2002 DODGE RAM fuse

harness connector for the heated mirror switch. If
OK, go to Step 5. If not OK, repair the open fused
ignition switch output (run/start) circuit to the fuse
in the JB as required.
(5) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Reconnect the 3-way instrument panel wire harness
connector for the heated mirror switch to the heated
mirror switch connector receptacle on the back of the
a/c heater control. Reconnect the battery negative
cable. Turn the ignition switch to the On position.
Depress and release the heated mirror switch. The
amber heated mirror system indicator lamp next to
the heated mirror switch button should light. If OK,
go to Step 6. If not OK, replace the faulty a/c heater
control.
(6) Back probe the fused heated mirror relay out-
put circuit cavity of the 3-way instrument panel wire
harness connector for the heated mirror switch on
the back of the a/c heater control and check for volt-
age (battery voltage less the resistance in both out-
side mirror heating grids). If OK, (Refer to 8 -
ELECTRICAL/HEATED MIRRORS/HEATED MIR-
ROR GRID - DIAGNOSIS AND TESTING).
HEATED MIRROR GRID
DESCRIPTION
Vehicles equipped with the optional heated mirror
system have an electrically operated heating grid
located behind the mirror glass of each power oper-
ated outside rear view mirror. The outside mirror
heating grid consists of two thin laminations of plas-
tic that approximate the outer dimensions and shape
of the mirror glass. A single length of resistor wire
weaves in a back and forth pattern between, and is
held in place by the two thin laminations of plastic.
The two ends of the resistor wire terminate near the
inboard edge of the grid, where they are soldered to
the ground feed and battery current feed wires con-
tained in the power mirror wire harness. The heating
grid is then sandwiched between the back of the
molded plastic mirror glass case and the mirror
glass, where it remains in direct contact with the
back of the mirror glass at all times.
The outside mirror heating grids cannot be
repaired and, if faulty or damaged, the entire outside
power mirror unit must be replaced. Refer to Power
Mirrors for the service procedures.
OPERATION
One end of the outside mirror heating grid resistor
wire is connected to a ground feed at all times
through a body ground screw located inside the left
rear corner of the truck cab. Battery current is
directed to the other end of the outside mirror heat-
ing grid resistor wire by the energized heated mirror
relay when the heated mirror switch is in the On
position. As electrical current passes through the
heating grid, the resistance of the wire in the heating
grid converts some of that electrical current into
heat. The heat produced by the heating grid is then
conducted through the back of the mirror glass to
help keep the glass clear of ice, snow or fog.
DIAGNOSIS AND TESTING - HEATED MIRROR
GRID
For circuit descriptions and diagrams (Refer to
Appropriate Wiring Information).
(1) Disconnect and isolate the battery negative
cable. Disconnect the door wire harness connector
from the power mirror wire harness connector at the
power mirror with the inoperative heating grid.
Check for continuity between the ground circuit cav-
ity in the door wire harness connector for the power
mirror and a good ground. 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. Turn on the
heated mirror system. Check for voltage (battery
voltage less the resistance in the outside mirror heat-
ing grid that is still connected) at the fused heated
mirror relay output circuit cavity in the door wire
harness connector for the power mirror. If OK, go to
Step 3. If not OK, repair the open fused heated mir-
ror relay output circuit to the heater and air condi-
tioner control unit as required.
(3) Check the outside mirror heating grid by test-
ing for continuity between the ground circuit and the
fused heated mirror relay output circuit cavities in
the power mirror wire harness connector. There
should be continuity. If not OK, replace the faulty
power mirror. If OK, check the resistance through
the outside mirror heating grid. The correct resis-
tance should be from 10 to 16 ohms when measured
at an ambient temperature of 21É C (70É F). If not
OK, replace the faulty power mirror.
8G - 4 HEATED MIRRORSBR/BE
MIRROR SWITCH (Continued)

²Heated Seat Elements- Four heated seat ele-
ments are used per vehicle, one for each front seat
back and one for each front seat cushion. The ele-
ments are integral to the individual front seat and
seat back cushions and cannot be removed once
installed at the factory. Service replacement seat
heating elements are available, without having to
replace the entire seat cushion or trim cover. Refer to
the procedure in this section.
²Heated Seat Sensors- Two heated seat sen-
sors are used per vehicle, one for each front seat. The
sensors are integral to the individual front seat heat-
ing elements and cannot be removed once installed at
the factory. Service replacement seat heating ele-
ments with the sensors are available, without having
to replace the entire seat cushion or trim cover. Refer
to the procedure in this section.
²Heated Seat Relay- The heated seat relay
controls the battery voltage and current supply to the
heated seat module and the rest of the heated seat
system. The heated seat relay is mounted in the
junction block and is not different than the other
relays used throughout the vehicle. Refer to the
Power Distribution section of the service manual for
more information on standard ISO relays.
Following are general descriptions of the major
components in the heated seat system. See the own-
er's manual in the vehicle glove box for more infor-
mation on the features, use and operation of the
heated seat system. Refer toWiring Diagramsfor
the location of complete heated seat system wiring
diagrams.
OPERATION
The heated seat module receives fused battery cur-
rent through the energized heated seat relay in the
Junction Block (JB) only when the engine is running.
The heated seat switches receive battery current
through fuse #2 in the Junction Block only when the
ignition switch is in the On position. The heated seat
module shares a common ground circuit with each of
the heated seat elements. The heated seat elements
will only operate when the surface temperature of
the seat cushion is below the designed temperature
set points of the system.
The heated seat system will also be turned off
automatically whenever the ignition switch is turned
to any position except On or if the engine quits run-
ning. If the ignition switch is turned to the Off posi-
tion or if the engine quits running while a heated
seat is turned ON, the heated seat will remain Off
after the engine is restarted until a heated seat
switch is depressed again.
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 usesits 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 a self-diagnos-
tic capability. When the module detects certain fail-
ures within the heated seat system, it will provide a
visual indication of the failure by flashing the indica-
tor lamps in the heated seat switches. 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 sensor
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 Flashing
8G - 6 HEATED SEAT SYSTEMBR/BE
HEATED SEAT SYSTEM (Continued)

tor receptacles on the switches so that the two
heated seat switches can only be connected to the
proper heated seat electrical.
The momentary, bidirectional rocker-type heated
seat switch provides a resistor-multiplexed signal to
the heated seat module on the mux circuit. Each
switch has a center neutral position and momentary
Low and High positions so that both the driver and
the front seat passenger can select a preferred level
of seat heating. Each heated seat switch has two
Light-Emitting Diode (LED) indicator lamps, which
indicate the selected mode (Low or High) of the seat
heater. These indicator lamps also provide diagnostic
feedback for the heated seat system. Each switch
also has an incandescent bulb, which provides dim-
mer controlled back lighting of the switch when the
headlamps or park lamps are on.
The two LED indicator lamps and the incandescent
bulb in each heated seat switch cannot be repaired. If
the indicator lamps or back lighting bulb are faulty
or damaged, the individual heated seat switch must
be replaced.
OPERATION
The heated seat switches receive battery current
through a fused ignition switch output (run) circuit
when the ignition switch is in the On position.
Depressing the heated seat switch rocker to its
momentary High or Low position provides a hard-
wired resistor multiplexed voltage request signal to
the heated seat module to power the heated seat ele-
ment of the selected seat and maintain the requested
temperature setting. If the heated seat switch is
depressed to a different position (Low or High) than
the currently selected state, the heated seat module
will change states to support the new selection. If a
heated seat switch is depressed a second time to the
same position as the currently selected state, the
heated seat module interprets the second input as a
request to turn the seat heater off. The heated seat
module will then turn the heated seat elements for
that seat off.
The indicator lamps in the heated seat switches
receive battery current through a fused ignition
switch output (run) circuit when the ignition switch
is in the On position. The ground side of each indi-
cator lamp is controlled by a separate (high or low/
driver or passenger) indicator lamp driver circuit by
the heated seat module. The heated seat module con-
trol of the switch indicator lamps also allows the
module to provide diagnostic feedback to the vehicle
operator to indicate monitored heated seat system
faults by flashing the indicator lamps on and off. One
side of the incandescent back lighting bulb in each
heated seat switch is connected to ground at all
times. The other side of the incandescent bulb is con-nected to the fused panel lamps dimmer switch sig-
nal circuit. These bulbs are energized when the park
lamps or headlamps are turned on, and their illumi-
nation intensity is controlled by the panel lamps dim-
mer switch.
DIAGNOSIS AND TESTING - HEATED SEAT
SWITCH
Refer toWiring Diagramsfor the location of com-
plete heated seat system wiring diagrams.
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. DISCON-
NECT AND ISOLATE THE BATTERY NEGATIVE
(GROUND) CABLE, THEN WAIT TWO MINUTES FOR
THE AIRBAG SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE AIRBAG SYSTEM. FAILURE TO TAKE
THE PROPER PRECAUTIONS COULD RESULT IN
ACCIDENTAL AIRBAG DEPLOYMENT AND POSSI-
BLE PERSONAL INJURY.
(1) If the problem being diagnosed involves inoper-
ative heated seat switch back lighting and the cluster
illumination lamps operate, go to Step 2. If the prob-
lem being diagnosed involves inoperative heated seat
switch back lighting and the cluster illumination
lamps are also inoperative, refer toInstrument
Clusterin the index of this service manual for the
proper cluster illumination lamps diagnosis and test-
ing procedures. If the problem being diagnosed
involves inoperative heated seat switch indicator
lamps and the heated seat elements do not heat,
refer to Step 4. If the problem being diagnosed
involves inoperative heated seat switch indicator
lamps and the heated seat elements do heat, go to
Step 8. If the problem being diagnosed involves a
heated seat switch indicator lamp that remains illu-
minated after the heated seat has been turned Off,
refer toHeated Seat Modulein Electronic Control
Modules for the location of the proper heated seat
module diagnosis and testing procedures. Also refer
to the Body Diagnostic Manual for additional diagno-
sis and testing procedures.
(2) Disconnect and isolate the battery negative
cable. Remove the heated seat switch and bezel unit
from the instrument panel. Disconnect the instru-
ment panel wire harness connector from the connec-
tor receptacle on the back of the heated seat switch
to be tested. Check for continuity between the ground
circuit cavity of the instrument panel wire harness
connector for the heated seat switch and a good
ground. There should be continuity. If OK, go to Step
8G - 8 HEATED SEAT SYSTEMBR/BE
DRIVER SEAT HEATER SWITCH (Continued)

3. If not OK, repair the open ground circuit to ground
as required.
(3) Reconnect the battery negative cable. Turn the
park lamps on with the headlamp switch. Rotate the
panel lamps dimmer thumbwheel on the headlamp
switch upward to just before the interior lamps
detent. Check for battery voltage at the fused panel
lamps dimmer switch signal circuit cavity of the
instrument panel wire harness connector for the
heated seat switch. If OK, replace the faulty heated
seat switch. If not OK, repair the open fused panel
lamps dimmer switch signal circuit to the fuse in the
Junction Block (JB) as required.
(4) Check the fused ignition switch output (run)
fuse in the Junction Block (JB). If OK, go to Step 5.
If not OK, repair the shorted circuit or component as
required and replace the faulty fuse.
(5) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run) fuse in the JB. If OK, go to Step 6. If
not OK, repair the open fused ignition switch output
(run) circuit to the ignition switch as required.
(6) Disconnect and isolate the battery negative
cable. Remove the heated seat switch and bezel unit
from the instrument panel. Disconnect the instru-
ment panel wire harness connector from the connec-
tor receptacle on the back of the heated seat switch
to be tested. Reconnect the battery negative cable.
Turn the ignition switch to the On position. Check
for battery voltage at the fused ignition switch out-
put (run) circuit cavity of the instrument panel wire
harness connector for the heated seat switch. If OK,
go to Step 7. If not OK, repair the open fused ignition
switch output (run) circuit to the JB fuse as required.
(7) Check the continuity and resistance values of
the heated seat switch in the Neutral, Low and High
positions as shown in the Heated Seat Switch Conti-
nuity chart (Fig. 3). If OK, refer toHeated Seat
Modulein Electronic Control Modules for the loca-
tion of the proper heated seat module diagnosis and
testing procedures. Also refer to the Body Diagnostic
Manual for additional diagnosis and testing proce-
dures. If not OK, replace the faulty heated seat
switch.
NOTE: ANY RESISTANCE VALUES (OHMSV) GIVEN
IN THE FOLLOWING TEXT ARE SUPPLIED USING
THE AUTOMATIC RANGE GENERATED BY A
FLUKETAUTOMOTIVE METER. IF ANOTHER TYPE
OF MEASURING DEVICE IS USED THE VALUES
GENERATED MAY NOT BE THE SAME AS THE
RESULTS SHOWN HERE, OR MAY HAVE TO BE
CONVERTED TO THE RANGE USED HERE.
Heated Seat Switch Continuity
Switch PositionContinuity
BetweenResistance
Neutral 4 & 6 2.2 Kilohms
Low 4 & 6 .415 Kilohms
High 4 & 6 33 Ohms
(8) Replace the inoperative heated seat switch
with a known good unit and test the operation of the
switch indicator lamps. If OK, discard the faulty
heated seat switch. If not OK, refer toHeated Seat
Modulein Electronic Control Modules for the loca-
tion of the proper heated seat module diagnosis and
testing procedures. Also refer to the Body Diagnostic
Manual for additional diagnosis and testing proce-
dures.
REMOVAL
Both heated seat switches and the heated seat
switch bezel are available individually for service
replacement.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cluster bezel from the instrument
panel. Refer toCluster Bezelin the index of this
service manual for the location of the proper cluster
bezel removal procedures.
(3) Remove the three screws that secure the
heated seat switch bezel to the instrument panel
(Fig. 4).
(4) Pull the heated seat switch bezel out from the
instrument panel far enough to access and disconnect
the two instrument panel wire harness connectors
from the connector receptacles on the backs of the
heated seat switches.
(5) Remove the heated seat switch bezel and both
switches from the instrument panel as a unit.
Fig. 3 Heated Seat Switch
BR/BEHEATED SEAT SYSTEM 8G - 9
DRIVER SEAT HEATER SWITCH (Continued)

ical dimensions are smaller than those of the conven-
tional ISO relay.
The heated seat relay cannot be repaired or
adjusted and, if faulty or damaged, 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 movable
contact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact. When the electromagnetic coil is de-ener-
gized, spring pressure returns the movable contact to
the normally closed position. The resistor or diode is
connected in parallel with the electromagnetic coil in
the relay, and helps to dissipate voltage spikes that
are produced when the coil is de-energized.
The heated seat relay is controlled by the premium
version of the Central Timer Module (CTM), which
controls the ground feed to the coil ground terminal
of the relay to energize and de-energize the electro-
magnetic coil of the relay. The CTM monitors engine
operation through messages it receives from the Pow-
ertrain Control Module (PCM) over the Chrysler Col-
lision Detection (CCD) data bus network. The CTM is
programmed to energize the relay only when the
engine is running, and to de-energize the relay when
the engine is not running. Refer toCentral Timer
Modulein the index of this service manual for the
location of more information on the premium CTM.
DIAGNOSIS AND TESTING - HEATED SEAT
RELAY
The heated seat relay (Fig. 15) is located in the
Junction Block (JB) on the left end of the instrument
panel in the passenger compartment of the vehicle.
Refer toWiring Diagramsfor the location of com-
plete heated seat system wiring diagrams.
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPT-
ING ANY STEERING WHEEL, STEERING COLUMN, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO MIN-
UTES FOR THE AIRBAG SYSTEM CAPACITOR TO DIS-
CHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE TO
TAKE THE PROPER PRECAUTIONS COULD RESULT
IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSI-
BLE PERSONAL INJURY.
RELAY TEST
(1) Remove the heated seat relay from the JB.
Refer toHeated Seat Relayin this section for the
location of the proper heated seat relay removal pro-
cedures.
(2) 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 3. If not OK, replace the faulty relay.
(3) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75   5 ohms. If OK, go to Step
4. If not OK, replace the faulty relay.
(4) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, perform the Relay Circuit Test that
follows. If not OK, replace the faulty relay.
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 fused B(+) fuse in the Power Distribu-
tion Center (PDC) as required.
(2) The relay normally closed terminal (87A) is
connected to terminal 30 in the de-energized position,
but is not used for this application. Go to Step 3.
(3) The relay normally open terminal (87) is con-
nected to the common feed terminal (30) in the ener-
gized position. This terminal supplies battery voltage
to the heated seat module. There should be continu-
ity between the cavity for relay terminal 87 and the
B(+) to heated seat module circuit cavity of the
heated seat module wire harness connector at all
times. If OK, go to Step 4. If not OK, repair the open
Fig. 15 Heated Seat Relay
TERMINAL LEGEND
NUMBER IDENTIFICATION
30 COMMON FEED
85 COIL GROUND
86 COIL BATTERY
87 NORMALLY OPEN
87A NORMALLY CLOSED
BR/BEHEATED SEAT SYSTEM 8G - 15
HEATED SEAT RELAY (Continued)

B(+) to heated seat module circuit to the heated seat
module as required.
(4) The coil battery terminal (86) is connected to
the electromagnet in the relay. It is connected to bat-
tery voltage and should be hot at all times. Check for
battery voltage at the cavity for relay terminal 86. If
OK, go to Step 5. If not OK, repair the open circuit to
the fused B(+) fuse in the PDC as required.
(5) The coil ground terminal (85) is connected to
the electromagnet in the relay. It is grounded by the
premium version of the Central Timer Module (CTM)
in response to an engine speed message received over
the Chrysler Collision Detection (CCD) data bus from
the Powertrain Control Module (PCM) when the
engine is running. Check for continuity between the
cavity for relay terminal 85 and the heated seat relay
control circuit cavity of the CTM wire harness con-
nector. There should be continuity at all times. If OK,
use a DRBIIItscan tool and the proper diagnostic
procedures manual to test the operation of the CTM
and CCD data bus. If not OK, repair the open heated
seat relay control circuit as required.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the fuse access panel by inserting a
finger in the finger recess molded into the panel and
then pulling the panel sharply away from the left
outboard end of the instrument panel.
(3) The heated seat relay is located on the forward
side of the Junction Block (JB), just above the com-
bination flasher (Fig. 16) .
(4) Grasp the heated seat relay firmly and pull it
straight out from the JB.
INSTALLATION
(1) Position the heated seat relay in the proper
receptacle in the JB.
(2) Align the heated seat relay terminals with the
terminal cavities in the JB receptacle.
(3) Push in firmly on the heated seat relay until
the terminals are fully seated in the terminal cavities
in the JB receptacle.
(4) Insert the tabs on the forward edge of the fuse
access panel in the notches on the forward edge of
the instrument panel fuse access panel opening.
(5) Press the rear edge of the fuse access panel in
toward the instrument panel until the panel snaps
back into place.
(6) Reconnect the battery negative cable.
PASSENGER SEAT HEATER
SWITCH
DESCRIPTION
The heated seat switches are both mounted in a
heated seat switch bezel (Fig. 17), which replaces the
standard equipment cubby bin located in the lower
right corner of the instrument cluster bezel next to
the radio receiver. The two switches are snapped into
the mounting holes of the heated seat switch bezel,
and the heated seat switch bezel is secured with
three screws to the instrument panel. The mounts for
the heated seat switch bezel are concealed behind the
instrument cluster bezel. The two heated seat
switches are identical in appearance and construc-
tion, except for the location of a keyway in the single
connector receptacle on the back of each switch. The
instrument panel wire harness connectors for the
heated seat switches are keyed to match the connec-
tor receptacles on the switches so that the two
heated seat switches can only be connected to the
proper heated seat electrical.
The momentary, bidirectional rocker-type heated
seat switch provides a resistor-multiplexed signal to
the heated seat module on the mux circuit. Each
switch has a center neutral position and momentary
Low and High positions so that both the driver and
Fig. 16 Heated Seat
1 - JUNCTION BLOCK
2 - HEATED SEAT RELAY
3 - INSTRUMENT PANEL
4 - COMBINATION FLASHER
8G - 16 HEATED SEAT SYSTEMBR/BE
HEATED SEAT RELAY (Continued)

the front seat passenger can select a preferred level
of seat heating. Each heated seat switch has two
Light-Emitting Diode (LED) indicator lamps, which
indicate the selected mode (Low or High) of the seat
heater. These indicator lamps also provide diagnostic
feedback for the heated seat system. Each switch
also has an incandescent bulb, which provides dim-
mer controlled back lighting of the switch when the
headlamps or park lamps are on.
The two LED indicator lamps and the incandescent
bulb in each heated seat switch cannot be repaired. If
the indicator lamps or back lighting bulb are faulty
or damaged, the individual heated seat switch must
be replaced.
OPERATION
The heated seat switches receive battery current
through a fused ignition switch output (run) circuit
when the ignition switch is in the On position.
Depressing the heated seat switch rocker to its
momentary High or Low position provides a hard-
wired resistor multiplexed voltage request signal to
the heated seat module to power the heated seat ele-
ment of the selected seat and maintain the requested
temperature setting. If the heated seat switch is
depressed to a different position (Low or High) than
the currently selected state, the heated seat module
will change states to support the new selection. If a
heated seat switch is depressed a second time to thesame position as the currently selected state, the
heated seat module interprets the second input as a
request to turn the seat heater off. The heated seat
module will then turn the heated seat elements for
that seat off.
The indicator lamps in the heated seat switches
receive battery current through a fused ignition
switch output (run) circuit when the ignition switch
is in the On position. The ground side of each indi-
cator lamp is controlled by a separate (high or low/
driver or passenger) indicator lamp driver circuit by
the heated seat module. The heated seat module con-
trol of the switch indicator lamps also allows the
module to provide diagnostic feedback to the vehicle
operator to indicate monitored heated seat system
faults by flashing the indicator lamps on and off. One
side of the incandescent back lighting bulb in each
heated seat switch is connected to ground at all
times. The other side of the incandescent bulb is con-
nected to the fused panel lamps dimmer switch sig-
nal circuit. These bulbs are energized when the park
lamps or headlamps are turned on, and their illumi-
nation intensity is controlled by the panel lamps dim-
mer switch.
DIAGNOSIS AND TESTING - HEATED SEAT
SWITCH
Refer toWiring Diagramsfor the location of com-
plete heated seat system wiring diagrams.
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. DISCON-
NECT AND ISOLATE THE BATTERY NEGATIVE
(GROUND) CABLE, THEN WAIT TWO MINUTES FOR
THE AIRBAG SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE AIRBAG SYSTEM. FAILURE TO TAKE
THE PROPER PRECAUTIONS COULD RESULT IN
ACCIDENTAL AIRBAG DEPLOYMENT AND POSSI-
BLE PERSONAL INJURY.
(1) If the problem being diagnosed involves inoper-
ative heated seat switch back lighting and the cluster
illumination lamps operate, go to Step 2. If the prob-
lem being diagnosed involves inoperative heated seat
switch back lighting and the cluster illumination
lamps are also inoperative, refer toInstrument
Clusterin the index of this service manual for the
proper cluster illumination lamps diagnosis and test-
ing procedures. If the problem being diagnosed
involves inoperative heated seat switch indicator
lamps and the heated seat elements do not heat,
refer to Step 4. If the problem being diagnosed
Fig. 17 Heated Seat Switches
1 - Driver Switch
2 - Passenger Switch
3 - Indicator Lamps
4 - Heated Seat Switch Bezel
BR/BEHEATED SEAT SYSTEM 8G - 17
PASSENGER SEAT HEATER SWITCH (Continued)

involves inoperative heated seat switch indicator
lamps and the heated seat elements do heat, go to
Step 8. If the problem being diagnosed involves a
heated seat switch indicator lamp that remains illu-
minated after the heated seat has been turned Off,
refer toHeated Seat Modulein Electronic Control
Modules for the location of the proper heated seat
module diagnosis and testing procedures. Also refer
to the Body Diagnostic Manual for additional diagno-
sis and testing procedures.
(2) Disconnect and isolate the battery negative
cable. Remove the heated seat switch and bezel unit
from the instrument panel. Disconnect the instru-
ment panel wire harness connector from the connec-
tor receptacle on the back of the heated seat switch
to be tested. Check for continuity between the ground
circuit cavity of the instrument panel wire harness
connector for the heated seat switch 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) Reconnect the battery negative cable. Turn the
park lamps on with the headlamp switch. Rotate the
panel lamps dimmer thumbwheel on the headlamp
switch upward to just before the interior lamps
detent. Check for battery voltage at the fused panel
lamps dimmer switch signal circuit cavity of the
instrument panel wire harness connector for the
heated seat switch. If OK, replace the faulty heated
seat switch. If not OK, repair the open fused panel
lamps dimmer switch signal circuit to the fuse in the
Junction Block (JB) as required.
(4) Check the fused ignition switch output (run)
fuse in the Junction Block (JB). If OK, go to Step 5.
If not OK, repair the shorted circuit or component as
required and replace the faulty fuse.
(5) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run) fuse in the JB. If OK, go to Step 6. If
not OK, repair the open fused ignition switch output
(run) circuit to the ignition switch as required.
(6) Disconnect and isolate the battery negative
cable. Remove the heated seat switch and bezel unit
from the instrument panel. Disconnect the instru-
ment panel wire harness connector from the connec-
tor receptacle on the back of the heated seat switch
to be tested. Reconnect the battery negative cable.
Turn the ignition switch to the On position. Check
for battery voltage at the fused ignition switch out-
put (run) circuit cavity of the instrument panel wire
harness connector for the heated seat switch. If OK,
go to Step 7. If not OK, repair the open fused ignition
switch output (run) circuit to the JB fuse as required.
(7) Check the continuity and resistance values of
the heated seat switch in the Neutral, Low and High
positions as shown in the Heated Seat Switch Conti-nuity chart (Fig. 18). If OK, refer toHeated Seat
Modulein Electronic Control Modules for the loca-
tion of the proper heated seat module diagnosis and
testing procedures. Also refer to the Body Diagnostic
Manual for additional diagnosis and testing proce-
dures. If not OK, replace the faulty heated seat
switch.
NOTE: ANY RESISTANCE VALUES (OHMSV) GIVEN
IN THE FOLLOWING TEXT ARE SUPPLIED USING
THE AUTOMATIC RANGE GENERATED BY A
FLUKETAUTOMOTIVE METER. IF ANOTHER TYPE
OF MEASURING DEVICE IS USED THE VALUES
GENERATED MAY NOT BE THE SAME AS THE
RESULTS SHOWN HERE, OR MAY HAVE TO BE
CONVERTED TO THE RANGE USED HERE.
Heated Seat Switch Continuity
Switch PositionContinuity
BetweenResistance
Neutral 4 & 6 2.2 Kilohms
Low 4 & 6 .415 Kilohms
High 4 & 6 33 Ohms
(8) Replace the inoperative heated seat switch
with a known good unit and test the operation of the
switch indicator lamps. If OK, discard the faulty
heated seat switch. If not OK, refer toHeated Seat
Modulein Electronic Control Modules for the loca-
tion of the proper heated seat module diagnosis and
testing procedures. Also refer to the Body Diagnostic
Manual for additional diagnosis and testing proce-
dures.
REMOVAL
Both heated seat switches and the heated seat
switch bezel are available individually for service
replacement.
Fig. 18 Heated Seat Switch
8G - 18 HEATED SEAT SYSTEMBR/BE
PASSENGER SEAT HEATER SWITCH (Continued)