2003 DODGE RAM instrument cluster

Instrument Cluster allows it to process those inputs
and send the proper messages to the radio receiver
over the Programmable Communication Interface
(PCI) bus network to control the radio volume up or
down, station seek up or down, preset station
advance, and mode advance functions.
Refer to the owner's manual for more information
on the features, use and operation of each of the
available audio systems.
DIAGNOSIS AND TESTING - AUDIO
Any diagnosis of the Audio system should
begin with the use of the DRB IIItdiagnostic
tool. For information on the use of the DRB
IIIt, refer to the appropriate Diagnostic Service
Manual.
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, details of wireharness routing and retention, connector pin-out
information and location views for the various wire
harness connectors, splices and grounds.
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, SEAT BELT TENSIONER, SIDE
AIRBAG, 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 ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
AUDIO SYSTEM DIAGNOSIS TABLE
CONDITION POSSIBLE CAUSES CORRECTION
NO AUDIO 1. Fuse faulty. 1. Check radio fuse and Ignition-Off Draw (IOD)
fuse in the Integrated Power Module (IPM).
Replace fuses, if required.
2. Radio/amplifier (if
equipped) connector faulty.2. Check for loose or corroded radio/amplifier
connector. Repair, if required.
3. Wiring faulty. 3. Check for shorted or open wires. Repair wiring,
if required.
4. Radio/amplifier (if
equipped) ground faulty.4. Check for continuity between radio chassis and
a known good ground. There should be
continuity. Repair ground, if required.
5. Radio/amplifier (if
equipped) faulty.5. Refer to appropriate Diagnostic Service
Manual.
6. Speakers faulty. 6. Replace speaker as necessary.
NO RADIO DISPLAY 1. Fuse faulty. 1. Check radio fuse and Ignition-Off Draw (IOD)
fuse in Integrated Power Module (IPM). Replace
fuses, if required.
2. Radio connector faulty. 2. Check for loose or corroded radio connector.
Repair, if required.
3. Wiring faulty. 3. Check for battery voltage at radio connector.
Repair wiring, if required.
4. Radio ground faulty. 4. Check for continuity between radio chassis and
a known good ground. There should be
continuity. Repair ground, if required.
5. Radio faulty. 5. Refer to appropriate Diagnostic Service
Manual.
8A - 2 AUDIODR
AUDIO (Continued)

CHIME/BUZZER
TABLE OF CONTENTS
page page
CHIME/BUZZER
DESCRIPTION..........................1
OPERATION............................1DIAGNOSIS AND TESTING - CHIME
CONDITIONS..........................2
CHIME/BUZZER
DESCRIPTION
The chime module is located within the instrument
cluster and is not serviceable. The chime system pro-
vides the driver with warning chimes for:
²Air Bag
²Seat Belt
²Low Fuel
²Door Ajar
²Low Wash
²Park Brake
²Over Speed
²Turn Signal On
²Key-In Ignition
²Exterior Lamps ON
²Warning Lamp Announcement
²Transmission Over Temperature
OPERATION
FASTEN SEAT BELT
The seat belt reminder system uses both visual
and audible signals. The Instrument Cluster moni-
tors the driver seat belt buckle switch. When the
ignition switch transitions from OFF to RUN and the
driver seat belt has not been buckled, the Instrument
Cluster will illuminate the seat belt indicator lamp
and sound the chime. The system will always illumi-
nate the seat belt reminder lamp for four to eight
seconds when the ignition switch is turned to the ON
position. The CHIME will sound during the same
time interval if the driver's seat belt is not fastened.
The warning lamp will remain illuminated as long as
the seat belt remains unbuckled, and the ignition
switch is in the RUN position. Passenger seat belts
are not connected to the system.
HEADLAMPS REMINDER
The Instrument Cluster monitors the multiplex
headlamp switch. The headlamp audible warning will
alert the driver that the exterior lamps have been
left on. If the ignition switch is left off, the driver's
door open, and the headlamp switch is in the parklamp or headlamp position, the chime will sound
until the headlamp switch is turned off, the door is
closed or the battery protection time out expires.
KEY IN IGNITION REMINDER
The Instrument Cluster monitors the ignition
switch. The chime will activate if the drivers door is
opened and the key is in the ignition switch, with the
ignition switch in either the OFF, LOCK, or the
accessory (ACC) position. The chime will continue
until the key is removed from the ignition switch or
the door is closed.
DOOR AJAR CHIME
The Instrument Cluster monitors the door ajar
switches. A chime will sound once when the door is
opened, the ignition is in RUN position and vehicle
speed is present.
TURN SIGNAL ON
The Instrument Cluster monitors the multiplex
multifunction switch. The instrument cluster shall
remind the driver that either turn signal has been
left on by a continuous chime after the turn signal
indicator is left ON for 1.0 miles and the vehicle
speed is 15 mph or greater.
LOW FUEL REMINDER
When the fuel level drops to approximately 1/8
tank, the fuel symbol will light and a single chime
will sound. The light will remain on until fuel is
added.
OVER SPEED
During any ignition ON, the Instrument Cluster
maintains the most recently received speed. If the
vehicle speed exceeds a preprogramed limit set in the
instrument cluster it will activate a single chime.
WARNING LAMP ANNOUNCEMENT
The Instrument Cluster monitors critical engine
and transmission system parameters. If any of the
systems are out of their operating parameters, the
instrument cluster will illuminate a lamp and acti-
vate and audible chime.
DRCHIME/BUZZER 8B - 1

LOW WASH INDICATOR
The Front Control Module (FCM) monitors the
washer reservoir. When the fluid is low the FCM
transmits a J1850 message over the bus. The instru-
ment cluster will chime and illuminate the LOW
WASH indicator. The indicator will remain on until
the fluid level is corrected.
AIR BAG
The Instrument Cluster monitors air bag system
via the J1850 bus communications from the air bag
module. The air bag module will transmit a message
once per second, over the J1850 bus, as to whether
the warning indicator should be on or off. The warn-
ing indicator indicates a part of the air bag system is
inoperative and needs to be serviced. Itdoes not
indicate that the air bag system will not deploy. If
the instrument cluster does not receive a message
from the air bag module for 3 consecutive seconds,
the Instrument will illuminate the warning indicator.The air bag module transmits a J1850 message
requesting the instrument cluster to perform a bulb
check each time the ignition is turned to the on posi-
tion
DIAGNOSIS AND TESTING - CHIME
CONDITIONS
NOTE: The Chime/Buzzer Warning System is Diag-
nosed using a DRBIIITScan Tool. Refer to the
proper Body Diagnostic Procedures Manual.
Visually inspect the related wiring harness connec-
tors. Look for broken, bent, pushed out, or corroded
terminals. If any of the conditions are present, repair
as necessary. If not use the DRBIIItscan tool and
the proper Body Diagnostic Procedure manual. For
complete circuit diagrams, refer toInstrument
Clusterin Wiring Systems.
8B - 2 CHIME/BUZZERDR
CHIME/BUZZER (Continued)

(2) Tighten bolts. Refer to torque specifications.
(3) Check pin connectors in the PCM and the three
32±way connectors (four 38±way connectors if
equipped with NGC) for corrosion or damage. Also,
the pin heights in connectors should all be same.
Repair as necessary before installing connectors.
(4) Install three 32±way connectors (four 38±way
connectors if equipped with NGC).
(5) Install cover over electrical connectors. Cover
snaps onto PCM.
(6) Install negative battery cable.
(7) Use the DRB scan tool to reprogram new PCM
with vehicles original Vehicle Identification Number
(VIN) and original vehicle mileage.
SENTRY KEY IMMOBILIZER
MODULE
DESCRIPTION
The Sentry Key Immobilizer Module (SKIM) con-
tains a Radio Frequency (RF) transceiver and a cen-
tral processing unit, which includes the Sentry Key
Immobilizer System (SKIS) program logic. The SKIS
programming enables the SKIM to program and
retain in memory the codes of at least two, but no
more than eight electronically coded Sentry Key
transponders. The SKIS programming also enables
the SKIM to communicate over the Programmable
Communication Interface (PCI) bus network with the
Powertrain Control Module (PCM), and/or the
DRBIIItscan tool.
OPERATION
The SKIM transmits and receives RF signals
through a tuned antenna enclosed within a molded
plastic ring that is integral to the SKIM housing.
When the SKIM is properly installed on the steering
column, the antenna ring is oriented around the igni-
tion lock cylinder housing. This antenna ring must be
located within eight millimeters (0.31 inches) of the
Sentry Key in order to ensure proper RF communica-
tion between the SKIM and the Sentry Key tran-
sponder.
For added system security, each SKIM is pro-
grammed with a unique ªSecret Keyº code and a
security code. The SKIM keeps the ªSecret Keyº code
in memory. The SKIM also sends the ªSecret Keyº
code to each of the programmed Sentry Key tran-
sponders. The security code is used by the assembly
plant to access the SKIS for initialization, or by the
dealer technician to access the system for service.
The SKIM also stores in its memory the Vehicle
Identification Number (VIN), which it learns through
a PCI bus message from the PCM during initializa-
tion.The SKIM and the PCM both use software that
includes a rolling code algorithm strategy, which
helps to reduce the possibility of unauthorized SKIS
disarming. The rolling code algorithm ensures secu-
rity by preventing an override of the SKIS through
the unauthorized substitution of the SKIM or the
PCM. However, the use of this strategy also means
that replacement of either the SKIM or the PCM
units will require a system initialization procedure to
restore system operation.
When the ignition switch is turned to the ON or
START positions, the SKIM transmits an RF signal
to excite the Sentry Key transponder. The SKIM then
listens for a return RF signal from the transponder
of the Sentry Key that is inserted in the ignition lock
cylinder. If the SKIM receives an RF signal with
valid ªSecret Keyº and transponder identification
codes, the SKIM sends a ªvalid keyº message to the
PCM over the PCI bus. If the SKIM receives an
invalid RF signal or no response, it sends ªinvalid
keyº messages to the PCM. The PCM will enable or
disable engine operation based upon the status of the
SKIM messages.
The SKIM also sends messages to the Instrument
Cluster which controls the VTSS indicator LED. The
SKIM sends messages to the Instrument Cluster to
turn the LED on for about three seconds when the
ignition switch is turned to the ON position as a bulb
test. After completion of the bulb test, the SKIM
sends bus messages to keep the LED off for a dura-
tion of about one second. Then the SKIM sends mes-
sages to turn the LED on or off based upon the
results of the SKIS self-tests. If the VTSS indicator
LED comes on and stays on after the bulb test, it
indicates that the SKIM has detected a system mal-
function and/or that the SKIS has become inopera-
tive.
If the SKIM detects an invalid key when the igni-
tion switch is turned to the ON position, it sends
messages to flash the VTSS indicator LED. The
SKIM can also send messages to flash the LED as an
indication to the customer that the SKIS has been
placed in it's ªCustomer Learnº programming mode.
See Sentry Key Immobilizer System Transponder
Programming in this section for more information on
the ªCustomer Learnº programming mode.
For diagnosis or initialization of the SKIM and the
PCM, a DRBIIItscan tool and the proper Powertrain
Diagnostic Procedures manual are required. The
SKIM cannot be repaired and, if faulty or damaged,
the unit must be replaced.
DRELECTRONIC CONTROL MODULES 8E - 13
POWERTRAIN CONTROL MODULE (Continued)

STANDARD PROCEDURE - PCM/SKIM
PROGRAMMING
NOTE: There are two procedures for transfering the
secret key to the SKIM:
²When ONLY the SKIM module is replaced, the
secret key is transfered from the PCM to the SKIM.
The ORGINAL KEYS may then be programmed to
the SKIM.
²When ONLY the PCM is replaced, then the
secret key is transfered from the SKIM to the PCM.
The ORGINAL KEYS may be used.
²When BOTH the SKIM and the PCM are
replaced the secret key is transferred from the
SKIM to the PCM, and NEW KEYS must be pro-
grammed.
NOTE: Before replacing the Powertrain Control
Module (PCM) for a failed driver, control circuit, or
ground circuit, be sure to check the related compo-
nent/circuit integrity for failures not detected due to
a double fault in the circuit. Most PCM driver/con-
trol circuit failures are caused by internal compo-
nent failures (i.e. relay and solenoids) and shorted
circuits (i.e. pull-ups, drivers and switched circuits).
These failures are difficult to detect when a double
fault has occurred and only one Diagnostic Trouble
Code (DTC) has set.
When a PCM (SBEC) and the Sentry Key Immobi-
lizer Module (SKIM) are replaced at the same time
perform the following steps in order:
(1) Program the new PCM (SBEC).
(2) Program the new SKIM.
(3) Replace all ignition keys and program them to
the new SKIM.
PROGRAMMING THE PCM (SBEC)
The Sentry Key Immobilizer System (SKIS) Secret
Key is an ID code that is unique to each SKIM. This
code is programmed and stored in the SKIM, PCM
and transponder chip (ignition keys). When replacing
the PCM it is necessary to program the secret key
into the new PCM using the DRBIIItscan tool. Per-
form the following steps to program the secret key
into the PCM.
(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRBIIItscan tool and select THEFT
ALARM, SKIM then MISCELLANEOUS.
(3) Select PCM REPLACED (GAS ENGINE).
(4) Enter secured access mode by entering the
vehicle four-digit PIN.
(5) Select ENTER to update PCM VIN.NOTE: If three attempts are made to enter secure
access mode using an incorrect PIN, secured
access mode will be locked out for one hour. To
exit this lockout mode, turn the ignition to the RUN
position for one hour then enter the correct PIN.
(Ensure all accessories are turned OFF. Also moni-
tor the battery state and connect a battery charger
if necessary).
(6) Press ENTER to transfer the secret key (the
SKIM will send the secret key to the PCM).
(7) Press Page Back to get to the Select System
menu and select ENGINE, MISCELLANEOUS, and
SRI MEMORY CHECK.
(8) The DRBIIItscan tool will ask, Is odometer
reading between XX and XX? Select the YES or NO
button on the DRB IIItscan tool. If NO is selected,
the DRBIIItscan tool will read, Enter odometer
Reading. Enter the odometer
reading from the instrument cluster and press
ENTER.
PROGRAMMING THE SKIM
(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRBIIItscan tool and select THEFT
ALARM, SKIM then MISCELLANEOUS.
(3) Select SKIM REPLACED (GAS ENGINE).
(4) Program the vehicle four-digit PIN into SKIM.
(5) Select COUNTRY CODE and enter the correct
country.
NOTE: Be sure to enter the correct country code. If
the incorrect country code is programmed into the
SKIM, the SKIM must be replaced.
(6) Select YES to update the VIN (the SKIM will
learn the VIN from the PCM).
(7) Press ENTER to transfer the secret key (the
PCM will send the secret key information to the
SKIM).
(8) Program ignition keys to the SKIM.
NOTE: If the PCM and the SKIM are replaced at the
same time, all vehicle keys will need to be replaced
and programmed to the new SKIM.
PROGRAMMING IGNITION KEYS TO THE SKIM
(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRBIIItscan tool and select THEFT
ALARM, SKIM then MISCELLANEOUS.
(3) Select PROGRAM IGNITION KEY'S.
(4) Enter secured access mode by entering the
vehicle four-digit PIN.
8E - 14 ELECTRONIC CONTROL MODULESDR
SENTRY KEY IMMOBILIZER MODULE (Continued)

ELECTRONIC MODULE IGNITION-OFF DRAW (IOD) TABLE
ModuleTime Out?
(If Yes, Interval And Wake-Up Input)IODIOD After Time
Out
ElectroMechanical
Instrument Cluster
(EMIC)No 0.44 milliampere N/A
Combination Flasher No 0.08 milliampere N/A
(2) Determine that the underhood lamp is operat-
ing properly, then disconnect the lamp wire harness
connector or remove the lamp bulb.
(3) Disconnect the battery negative cable.
(4) Set an electronic digital multi-meter to its
highest amperage scale. Connect the multi-meter
between the disconnected battery negative cable ter-
minal clamp and the battery negative terminal post.
Make sure that the doors remain closed so that the
illuminated entry system is not activated. The multi-
meter amperage reading may remain high for up to
three minutes, or may not give any reading at all
while set in the highest amperage scale, depending
upon the electrical equipment in the vehicle. The
multi-meter leads must be securely clamped to the
battery negative cable terminal clamp and the bat-
tery negative terminal post. If continuity between the
battery negative terminal post and the negative cable
terminal clamp is lost during any part of the IOD
test, the electronic timer function will be activated
and all of the tests will have to be repeated.
(5) After about three minutes, the high-amperage
IOD reading on the multi-meter should become very
low or nonexistent, depending upon the electrical
equipment in the vehicle. If the amperage reading
remains high, remove and replace each fuse or circuit
breaker in the Integrated Power Module (IPM), one
at a time until the amperage reading becomes very
low, or nonexistent. Refer to the appropriate wiring
information in this service manual for complete Inte-
grated Power Module fuse, circuit breaker, and cir-
cuit identification. This will isolate each circuit and
identify the circuit that is the source of the high-am-
perage IOD. If the amperage reading remains high
after removing and replacing each fuse and circuit
breaker, disconnect the wire harness from the gener-
ator. If the amperage reading now becomes very low
or nonexistent, refer to Charging System for the
proper charging system diagnosis and testing proce-
dures. After the high-amperage IOD has been cor-
rected, switch the multi-meter to progressively lower
amperage scales and, if necessary, repeat the fuse
and circuit breaker remove-and-replace process to
identify and correct all sources of excessive IOD. It is
now safe to select the lowest milliampere scale of the
multi-meter to check the low-amperage IOD.CAUTION: Do not open any doors, or turn on any
electrical accessories with the lowest milliampere
scale selected, or the multi-meter may be damaged.
(6) Observe the multi-meter reading. The low-am-
perage IOD should not exceed thirty-five milliam-
peres (0.035 ampere). If the current draw exceeds
thirty-five milliamperes, isolate each circuit using the
fuse and circuit breaker remove-and-replace process
in Step 5. The multi-meter reading will drop to
within the acceptable limit when the source of the
excessive current draw is disconnected. Repair this
circuit as required; whether a wiring short, incorrect
switch adjustment, or a component failure is at fault.
STANDARD PROCEDURE - USING MICRO 420
BATTERY TESTER
Always use the Micro 420 Instruction Manual that
was supplied with the tester as a reference. If the
Instruction Manual is not available the following pro-
cedure can be used:
Fig. 9 MICRO 420 BATTERY TESTER
8F - 12 BATTERY SYSTEMDR
BATTERY (Continued)

Diagnostic logic is built into the heated seat mod-
ule to help the person trying to locate the problem by
the most efficient means possible. Anytime a problem
is suspected, locate the diagnosis and testing proce-
dure for the component in question and follow the
steps until the specific problem is located and
resolved. Once the problem is thought to be cor-
rected, verify correct system operation. If the heated
seat system is functioning correctly return the vehi-
cle to service.
If a problem could not be verified such as not find-
ing anything wrong when following the diagnostic
procedure, this is a good indication that a INTER-
MITTENT problem may be present. You must then
attempt to find the intermittent problem, such as
moving the heating element within the seat while
testing continuity or wiggling the wire harness's/elec-
trical connectors under the seat while testing conti-
nuity. Always, eliminate all other potential problems
before attempting to replace the heated seat module.
PRELIMINARY TEST
Refer toWiringfor the location of complete heated
seat system wiring diagrams. Before testing the indi-
vidual components in the heated seat system, per-
form the following preliminary checks:
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
CABLE, THEN WAIT TWO MINUTES FOR THE AIR-
BAG 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.
²If the heated seat switch back lighting and the
cluster illumination lamps do not illuminate with the
headlamps or park lamps turned On, refer to the
Instrument Clustersection of the service manual
for the location of cluster illumination lamp diagnosis
and testing procedures. If the heated seat switch
back lighting does not illuminate, but the cluster illu-
mination lamps do illuminate with the headlamps or
park lamps turned On, refer toDiagnosis and Test-
ing the Heated Seat Switchin this section for the
location of the heated seat switch diagnosis and test-
ing procedures.
²If a single LED indicator lamp for one heated
seat switch does not operate and the heated seat ele-
ments do heat, refer toDiagnosis and Testing theHeated Seat Switchin this section for heated seat
switch diagnosis and testing procedures.
²If both LED indicator lamps for a heated seat
switch operate, but the heated seat elements do not
heat, refer toDiagnosis and Testing the Heated
Seat Modulein Electronic Control Modules for
heated seat module diagnosis and testing procedures.
²If the indicator lamp on either heated seat
switch remains illuminated after the heated seat has
been turned Off, refer toDiagnosis and Testing
the Heated Seat Modulein Electronic Control
Modules for heated seat module diagnosis and test-
ing procedures.
HEATED SEAT ELEMENT
DESCRIPTION
Vehicles equipped with the optional heated seat
system have two sets of electrically operated heating
element grids located in each front seat, one set for
the seat cushion and the other set for the seat back.
Each of the heated seat element grids consists of a
single length of resistor wire that is routed in a zig-
zag pattern and captured between a covering and the
adhesive foam rubber backing. Short pigtail wires
with connectors (Fig. 2) are soldered to each end of
each resistor wire element grid, which connect all of
Fig. 2 Heating Element Installed on Seat Cushion
Foam
1 - SEAT BACK WIRE HARNESS
2 - HEATED SEAT WIRE HARNESS CONNECTOR
3 - HEATED SEAT CUSHION ELEMENT
DRHEATED SEAT SYSTEM 8G - 5
HEATED SEAT SYSTEM (Continued)

diagnostic feedback for the heated seat system. Each
switch also has an incandescent bulb, which provides
dimmer controlled back lighting of the switch when
the headlamps or park lamps are on.
The heated seat switches are both mounted in the
instrument panel center bezel, located in the lower
center of the instrument panel. The two switches are
snapped into the mounting holes of the heated seat
switch bezel, and the heated seat switch bezel is
secured with screws to the instrument panel center
bezel. The heated seat switches are differentiated by
the keyway in the connector receptacle on the backs
of the switches and keyway on the switch housing.
The instrument panel wire harness connectors for
the heated seat switches are keyed to match the con-
nector receptacles on the switches so that the two
heated seat switches can only be connected to the
proper heated seat electrical.
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 resistance signal to the heated seat module.
This signal tells the module to energize the heated
seat element 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 sec-
ond time, the heated seat module interprets the sec-
ond input as a request to turn the seat heater OFF.
The High and Low LED 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 indicator lamp is controlled by the heated
seat module. This control of the switch indicator
lamps also allows the module to provide diagnostic
feedback to the vehicle operator or technician to indi-
cate heated seat system faults by flashing the indica-
tor lamps on and off. One side of the incandescent
back lighting bulb in each heated seat switch is con-
nected to ground at all times. The other side of the
incandescent bulb is connected to the fused panel
lamps dimmer switch signal circuit. These bulbs are
energized when the park lamps or headlamps are
turned on, and their illumination intensity is con-
trolled by the panel lamps dimmer switch.
DIAGNOSIS AND TESTING - HEATED SEAT
SWITCH
Refer toWiring Diagramsfor connector pin-outs
and the location of complete heated seat system wir-
ing 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 to 8 - ELECTRI-
CAL/INSTRUMENT CLUSTER - DIAGNOSIS AND
TESTING). If the problem being diagnosed involves
Fig. 4 HEATED SEAT SWITCH
1 - HEATED SEAT SWITCH
2 - LIGHT-EMITTING DIODE (LED) INDICATOR LAMPS
8G - 8 HEATED SEAT SYSTEMDR
HEATED SEAT SWITCH (Continued)