electrical DODGE RAM 2003 Service Manual Online

heated mirror switch is depressed and released a sec-
ond time during the same ignition cycle, the elec-
tronic control logic and timer circuitry will
automatically turn the heated mirror system off after
a programmed time interval of about five minutes.
The heated mirror system will be shut off automati-
cally if the ignition switch is turned to the Off or
Accessory positions. After the heated mirror system
is turned On, it can also be turned off manually by
depressing and releasing the heated mirror switch a
second time.
When the heated mirror system is turned On, the
heated mirror system control logic and timer cir-
cuitry energizes the heated mirror system indicator
lamp and the heated mirror relay. When energized,
the heated mirror relay supplies fused ignition
switch output (run/start) current from a fuse in the
JB to the outside mirror heating grids located behind
the mirror glass of each of the outside rear view mir-
rors. When energized, each of the outside mirror
heating grids produces enough heat to warm the
glass of the outside rear view mirrors.
DIAGNOSIS AND TESTING - HEATED MIRROR
SYSTEM
If only one of the outside mirror heating grids is
inoperative, perform continuity checks on the circuits
and heater grid for that mirror only. If both outside
mirror heating grids are inoperative, proceed with
the heated mirror system diagnosis as follows. (Refer
to Appropriate 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 ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.The operation of the heated mirror system can be
confirmed in one of the following manners:
1. Turn the ignition switch to the On position.
While monitoring the instrument panel voltmeter,
momentarily depress and release the heated mirror
switch. When the heated mirror system is turned On,
a distinct voltmeter needle deflection should be
noted.
2. Turn the ignition switch to the On position.
Momentarily depress and release the heated mirror
switch to turn the heated mirror system On. The
heated mirror operation can be checked by feeling
the outside rear view mirror glass. A distinct differ-
ence in temperature between the unheated and
heated mirror glass can be detected within three to
four minutes of system operation.
The above checks will confirm system operation.
Illumination of the heated mirror system indicator
lamp means that there is electrical current available
at the heated mirror relay, but does not confirm that
the electrical current is reaching the outside mirror
heating grids.
If the heated mirror system does not operate, the
problem should be isolated in the following manner:
(1) Confirm that the ignition switch is in the On
position.
(2) Check the fuses in the Power Distribution Cen-
ter (PDC) and in the Junction Block (JB). The fuses
must be tight in their receptacles and all electrical
connections must be secure.
When the above steps have been completed and
both outside mirror heating grids are still inopera-
tive, one or more of the following is faulty:
²Heated mirror switch, electronic control logic
and timer circuitry, and heated mirror relay.
²Heated mirror wire harness circuits or connec-
tors.
²Outside mirror heating grid (both mirror grids
would have to be faulty).
If turning On the heated mirror system produces a
severe voltmeter deflection or fuse failures, check for
a shorted circuit between the output of the heated
mirror relay and the outside mirror heating grids.
8G - 2 HEATED MIRRORSDR
HEATED MIRRORS (Continued)

HEATED SEAT SYSTEM
TABLE OF CONTENTS
page page
HEATED SEAT SYSTEM
DESCRIPTION..........................3
OPERATION............................4
DIAGNOSIS AND TESTING - HEATED SEAT
SYSTEM.............................4
HEATED SEAT ELEMENT
DESCRIPTION..........................5
OPERATION............................6
DIAGNOSIS AND TESTING - HEATED SEAT
ELEMENT............................6
REMOVAL.............................6
INSTALLATION..........................6
HEATED SEAT SENSOR
DESCRIPTION..........................7OPERATION............................7
DIAGNOSIS AND TESTING - HEATED SEAT
SENSOR.............................7
REMOVAL.............................7
HEATED SEAT SWITCH
DESCRIPTION..........................7
OPERATION............................8
DIAGNOSIS AND TESTING - HEATED SEAT
SWITCH.............................8
REMOVAL.............................9
INSTALLATION..........................9
HEATED SEAT SYSTEM
DESCRIPTION
Individually controlled, electrically heated front
seats are available as a factory-installed option on
some DR models. Vehicles with this option can be
visually identified by the leather trim seats and two
separate heated seat switches mounted in the lower
center of the instrument panel. The heated seat sys-
tem allows the front seat driver and passenger to
select from two different levels of electrical seat heat-
ing, or no seat heating to suit their individual com-
fort requirements. The heated seat system for this
vehicle includes the following major components,
which are described in further detail later in this sec-
tion:
²Heated Seat Switches- Two heated seat
switches are used per vehicle. One switch is used for
each front seat. The switches are mounted in the
instrument panel, below the radio (Fig. 1). Each
switch also includes two Light-Emitting Diode (LED)
indicator lamps and an incandescent back lighting
bulb.
²Heated Seat Module- also referred to as the
Seat Heat Interface Module (SHIM), this module con-
tains the solid state electronic control and diagnostic
logic circuitry for the heated seat system. One heated
seat module is used per vehicle and is mounted
under the drivers front seat cushion (Fig. 1). Refer to
the Electronic Control Modules section of the service
manual for additional heated seat module informa-
tion.²Heated Seat Elements- Four heated seat ele-
ments are used per vehicle. One element is used for
each front seat back and one element and sensor
assembly is used for each front seat cushion (Fig. 1).
The heating elements are integral to the individual
front seat and seat back cushions and cannot be
removed once installed at the factory. Replacement
seat heating elements are available, without having
to replace the entire seat cushion or trim cover. Refer
to the detailed procedure later in this section.
²Heated Seat Sensors- Two heated seat sen-
sors are used per vehicle. One heated seat tempera-
ture sensor is used for each front seat cushion. The
sensors are integral to the individual front seat cush-
ion heating elements (Fig. 1) and cannot be removed
once installed at the factory. Replacement seat heat-
ing elements with the sensors are available, without
having to replace the entire seat cushion or trim
cover. Refer to the detailed procedure later in this
section.
Following are general descriptions and operations
of the major components in the heated seat 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. Refer toWiringfor the
location of complete heated seat system wiring dia-
grams.
DRHEATED SEAT SYSTEM 8G - 3

OPERATION
The heated seat module receives fused battery cur-
rent through the Integrated Power Module only when
the engine is running. The heated seat switches
receive battery current through fuse #48 in the Inte-
grated Power Module 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 system will only operate
when the surface temperature of the seat cushion is
below the designed temperature set points of the sys-
tem.
The heated seat system will also automatically
turn off 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 ON, the heated seat will remain Off after the
engine is restarted until a heated seat switch is
depressed again. This helps prevent the vehicles bat-
tery from being drained by the heated seat system.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 uses
its internal programming to control 12v to the heated
seat elements in both front seats and to control the
heated seat LED indicator lamps located in both of
the heated seat switches. The heated seat module is
also programmed to provide self-diagnostics, if a
problem with the heated seat system is detected. If
the module detects certain failures within the heated
seat system, it will provide a visual indication of the
failure by flashing the indicator lamps in the appro-
priate heated seat switch. The heated seat module
will automatically turn off the heated seat elements
if it detects a short or open in the heated seat ele-
ment 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
SYSTEM SELF-DIAGNOSIS table for failure identi-
fication. The drivers heated seat switch indicator
lamps will flash if a failure occurs in the driver
heated seat, and the passengers heated seat switch
indicator lamps will flash for a passenger heated seat
failure. If a monitored heated seat system failure
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
Fig. 1 DR Heated Seat System Diagram
1 - WIRE HARNESS
2 - DRIVER HEATED SEAT SWITCH
3 - PASSENGER HEATED SEAT SWITCH
4 - PASSENGER HEATED SEAT CUSHION ELEMENT
5 - SEAT CUSHION/BACK ELEMENT ELECTRICAL CONNECTOR
LOCATION
6 - DRIVER HEATED SEAT BACK ELEMENT
7 - DRIVER HEATED SEAT CUSHION ELEMENT
8 - HEATED SEAT MODULE
8G - 4 HEATED SEAT SYSTEMDR
HEATED SEAT SYSTEM (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)

the element grids to the heated seat module through
the seat wire harness.
One temperature sensor is used for each front seat,
and it is located in the center insert area of the seat
cushion element. The heated seat sensors and their
pigtail wires are also captured between a covering
and the adhesive foam rubber backing. The heated
seat sensors are Negative Thermal Coefficient (NTC)
thermistors. The sensors for both front seats receive
a voltage feed from a single output of the heated seat
module, but the module receives individual sensor
inputs from the driver side and passenger side sen-
sors.
The heated seat elements and sensors should not
be repaired. If damaged or faulty, the heated seat ele-
ment assembly must be replaced.
OPERATION
One end of the heated seat element resistor wire is
connected to ground at all times through a splice in
the heated seat module ground circuit. Battery cur-
rent is directed to the other end of the heated seat
element resistor wire by the energized N-channel
Field Effect Transistor (N-FET) located within the
heated seat module. The heated seat module will
energize the N-FET only when the heated seat
switch is in the Low or High position and the heated
seat sensor indicates that the seat cushion surface
temperature is below the selected (Low or High) tem-
perature set point. As electrical current passes
through the heating element grid, the resistance of
the wire used in the element disperses some of that
electrical current in the form of heat. The heat pro-
duced by the heated seat element grid then radiates
through the seat trim cover, warming its occupant.
The resistance of the heated seat sensor increases
and decreases as the surface temperature of the seat
cushion cover changes. The heated seat module sup-
plies each sensor with a 5v voltage feed, then uses
the sensor resistance to determine when the heated
seat element grids need to be cycled on or off in order
to maintain the selected temperature set point.
DIAGNOSIS AND TESTING - HEATED SEAT
ELEMENT
The heated seat module will self-diagnose shorted
or open heated seat element circuits and sensor cir-
cuits. Refer to Heated Seat System Diagnosis and
Testing in this section for additional diagnosis and
testing procedures. To manually check the heated
seat element, proceed as follows. The wire harness
connectors for the seat cushion and seat back heating
elements and sensor are located on the right side of
the seat, near the edge of the seat cushion frame.
The proper connector can be identified by the foam
wrapping.NOTE: When checking heated seat elements for
continuity, be certain to move the heating element
being checked. Moving the element, such as sitting
in the seat will eliminate the possibility of an inter-
mittent open in the element which would only be
evident if the element was in a certain position.
Failure to check the element in various positions
could result in an incomplete test.
(1) Position the appropriate seat in the full for-
ward position.
(2) Make certain the ignition switch is in the OFF
position.
(3) Disconnect the heated seat element connector
which requires testing. Check for continuity between
the two heated seat element circuit cavities while
moving the appropriate seat cushion. Refer toWir-
ingfor the location of complete heated seat system
wiring diagrams. There should be continuity. If OK,
the elements within the seat assembly test OK, go to
Step 4. If not OK, replace the faulty seat heating ele-
ment, refer to the procedure in this section.
(4) Test the seat wire harness between the heated
seat module connector and the appropriate heated
seat wire harness connector for shorted or open cir-
cuits. If OK, element is OK, proceed with testing the
heated seat sensor and module. If not OK, repair the
shorted or open seat wire harness as required.
REMOVAL
Do not remove the heating element from the seat
or seat back cushion. The original element is perma-
nently attached to the seat cushions and cannot be
removed without damaging the cushion. The replace-
ment heating element is designed to be applied
directly over the original seat heating element.
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the appropriate seat cushion or seat
back trim cover. Refer to the Body section of this
manual for the procedures.
(3) Disconnect the inoperative heated seat cushion
or seat back element electrical connectors.
(4) Locate the wires leading from the inoperative
heating element and cut them off flush with the edge
of the original heating element.
INSTALLATION
(1) Peel off the adhesive backing on the back of the
replacement heating element and stick directly over
the original heating element (Fig. 3).
CAUTION: During the installation of the replace-
ment heating element, be careful not to fold or
crease the element assembly. Folds or creases will
cause premature failure.
8G - 6 HEATED SEAT SYSTEMDR
HEATED SEAT ELEMENT (Continued)

(2) Connect the new heating element electrical
connectors (Fig. 2).
(3) Connect the battery negative 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.
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.
OPERATION
When the temperature of the seat cushion cover
rises, the resistance of the sensor decreases. The
heated seat module supplies five-volts to one side of
each sensor, and monitors the voltage drop through
the sensor on a return circuit. The heated seat mod-
ule uses this temperature sensor input to monitorthe temperature of the seat, and regulates the cur-
rent flow to the seat heating elements accordingly.
DIAGNOSIS AND TESTING - HEATED SEAT
SENSOR
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 val-
ues generated may not be the same as the results
shown here, or may have to be converted to the
range used here.
(1) Position the driver seat in the full rearward
position.
(2) Unclip the heated seat module from the bottom
of the drivers seat cushion pan.
(3) Back-probe the heated seat module wire har-
ness connector, do not disconnect. Check cavity (#7
for passenger, #8 for driver seat) for a range in volt-
age from approx. 1.72 ± 3.0 volts. It should be within
this range, If OK check the heated seat element. If
NOT OK, check for the proper 5 volt supply to the
heated seat sensor, from the module. Refer to Wiring
for specific information. If 5 volts is not being sup-
plied to the sensor from the module, replace the
heated seat module.
(4) Test the seat wire harness between the heated
seat module connector and the heated seat wire har-
ness connector for shorted or open circuits. If OK,
refer toDiagnosis and Testing the Heated Seat
Modulein Electronic Control Modules, for the
proper heated seat module diagnosis and testing pro-
cedures. If not OK, repair the shorted or open heated
seat wire harness as required.
REMOVAL
(1) For heated seat sensor replacement procedure
(Refer to 8 - ELECTRICAL/HEATED SEATS/
HEATED SEAT ELEMENT - REMOVAL).
HEATED SEAT SWITCH
DESCRIPTION
The momentary, bidirectional rocker-type heated
seat switch (Fig. 4) provides a resistor-multiplexed
signal to the heated seat module via a 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 pre-
ferred 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
Fig. 3 Heating Element Installation
1 - ORIGINAL (INOPERATIVE) HEATING ELEMENT
2 - REPLACEMENT HEATING ELEMENT
DRHEATED SEAT SYSTEM 8G - 7
HEATED SEAT ELEMENT (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)

inoperative heated seat switch indicator lamps and
the heated seat elements do not heat, proceed. If the
problem being diagnosed involves inoperative heated
seat switch indicator lamps and the heated seat ele-
ments do heat, go to Step 6. If the problem being
diagnosed involves a heated seat switch indicator
lamp that remains illuminated after the heated seat
has been turned Off, (Refer to 8 - ELECTRICAL/
ELECTRONIC CONTROL MODULES/MEMORY
HEATED SEAT/MIRROR MODULE - DIAGNOSIS
AND TESTING).
(2) Disconnect and isolate the battery negative
cable. Remove the heated seat switch and bezel unit
from the instrument panel. Disconnect the heated
seat switch to be tested. Check for continuity
between the ground circuit cavity of the heated seat
switch and a good ground. There should be continu-
ity. 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 thumb wheel on the headlamp
switch upward to just before the interior lamps
detent. Check for battery voltage at the fused panel
lamps dimmer circuit cavity of the heated seat
switch. If OK, go to Step 4. If not OK, repair the
open fused panel lamps dimmer switch signal circuit
to the fuse in the Integrated Power Module as
required.
(4) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run) circuit cavity of the heated seat switch.
If OK, go to Step 5. If not OK, repair the open fused
ignition switch output (run) circuit as required.
(5) 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. If OK, refer to Step 6. If not OK, replace
the faulty heated seat switch.
HEATED SEAT SWITCH CONTINUITY
Switch PositionContinuity
BetweenResistance
Neutral 4 & 6 2.2 Kilohms
Low 4 & 6 .415 Kilohms
High 4 & 6 33 Ohms(6) 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 to 8 - ELEC-
TRICAL/ELECTRONIC CONTROL MODULES/
MEMORY HEATED SEAT/MIRROR MODULE -
DIAGNOSIS AND TESTING).
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Wait two minutes for the system reserve capac-
itor to discharge before beginning any airbag or
instrument panel service.
(3) Remove the center bezel from the instrument
panel (Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL CENTER BEZEL - REMOV-
AL).
(4) Remove the screws that secure the heated seat
switch bezel to the instrument panel center bezel.
(5) Remove the heated seat switch bezel and both
switches from the instrument panel as a unit.
(6) From the back of the heated seat switch bezel,
gently pry the switch free and push the heated seat
switch out through the front of the bezel.
INSTALLATION
NOTE: When installing the heated seat switches, be
certain they are installed in the proper mounting
holes of the heated seat switch 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 (Fig.
4).
(1) From the back of the heated seat switch bezel,
gently push the heated seat switch in through the
front of the bezel.
(2) Position the heated seat switch bezel to the
instrument panel center bezel and install the retain-
ing screws.
(3) Install the center bezel on the instrument
panel (Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL CENTER BEZEL - INSTAL-
LATION).
(4) Connect the battery negative cable.
(5) Verify vehicle and system operation.
DRHEATED SEAT SYSTEM 8G - 9
HEATED SEAT SWITCH (Continued)

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.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Disconnect the wire harness connectors from
the horns (Fig. 1).
(3) Remove mounting bolt and remove horns.
INSTALLATION
(1) Position horns and install mounting bolt.
Tighten the bolt to 10 N´m (85 in. lbs.).
(2) Connect wire harness connectors.
(3) Connect battery negative cable.
HORN SWITCH
DESCRIPTION
The horn switch is molded into the driver airbag.
The horn switch can not be serviced separately. For
service procedures, (Refer to 8 - ELECTRICAL/RE-
STRAINTS/DRIVER AIRBAG - REMOVAL).
DIAGNOSIS AND TESTING - HORN SWITCH
The most reliable, efficient, and accurate
means to diagnose the horn system requires the
use of a DRBIIItscan tool and the proper Diag-
nostic Procedures manual. The DRBIIItscan
tool can provide confirmation that the PCI data
bus is functional, that all of the electronic mod-
ules are sending and receiving the proper mes-
sages on the PCI data bus, and that the horns
are being sent the proper hard wired outputs
for them to perform their functions.
For complete circuit diagrams, refer to the appro-
priate wiring information. The wiring information
includes wiring diagrams, proper wire and connector
repair procedures, details of wire harness routing
and retention, connector pin-out information and
location views for the various wire harness connec-
tors, 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.
Fig. 1 HORN
1 - WIRE HARNESS CONNECTORS
2 - HORNS
3 - MOUNTING BOLT
8H - 2 HORNDR
HORN (Continued)

IGNITION CONTROL
TABLE OF CONTENTS
page page
IGNITION CONTROL
DESCRIPTION..........................1
SPECIFICATIONS
SPECIFICATIONS - TORQUE - IGNITION....3
ENGINE FIRING ORDER - 3.7L V-6.........4
ENGINE FIRING ORDER ± 4.7L V-8........4
FIRING ORDER / CABLE ROUTING ± 5.7L
V-8 ENGINE...........................4
ENGINE FIRING ORDER - 5.9L V-8.........4
SPARK PLUG CABLE ORDER ± 8.0L V-10
ENGINE..............................5
SPARK PLUG CABLE RESISTANCE........5
SPARK PLUGS........................5
IGNITION COIL RESISTANCE - 3.7L V-6.....6
IGNITION COIL RESISTANCE - 4.7L V-8.....6
IGNITION COIL RESISTANCE - 5.7L V-8.....6
IGNITION COIL RESISTANCE - 5.9L........6
IGNITION COIL RESISTANCE ± 8.0L V-10
ENGINE..............................6
IGNITION TIMING......................6
AUTOMATIC SHUT DOWN RELAY
DESCRIPTION - PCM OUTPUT.............6
OPERATION
OPERATION - PCM OUTPUT.............6
OPERATION - ASD SENSE - PCM INPUT....6
DIAGNOSIS AND TESTING - ASD AND FUEL
PUMP RELAYS........................7
REMOVAL.............................7
INSTALLATION..........................8
CAMSHAFT POSITION SENSOR
DESCRIPTION..........................8
OPERATION............................8
REMOVAL.............................11
INSTALLATION.........................14
DISTRIBUTOR
DESCRIPTION.........................16
OPERATION...........................16
REMOVAL.............................17INSTALLATION.........................18
DISTRIBUTOR CAP
DIAGNOSIS AND TESTING - DISTRIBUTOR
CAP - 5.9L V-8........................18
DISTRIBUTOR ROTOR
DIAGNOSIS AND TESTING - DISTRIBUTOR
ROTOR - 5.9L V-8.....................19
IGNITION COIL
DESCRIPTION.........................19
OPERATION...........................20
REMOVAL.............................23
INSTALLATION.........................24
KNOCK SENSOR
DESCRIPTION.........................25
OPERATION...........................25
REMOVAL.............................25
INSTALLATION.........................26
SPARK PLUG
DESCRIPTION.........................27
DIAGNOSIS AND TESTING - SPARK PLUG
CONDITIONS.........................27
REMOVAL.............................30
CLEANING
CLEANING AND ADJUSTMENT...........31
INSTALLATION.........................31
IGNITION COIL CAPACITOR
DESCRIPTION.........................33
OPERATION...........................33
REMOVAL.............................33
INSTALLATION.........................33
SPARK PLUG CABLE
DESCRIPTION.........................33
OPERATION...........................33
DIAGNOSIS AND TESTING - SPARK PLUG
CABLES............................33
REMOVAL.............................34
INSTALLATION.........................35
IGNITION CONTROL
DESCRIPTION
The ignition system is controlled by the Powertrain
Control Module (PCM) on all engines.
3.7L V-6 ENGINE
The 3.7L V-6 engine uses a separate ignition coil
for each cylinder. The one-piece coil bolts directly tothe cylinder head. Rubber boots seal the secondary
terminal ends of the coils to the top of all 6 spark
plugs. A separate electrical connector is used for each
coil.
Because of coil design, spark plug cables (second-
ary cables) are not used. A distributor is not used
with the 3.7L engine.
Two knock sensors (one for each cylinder bank) are
used to help control spark knock.
DRIGNITION CONTROL 8I - 1