
ULES/POWERTRAIN CONTROL MODULE -
DESCRIPTION) section for more DTC information.The Charging system ªBatteryº light indicates
problems with the charging system (voltage too high/
low, generator failure, etc.). If an extreme condition is
indicated, the lamp will be illuminated. The signal to
activate the lamp is sent via the PCI bus circuits.
The lamp is located on the instrument panel. Refer
to the Instrument Cluster section for additional infor-
mation. The PCM uses the ambient air temperature sensor
to control the charge system voltage. This tempera-
ture, along with data from monitored line voltage, is
used by the PCM to vary the battery charging rate.
The system voltage is higher at cold temperatures
and is gradually reduced as the calculated battery
temperature increases. The ambient temperature sensor is used to control
the battery voltage based upon ambient temperature
(approximation of battery temperature). The PCM
maintains the optimal output of the generator by
monitoring battery voltage and controlling it to a
range of 13.5 - 14.7 volts based on battery tempera-
ture.
DIAGNOSIS AND TESTING - ON-BOARD
DIAGNOSTIC SYSTEM
The Powertrain Control Module (PCM) monitors
critical input and output circuits of the charging sys-
tem, making sure they are operational. A Diagnostic
Trouble Code (DTC) is assigned to each input and
output circuit monitored by the OBD system. Some
circuits are checked continuously and some are
checked only under certain conditions. If the OBD system senses that a monitored circuit
is bad, it will put a DTC into electronic memory. The
DTC will stay in electronic memory as long as the
circuit continues to be bad. The PCM is programmed
to clear the memory after 40 good trip if the problem
does not occur again.
DIAGNOSTIC TROUBLE CODES
A DTC description can be read using the DRBIII t
scan tool. Refer to the appropriate Powertrain Diag-
nostic Procedures manual for information. A DTC does not identify which component in a cir-
cuit is bad. Thus, a DTC should be treated as a
symptom, not as the cause for the problem. In some
cases, because of the design of the diagnostic test
procedure, a DTC can be the reason for another DTC
to be set. Therefore, it is important that the test pro-
cedures be followed in sequence, to understand what
caused a DTC to be set. ERASING DIAGNOSTIC TROUBLE CODES
The DRBIII tScan Tool must be used to erase a
DTC. The following procedures may be used to diagnose
the charging system if: ² the check gauges lamp or battery lamp is illumi-
nated with the engine running ² the voltmeter (if equipped) does not register
properly ² an undercharged or overcharged battery condi-
tion occurs. Remember that an undercharged battery is often
caused by: ² accessories being left on with the engine not
running ² a faulty or improperly adjusted switch that
allows a lamp to stay on. Refer to Ignition-Off Draw
Test (Refer t o 8 - ELECTRICAL/BATTERY SYSTEM/
BATTERY - STANDARD PROCEDURE) ² loose generator belt.
INSPECTION The Powertrain Control Module (PCM) monitors
critical input and output circuits of the charging sys-
tem, making sure they are operational. A Diagnostic
Trouble Code (DTC) is assigned to each input and
output circuit monitored by the On-Board Diagnostic
(OBD) system. Some charging system circuits are
checked continuously, and some are checked only
under certain conditions. Refer to Diagnostic Trouble Codes in; Powertrain
Control Module; Electronic Control Modules for more
DTC information. This will include a complete list of
DTC's including DTC's for the charging system. To perform a complete test of the charging system,
refer to the appropriate Powertrain Diagnostic Proce-
dures service manual and the DRBIII tscan tool.
Perform the following inspections before attaching
the scan tool. (1) Inspect the battery condition. Refer to the Bat-
tery section (Refer t o 8 - ELECTRICAL/BATTERY
SYSTEM - DIAGNOSIS AND TESTING) for proce-
dures. (2) Inspect condition of battery cable terminals,
battery posts, connections at engine block, starter
solenoid and relay. They should be clean and tight.
Repair as required. (3) Inspect all fuses in both the fuseblock and
Power Distribution Center (PDC) or IPM (if
equipped) for tightness in receptacles. They should be
properly installed and tight. Repair or replace as
required. (4) Inspect generator mounting bolts for tightness.
Replace or tighten bolts if required. Refer to the Gen-
erator Removal/Installation section of this group for
RS CHARGING8Fs-21
CHARGING (Continued)

(2) Perform Starter Solenoid test BEFORE per-
forming the starter relay test. (3) Perform a visual inspection of the starter/
starter solenoid for corrosion, loose connections or
faulty wiring. (4) Locate and remove the starter relay from the
Power Distribution Center (PDC). Refer to the PDC
label for relay identification and location. (5) Connect a remote starter switch or a jumper
wire between the remote battery positive post and
terminal 87 of the starter relay connector. (a) If engine cranks, starter/starter solenoid is
good. Go to the Starter Relay Test. (b) If engine does not crank or solenoid chatters,
check wiring and connectors from starter relay to
starter solenoid and from the battery positive ter-
minal to starter post for loose or corroded connec-
tions. Particularly at starter terminals. (c) Repeat test. If engine still fails to crank prop-
erly, trouble is within starter or starter mounted
solenoid, and replace starter. Inspect the ring gear
teeth.
STARTER RELAY
WARNING: CHECK TO ENSURE THAT THE TRANS-
MISSION IS IN THE PARK/NEUTRAL POSITION
WITH THE PARKING BRAKE APPLIED. THIS MAY
RESULT IN PERSONAL INJURY OR DEATH.
RELAY TEST
The starter relay is located in the Power Distribu-
tion Center (PDC) in the engine compartment. Refer
to the PDC label for relay identification and location. Remove the starter relay from the PDC as
described in this group to perform the following tests: (1) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 2. If not OK, replace the faulty relay. (2) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75 5 ohms. If OK, go to Step
3. If not OK, replace the faulty relay. (3) Connect a battery B+ lead to terminals 85 and
a ground lead to terminal 86 to energize the relay.
The relay should click. Also test for continuity
between terminals 30 and 87, and no continuity
between terminals 87A and 30. If OK, refer to Relay
Circuit Test procedure. If not OK, replace the faulty
relay.
CAV FUNCTION
30 B (+)
85 IGNITION SWITCH OUTPUT
86 PCM-CONTROLLED GROUND
87 STARTER RELAY OUTPUT
87A NO CONNECT
RELAY CIRCUIT TEST
(1) The relay common feed terminal cavity (30) is
connected to battery voltage and should be hot at all
times. If OK, go to Step 2. If not OK, repair the open
circuit to the PDC fuse as required.
Starter Relay Pinout
Starter Relay Pinout
Starter Relay Pinout
RS STARTING8Fs-33
STARTING (Continued)

HEATED SYSTEMS
TABLE OF CONTENTS
page page
HEATED GLASS........................... 1
HEATED MIRRORS......................... 6HEATED SEAT SYSTEM..................... 7
HEATED GLASS
TABLE OF CONTENTS
page page
HEATED GLASS
DESCRIPTION..........................1
OPERATION............................2
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER SYSTEM...................2
REAR WINDOW DEFOGGER RELAY
DESCRIPTION..........................3
OPERATION............................3REMOVAL.............................3
INSTALLATION..........................3
REAR WINDOW DEFOGGER SWITCH
DESCRIPTION..........................4
OPERATION............................4
REAR WINDOW DEFOGGER GRID
STANDARD PROCEDURE - GRID LINE AND
TERMINAL REPAIR.....................4
HEATED GLASS
DESCRIPTION
CAUTION: Grid lines can be damaged or scraped
off with sharp instruments. Care should be taken in
cleaning glass or removing foreign materials,
decals or stickers. Normal glass cleaning solvents
or hot water used with rags or toweling is recom-
mended.
The rear window defogger system consists of two
vertical bus bars linked by a series of grid lines fired
onto the inside surface of the rear window (Fig. 1).
The rear window defogger system is turned ON or
OFF by a control switch located on the A/C-heater
control at the center of the instrument panel and by
a rear window defogger relay timing circuit integral
to the integrated power module (IPM) (Refer to 8 -
ELECTRICAL/HEATED GLASS/REAR WINDOW
DEFOGGER SWITCH - DESCRIPTION).
Circuit protection is provided by a 40 amp fuse
located in the IPM.
Fig. 1 Rear Window Defogger - Typical
1 - REAR DEFOGGER GRID
2 - REAR WINDOW
RSHEATED SYSTEMS8G-1

OPERATION
When the rear window defogger button is
depressed to the On position, current is directed to
the rear defogger grid lines and the heated power
mirrors (if equipped). The heated grid lines heat the
glass to help clear the rear window and side mirror
surfaces of fog or frost.
The defogger system is controlled by a momentary
switch located in the A/C-heater control on the
instrument panel. A yellow indicator in the switch
will illuminate to indicate when the defogger system
is turned on. The integrated power module (IPM)
contains the defogger system control circuitry.
NOTE:
The rear window defogger turns off automat-
ically after approximately 10 minutes of initial opera-
tion. Each following activation cycle of the defogger
system will last approximately five minutes.
The defogger system will be automatically turned
off after a programmed time interval of about ten
minutes. After the initial time interval has expired, if
the defogger switch is turned on again during the
same ignition cycle, the defogger system will auto-
matically turn off after about five minutes.
The defogger system will automatically shut off if
the ignition switch is turned to the Off position, or it
can be turned off manually by depressing the defog-
ger switch a second time.
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER SYSTEM
The electrically heated rear window defogger oper-
ation can be checked on the vehicle in the following
manner:
(1) Turn the ignition switch to the On position.
(2) Make sure that the defogger switch is Off.
(3) Using a ammeter on the battery, turn the rear
defogger control switch to the On position, a distinct
increase in amperage draw should be noted.
(4) The rear window defogger operation can be
checked by feeling the glass. A distinct difference in
temperature between the grid lines and adjacent
clear glass should be detected in three to four min-
utes of operation.
(5) Using a DC voltmeter, contact the negative
lead to Point B, and the positive lead to Point A (Fig.
2). The voltmeter should read 10-14 volts.
NOTE: Illumination of the LED indicator means that
there is power available at the switch, but does not
necessarily verify system operation.
(6) If turning the defogger switch On produced no
distinct current draw on the ammeter, the problem
should be isolated in the following manner:²Confirm that the ignition switch is On.
²Make sure that the heated rear window feed
wire is connected to the terminal and that the
ground wire is in fact grounded.
²Make sure that fuse 13 (40 amp) in the inte-
grated power module (IPM) is OK.
(7) When the above steps have been completed and
the system is still inoperative, one or more of the fol-
lowing could be defective. It may be necessary to con-
nect a DRBIIItscan tool to perform further
diagnostics. Refer to Body Diagnostic Procedures.
²Rear window defogger switch in the A/C-heater
control.
²J1850 bus communication between the A/C-
heater control and the front control module (FCM).
²Rear window defogger relay in the IPM.
²Rear window defogger relay control circuity in
the IPM.
²Check for a loose wire connector or a wire
pushed out of a connector.
²Rear window grid lines (all grid lines would
have to be broken, or one of the feed wires not con-
nected for the system to be inoperative).
(8) If turning the rear window defogger switch On
produces severe voltmeter deflection, the circuit
should be closely checked for a shorting condition.
(9) If the system operation has been verified but
LED indicator does not illuminate, replace the A/C-
heater control.
(10) For detailed wiring information, refer to Wir-
ing Diagrams.
Fig. 2 Grid Line Test
1 - VOLTMETER
2 - VOLTAGE FEED (A)
3 - FEED WIRE
4 - MID-POINT (C)
5 - HEATED WINDOW GRID
6 - GROUND WIRE
7 - GROUND (B)
8G - 2 HEATED GLASSRS
HEATED GLASS (Continued)

REAR WINDOW DEFOGGER
RELAY
DESCRIPTION
The rear window defogger relay (Fig. 3) is a Inter-
national Standards Organization (ISO)-type relay.
Relays conforming to the ISO specifications have
common physical dimensions, current capacities, ter-
minal patterns, and terminal functions. The rear
window defogger relay is a electromechanical device
that switches battery current through a fuse in the
integrated power module (IPM) to the rear window
defogger grid and switches battery current through a
positive thermal coefficient (PTC) in the IMP to the
outside mirror heating grids. The relay is energized
when the relay coil is provided a ground path by the
rear window defogger relay control in the front con-
trol module (FCM).
The rear window defogger relay is located in the
IPM in the engine compartment. See the fuse and
relay layout map on the inner surface of the IPM
cover for rear window defogger relay identification
and location.
The rear window defogger relay cannot be adjusted
or repaired and, if damaged or faulty, it must be
replaced.
OPERATION
The ISO relay consists of an electromagnetic coil, a
resistor or diode, and three (two fixed and one mov-
able) electrical contacts. The movable (common feed)
relay contact is held against one of the fixed contacts
(normally closed) by spring pressure. When the elec-
tromagnetic coil is energized, it draws the movablecontact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact.
When the electromagnetic coil is de-energized,
spring pressure returns the movable contact to the
normally closed position. The resistor is connected in
parallel with the electromagnetic coil in the relay,
and helps to dissipate voltage spikes that are pro-
duced when the coil is de-energized.
Refer to the appropriate wiring information for
diagnosis and testing of the ISO relay and for com-
plete rear window defogger system wiring diagrams.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cover from the Integrated Power
Module (IPM) (Fig. 4).
(3) Refer to the fuse and relay layout map molded
into the inner surface of the IPM cover for rear win-
dow defogger relay identification and location.
(4) Remove the rear window defogger relay from
the IPM.
INSTALLATION
(1) Refer to the fuse and relay layout map molded
into the inner surface of the Integrated Power Mod-
ule (IPM) cover for rear window defogger relay iden-
tification and location.
Fig. 3 Rear Window Defogger Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
Fig. 4 Integrated Power Module
1 - BATTERY THERMAL GUARD
2 - INTEGRATED POWER MODULE (IPM)
3 - FRONT CONTROL MODULE
RSHEATED GLASS8G-3

Refer to the description of the heated seat switch
later in this section for additional information.
Hard wired circuitry connects the heated seat sys-
tem components to each other through the electrical
system 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
heated seat system components through the use of a
combination of soldered splices and splice block con-
nectors. Refer to Wiring for complete system wiring
schematics. The wiring information also includes the
proper wire and connector repair procedures, further
details on wire harness routing and retention, as well
as pin-out and location views for the various wire
harness connectors, splices and grounds.
OPERATION
The heated seat system components operate on
battery current received through a fuse in the Inte-
grated Power Module (IPM) on a fused ignition
switch output (run) circuit from the Body Control
Module. The system will only operate when the igni-
tion switch is in the On position. The heated seat
system will be turned Off automatically whenever
the ignition switch is turned to any position except
On. Also, the heated seat system will not operate
when the surface temperature of the seat cushion
cover at either heated seat sensor is above the
designed temperature set points of the system. See
the owner's manual in the vehicle glove box for more
information on the features, use and operation of the
heated seat system.
DIAGNOSIS AND TESTING - HEATED SEAT
SYSTEM
The most reliable, efficient, and accurate means to
diagnose the heated seat 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 heated seat modules are receiving the
proper hard wired inputs from and relaying the
proper hard wired outputs to the Body Control Mod-
ule in order to perform its functions. Refer toWiring
Diagramsfor complete wiring schematics. The wir-
ing information also includes the 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 connec-
tors, splices and grounds.
DRIVER HEATED SEAT
SWITCH
DESCRIPTION
The heated seat switches are mounted in the
instrument panel center bezel (Fig. 2). The two three-
position rocker-type switches, one switch for each
front seat, are incorporated into one large switch
assembly that also includes the hazard, rear window
wiper and washer switches. The heated seat switches
each provide a resistor multiplexed signal to its
respective Heated Seat Module (HSM) through sepa-
rate hard wired circuits. Each switch has an Off,
Low, and High position so that both the driver and
the front seat passenger can select a preferred seat
heating mode. Each switch has two Light-Emitting
Diodes (LED) which light to indicate that the heater
for the seat is turned on.
The heated seat switches and their LEDs cannot
be repaired. If either switch or LED is faulty or dam-
aged, the entire switch assembly must be replaced.
OPERATION
There are three positions that can be selected with
each of the heated seat switches: Off, Low, or High.
When the left side of the switch rocker is fully
depressed, the Low position is selected and the low
position LED indicator illuminates. When the right
side of the switch rocker is fully depressed, the High
position is selected and the high position LED indi-
Fig. 2 HEATED SEAT SWITCH LOCATION
1 - HEATED SEAT SWITCHES
8G - 8 HEATED SEAT SYSTEMRS
HEATED SEAT SYSTEM (Continued)

cator illuminates. When the switch rocker is moved
to its neutral position (middle), Off is selected and
both LED indicators are extinguished.
Each switch provides separate resistor multiplexed
hard wire inputs to its respective Heated Seat Mod-
ule (HSM) to indicate the selected switch position.
The heated seat module responds to the heated seat
switch status messages by controlling the output to
the seat heater elements of the selected seat. The
Low heat position set point is about 36É C (97É F),
and the High heat position set point is about 41É C
(105É F).
DIAGNOSIS AND TESTING - DRIVER HEATED
SEAT SWITCH
For complete circuit diagrams, refer toWiring
Diagrams.
WARNING: REFER TO THE RESTRAINTS SECTION
OF THIS MANUAL BEFORE ATTEMPTING ANY
STEERING WHEEL, STEERING COLUMN, SEAT OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
CHECKING SWITCH SIGNAL AND WIRING AT THE
MODULE
(1) Disconnect and isolate the battery negative
cable.
(2) Access and disconnect the gray 4-way connector
from the heated seat module. Visually inspect wiring
terminals for damage that would prevent positive
connection. If not OK, repair or replace the necessary
components.
(3) Place the heated seat switch in the LO posi-
tion. Using an Ohmmeter, check the resistance
between cavities 2 and 3 of the gray connector noted
above. Resistance should be about 3.5 kilohms (3500
ohms). If not OK, check resistance directly at switch,
as noted below. If OK, proceed to the next step. If not
OK, replace the faulty switch.
(4) Place the heated seat switch in the HI position.
Using an ohmmeter, check the resistance between
cavities 2 and 3 of the gray connector noted above.
Resistance should be about 1.4 kilohms (1400 ohms).
If not OK, check resistance directly at switch, as
noted below. If OK, proceed. If not OK replace the
faulty switch.
(5) With the system ON in the HI position, check
for battery voltage and ground at cavities 4 and 1. If
OK, proceed with testing remaining components. If
not OK, repair open or shorted wiring.
CHECKING SWITCH ONLY
(1) Disconnect and isolate the battery negative
cable. Remove the center bezel from the instrument
panel (Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL CENTER BEZEL -
REMOVAL). Check for continuity between the
ground circuit cavity (#10) of the instrument panel
switch bank electrical connector and a good ground.
There should be continuity. If OK, go to Step 2. If not
OK, repair the open ground circuit to ground as
required.
(2) Reconnect the battery negative cable. Turn the
ignition switch to the On position. Check for battery
voltage at the fused ignition switch output (run) cir-
cuit cavity of the instrument panel switch bank con-
nector (#4). If OK, turn the ignition switch to the Off
position, and go to Step 3. If not OK, repair the open
fused ignition switch output (run) circuit as required.
(3) Test the heated seat switch as shown in the
Heated Seat Switch Test chart and the connector pin-
out below (Fig. 3). If OK, go to Step 4. If not OK,
replace the faulty switch bank assembly.
DRIVER HEATED SEAT SWITCH TEST
SWITCH
POSITIONRESISTANCE
BETWEENRESISTANCE
(OHMS)
Off Pin4&5OPEN
Low Pin4&53570
High Pin4&51430
All resistance values are 1%.
Fig. 3 Instrument Panel Switch Bank Connector
RSHEATED SEAT SYSTEM8G-9
DRIVER HEATED SEAT SWITCH (Continued)

Low heat position set point is about 36É C (97É F),
and the High heat position set point is about 41É C
(105É F).
DIAGNOSIS AND TESTING - PASSENGER
HEATED SEAT SWITCH
For complete circuit diagrams, refer toWiring
Diagrams.
WARNING: REFER TO THE RESTRAINTS SECTION
OF THIS MANUAL BEFORE ATTEMPTING ANY
STEERING WHEEL, STEERING COLUMN, SEAT OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
CHECKING SWITCH SIGNAL AND WIRING AT THE
MODULE
(1) Disconnect and isolate the battery negative
cable.
(2) Access and disconnect the gray 4-way connector
from the heated seat module. Visually inspect wiring
terminals for damage that would prevent positive
connection. If not OK, repair or replace the necessary
components.
(3) Reconnect the negative battery cable and Turn
heated seat ON in the LO position. Using an Ohm-
meter, check the resistance between cavities 2 and 3
of the gray connector noted above. Resistance should
be about 3.5 kiloohms (3500 ohms). If not OK, check
resistance directly at switch, as noted below. If OK,
proceed. If NOT OK replace the switch or faulty wir-
ing.
(4) Turn heated seat ON in the HI position. Using
an Ohmmeter, check the resistance between cavities
2 and 3 of the gray connector noted above. Resistance
should be about 1.4 kiloohms (1400 ohms). If not OK,
check resistance directly at switch, as noted below. If
OK, proceed. If NOT OK replace the switch or faulty
wiring.
(5) With the system ON in the HI position, Check
for battery voltage and ground at cavities 4 and 1. If
OK, proceed with testing remaining components. If
NOT OK, repair open or wiring short.
CHECKING SWITCH ONLY
(1) Disconnect and isolate the battery negative
cable. Remove the center bezel from the instrument
panel (Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL CENTER BEZEL -
REMOVAL). Check for continuity between the
ground circuit cavity (#10) of the instrument panel
switch bank electrical connector and a good ground.There should be continuity. If OK, go to Step 2. If not
OK, repair the open ground circuit to ground as
required.
(2) Reconnect the battery negative cable. Turn the
ignition switch to the On position. Check for battery
voltage at the fused ignition switch output (run) cir-
cuit cavity of the instrument panel switch bank con-
nector (#4). If OK, turn the ignition switch to the Off
position, and go to Step 3. If not OK, repair the open
fused ignition switch output (run) circuit as required.
(3) Test the heated seat switch as shown in the
Heated Seat Switch Test chart and the connector pin-
out below (Fig. 7). If OK, go to Step 4. If not OK,
replace the faulty switch bank assembly.
PASSENGER HEATED SEAT SWITCH TEST
SWITCH
POSITIONRESISTANCE
BETWEENRESISTANCE
(OHMS)
Off Pin3&4OPEN
Low Pin3&43570
High Pin3&41430
All resistance values are 1%.
(4) Reconnect the instrument panel switch bank
and test the heated seat system for proper operation.
If the system is still inoperative proceed with check-
ing remaining components.
Fig. 7 Instrument Panel Switch Bank Connector
RSHEATED SEAT SYSTEM8G-13
PASSENGER HEATED SEAT SWITCH (Continued)