2002 JEEP GRAND CHEROKEE service

repaired and, if faulty or damaged, the entire a/c
heater control must be replaced. (Refer to 24 - HEAT-
ING & AIR CONDITIONING/CONTROLS/A/C
HEATER CONTROL - REMOVAL)
OPERATION
When the rear window defogger switch push but-
ton is depressed, it momentarily closes the rear win-
dow defogger switch sense circuit for the BCM to
ground. The BCM monitors the rear window defogger
switch sense circuit. Each time the BCM rear win-
dow defogger timer and logic circuitry sees another
input from the switch, it toggles a control output to
the rear window defogger relay. Energizing the rear
window defogger relay provides electrical current to
the rear window defogger grid and to the LED indi-
cator in the switch, which lights to indicate when the
defogger system is turned on. A dedicated fuse in the
junction block protects the rear window defogger
relay output circuit to the LED indicator.
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER SWITCH
For complete circuit diagrams, refer to the Appro-
priate 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 a/c heater control from the instru-
ment panel and disconnect the 11-way (manual tem-
perature control) or 16-way (automatic zone control)
instrument panel wire harness connector from the a/c
heater control receptacle.
(2) Check for continuity between the ground cir-
cuit cavity of the 11-way or 16-way instrument panel
wire harness connector for the a/c heater control and
a good ground. There should be continuity. If OK, go
to Step 3. If not OK, repair the open ground circuit to
ground as required.
(3) Connect two jumper wires to the a/c heater
control 11-way or 16-way connector receptacle. Con-
nect one jumper from the ground circuit terminal inthe 11-way or 16-way a/c heater control connector
receptacle to a good ground. Connect the other
jumper from the fused rear window defogger relay
output circuit terminal of the 11-way or 16-way con-
nector receptacle to a 12-volt battery feed. The rear
window defogger switch LED indicator should light.
If OK, go to Step 4. If not OK, replace the faulty a/c
heater control.
(4) Check for continuity between the ground cir-
cuit and rear window defogger switch sense circuit
terminals of the 11-way or 16-way a/c heater control
connector receptacle. There should be momentary
continuity as the rear window defogger switch push
button is depressed, and then no continuity. If OK, go
to Step 5. If not OK, replace the faulty a/c heater
control.
(5) Disconnect the 22-way instrument panel wire
harness connector from the Body Control Module
(BCM) connector receptacle. Check for continuity
between the rear window defogger switch sense cir-
cuit cavity of the 11-way or 16-way instrument panel
wire harness connector for the a/c heater control and
a good ground. There should be no continuity. If OK,
go to Step 6. If not OK, repair the shorted rear win-
dow defogger switch sense circuit as required.
(6) Check for continuity between the rear window
defogger switch sense circuit cavities of the 11-way or
16-way instrument panel wire harness connector for
the a/c heater control and the 22-way instrument
panel wire harness connector for the BCM. There
should be continuity. If OK, refer to (Refer to 8 -
ELECTRICAL/HEATED GLASS/REAR WINDOW
DEFOGGER RELAY - DIAGNOSIS AND TESTING).
REMOVAL
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.
(Refer to 24 - HEATING & AIR CONDITIONING/
CONTROLS/A/C HEATER CONTROL - REMOVAL)
WJHEATED GLASS 8G - 7
REAR WINDOW DEFOGGER SWITCH (Continued)

these electronic modules or of the PCI data bus net-
work, the use of a DRBtscan tool and the proper
Diagnostic Procedures manual are recommended.
The electronic modules that may affect heated seat
system operation are as follows:
²Body Control Module (BCM)- Refer toBody
Control Modulein Electronic Control Modules for
more information.
²Heated Seat Module (HSM)- Refer toHeated
Seat Modulein Electronic Control Modules for more
information.
²Memory Heated Seat Module (MHSM)-If
the vehicle is equipped with the Memory System,
refer toMemory Seat Modulein Electronic Control
Modules for more information.
Refer toPower Seats Premium I/IIIin the Con-
tents of Wiring Diagrams for complete circuit dia-
grams. Following are general descriptions of the
major components in the heated seat system.
OPERATION
The heated seat system will only operate when the
ignition switch is in the On position, and the surface
temperature at the front seat heating element sen-
sors is below the designed temperature set points of
the system. The heated seat system will not operate
in ambient temperatures greater than about 41É C
(105É F). The front seat heating elements and sensors
are hard wired to the Heated Seat Module (HSM) or
the Memory Heated Seat Module (MHSM).
The heated seat switches are hard wired to the
Body Control Module (BCM). The BCM monitors the
heated seat switch inputs, then sends heated seat
switch status messages to the HSM or MHSM over
the Programmable Communications Interface (PCI)
data bus. The HSM or MHSM contains the control
logic for the heated seat system. The HSM or MHSM
responds to the heated seat switch status messages,
ignition switch status messages, and the front seat
heating element sensor inputs by controlling the out-
put to the front seat heating elements through inte-
gral solid-state relays.
When a seat heater is turned on, the sensor
located on the seat cushion electric heater element
provides the HSM or MHSM with an input indicating
the surface temperature of the seat cushion. If the
surface temperature input is below the temperature
set point for the selected Low or High heated seat
switch position, the HSM or MHSM energizes the
integral solid-state relay, which supplies battery cur-
rent to the heating elements in the seat cushion and
back. When the sensor input indicates the correct
temperature set point has been achieved, the HSM or
MHSM de-energizes the solid-state relay. The HSM
or MHSM will continue to cycle the solid-state relay
as needed to maintain the temperature set point.The HSM or MHSM and the seat heater elements
operate on non-switched battery current supplied
through the power seat circuit breaker in the junc-
tion block. However, the HSM or MHSM will auto-
matically turn off the heating elements if it detects
an open or short in the sensor circuit, a short or open
in the heating element circuit causing an excessive
current draw, or when the ignition switch is turned
to the Off position.
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
Following are tests that will help to diagnose the
components and circuits that are hard wired inputs
or outputs of the heated seat system. However, these
tests may not prove conclusive in the diagnosis of
this system. In order to obtain conclusive testing of
the heated seat system, the Programmable Commu-
nications Interface (PCI) data bus network and all of
the electronic modules that provide inputs to, or
receive outputs from the heated seat system compo-
nents must be checked.
The most reliable, efficient, and accurate means to
diagnose the heated seat system requires the use of a
DRB scan tool and the proper Diagnostic Procedures
manual. The DRBtscan tool can provide confirma-
tion 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
Heated Seat Module (HSM) or Memory Heated Seat
Module (MHSM) is receiving the proper hard wired
inputs and relaying the proper hard wired outputs to
perform its heated seat system functions.
For complete circuit diagrams, refer toWiring
Diagrams.
NOTE: DO NOT ATTEMPT TO SWAP MEMORY OR
NON-MEMORY HEATED SEAT MODULES FROM
ONE VEHICLE TO ANOTHER. MOST OF THESE
MODULES ARE VEHICLE FEATURE SPECIFIC AND
THEREFORE NOT INTERCHANGEABLE. ALWAYS
USE THE CORRECT PART NUMBERED MODULE
WHEN DIAGNOSING OR REPLACING A MODULE.
WARNING: REFER TO THE RESTRAINTS SECTION
OF THIS MANUAL BEFORE ATTEMPTING ANY
STEERING WHEEL, STEERING COLUMN, 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.
8G - 10 HEATED SEAT SYSTEMWJ
HEATED SEAT SYSTEM (Continued)

PRELIMINARY TEST
Before testing the individual components in the
heated seat system, check the following:
²If the heated seat switch LED indicators do not
light with the ignition switch in the On position and
the heated seat switch in the Low or High position,
check the fused ignition switch output (run) fuse in
the junction block. If OK, refer toHeated Seat
Switch Diagnosis and Testingin this section. If
not OK, repair the shorted circuit or component as
required and replace the faulty fuse.
²If the heated seat switch LED indicators light,
but the heating elements do not heat, check the
power seat circuit breaker in the junction block. If
OK, refer toHeated Seat Element Diagnosis and
Testingin this section of the manual. If not OK,
replace the faulty power seat circuit breaker.
DRIVER HEATED SEAT
SWITCH
DESCRIPTION
The heated seat switches are mounted in the
instrument panel center lower bezel (Fig. 2), which is
located near the bottom of the instrument panel cen-
ter stack. The two three-position rocker-type
switches, one switch for each front seat, provide a
resistor multiplexed signal to the Body Control Mod-
ule (BCM) through separate 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), one each for
the Low position and the High position, which light
to indicate that the heater for the seat that the
switch controls is turned on. Each switch is also back
lit by a replaceable incandescent bulb.
The heated seat switches and their LEDs cannot
be repaired. If either switch or LED is faulty or dam-
aged, the entire switch unit must be replaced. The
incandescent switch illumination bulb and bulb
holder units are available for service replacement.
OPERATION
There are three positions that can be selected with
each of the heated seat switches: Off, Low, or High.
When the top of the switch rocker is fully depressed,
the High position is selected and the high position
LED indicator illuminates. When the bottom of the
switch rocker is fully depressed, the Low position is
selected and the low position LED indicator illumi-
nates. When the switch rocker is moved to its neutral
position, Off is selected and both LED indicators are
extinguished.
Both switches provide separate resistor multi-
plexed hard wire inputs to the BCM to indicate the
selected switch position. The BCM monitors the
switch inputs and sends heated seat switch status
messages to the Heated Seat Module (HSM) or the
Memory Heated Seat Module (MHSM) over the Pro-
grammable Communications Interface (PCI) data
bus. The HSM or MHSM 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, 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.
(1) Check the fused ignition switch output (run)
fuse in the junction block. If OK, go to Step 2. If not
Fig. 2 HEATED SEAT SWITCHES
1 - HEATED SEAT SWITCHES
WJHEATED SEAT SYSTEM 8G - 11
HEATED SEAT SYSTEM (Continued)

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) fuse in the junction block. If OK, go to
Step 3. If not OK, repair the open fused ignition
switch output (run) circuit to the ignition switch as
required.
(3) Disconnect and isolate the battery negative
cable. Remove the lower center bezel from the instru-
ment panel and disconnect the instrument panel wire
harness connectors from both heated seat switch con-
nector receptacles. Check for continuity between the
ground circuit cavity of the instrument panel wire
harness connector for the inoperative heated seat
switch(es) and a good ground. There should be conti-
nuity. If OK, go to Step 4. If not OK, repair the open
ground circuit to ground as required.
(4) 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 wire harness con-
nector for the inoperative heated seat switch(es). If
OK, turn the ignition switch to the Off position, dis-
connect and isolate the battery negative cable, and go
to Step 5. If not OK, repair the open fused ignition
switch output (run) circuit to the junction block fuse
as required.
(5) Test the heated seat switch(es) (Fig. 3) as
shown in the Heated Seat Switch Test chart. If OK,
go to Step 6. If not OK, replace the faulty heated seat
switch(es).
HEATED SEAT SWITCH TEST
SWITCH
POSITIONRESISTANCE
BETWEENRESISTANCE
(OHMS)
Off Pin1&6 55
Low Pin1&61430
High Pin1&6 365
All resistance values are  5%.
(6) Disconnect the 22-way instrument panel wire
harness connector from the Body Control Module
(BCM) connector receptacle. Check for continuity
between the seat heater switch sensor ground circuit
cavity of the instrument panel wire harness connec-
tor for the inoperative heated seat switch(es) and a
good ground. There should be no continuity. If OK, go
to Step 7. If not OK, repair the shorted seat heater
switch sensor ground circuit as required.
(7) Check for continuity between the seat heater
switch sensor ground circuit cavities of the instru-
ment panel wire harness connector for the in opera-
tive heated seat switch(es) and the 22-way
instrument panel wire harness connector for theBCM. There should be continuity. If OK, go to Step 8.
If not OK, repair the open seat heater switch sensor
ground circuit as required.
(8) Check for continuity between the seat heater
switch mux circuit cavity of the instrument panel
wire harness connector for the inoperative heated
seat switch and a good ground. There should be no
continuity. If OK, go to Step 9. If not OK, repair the
shorted seat heater switch mux circuit as required.
(9) Check for continuity between the seat heater
switch mux circuit cavity of the instrument panel
wire harness connector for the inoperative heated
seat switch and the 22-way instrument panel wire
harness connector for the BCM. There should be con-
tinuity. If OK, use a DRBtscan tool and the proper
Diagnostic Procedures manual to test the BCM. If
not OK, repair the open seat heater switch mux cir-
cuit as required.
REMOVAL
WARNING: REFER TO THE RESTRAINTS SECTION
OF THIS MANUAL BEFORE ATTEMPTING ANY
STEERING WHEEL, STEERING COLUMN, 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.
(1) Disconnect and isolate the battery negative
cable.
Fig. 3 Rear of Heated Seat Switch
1 - LEFT SHOWN (RIGHT TYPICAL)
2 - ILLUMINATION LAMP
3 - CONNECTOR RECEPTACLE
4 - HEATED SEAT SWITCH
8G - 12 HEATED SEAT SYSTEMWJ
DRIVER HEATED SEAT SWITCH (Continued)

(2) Remove the center lower bezel from the instru-
ment panel. Refer toInstrument Panel Center
Lower Bezelin the Body section of this manual for
the procedure.
(3) Remove the four screws that secure the heated
seat switch to the back of the instrument panel cen-
ter lower bezel (Fig. 4).
(4) Remove the heated seat switch from the back
of the instrument panel center lower bezel.
INSTALLATION
(1) Position the heated seat switch onto the back
of the instrument panel center lower bezel.
(2) Install and tighten the four screws that secure
the heated seat switch to the back of the instrument
panel center lower bezel. Tighten the screws to 1.5
N´m (13 in. lbs.).
(3) Install the center lower bezel onto the instru-
ment panel. Refer toInstrument Panel Center
Lower Bezelin the Body section of this manual for
the procedure.
(4) Reconnect the battery negative cable.
HEATED SEAT ELEMENT
DESCRIPTION
The heated seat system includes two seat heating ele-
ments in each front seat, one for the seat cushion (Fig.
5)and the other for the seat back. One type of heated
seat element is offered. All models use two resistor wire
heating elements for each seat that are connected in
series with the Heated Seat Module (HSM).
The seat heating elements are glued to the seat and
seat back cushions. The heated seat elements can be
replaced if faulty or damaged, service replacement seat
or seat back elements are available. Refer to the pro-
cedure in this section for detailed instructions.
OPERATION
The heated seat elements resist the flow of electri-
cal current. When battery current is passed through
the elements, the energy lost by the resistance of the
elements to the current flow is released in the form
of heat. The temperature sensor is a NTC thermistor.
When the temperature of the seat cushion cover
rises, the resistance of the sensor decreases. The
HSM or MHSM supplies a five-volt current to one
side of each sensor, and monitors the voltage drop
through the sensor on a return circuit. The MSM or
MHSM uses this temperature sensor input to moni-
tor the temperature of the seat, and regulates the
current flow to the seat heating elements accordingly.
Fig. 4 Heated Seat Switch Remove/Install
1 - HEATED SEAT SWITCHES
2 - SCREWS (4)
3 - CENTER LOWER BEZEL
4 - CIGAR LIGHTER
5 - ILLUMINATION LAMPS
6 - POWER OUTLET
Fig. 5 HEATING ELEMENT INSTALLED
1 - SEAT BACK WIRE HARNESS
2 - HEATED SEAT WIRE HARNESS CONNECTOR
3 - HEATED SEAT CUSHION ELEMENT
WJHEATED SEAT SYSTEM 8G - 13
DRIVER HEATED SEAT SWITCH (Continued)

HEATED SEAT SENSOR
DESCRIPTION
The heated seat temperature sensor is a Negative
Temperature Coefficient (NTC) thermistor. One tem-
perature sensor is used for each seat. This tempera-
ture sensor is located in the seat cushion heating
element on all models.
The heated seat temperature sensor cannot be
repaired or adjusted and must be replaced if defec-
tive. The heated seat cushion element must be
replaced if the temperature sensor is defective. Refer
to the procedure in this section of the service man-
ual.
DIAGNOSIS AND TESTING - HEATED SEAT
SENSOR
For complete circuit diagrams, refer toWiring
Diagrams.
(1) Disconnect the Heated Seat Module (HSM) or
Memory Heated Seat Module (MHSM) C1 connector.
Check for continuity between the SEAT SENSOR 5V
SUPPLY circuit cavity and the seat cushion frame.
There should beNOcontinuity. If OK, go to Step 2.
If not OK, repair the shorted seat sensor 5V supply
circuit as required.
(2) Check for continuity between the SEAT SEN-
SOR 5V SUPPLY circuit cavity of the 4-way power
seat wire harness connector and the C1 connector for
the HSM or MHSM. There should be continuity. If
OK, go to Step 3. If not OK, repair the open seat sen-
sor 5V supply circuit as required.
(3) Connect the module electrical connector. Turn
system ON, using a voltmeter, backprobe the HSM or
MHSM C1 connector on the SEAT TEMPERATURE
SENSOR INPUT circuit cavity. Voltage should be
present (2-4 volts). If OK, proceed with testing the
other components in the heated seat system. If not
OK, refer to Heated Seat Module Diagnosis and Test-
ing in the electronic control modules section of this
manual.
REMOVAL
(1) For heated seat sensor replacement procedure
(Refer to 8 - ELECTRICAL/HEATED SEATS/
HEATED SEAT ELEMENT - REMOVAL).
PASSENGER HEATED SEAT
SWITCH
DESCRIPTION
The heated seat switches are mounted in the
instrument panel center lower bezel (Fig. 7), which is
located near the bottom of the instrument panel cen-
ter stack. The two three-position rocker-type
switches, one switch for each front seat, provide a
resistor multiplexed signal to the Body Control Mod-
ule (BCM) through separate 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), one each for
the Low position and the High position, which light
to indicate that the heater for the seat that the
switch controls is turned on. Each switch is also back
lit by a replaceable incandescent bulb.
The heated seat switches and their LEDs cannot
be repaired. If either switch or LED is faulty or dam-
aged, the entire switch unit must be replaced. The
incandescent switch illumination bulb and bulb
holder units are available for service replacement.
Fig. 7 HEATED SEAT SWITCHES
1 - HEATED SEAT SWITCHES
WJHEATED SEAT SYSTEM 8G - 15

OPERATION
There are three positions that can be selected with
each of the heated seat switches: Off, Low, or High.
When the top of the switch rocker is fully depressed,
the High position is selected and the high position
LED indicator illuminates. When the bottom of the
switch rocker is fully depressed, the Low position is
selected and the low position LED indicator illumi-
nates. When the switch rocker is moved to its neutral
position, Off is selected and both LED indicators are
extinguished.
Both switches provide separate resistor multi-
plexed hard wire inputs to the BCM to indicate the
selected switch position. The BCM monitors the
switch inputs and sends heated seat switch status
messages to the Heated Seat Module (HSM) or the
Memory Heated Seat Module (MHSM) over the Pro-
grammable Communications Interface (PCI) data
bus. The HSM or MHSM 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 - 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, 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.
(1) Check the fused ignition switch output (run)
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) fuse in the junction block. If OK, go to
Step 3. If not OK, repair the open fused ignition
switch output (run) circuit to the ignition switch as
required.
(3) Disconnect and isolate the battery negative
cable. Remove the lower center bezel from the instru-
ment panel and disconnect the instrument panel wire
harness connectors from both heated seat switch con-
nector receptacles. Check for continuity between the
ground circuit cavity of the instrument panel wire
harness connector for the inoperative heated seatswitch(es) and a good ground. There should be conti-
nuity. If OK, go to Step 4. If not OK, repair the open
ground circuit to ground as required.
(4) 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 wire harness con-
nector for the inoperative heated seat switch(es). If
OK, turn the ignition switch to the Off position, dis-
connect and isolate the battery negative cable, and go
to Step 5. If not OK, repair the open fused ignition
switch output (run) circuit to the junction block fuse
as required.
(5) Test the heated seat switch(es) (Fig. 8) as
shown in the Heated Seat Switch Test chart. If OK,
go to Step 6. If not OK, replace the faulty heated seat
switch(es).
HEATED SEAT SWITCH TEST
SWITCH
POSITIONRESISTANCE
BETWEENRESISTANCE
(OHMS)
Off Pin1&6 55
Low Pin1&61430
High Pin1&6 365
All resistance values are  5%.
Fig. 8 Rear of Heated Seat Switch
1 - LEFT SHOWN (RIGHT TYPICAL)
2 - ILLUMINATION LAMP
3 - CONNECTOR RECEPTACLE
4 - HEATED SEAT SWITCH
8G - 16 HEATED SEAT SYSTEMWJ
PASSENGER HEATED SEAT SWITCH (Continued)

(6) Disconnect the 22-way instrument panel wire
harness connector from the Body Control Module
(BCM) connector receptacle. Check for continuity
between the seat heater switch sensor ground circuit
cavity of the instrument panel wire harness connec-
tor for the inoperative heated seat switch(es) and a
good ground. There should be no continuity. If OK, go
to Step 7. If not OK, repair the shorted seat heater
switch sensor ground circuit as required.
(7) Check for continuity between the seat heater
switch sensor ground circuit cavities of the instru-
ment panel wire harness connector for the in opera-
tive heated seat switch(es) and the 22-way
instrument panel wire harness connector for the
BCM. There should be continuity. If OK, go to Step 8.
If not OK, repair the open seat heater switch sensor
ground circuit as required.
(8) Check for continuity between the seat heater
switch mux circuit cavity of the instrument panel
wire harness connector for the inoperative heated
seat switch and a good ground. There should be no
continuity. If OK, go to Step 9. If not OK, repair the
shorted seat heater switch mux circuit as required.
(9) Check for continuity between the seat heater
switch mux circuit cavity of the instrument panel
wire harness connector for the inoperative heated
seat switch and the 22-way instrument panel wire
harness connector for the BCM. There should be con-
tinuity. If OK, use a DRBtscan tool and the proper
Diagnostic Procedures manual to test the BCM. If
not OK, repair the open seat heater switch mux cir-
cuit as required.
REMOVAL
WARNING: REFER TO THE RESTRAINTS SECTION
OF THIS MANUAL BEFORE ATTEMPTING ANY
STEERING WHEEL, STEERING COLUMN, 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.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the center lower bezel from the instru-
ment panel. Refer toInstrument Panel CenterLower Bezelin the Body section of this manual for
the procedure.
(3) Remove the four screws that secure the heated
seat switch to the back of the instrument panel cen-
ter lower bezel (Fig. 9).
(4) Remove the heated seat switch from the back
of the instrument panel center lower bezel.INSTALLATION
(1) Position the heated seat switch onto the back
of the instrument panel center lower bezel.
(2) Install and tighten the four screws that secure
the heated seat switch to the back of the instrument
panel center lower bezel. Tighten the screws to 1.5
N´m (13 in. lbs.).
(3) Install the center lower bezel onto the instru-
ment panel. Refer toInstrument Panel Center
Lower Bezelin the Body section of this manual for
the procedure.
(4) Reconnect the battery negative cable.
Fig. 9 Heated Seat Switch Remove/Install
1 - HEATED SEAT SWITCHES
2 - SCREWS (4)
3 - CENTER LOWER BEZEL
4 - CIGAR LIGHTER
5 - ILLUMINATION LAMPS
6 - POWER OUTLET
WJHEATED SEAT SYSTEM 8G - 17
PASSENGER HEATED SEAT SWITCH (Continued)