2002 JEEP LIBERTY Amp wired

There are two different versions of the BCM: base
and premium. The base BCM is a subset of the com-
ponents in the premium version. Basically, the base
version BCM does not support the following features:
Compass Mini-Trip Computer (CMTC), fog lamps
(front and/or rear), Remote Keyless Entry (RKE),
remote radio switches, or Vehicle Theft Security Sys-
tem (VTSS). Both versions of the BCM utilize inte-
grated circuitry and information carried on the
Programmable Communications Interface (PCI) databus network along with many hard wired inputs to
monitor many sensor and switch inputs throughout
the vehicle. In response to those inputs, the internal
circuitry and programming of the BCM allow it to
control and integrate many electronic functions and
features of the vehicle through both hard wired out-
puts and the transmission of electronic message out-
puts to other electronic modules in the vehicle over
the PCI data bus. The electronic functions and fea-
tures that the BCM supports or controls include the
following:
²A/C Select Switch Status- The BCM monitors
an input from, and transmits the status of the A/C
switch on the heater-A/C control.
²Ambient Temperature Data- The premium
BCM monitors and transmits the ambient tempera-
ture sensor input data.
²Cargo Lamp Disable- The BCM monitors an
input from the cargo lamp switch to provide an inte-
rior lighting disable feature.
²Chimes- The chime tone generator is located
on the ElectroMechanical Instrument Cluster (EMIC)
circuit board, but the EMIC goes to sleep with the
ignition switch in the Off position. The BCM provides
a wake-up output to the EMIC based upon inputs
from the key-in ignition switch or the exterior light-
ing switch, then sends electronic chime request mes-
sages to the EMIC for the headlamps-on warning
and key-in ignition warning.
²Door Lock Inhibit- The BCM monitors the
key-in ignition switch and the driver side front door
ajar switch to provide a door lock inhibit feature.
²Exterior Lamp Load Shedding- The BCM
provides a battery saver feature which will automat-
ically turn off exterior lamps that remain on after a
timed interval.
²Exterior Lamp Status- The BCM monitors
the status of the park lamp, low beam, high beam or
Daytime Running Lamp (DRL - Canada only), front
fog lamp (optional), and rear fog lamp (in required
markets only) relays.
²Exterior Lighting Control- The BCM pro-
vides exterior lamp control for standard head and
park lamps, as well as Daytime Running Lamps
(DRL - Canada only), front fog lamps (optional), and
rear fog lamps (in required markets only). This
includes support for features including optical horn
(also known as flash-to-pass) and headlamp time
delay.
²Flip-Up Glass Control- The BCM monitors
the tailgate cylinder lock switch, the tailgate handle
switch, the Remote Keyless Entry (RKE) module
inputs and the rear wiper switch to provide control
for the rear flip-up glass actuator.
Fig. 1 Body Control Module Location
1 - DRIVER DOOR
2 - INSTRUMENT PANEL END BRACKET
3 - JUNCTION BLOCK
4 - BODY CONTROL MODULE
Fig. 2 Body Control Module
1 - BODY CONTROL MODULE (FRONT VIEW)
2 - REMOTE KEYLESS ENTRY MODULE RECEPTACLE
3 - BCM-RKE CONNECTOR
4 - BODY CONTROL MODULE (BACK VIEW)
5 - JB-BCM CONNECTOR
6 - CONNECTOR RECEPTACLE (2)
KJELECTRONIC CONTROL MODULES 8E - 3
BODY CONTROL MODULE (Continued)

²Fog Lamp Control- The premium BCM pro-
vides fog lamp control for front fog lamps (optional),
and rear fog lamps (in required markets only).
²Front Wiper System Status- The BCM moni-
tors the status of the front wiper motor park switch.
²Fuel Economy and Distance to Empty Cal-
culations- The BCM calculates and transmits the
fuel economy and Distance To Empty (DTE) data.
²Headlamp Time Delay- The BCM provides a
headlamp time delay feature with the ignition switch
in the Off position.
²Heated Rear Glass Control- The BCM pro-
vides control and timer functions for the heated rear
glass feature and transmits the system status.
²Ignition On/Off Timer- The BCM monitors
and transmits the elapsed ignition On timer data
and monitors the ignition Off time.
²Ignition Switch Position Status- The BCM
monitors and transmits the status of the ignition
switch.
²Instrument Panel Dimming- The BCM mon-
itors and transmits the selected illumination inten-
sity level of the panel lamps dimmer switch.
²Interior Lamp Load Shedding- The BCM
provides a battery saver feature which will automat-
ically turn off all interior lamps that remain on after
a timed interval.
²Interior Lighting Control- The BCM moni-
tors inputs from the interior lighting switch, the door
ajar switches, the flip-up glass ajar switch, the tail-
gate ajar switch, the cargo lamp switch, the reading
lamp switches, and the Remote Keyless Entry (RKE)
module to provide courtesy lamp control. This
includes support for timed illuminated entry with
theater-style fade-to-off and courtesy illumination
defeat features.
²Intermittent Wipe and Front Wiper System
Control- The BCM monitors inputs from the front
wiper and washer switch and the front wiper motor
park switch to provide front wiper system control
through the wiper on/off and high/low relays. This
includes support for adjustable intermittent wipe,
mist wipe (also known as pulse wipe), and wipe-after-
wash features.
²Key-In-Ignition Switch Status- The BCM
monitors and transmits the status of the key-in-igni-
tion switch.
²Panic Mode- The BCM provides support for
the Remote Keyless Entry (RKE) system panic mode
feature.
²Parade Mode- The BCM provides a parade
mode (also known as funeral mode) that allows the
interior Vacuum Fluorescent Displays (VFD) to be
illuminated at full intensity while driving in daylight
with the exterior lamps On.²Power Locks- The BCM monitors inputs from
the power lock switches and the Remote Keyless
Entry (RKE) module (optional) to provide control of
the power lock motors through outputs to the lock,
unlock, and driver unlock (RKE only) relays. This
includes support for rolling door locks (also known as
automatic door locks) and a door lock inhibit mode.
²Programmable Features- The BCM provides
support for several standard and optional program-
mable features, including: rolling door locks, head-
lamp time delay interval, Remote Keyless Entry
(RKE) driver-door-only or unlock-all-doors, RKE opti-
cal chirp, and RKE audible chirp.
²Remote Keyless Entry- The premium BCM
provides the optional Remote Keyless Entry (RKE)
system features, including support for the RKE Lock,
Unlock (with optional driver-door-only unlock, and
unlock-all-doors), rear flip-up glass control, Panic,
audible chirp, optical chirp, and illuminated entry
modes, as well as the ability to be programmed to
recognize up to four RKE transmitters.
²Rolling Door Locks- The BCM provides sup-
port for the power lock system rolling door locks fea-
ture (also known as automatic door locks).
²Tailgate and Flip-Up Glass Ajar Status- The
BCM monitors and transmits the status of the tail-
gate and rear flip-up glass ajar switches.
²Remote Radio Switch Interface- The pre-
mium BCM monitors and transmits the status of the
optional remote radio switches.
²Self-Diagnostics- The BCM provides support
for diagnostics through communication with the
DRBIIItscan tool over the PCI data bus network.
Each analog and digital input can be verified, and
each output can be actuated through the use of this
diagnostic protocol. The BCM also stores Diagnostic
Trouble Codes (DTCs) to assist in troubleshooting
this unit.
²Vacuum Fluorescent Display Synchroniza-
tion- The BCM transmits panel lamp intensity data
which allows modules with Vacuum Fluorescent Dis-
plays (VFD) to coordinate their illumination inten-
sity.
²Vehicle Speed System- The BCM monitors a
vehicle speed input from the vehicle speed sensor
(without Antilock Brake System [ABS]) or from the
Controller Antilock Brake (CAB)(with ABS), calcu-
lates the vehicle speed based upon a programmed
axle ratio/tire size (electronic pinion factor), and
transmits the vehicle speed information to the Pow-
ertrain Control Module (PCM) on a hard wired out-
put circuit.
²Vehicle Theft Security System- The pre-
mium BCM monitors inputs from the door cylinder
lock switches, the tailgate cylinder lock switch, the
door ajar switches, the tailgate ajar switch, the
8E - 4 ELECTRONIC CONTROL MODULESKJ
BODY CONTROL MODULE (Continued)

flip-up glass ajar switch, the hood ajar switch (in
required markets only), and the Remote Keyless
Entry (RKE) module to control the features of the
optional Vehicle Theft Security System (VTSS).
Hard wired circuitry connects the BCM to the elec-
trical 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
BCM 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.
Many of the electronic features in the vehicle con-
trolled or supported by the BCM are programmable
using a customer programming procedure or the
DRBIIItscan tool. In addition, the BCM software is
Flash compatible, which means it can be repro-
grammed using Flash reprogramming procedures.
However, if any of the BCM hardware components is
damaged or faulty, the entire BCM unit must be
replaced.
OPERATION
The microprocessor-based Body Control Module
(BCM) monitors many hard wired switch and sensor
inputs as well as those resources it shares with other
electronic modules in the vehicle through its commu-
nication over the Programmable Communications
Interface (PCI) data bus network. The internal pro-
gramming and all of these inputs allow the BCM
microprocessor to determine the tasks it needs to
perform and their priorities, as well as both the stan-
dard and optional features that it should provide.
The BCM programming then performs those tasks
and provides those features through both PCI data
bus communication with other electronic modules
and through hard wired outputs through a number of
driver circuits, relays, and actuators. These outputs
allow the BCM the ability to control numerous acces-
sory systems in the vehicle.
The BCM operates on battery current received
through a fuse in the Junction Block (JB) on a non-
switched fused B(+) circuit, through another fuse in
the JB on a fused ignition switch output (run-start)
circuit, and through a third fuse in the JB on a fused
ignition switch output (run-acc) circuit. This arrange-
ment allows the BCM to provide some features
regardless of the ignition switch position, while other
features will operate only with the ignition switch inthe On, Start, and/or Accessory positions. All of the
battery current circuits are connected to the BCM
through the JB/BCM connector. The BCM receives
ground through five separate circuits. Three of these
circuits are connected to the BCM through a connec-
tor and take out of the instrument panel wire har-
ness on three separate ground circuits, while the
other two circuits are connected to the BCM through
the JB/BCM connector. All of these circuits are
grounded through a splice block located in the instru-
ment panel wire harness with an eyelet terminal con-
nector that is secured by a nut to a ground stud on
the driver side instrument panel end bracket near
the JB.
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 following:
²A/C on/off control
²Ambient temperature sensor signal
²Body control module flash enable
²Door lock switch mux
²Driver door ajar switch sense
²Flip-up glass ajar switch sense
²Flip-up glass release switch sense
²Fog lamp switch sense
²Front wiper park switch sense
²Front wiper switch mux
²Front washer pump driver
²Fused B(+)
²Fused ignition switch output (run-acc)
²Fused ignition switch output (run-start)
²Headlamp switch mux
²High beam switch sense
²Hood ajar switch sense - premium with
VTSS - in markets where required only
²Key-in ignition switch sense
²Left cylinder lock switch sense - premium
with VTSS only - omitted in some markets as
required
²Panel lamps dimmer switch mux
²Passenger doors ajar switch sense (input
from three ajar switches connected in parallel)
²Radio control mux - premium with remote
radio switches only
²Rear courtesy lamp control
²Rear window defogger control
²Rear wiper intermittent driver
²Rear wiper on driver
²Right cylinder lock switch sense - premium
with VTSS only - omitted in some markets as
required
KJELECTRONIC CONTROL MODULES 8E - 5
BODY CONTROL MODULE (Continued)

²RKE antenna (two circuits) - premium with
RKE only
²Tailgate ajar switch sense
²Tailgate cylinder lock switch sense
²Vehicle speed sensor
Refer to the appropriate wiring information for
additional details.
HARD WIRED OUTPUTS The hard wired outputs
of the BCM include the following:
²Courtesy lamp driver
²Courtesy lamp load shed
²Door lock relay control
²Driver door unlock relay control - premium
with RKE only
²Flip-up glass release motor driver
²Front fog lamp relay control - premium
with front fog lamps only
²Front wiper high/low relay control
²Front wiper on/off relay control
²Hazard lamp control
²High beam relay control
²Horn relay control - premium with RKE
only
²Instrument cluster wake up signal
²Low beam relay control
²Park lamp relay control
²Passenger door unlock relay control
²Rear fog lamp relay control - premium with
rear fog lamps in markets where required only
²Rear window defogger relay control
²RKE supply - premium with RKE only
²Tailgate lock driver
²Tailgate unlock driver
²Vehicle speed output
²Vehicle speed sensor supply
²VTSS indicator driver - premium with
VTSS only
Refer to the appropriate wiring information for
additional details.
GROUNDS The BCM receives ground through five
separate circuits, and also supplies a ground path to
several switches through the following hard wired
circuits:
²Ambient temperature sensor return
²Door lock switch ground
²Headlamp switch return
²Radio control mux return
²RKE ground - premium with RKE only
²Tailgate switch ground
Refer to the appropriate wiring information for
additional details.
COMMUNICATION Not including the two RKE
antenna circuits (RKE antenna + and ±), which
merely pass through the premium BCM from the
RKE module to the external RKE antenna in theinstrument panel wire harness, the BCM has the fol-
lowing communication circuits:
²PCI bus
²RKE program serial data - premium with
RKE only
²RKE transmit serial data - premium with
RKE only
Refer to the appropriate wiring information for
additional details.
MESSAGING The BCM uses the following mes-
sages received from other electronic modules over the
PCI data bus:
²Battery Temperature (PCM)
²Compass Mini-Trip Computer Button Sta-
tus (CMTC) - premium only
²Coolant Temperature (PCM)
²Distance Pulses (PCM)
²Engine Speed (PCM)
²Fuel Tank Level (PCM)
²Fuel Used (PCM)
²Intrusion Transceiver Module Commands
(ITM) - premium in markets where required
only
²Manifold Absolute Pressure (PCM)
²OK to Lock - Rolling Locks (PCM)
²SKIS Status (SKIM)
²Vehicle Identification Number (PCM)
²Vehicle Speed (PCM)
The BCM provides the following messages to other
electronic modules over the PCI data bus:
²A/C Select Switch Status (PCM)
²Country Code (EMIC, PCM, CMTC)
²Distance to Empty (CMTC) - premium only
²Door Ajar Status (EMIC)
²Exterior Lighting Status (EMIC)
²Flip-up Glass Ajar Status (EMIC)
²Fuel Economy (Average and Instantaneous)
(CMTC) - premium only
²Hood Ajar Status (ITM) - premium in mar-
kets where required only
²Ignition On Timer (CMTC) - premium only
²Intrusion Transceiver Module Commands
(ITM) - premium in markets where required
only
²Key-In Ignition Switch Status (EMIC)
²Outside Temperature (CMTC) - premium
only
²Panel Lamp Intensity (CMTC, Radio)
²Tailgate Ajar Status (EMIC)
²Radio Mode (Radio) - premium only
²Radio Preset Scan (Radio) - premium only
²Radio Seek Down (Radio) - premium only
²Radio Seek Up (Radio) - premium only
²Radio Volume Down (Radio) - premium
only
²Radio Volume Up (Radio) - premium only
8E - 6 ELECTRONIC CONTROL MODULESKJ
BODY CONTROL MODULE (Continued)

INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
(1) Position the Sentry Key Immobilizer Module
(SKIM) to the right side of the steering column (Fig.
11). Lift the multi-function switch upward off of the
upper steering column housing far enough to insert
the SKIM antenna ring formation between the igni-
tion key release button and the multi-function switch
housing.
(2) Slide the SKIM antenna ring around the igni-
tion switch lock cylinder housing, then rotate the
SKIM and its mounting bracket upwards and toward
the steering column.
(3) Align the SKIM mounting bracket clip forma-
tion with the right lower flange of the steering col-
umn jacket and, using hand pressure, push upward
firmly and evenly on the connector end of the SKIM
mounting bracket to engage this clip with the steer-
ing column jacket.
(4) Reconnect the instrument panel wire harness
connector for the SKIM to the module connector
receptacle.
(5) Position both the upper and lower shrouds onto
the steering column.
(6) Align the snap features on the lower shroud
with the receptacles on the upper shroud and apply
hand pressure to snap them together.
(7) From below the steering column, install and
tighten the two screws that secure the lower shroud
to the upper shroud. Tighten the screws to 2 N´m (18
in. lbs.).
(8) If the vehicle is equipped with the optional tilt
steering column, move the tilt steering column to the
fully raised position and secure it in place by moving
the tilt release lever back to the locked (up) position.
(9) Reconnect the battery negative cable.NOTE: If the SKIM has been replaced with a new
unit, the Sentry Key Immobilizer System (SKIS)
MUST be initialized before the vehicle can be oper-
ated. (Refer to 8 - ELECTRICAL/VEHICLE THEFT
SECURITY - STANDARD PROCEDURE - SKIS INI-
TIALIZATION).
TRANSMISSION CONTROL
MODULE
DESCRIPTION
The Transmission Control Module (TCM) is located
in the engine compartment on the right (passenger)
side and is mounted to the inner fender (Fig. 12).
OPERATION
The Transmission Control Module (TCM) is the
controlling unit for all electronic operations of the
transmission. The TCM receives information regard-
ing vehicle operation from both direct and indirect
inputs, and selects the operational mode of the trans-
mission. Direct inputs are hardwired to, and used
specifically by the TCM. Indirect inputs originate
from other components/modules, and are shared with
the TCM via the vehicle communication bus.
Some examples ofdirect inputsto the TCM are:
²Battery (B+) voltage
²Ignition ªONº voltage
²Transmission Control Relay (Switched B+)
²Throttle Position Sensor
²Crankshaft Position Sensor
²Transmission Range Sensor
²Pressure Switches
²Transmission Temperature Sensor
²Input Shaft Speed Sensor
Fig. 12 Transmission Control Module Location
1 - Transmission Control Module
8E - 18 ELECTRONIC CONTROL MODULESKJ
SENTRY KEY IMMOBILIZER MODULE (Continued)

WINDOW DEFOGGER
TABLE OF CONTENTS
page page
WINDOW DEFOGGER
DESCRIPTION - REAR WINDOW DEFOGGER . . 3
OPERATION - REAR WINDOW DEFOGGER....3
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER SYSTEM...................4
STANDARD PROCEDURE - REAR GLASS
HEATING GRID REPAIR.................4
REAR WINDOW DEFOGGER GRID
DESCRIPTION..........................5
OPERATION............................5
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER GRID......................5
REAR WINDOW DEFOGGER RELAY
DESCRIPTION..........................6
OPERATION............................6DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER RELAY.....................6
REMOVAL.............................7
INSTALLATION..........................7
REAR WINDOW DEFOGGER SWITCH
DESCRIPTION..........................8
OPERATION............................8
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - REAR
WINDOW DEFOGGER SWITCH...........8
DIAGNOSIS AND TESTING - REAR HVAC
CONTROL ASSEMBLY WINDOW
DEFOGGER FUNCTION.................9
REMOVAL.............................9
INSTALLATION..........................9
WINDOW DEFOGGER
DESCRIPTION - REAR WINDOW DEFOGGER
The rear window defogger system will only operate
when the ignition switch is in the run position. When
the defogger switch is in the run position, an electric
heater grid on the rear window glass is energized.
Vehicles with the heated mirror options also have
heater grids located behind the outside rear view
mirror glass. Each of these grids produce heat to help
clear the rear window glass and outside rear view
mirrors of ice, snow, or fog.
OPERATION - REAR WINDOW DEFOGGER
The rear window defogger system is controlled by a
switch installed with the HVAC control assembly. An
amber indicator lamp in the switch button will light
to indicate when the rear window defogger system is
turned on. The HVAC control head circuitry, which
contains the defogger system timer logic, monitors
the state of the defogger switch through a hard-wired
input. The instrument cluster circuitry controls therear window defogger system through a hard-wired
control output to the rear window defogger relay. The
rear window defogger timer and logic circuitry cannot
be adjusted or repaired and, if faulty or damaged, the
HVAC control head assembly must be replaced.
The rear window defogger system will be automat-
ically turned off after a programmed time interval of
about ten minutes. After the initial time interval has
expired, if the rear window defogger switch is turned
on again during the same ignition cycle, the defogger
system will automatically turn off after about five
minutes.
The rear window defogger system will automati-
cally shut off if the ignition switch is turned to the
Off position, or it can be turned off manually by
depressing the instrument panel switch. Following
are general descriptions of the major components in
the rear window defogger system. Refer to the own-
er's manual in the vehicle glove box for more infor-
mation on the features, use and operation of the
defogger system.
KJWINDOW DEFOGGER 8G - 3

REAR WINDOW DEFOGGER
SWITCH
DESCRIPTION
The rear window defogger switch is installed in the
instrument panel HVAC contol head assembly. The
momentary-type switch provides a hard-wired ground
signal to the HVAC control head each time it is
depressed. The instrument cluster rear window
defogger timer and logic circuitry responds by ener-
gizing or de-energizing the rear window defogger
relay.
OPERATION
Energizing the rear window defogger relay pro-
vides electrical current to the rear window defogger
grid and, if the vehicle is so equipped, the outside
rear view mirror heating grids. An amber indicator
lamp in the defogger switch, which lights to indicate
when the defogger system is turned On, is also pow-
ered by the defogger relay output.
The defogger switch illumination lamp and indica-
tor lamp bulbs are serviceable. The defogger switch
cannot be repaired and, if faulty or damaged the
entire HVAC control head assembly must be
replaced.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER SWITCH
For circuit descriptions and diagrams, (Refer to
Appropriate Wiring Information).
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 AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable. Remove the HVAC control head assembly from
the instrument panel and unplug the defogger switch
wire harness connector-B.
(2) Check for continuity between the ground cir-
cuit cavity of the defogger switch wire harness con-nector and a good ground. There should be
continuity. If OK, go to Step 3. If not OK, repair the
open circuit as required.
(3) Check for continuity between the ground cir-
cuit terminal and the rear window defogger switch
sense circuit terminal on the back of the defogger
switch housing (Fig. 5). There should be momentary
continuity as the defogger switch button is depressed,
and then no continuity. If OK, (Refer to 8 - ELEC-
TRICAL/HEATED GLASS/REAR WINDOW DEFOG-
GER SWITCH - DIAGNOSIS AND TESTING -
INSTRUMENT CLUSTER REAR WINDOW DEFOG-
GER FUNCTION) If not OK, replace the faulty
switch (Fig. 5).
(4) Check switch position continuity between:
CONTACT PINS
1 - OFF LAMPS A-1 - A-7
2 - ON MOMENTARY B-6 - B-8
3 - ILLUMINATION LAMP A-7 - A-1
4 - INDICATOR LAMP B-12 - B-7
Fig. 5 A/C HEATER CONTROL HEAD (Rear View)
1 - A/C HEATER CONTROL HEAD
2 - A/C HEATER CONTROL HEAD LIGHT
3 - REAR WINDOW DEFOGGER SWITCH AND TEMPERATURE
BLEND DOOR- CONNECTOR B (12 PIN)
4 - A/C HEATER CONTROL HEAD LIGHT
5 - MODE SELECT CONTROL
6 - BLOWER SPEED CONTROL- CONNECTOR A (7 PIN)
7 - MOUNTING SCREWS (4)
8G - 8 WINDOW DEFOGGERKJ

The heated seat module monitors inputs from the
heated seat sensors and the heated seat switches. In
response to these inputs the heated seat module uses
its internal programming to control outputs to the
heated seat elements in both front seats and to con-
trol the heated seat LED indicator lamps located in
both of the heated seat switches. The heated seat
module is also programmed to provide self-diagnostic
capability. When the module detects certain failures
within the heated seat system, it will provide a
visual indication of the failure by flashing the indica-
tor lamps in the affected heated seat switch. The
heated seat module will automatically turn off the
heated seat elements if it detects a short or open in
the heated seat element circuit or a heated seat sen-
sor value that is out of range.
DIAGNOSIS AND TESTING - HEATED SEAT
SYSTEM
HEATED SEAT SYSTEM SELF-DIAGNOSIS
The heated seat system is capable of performing
some self-diagnostics. The following table depicts the
various monitored failures which will be reported to
the vehicle operator or technician by flashing the
individual heated seat switch Light Emitting Diode
(LED) indicator lamps. Refer to the Heated Seat Sys-
tem Self-Diagnosis table for failure identification.
The driver side heated seat switch indicator lamps
will flash if a failure occurs in the driver side heated
seat, and the passenger side heated seat switch indi-
cator lamps will flash for a passenger side heated
seat failure. If a monitored heated seat system fail-
ure occurs, the switch indicator lamps will flash at a
pulse rate of about one-half second on, followed by
about one-half second off for a duration of about one
minute after the switch for the faulty heated seat is
depressed in either the Low or High direction. This
process will repeat every time the faulty heated seat
switch is actuated until the problem has been cor-
rected.
Heated Seat System Self-Diagnosis
Monitored FailureSwitch High
Indicator LampSwitch Low
Indicator Lamp
Heated Seat
Element ShortedFlashing Flashing
Heated Seat
Element OpenFlashing Off
Heated Seat
Sensor Value Out
of RangeOff FlashingIf the heated seat system failure is identified by
flashing heated seat switch indicator lamps, go to the
appropriate diagnosis and testing procedure in this
section and confirm the condition, using the step by
step procedure. If the monitored failure is confirmed,
replace the component. If the monitored failure is not
confirmed, replace the heated seat module with a
known good unit and retest the system.
HEATED SEAT SYSTEM TESTING
Refer toWiring Diagramsfor the location of com-
plete heated seat system wiring diagrams. Before
testing the individual components in the heated seat
system, perform the following preliminary checks:
²If a single indicator lamp for one heated seat
switch does not operate and the heated seat elements
do heat, refer toDiagnosis and Testing the
Heated Seat Switchin this section for the location
of heated seat switch diagnosis and testing proce-
dures.
²If both indicator lamps for a heated seat switch
operate, but the heated seat elements do not heat,
refer toDiagnosis and Testing the Heated Seat
Modulein Electronic Control Modules for the loca-
tion of heated seat module diagnosis and testing pro-
cedures.
²If an indicator lamp on either heated seat switch
remains illuminated after the heated seat has been
turned Off, refer toDiagnosis and Testing the
Heated Seat Modulein Electronic Control Modules
for the location of heated seat module diagnosis and
testing procedures. Also refer to the Body Diagnostic
Manual for additional diagnosis and testing proce-
dures.
DRIVER SEAT HEATER
SWITCH
DESCRIPTION
The heated seat switches are located on the out-
board cushion side shield of the driver and passenger
front seats (Fig. 1). The two, three-position rocker
type switches provide a resistor multiplexed signal to
the Heated Seat Module through separate hard wired
circuits. Each switch has an Off, Low and High set-
ting. Each switch contains two light emitting diodes
(LED), one for each High and Low setting to let the
occupant know that the seat heater system is on.
The heated seat switches and their LED's cannot
be repaired. If either switch is faulty or damaged the
entire switch must be replaced.
KJHEATED SEAT SYSTEM 8G - 11
HEATED SEAT SYSTEM (Continued)