - 7
CONTROLLER ANTILOCK BRAKE (Continued)

Frequency (RF) Remote Keyless Entry (RKE)
receiver. The DDM and PDM control and integrate
many functions and features of the vehicle through
both hard wired outputs and messages over the PCI
data bus. The functions and features that the door
modules support or control include the following:
²Automatic Door Lock- The two door modules
provide an automatic door lock feature which locks
the doors when the vehicle is moving. This is a pro-
grammable feature.
²Automatic Door Unlock On Exit- The two
door modules provide an automatic door unlock on
exit feature. This feature will unlock all the doors if
they were locked via the automatic door lock feature
after the vehicle has stopped moving and the driver
door is opened. This is a programmable feature via
the EVIC.
²Customer Programmable Features- Each
door module provides support for certain customer
programmable features that are monitored on the
PCI bus.
²Cylinder Lock Switch Status- The DDM
monitors and transmits the status of the cylinder
lock switch on the driver side front door lock cylin-
der.
²Door Courtesy Lamp Control- Each door
module provides control of its own optional front
door-mounted courtesy lamp.
²Door Lock Inhibit- Each door module pro-
vides a door lock inhibit feature which prevents the
doors from being locked with a power lock switch ifthe key was left in the ignition and a front door is
open.
²Express-Down Window- The DDM provides
an express-down feature for the driver side front door
window only.
²Extended Window Operation- Both door
modules provide an extended power window opera-
tion feature that allows operation of the power win-
dows for 45 seconds following ignition Off or until a
front door is opened.
²Front Door Ajar Switch Status- Each door
module monitors and transmits the status of its own
front door ajar switch.
²Heated Mirrors- Each door module provides
control for its own optional heated outside rear view
mirror.
²Illuminated Entry- Each door module sup-
ports an illuminated entry feature through its own
optional front door-mounted courtesy lamp.
²Memory Mirrors- Each door module provides
control for its own optional memory outside rear view
mirror.
²Memory Switch- The DDM monitors the sta-
tus of the optional memory switch and controls the
illumination of the memory switch ªsetº Light Emit-
ting Diode (LED) indicator and illumination lamps.
²Memory System- The DDM transmits memory
set and recall messages based upon inputs from the
memory switch. If the optional RKE linked to mem-
ory feature is enabled, the DDM will also transmit
memory recall messages based upon memory
requests received from the Remote Keyless Entry
(RKE) system in the PDM. Certain memory system
features are programmable.
²Power Foldaway Mirrors - Export Only-
Each door module provides support for the optional
power foldaway outside mirrors. The DDM also
houses the control switch for this system.
²Power Lock Control- The DDM provides con-
trol for the driver side front door power lock motor,
while the PDM provides control for the power lock
motors of the three remaining doors and the liftgate.
²Power Lock Switch Status- Each door mod-
ule monitors and transmits the status of its own inte-
gral power lock switch.
²Power Window Control- Each door module
provides control for both the front and rear door
power window motors and the rear door power win-
dow switches on the same side of the vehicle.
²Power Window Switch Status- The DDM
monitors and transmits the status of its integral pas-
senger side front and rear power window switches.
²Remote Keyless Entry- The PDM monitors
and transmits the status of the Remote Keyless
Entry (RKE) system and provides support for the
RKE Lock (with the optional horn chirp and park
Fig. 7 Door Module
1 - FRONT DOOR TRIM PANEL
2 - SCREW (5)
3 - DOOR MODULE
8E - 8 ELECTRONIC CONTROL MODULESWJ
DOOR MODULE (Continued)

lamp flash features), Unlock with the optional RKE
unlock, and Panic Mode functions. The optional RKE
features are programmable.
²Switch Illumination- Each door module pro-
vides control of the power window and power lock
switch illumination for the front and rear doors on
the same side of the vehicle. The DDM provides con-
trol of the power mirror switch illumination.
²Window Lockout- The DDM monitors and
transmits the status of its integral window lockout
switch to provide the power window lockout feature
and coordinate power window switch knob illumina-
tion.
The door modules are serviced only as complete
units. Many of the features in the vehicle controlled
or supported by the door modules are programmable
using either the Electronic Vehicle Information Cen-
ter (EVIC) user interface, or the DRBIIItscan tool. If
a door module is damaged or faulty, the entire door
module unit must be replaced.
OPERATION
The microprocessor-based DDM and PDM hard-
ware and software monitors integral and hard wired
external switch inputs as well as those resources it
shares with other electronic modules in the vehicle
through its communication over the PCI data bus
network. The internal programming and all of these
inputs allow the DDM or PDM microprocessor to
determine the tasks it needs to perform and their
priorities, as well as both the standard and optional
features that it should provide.
The DDM and PDM are powered by a fused bat-
tery circuit so that they can operate regardless of the
ignition switch position. The DDM and PDM cir-
cuitry is grounded to the chassis beneath the front
seat.
The DDM and PDM can be diagnosed using a
DRBIIItscan tool. Refer to the appropriate diagnos-
tic information.
HARD WIRED INPUTS
The hard wired inputs to the door modules include
the following:
²Door ajar switch sense
²Driver door key cylinder switch sense (DDM)
²Fused B(+)
²Ground
²Memory switch mux (DDM)
²Mirror horizontal position signal
²Mirror vertical position signal
²PCI bus
HARD WIRED OUTPUTS
The hard wired outputs of the door modules
include the following:
²Courtesy lamp driver
²Courtesy lamp ground
²Diagnostic out (DDM)
²Door/liftgate lock driver
²Door/liftgate unlock driver
²Door switch illumination (rear power window)
²Front window driver (down)
²Front window driver (up)
²Memory set indicator driver (DDM)
²Memory switch return (DDM)
²Mirror common driver
²Mirror heater ground
²Mirror heater 12V supply
²Rear window driver (down)
²Rear window driver (up)
²Mirror horizontal driver
²Mirror sensor ground
²Mirror vertical driver
²PCI bus
²Switch illumination driver (memory - DDM)
MESSAGING
The door modules use the following messages
received from other electronic modules over the PCI
data bus:
²Accessory Delay Control (PDM)
²Courtesy Lamp Status (BCM)
²Door Ajar Status/Rear Doors (BCM)
²Door Lock Status (DDM/PDM)
²Ignition Switch Position (BCM)
²Key-In Ignition Status (BCM)
²Programmable Features Preferences/Auto Lock/
Auto Unlock/RKE Unlock Sequence/RKE Link to
Memory (EVIC)
²Memory Recall (DDM)
²Rear Window Defogger Relay Status (BCM)
²Vehicle Speed (PCM)
The door modules provide the following messages
to other electronic modules over the PCI data bus:
²Cylinder Lock Switch Status (BCM)
²Door Ajar Status/Front Doors (BCM/DDM/PDM)
²Door Lock Status (DDM/PDM)
²Memory Recall (PDM/MHSM/MSM/Radio)
²Memory Set Switch Status (PDM/MHSM/MSM/
Radio)
²Panic Control (BCM)
²Power Window Switch Status (PDM)
²RKE Status (BCM/DDM)
²Window Lockout Switch Status (PDM)
WJELECTRONIC CONTROL MODULES 8E - 9
DOOR MODULE (Continued)

DIAGNOSIS AND TESTING - DOOR MODULE
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
The hard wired inputs to and outputs from the
Driver Door Module (DDM) or the Passenger Door
Module (PDM) may be diagnosed and tested using
conventional diagnostic tools and procedures. It is
suggested that the proper operation of the inopera-
tive power window motor, power door lock motor,
power liftgate lock motor, power mirror motors, or
heated mirror grid be confirmed using jumper wires
to bypass the door module. If the inoperative compo-
nent operates when the door module is bypassed,
check the circuits between the component and the
door module, as well as the fused B(+) and ground
circuits of the door module for shorts or opens.
These conventional diagnostic methods may not
prove conclusive in the diagnosis of the DDM or the
PDM. In order to obtain conclusive testing of these
modules, the Programmable Communications Inter-
face (PCI) data bus network and all of the modules
that provide inputs to or receive outputs from the
door modules must also be checked. The most reli-
able, efficient, and accurate means to diagnose the
DDM, the PDM, the PCI data bus network, and the
modules that provide inputs to or receive outputs
from the door modules requires the use of a DRBIIIt
scan tool and the appropriate diagnostic information.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the trim panel from the front door.
(Refer to 23 - BODY/DOOR - FRONT/TRIM PANEL -
REMOVAL).
(3) Remove the door module from the back of the
front door trim panel (Fig. 8).
(4) Remove the door module from the front door
trim panel.
INSTALLATION
(1) Position the door module onto the front door
trim panel.
(2) Install the door module to the back of the front
door trim panel (Fig. 8). Tighten the screws to 2.2
N´m (20 in. lbs.).
(3) Reinstall the trim panel onto the front door.
(Refer to 23 - BODY/DOOR - FRONT/TRIM PANEL -
INSTALLATION).
(4) Reconnect the battery negative cable.
MEMORY HEATED SEAT/
MIRROR MODULE
DESCRIPTION
There are two different modules that can be used
in the optional heated seat system. The Heated Seat
Module (HSM) is used on vehicles that are not
equipped with the optional Memory System. The
Memory Heated Seat Module (MHSM) is used on
vehicles that are equipped with the optional Memory
System and the optional heated seat system.Refer to
Memory Systemin Power Seat Systems for more
information on the memory system option.
The module is mounted on a bracket that is located
between the power seat track and the seat cushion
frame (Fig. 9). The HSM or MHSM is used to control
the heated seat system functions for both front seats.
The HSM or MHSM contains a central processing
unit that communicates with other modules on the
Fig. 8 Door Module Remove/Install
1 - FRONT DOOR TRIM PANEL
2 - SCREW (5)
3 - DOOR MODULE
8E - 10 ELECTRONIC CONTROL MODULESWJ
DOOR MODULE (Continued)

Programmable Communications Interface (PCI) data
bus network.
For diagnosis of the HSM, MHSM or the PCI data
bus, a DRBIIItscan tool and the proper Diagnostic
Procedures manual are recommended. The HSM or
MHSM cannot be repaired and, if faulty or damaged,
it must be replaced.
OPERATION
The MSM receives hard wired inputs from the
power seat switch and the potentiometers on each of
the driver side power seat motors. The MSM receives
messages over the PCI data bus from the Driver
Door Module (DDM) (memory switch status), the
Powertrain Control Module (PCM) (vehicle speed sta-
tus), and the Body Control Module (seat belt switch
status).The MSM will prevent the seat memory recall
function from being initiated if the driver side seat
belt is buckled, if the transmission gear selector lever
is not in the Park or Neutral positions, or if the vehi-
cle is moving.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - HEATED SEAT
MODULE
Visually inspect the related wiring harness connec-
tors. Look for broken, bent, pushed out, or corroded
terminals. If any of the above conditions are present,
repair as necessary. If not, use a DRBIIItscan tool
and the proper Diagnostic Procedures Manual to test
the HSM or MHSM. For complete circuit diagrams,
refer toPower Seat Premium I/IIIin Wiring Dia-
grams.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the driver side front bucket seat from
the power seat track unit. Refer toBucket Seat
Track Adjusterin Body for the procedure.
(3) Lift the heated seat module off of the power
seat track and disconnect the power seat wire har-
ness connectors (Fig. 10).
(4) Remove the module from the bracket.
Fig. 9 Heated Seat Module Remove/Install
1 - NUT (4)
2 - SEAT CUSHION FRAME
3 - POWER SEAT TRACK
4 - STUD (4)
5 - MODULE
6 - BRACKET
Fig. 10 Heated Seat Module Remove/Install
1 - NUT (4)
2 - SEAT CUSHION FRAME
3 - POWER SEAT TRACK
4 - STUD (4)
5 - MODULE
6 - BRACKET
WJELECTRONIC CONTROL MODULES 8E - 11
MEMORY HEATED SEAT/MIRROR MODULE (Continued)

HEATED SYSTEMS
TABLE OF CONTENTS
page page
HEATED GLASS........................... 1
HEATED MIRRORS......................... 8HEATED SEAT SYSTEM..................... 9
HEATED GLASS
TABLE OF CONTENTS
page page
HEATED GLASS
DESCRIPTION - REAR WINDOW DEFOGGER . . 1
OPERATION - REAR WINDOW DEFOGGER....2
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER SYSTEM...................2
REAR WINDOW DEFOGGER GRID
DESCRIPTION..........................3
OPERATION............................3
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER GRID......................3
STANDARD PROCEDURE - REAR GLASS
HEATING GRID REPAIR.................4
REAR WINDOW DEFOGGER RELAY
DESCRIPTION..........................5OPERATION............................5
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER RELAY.....................5
REMOVAL.............................6
INSTALLATION..........................6
REAR WINDOW DEFOGGER SWITCH
DESCRIPTION..........................6
OPERATION............................7
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER SWITCH...................7
REMOVAL.............................7
HEATED GLASS
DESCRIPTION - REAR WINDOW DEFOGGER
An electrically heated rear window defogger is
standard factory-installed equipment on this model.
Electrically heated outside rear view mirrors are
available factory-installed optional equipment. When
the rear window defogger system is turned on, elec-
tric heater grids on the liftgate flip-up glass and
behind both outside rear view mirror glasses are
energized. These electric heater grids produce heat to
help clear the rear window glass and the outside rear
view mirrors of ice, snow, or fog. The rear window
defogger system control circuit uses ignition switched
battery current, so the system will only operate when
the ignition switch is in the On position.
This group covers the following components of the
rear window defogger system:
²Rear glass heating grid
²Rear window defogger relay²Rear window defogger switch.
Certain functions and features of the rear window
defogger system rely upon resources shared with
other electronic modules in the vehicle over the Pro-
grammable Communications Interface (PCI) data bus
network. The PCI data bus network allows the shar-
ing of sensor information. This helps to reduce wire
harness complexity, internal controller hardware, and
component sensor current loads. At the same time,
this system provides increased reliability, enhanced
diagnostics, and allows the addition of many new fea-
ture capabilities. For diagnosis of these electronic
modules or of the PCI data bus network, use a
DRBIIItscan tool and (Refer to Appropriate Diagnos-
tic Information).
The other electronic modules that may affect
proper system operation are:
²Body Control Module (BCM)- Refer to Elec-
tronic Control Modules for more information.
²Driver Door Module (DDM)- Refer to Elec-
tronic Control Modules for more information.
WJHEATED SYSTEMS 8G - 1