OPERATION
The data link connector (diagnostic connector)
links the DRB scan tool with the Powertrain Control
Module (PCM). Refer to On-Board Diagnostics in the
General Diagnosis section of this group.
FRONT CONTROL MODULE
DESCRIPTION
The Front Control Module (FCM) is a micro con-
troller based module located in the engine compart-
ment. This FCM mates to the power distribution
center to form the Integrated Power Module (IPM).
The IPM connects directly to the battery and pro-
vides the primary means of circuit protection and
power distribution for all vehicle electrical systems.
The FCM controls power to some of these vehicle sys-
tems electrical and electromechanical loads based on
inputs received from hard wired switch inputs and
data received on the Programmable Communications
Interface (PCI) data bus.
For information on the IPM, (Refer to 8 - ELEC-
TRICAL/POWER DISTRIBUTION/INTEGRATED
POWER MODULE - DESCRIPTION)
OPERATION
As messages are sent over the Programmable Com-
munications Interface (PCI) data bus, the Front Con-
trol Module (FCM) reads these messages and controls
power to some of the vehicles electrical systems by
completing the circuit to ground (low side driver) or
completing the circuit to 12 volt power (high side
driver).
The following functions arecontrolledby the
Front Control Module:²Accessory Relay Actuation
²Brake Transmission Shift Interlock Functions
(BTSI)
²Diesel Cabin Heater (Diesel Engine Vehicles)
²Electronic Back Light (EBL) Rear Defogger
²Electronic Transaxle (Gasoline engine Vehicles)
²Front and Rear Blower Motor Relay Actuation
²Front Fog Lamp Relay Actuation
²Front Washer Motor
²Front Windshield Wiper ªHIº & ªLOº Relay
Actuation
²Front Windshield Wiper ªONº Relay Actuation
²Headlamp Power with Voltage Regulation
²Horn Relay Actuation
²Headlamp Washer Relay Actuation
²Name Brand Speaker (NBS) Relay Actuation
²Occupant Restraint Controller Voltage
²Park Lamp Relay Actuation
²Rear Washer Motor
²Side Airbag Voltage
The following inputs areReceived/Monitoredby
the Front Control Module:
²Ambient Temperature Sensing
²Back-Up switch
²Brake Fluid Level
²B+ Connection Detection
²Engine Crank Signal (Diesel Engine Vehicles)
²Horn Input
²Ignition Switch Start Only
²Ignition Switch Run and Start Only
²Stop Lamp Sense
²Washer Fluid Level
²Windshield Wiper Park
DIAGNOSIS AND TESTING - FRONT CONTROL
MODULE
The Front Control Module (FCM) is a printed cir-
cuit board based module with a on-board micro-pro-
cessor. The FCM interfaces with other electronic
modules in the vehicle via the Programmable Com-
munications Interface (PCI) data bus. In order to
obtain conclusive testing the PCI data bus and all of
the electronic modules that provide inputs to, or
receive outputs from the FCM must be checked. All
PCI communication faults must be resolved prior to
further diagnosing any front control module related
issues.
The FCM was designed to be diagnosed with an
appropriate diagnostic scan tool, such as the DRB
IIIt. The most reliable, efficient, and accurate means
to diagnose the front control module requires the use
of a DRB IIItscan tool and the proper Body Diag-
nostic Procedures manual.
Before any testing of the FCM is attempted, the
battery should be fully charged and all wire harness
Fig. 4 DATA LINK CONNECTOR
RSELECTRONIC CONTROL MODULES8E-7
DATA LINK CONNECTOR (Continued)
Refer to the appropriate Powertrain Diagnostic Man-
ual and the DRBIIItscan tool.
(1) Install PCM module to the mounting bracket.
(2) Install electrical connectors and lock.
(3) Install the splash shield.
(4) Lower vehicle.
(5) Connect the negative battery cable.
(6) Using DRBIIItscan tool, program mileage and
vehicle identification number (VIN) into PCM. Refer
to the DRBIIItscan tool and the appropriate Power-
train Diagnostic Manual.
SENTRY KEY IMMOBILIZER
MODULE
DESCRIPTION
The Sentry Key Immobilizer Module (SKIM) con-
tains a Radio Frequency (RF) transceiver and a
microprocessor. The SKIM retains in memory the ID
numbers of any Sentry Key that is programmed to it.
The maximum number of keys that may be pro-
grammed to each module is eight (8). The SKIM also
communicates over the Programmable Communica-
tion Interface (PCI) data bus with the Powertrain
Control Module (PCM), the Body Control Module
(BCM), the Mechanical Instrument Cluster (MIC),
and the DRB IIItscan tool. The SKIM transmits and
receives RF signals through a tuned antenna
enclosed within a molded plastic ring formation that
is integral to the SKIM housing. When the SKIM is
properly installed on the steering column, the
antenna ring fits snugly around the circumference of
the ignition lock cylinder housing. If this ring is not
mounted properly, communication problems may
arise in the form of transponder-related faults.
For added system security, each SKIM is pro-
grammed with a unique9Secret Key9code. This code
is stored in memory and is sent over the PCI bus to
the PCM and to each key that is programmed to
work with the vehicle. The9Secret Key9code is there-
fore a common element found in all components of
the Sentry Key Immobilizer System (SKIS). In the
event that a SKIM replacement is required, the
9Secret Key9code can be restored from the PCM by
following the SKIM replacement procedure found in
the DRB IIItscan tool. Proper completion of this
task will allow the existing ignition keys to be repro-
grammed. Therefore, new keys will NOT be needed.
In the event that the original9Secret Key9code can
not be recovered, new ignition keys will be required.
The DRB IIItscan tool will alert the technician if
key replacement is necessary. Another security code,
called a PIN, is used to gain secured access to the
SKIM for service. The SKIM also stores in its mem-
ory the Vehicle Identification Number (VIN), which itlearns through a bus message from the assembly
plant tester. The SKIS scrambles the information
that is communicated between its components in
order to reduce the possibility of unauthorized SKIM
access and/or disabling.
OPERATION
When the ignition switch is moved to the RUN
position, the Sentry Key Immobilizer Module (SKIM)
transmits an Radio Frequency (RF) signal to the
transponder in the ignition key. The SKIM then
waits for a response RF signal from the transponder
in the key. If the response received identifies the key
as valid, the SKIM sends a9valid key9message to
the Powertrain Control Module (PCM) over the Pro-
grammable Communication Interface (PCI) data bus.
If the response received identifies the key as invalid
or no response is received from the transponder in
the ignition key, the SKIM sends an9invalid key9
message to the PCM. The PCM will enable or disable
engine operation based upon the status of the SKIM
messages. It is important to note that the default
condition in the PCM is9invalid key.9Therefore, if no
response is received by the PCM, the engine will be
immobilized after two (2) seconds of running.
The SKIM also sends indicator light status mes-
sages to the Mechanical Instrument Cluster (MIC) to
operate the light. This is the method used to turn the
light ON solid or to flash it after the indicator light
test is complete to signify a fault in the SKIS. If the
light comes ON and stays ON solid after the indica-
tor light test, this signifies that the SKIM has
detected a system malfunction and/or that the SKIS
has become inoperative. If the SKIM detects an
invalid keyORa key-related fault exists, the indica-
tor light will flash following the indicator light test.
The SKIM may also request an audible chime if the
customer key programming feature is available and
the procedure is being utilized (Refer to 8 - ELEC-
TRICAL/VEHICLE THEFT SECURITY/TRANSPON-
DER KEY - STANDARD PROCEDURE).
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove Lower Instrument Panel Cover. Refer
to Body, Instrument Panel, Lower Instrument Panel
Cover, Removal.
(3) Remove the steering column upper and lower
shrouds. Refer to Steering, Column, Column Shroud,
Removal.
(4) Disengage the steering column wire harness
from the Sentry Key Immobilizer Module (SKIM).
(5) Remove the one screws securing the SKIM to
the steering column.
8E - 18 ELECTRONIC CONTROL MODULESRS
POWERTRAIN CONTROL MODULE (Continued)
BODY CONTROL MODULE
TABLE OF CONTENTS
page page
BODY CONTROL MODULE DESCRIPTION ..........................1
OPERATION ............................1 REMOVAL
.............................3
INSTALLATION ..........................3
BODY CONTROL MODULE
DESCRIPTION
The Body Control Module (BCM) is located in the
passenger compartment, attached to the bulkhead
underneath the left side of the instrument panel. The BCM utilizes integrated circuitry and informa-
tion carried on the Programmable Communications
Interface (PCI) data bus network along with many
hard wired inputs to monitor many sensor and
switch inputs throughout the vehicle. 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 outputs and the transmis-
sion of electronic message outputs to other electronic
modules in the vehicle over the PCI data bus.
OPERATION
The Body Control Module (BCM) supplies vehicle
occupants with visual and audible information and
controls various vehicle functions. To provide and
receive information, the BCM is interfaced to the
vehicle's serial bus communications network, referred
to as the Programmable Communications Interface
(PCI) bus. This network consists of the;
² Powertrain Control Module (PCM)
² Transmission Control Module (TCM)
² Mechanical Instrument Cluster (MIC)
² Occupant Restraint Controller (ORC)
² Compass/Mini-Trip Computer (CMTC)
² Electronic Vehicle Information Center (EVIC)
² Controller Antilock Brake (CAB)
² HVAC Control Module
² Sliding Door Control Modules (driver and pas-
senger side doors) ² Power Liftgate Module (PLG) ²
Audio system equipped with RAZ, RBU, RBK,
and RBB radios. ² Sentry Key Remote Entry Module (SKREEM).
² Side Impact Airbag Control Module (SIACM)
² Memory Seat Module (MSM)
² Sentry Key Immobilizer Module (SKIM)
The BCM is operational when battery power is
supplied to the module. The BCM provides the following features:
² Power Door Locks
² Automatic Door Locks
² Battery Protection - The BCM will automatically
turn off all exterior lamps after 3 minutes, and all
interior lamps after 15 minutes after the ignition is
turned off, if they are not turned off by the driver. ² Chime Control
² Compass/Mini-Trip support.
² Interior Lighting (Courtesy/Reading Lamps)
² BCM Diagnostic Reporting
² Electronic Liftgate Release (with Power Door
Locks) ² Exterior Lighting
² Headlamp Time Delay (with/without Automatic
Headlamps) ² Illuminated Entry
² Fade to Off Interior Lamps - This feature dims
the interior lighting (courtesy lamps) gradually if the
BCM does not receive any new inputs that would
cause the interior lamps to remain on. ² Pulse Width Modulated Instrument Panel Dim-
ming ² Door Lock Inhibit - This feature disables the
door lock functions if the key is in the ignition and
either front door is ajar. Pressing the Remote Keyless
Entry (RKE) lock/unlock button under these condi-
tions result in normal lock/unlock activation. The BCM has the ability to LEARN additional fea-
tures in the vehicle, provided the appropriate switch
input and PCI data bus messages are received. Refer
to the LEARNED FEATURES table.
RS BODY CONTROL MODULE8Es-1
the START position. If voltage reads above 0.2 volt,
correct poor starter to engine ground.
(a) Connect the positive voltmeter lead to the
battery positive terminal, and negative lead to bat-
tery cable terminal on starter solenoid. Rotate and
hold the ignition switch in the START position. If
voltage reads above 0.2 volt, correct poor contact at
battery cable to solenoid connection. If reading is
still above 0.2 volt after correcting poor contacts,
replace battery positive cable.
(b) If resistance tests do not detect feed circuit
failures, replace the starter motor.
DIAGNOSIS AND TESTING - FEED CIRCUIT
TEST
NOTE: The following results are based upon the
vehicle being at room temperature.
The following procedure will require a suitable
volt-ampere tester (Fig. 1).
CAUTION: Before performing any starter tests, the
ignition and fuel systems must be disabled.(1) Check battery before performing this test. Bat-
tery must be fully charged.
(2) Connect a volt-ampere tester to the battery ter-
minals. Refer to the operating instructions provided
with the tester being used.
(3) To disable the ignition and fuel systems, dis-
connect the Automatic Shutdown Relay (ASD). The
ASD relay is located in the Power Distribution Cen-
ter (PDC). Refer to the PDC cover for proper relay
location.
(4) Verify that all lights and accessories are OFF,
and the transmission shift selector is in the PARK
and SET parking brake.
CAUTION: Do not overheat the starter motor or
draw the battery voltage below 9.6 volts during
cranking operations.
(5) Rotate and hold the ignition switch in the
START position. Observe the volt-ampere tester (Fig.
1).
²If voltage reads above 9.6 volts, and amperage
draw reads above 280 amps, check for engine seizing
or faulty starter.
²If voltage reads 12.4 volts or greater and amper-
age reads 0 to 10 amps, check for corroded cables
and/or bad connections.
²Voltage below 9.6 volts and amperage draw
above 300 amps, the problem is the starter. Replace
the starter refer to starter removal.
(6) After the starting system problems have been
corrected, verify the battery state-of-charge and
charge battery if necessary. Disconnect all testing
equipment and connect ASD relay. Start the vehicle
several times to assure the problem has been cor-
rected.
SPECIFICATIONS
Torques
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Starter Mounting Bolts 47.4 35
Starter Solenoid Battery
Nut11.3 8.3 100
Fig. 1 Volt Ampere Tester
RSSTARTING8F-33
STARTING (Continued)
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)
battery cable to solenoid connection. If reading is
still above 0.2 volt after correcting poor contacts,
replace battery positive cable.(b) If resistance tests do not detect feed circuit
failures, replace the starter motor.
DIAGNOSIS AND TESTING - FEED CIRCUIT
TEST
NOTE: The following results are based upon the
vehicle being at room temperature.
The following procedure will require a suitable
volt-ampere tester (Fig. 1).
CAUTION: Before performing any starter tests, the
ignition and fuel systems must be disabled.
(1) Check battery before performing this test. Bat-
tery must be fully charged. (2) Connect a volt-ampere tester to the battery ter-
minals. Refer to the operating instructions provided
with the tester being used. (3) To disable the ignition and fuel systems, dis-
connect the Automatic Shutdown Relay (ASD). The
ASD relay is located in the Power Distribution Cen-
ter (PDC). Refer to the PDC cover for proper relay
location. (4) Verify that all lights and accessories are OFF,
and the transmission shift selector is in the PARK
and SET parking brake.
CAUTION: Do not overheat the starter motor or
draw the battery voltage below 9.6 volts during
cranking operations.
(5) Rotate and hold the ignition switch in the
START position. Observe the volt-ampere tester (Fig.
1). ² If voltage reads above 9.6 volts, and amperage
draw reads above 280 amps, check for engine seizing
or faulty starter. ² If voltage reads 12.4 volts or greater and amper-
age reads 0 to 10 amps, check for corroded cables
and/or bad connections. ² Voltage below 9.6 volts and amperage draw
above 300 amps, the problem is the starter. Replace
the starter refer to starter removal. (6) After the starting system problems have been
corrected, verify the battery state-of-charge and
charge battery if necessary. Disconnect all testing
equipment and connect ASD relay. Start the vehicle
several times to assure the problem has been cor-
rected.
SPECIFICATIONS
Torques
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Starter Mounting Bolts 47.4 35
Starter Solenoid Battery Nut 11.3 8.3 100
Fig. 1 Volt Ampere Tester
RS
STARTING8Fs-35
STARTING (Continued)
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)
(3) Connect the negative battery cable.
(4) Verify heated seat system operation.
(5) Install the appropriate seat cushion or seat
back trim cover. Make certain the seat wire harness
is correctly routed through the seat and seat back.
The excess wire between the cushion and back ele-
ments should be securely tucked between the rear of
the cushion foam and the rear carpet flap of the trim
cover.
HEATED SEAT SENSOR
DESCRIPTION
Two heated seat sensors are used per vehicle, one
in each front seat cushion heating element. The
heated seat temperature sensor is a Negative Tem-
perature Coefficient (NTC) thermistor.
The heated seat sensors cannot be repaired or
adjusted and if found to be faulty, the complete
heated seat cushion element must be replaced.
OPERATION
The temperature sensor is a NTC thermistor.
When the temperature of the seat cushion cover
rises, the resistance of the sensor decreases. The
heated seat module supplies a five-volt current to one
side of each sensor, and monitors the voltage drop
through the sensor on a return circuit. The heated
seat module uses this temperature sensor input to
monitor the temperature of the seat, and regulates
the current flow to the seat heating elements accord-
ingly.
DIAGNOSIS AND TESTING - HEATED SEAT
SENSOR
For complete circuit diagrams, refer toWiring
Diagrams.
(1) Disconnect and isolate the battery negative
cable. Disconnect the green 4-way heated seat mod-
ule wire harness connector.
(2) Using an ohmmeter, check the resistance
between cavities 2 and 3. The sensor resistance
should be between 50 kilohms at 15É C (60É F) and 2
kilohms at 30É C (85É F). If not OK, replace the
faulty seat element and sensor assembly.
PASSENGER HEATED SEAT
SWITCH
DESCRIPTION
The heated seat switches are mounted in the
instrument panel center bezel (Fig. 6). The two three-
position rocker-type switches, one switch for each
front seat, are incorporated into one large switchassembly 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-
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
Fig. 6 HEATED SEAT SWITCH LOCATION
1 - HEATED SEAT SWITCHES
8G - 12 HEATED SEAT SYSTEMRS
HEATED SEAT ELEMENTS (Continued)