2002 JEEP GRAND CHEROKEE power lock system

(5) Install and tighten the nut that secures the
battery positive cable eyelet terminal to the B(+) ter-
minal stud on the starter solenoid. Tighten the nut to
11.3 N´m (100 in. lbs.).
(6) Install and tighten the screw that secures the
battery negative cable ground eyelet terminal to the
right side of the engine block. Tighten the screw to
10.2 N´m (90 in. lbs.) for 4.0L engines, or 13.0 N´m
(115 in. lbs.) for 4.7L engines.
(7) Reconnect the battery wire harness connector
to the generator field terminal connector receptacle
on the back of the generator.
(8) Install the generator output cable eyelet termi-
nal onto the generator output terminal stud.
(9) Install and tighten the nut that secures the
generator output cable eyelet terminal to the genera-
tor output terminal stud. Tighten the nut to 10.7
N´m (95 in. lbs.).
(10) Position the cover for the generator output
terminal stud housing onto the back of the generator
and snap it into place.
(11) On models with the 4.7L engine, install the
battery harness clip onto the stud on the right side of
the intake manifold, then install and tighten the nut
that secures the clip to the stud. Tighten the nut to
11.3 N´m (100 in. lbs.).
(12) Install and tighten the screw that secures the
battery negative cable eyelet terminal to the inner
fender shield near the front of the battery. Tighten
the screw to 28.2 N´m (250 in. lbs.).(13) Reconnect the battery wire harness connector
to the right headlamp and dash wire harness connec-
tor located near the front of the battery.
(14) Install the battery positive cable and genera-
tor output cable eyelet terminal onto the PDC B(+)
terminal studs.
(15) Install and tighten the two nuts that secure
the battery positive cable and generator output cable
eyelet terminal to the PDC B(+) terminal studs.
Tighten the nuts to 11.3 N´m (100 in. lbs.).
(16) Close and latch the PDC cover.
(17) Reconnect the battery positive cable terminal
clamp to the battery positive terminal post. Tighten
the terminal clamp pinch-bolt hex nut to 6.8 N´m (60
in. lbs.).
(18) Reconnect the battery negative cable terminal
clamp to the battery negative terminal post. Tighten
the terminal clamp pinch-bolt hex nut to 6.8 N´m (60
in. lbs.).
(19) Apply a thin coating of petroleum jelly or
chassis grease to the exposed surfaces of the battery
cable terminal clamps and the battery terminal
posts.BATTERY TRAY
DESCRIPTION
The battery is mounted in a molded plastic battery
tray and support unit (Fig. 25) located in the right
front corner of the engine compartment. The battery
tray and support unit is secured at the rear with a
nut to a stud on the front wheelhouse inner panel, at
the outboard side with a screw to the side cowl rein-
forcement panel, and at the front with a screw
through a U-nut on a bracket of the radiator support.
The battery tray and support unit also includes
three upright stanchions that are molded into the
outboard side of the unit. These stanchions support
the Power Distribution Center (PDC). Refer to
Power Distribution Centerin the Power Distribu-
tion section of this service manual for more informa-
tion on the PDC.
A hole in the bottom of the battery tray is fitted
with a battery temperature sensor. Refer toBattery
Temperature Sensorin the Charging section of
this service manual for more information on the bat-
tery temperature sensor. Refer toBattery Hold
Downin this section of the service manual for more
information on the battery hold down hardware.
Fig. 24 Battery Cables - 4.7L Engine
1 - BATTERY POSITIVE CABLE
2 - BATTERY NEGATIVE CABLE
3 - CLIPS
WJBATTERY SYSTEM 8F - 21
BATTERY CABLE (Continued)

²a faulty or improperly adjusted switch that
allows a lamp to stay on. Refer to Ignition-Off Draw
Test in 8, Battery for more information.
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 DRBtscan tool. Per-
form the following inspections before attaching the
scan tool.(1) Inspect the battery condition. Refer to 8, Bat-
tery for procedures.
(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) 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
torque specifications.
(5) Inspect generator drive belt condition and ten-
sion. Tighten or replace belt as required. Refer to
Belt Tension Specifications in 7, Cooling System.
(6) Inspect automatic belt tensioner (if equipped).
Refer to 7, Cooling System for information.
(7) Inspect generator electrical connections at gen-
erator field, battery output, and ground terminal (if
equipped). Also check generator ground wire connec-
tion at engine (if equipped). They should all be clean
and tight. Repair as required.
SPECIFICATIONS
GENERATOR RATINGS - GAS POWERED
TYPE PART NUMBER RATED SAE AMPS ENGINES MINIMUM TEST AMPS
BOSCH 56041322 136 4.0L 6-Cylinder 100
DENSO 56041324 136 4.7L V-8 100
TORQUE - GAS POWERED
DESCRIPTION N-m Ft. Lbs. In. Lbs.
Generator Mounting Bolts-4.0L 55 41
Generator Vertical Mounting Bolt-4.7L 40 29
Generator (long) Horizontal Mounting
Bolt-4.7L55 41
Generator (short) Horizontal Mounting
Bolt-4.7L55 41
Generator B+ Terminal Nut 11 95
WJCHARGING 8F - 25
CHARGING (Continued)

STARTING
TABLE OF CONTENTS
page page
STARTING
DESCRIPTION.........................29
OPERATION...........................30
DIAGNOSIS AND TESTING - STARTING
SYSTEM............................30
SPECIFICATIONS
TORQUE - STARTER...................35
STARTER MOTOR - GAS POWERED......35
STARTER MOTOR
DESCRIPTION.........................35
OPERATION...........................36DIAGNOSIS AND TESTING - STARTER
MOTOR .............................36
REMOVAL.............................37
INSTALLATION.........................38
STARTER MOTOR RELAY
DESCRIPTION.........................38
OPERATION...........................38
DIAGNOSIS AND TESTING - STARTER RELAY . 38
REMOVAL.............................39
INSTALLATION.........................40
STARTING
DESCRIPTION
An electrically operated engine starting system is
standard factory-installed equipment on this model.
The starting system is designed to provide the vehi-
cle operator with a convenient, efficient and reliable
means of cranking and starting the internal combus-
tion engine used to power the vehicle and all of its
accessory systems from within the safe and secure
confines of the passenger compartment. See the own-
er's manual in the vehicle glove box for more infor-
mation and instructions on the recommended use
and operation of the factory-installed starting sys-
tem.
The starting system consists of the following com-
ponents:
²Battery
²Starter relay
²Starter motor (including an integral starter sole-
noid)
²Ignition switch
²Park/neutral position switch
²Wire harnesses and connections (including the
battery cables).
This group provides complete service information
for the starter motor and the starter relay. Complete
service information for the other starting system
components can be located as follows:
²Refer toBatteryin the proper section of Group
8A - Battery for complete service information for the
battery.
²Refer toIgnition Switch and Key Lock Cyl-
inderin the proper section of Group 8D - Ignition
System for complete service information for the igni-
tion switch.²Refer toPark/Neutral Position Switchin the
proper section of Group 21 - Transmission for com-
plete service information for the park/neutral posi-
tion switch.
²Refer to the proper section ofGroup 8W - Wir-
ing Diagramsfor complete service information and
circuit diagrams for the starting system wiring com-
ponents.
Group 8A covers the Battery, Group 8B covers the
Starting Systems, and Group 8C covers the Charging
System. We have separated these systems to make it
easier to locate the information you are seeking
within this Service Manual. However, when attempt-
ing to diagnose any of these systems, it is important
that you keep their interdependency in mind.
The battery, starting, and charging systems in the
vehicle operate with one another, and must be tested
as a complete system. In order for the vehicle to start
and charge properly, all of the components that are
used in these systems must perform within specifica-
tions.
The diagnostic procedures used in each of these
groups include the most basic conventional diagnostic
methods, to the more sophisticated On-Board Diag-
nostics (OBD) built into the Powertrain Control Mod-
ule (PCM). Use of an induction-type milliampere
ammeter, volt/ohmmeter, battery charger, carbon pile
rheostat (load tester), and 12-volt test lamp may be
required.
All OBD-sensed systems are monitored by the
PCM. Each monitored circuit is assigned a Diagnos-
tic Trouble Code (DTC). The PCM will store a DTC in
electronic memory for any failure it detects. Refer to
On-Board Diagnostic Test For Charging System
in the Diagnosis and Testing section of Group 8C -
Charging System for more information.
WJSTARTING 8F - 29

INSPECTION
For complete circuit diagrams, refer toStarting
Systemin the Contents of Group 8W - Wiring Dia-
grams. Before removing any unit from the starting
system for repair or diagnosis, perform the following
inspections:
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO GROUP 8M - PASSIVE
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING WHEEL, STEERING COLUMN, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
²Battery- Visually inspect the battery for indi-
cations of physical damage and loose or corroded
cable connections. Determine the state-of-charge and
cranking capacity of the battery. Charge or replace
the battery, if required. Refer toBatteryin the
proper section of Group 8A - Battery for complete ser-
vice information for the battery.
²Ignition Switch- Visually inspect the ignition
switch for indications of physical damage and loose
or corroded wire harness connections. Refer toIgni-
tion Switch and Key Lock Cylinderin the proper
section of Group 8D - Ignition System for complete
service information for the ignition switch.
²Park/Neutral Position Switch- Visually
inspect the park/neutral position switch for indica-
tions of physical damage and loose or corroded wire
harness connections. Refer toPark/Neutral Posi-
tion Switchin the proper section of Group 21 -
Transmission for complete service information for the
park/neutral position switch.
²Starter Relay- Visually inspect the starter
relay for indications of physical damage and loose or
corroded wire harness connections.
²Starter Motor- Visually inspect the starter
motor for indications of physical damage and loose or
corroded wire harness connections.
²Starter Solenoid- Visually inspect the starter
solenoid for indications of physical damage and loose
or corroded wire harness connections.
²Wiring- Visually inspect the wire harnesses for
damage. Repair or replace any faulty wiring, as
required. Refer to the proper section ofGroup 8W -
Wiring Diagramsfor complete service information
and circuit diagrams for the starting system wiring
components.TESTING
COLD CRANKING TEST
For complete circuit diagrams, refer toStarting
Systemin the Contents of Group 8W - Wiring Dia-
grams. The battery must be fully-charged and load-
tested before proceeding. Refer toBatteryin the
Diagnosis and Testing section of Group 8A - Battery
for the procedures.
(1) Connect a suitable volt-ampere tester to the
battery terminals (Fig. 1). See the instructions pro-
vided by the manufacturer of the volt-ampere tester
being used.
(2) Fully engage the parking brake.
(3) Place the automatic transmission gearshift
selector lever in the Park position.
(4) Verify that all lamps and accessories are
turned off.
(5) To prevent the engine from starting, remove
the Automatic ShutDown (ASD) relay. The ASD relay
is located in the Power Distribution Center (PDC), in
the engine compartment. Refer to the fuse and relay
layout label affixed to the underside of the PDC cover
for ASD relay identification and location.
(6) Rotate and hold the ignition switch in the Start
position. Note the cranking voltage and current
(amperage) draw readings shown on the volt-ampere
tester.
(a) If the voltage reads below 9.6 volts, refer to
Starter Motorin the Diagnosis and Testing sec-
tion of this group. If the starter motor is OK, refer
toEngine Diagnosisin the Diagnosis and Testing
section of Group 9 - Engine for further testing of
the engine. If the starter motor is not OK, replace
the faulty starter motor.
Fig. 1 Volts-Amps Tester Connections - Typical
1 - POSITIVE CLAMP
2 - NEGATIVE CLAMP
3 - INDUCTION AMMETER CLAMP
8F - 32 STARTINGWJ
STARTING (Continued)

(1) Remove the starter relay from the PDC. Refer
toStarter Relayin the Removal and Installation
section of this group for the procedures.
(2) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 3. If not OK, replace the faulty relay.
(3) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75   5 ohms. If OK, go to Step
4. If not OK, replace the faulty relay.
(4) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, perform the Relay Circuit Test that
follows. If not OK, replace the faulty relay.
RELAY CIRCUIT TEST
(1) The relay common feed terminal cavity (30) is
connected to battery voltage and should be hot at all
times. If OK, go to Step 2. If not OK, repair the open
circuit to the fuse in the PDC as required.
(2) The relay normally closed terminal (87A) is
connected to terminal 30 in the de-energized position,
but is not used for this application. Go to Step 3.
(3) The relay normally open terminal (87) is con-
nected to the common feed terminal (30) in the ener-
gized position. This terminal supplies battery voltage
to the starter solenoid field coils. There should be
continuity between the cavity for relay terminal 87
and the starter solenoid terminal at all times. If OK,
go to Step 4. If not OK, repair the open circuit to the
starter solenoid as required.
(4) The coil battery terminal (86) is connected to
the electromagnet in the relay. It is energized when
the ignition switch is held in the Start position.
Check for battery voltage at the cavity for relay ter-
minal 86 with the ignition switch in the Start posi-tion, and no voltage when the ignition switch is
released to the On position. If OK, go to Step 5. If
not OK, check for an open or short circuit to the igni-
tion switch and repair, if required. If the circuit to
the ignition switch is OK, refer toIgnition Switch
and Key Lock Cylinderin the Diagnosis and Test-
ing section of Group 8D - Ignition System for testing
of the ignition switch.
(5) The coil ground terminal (85) is connected to
the electromagnet in the relay. It is grounded
through the park/neutral position switch only when
the gearshift selector lever is in the Park or Neutral
positions. Check for continuity to ground at the cav-
ity for relay terminal 85. If not OK, check for an
open or short circuit to the park/neutral position
switch and repair, if required. If the circuit to the
park/neutral position switch is OK, refer toPark/
Neutral Position Switchin the Diagnosis and
Testing section of Group 21 - Transmission for testing
of the park/neutral position switch.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cover from the Power Distribution
Center (PDC) (Fig. 14) .
Fig. 13 Starter Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
Fig. 14 Power Distribution Center
1 - RIGHT FENDER
2 - BATTERY
3 - POWER DISTRIBUTION CENTER
4 - COVER
WJSTARTING 8F - 39
STARTER MOTOR RELAY (Continued)

not attach the wire harness connectors until the cur-
ing process is complete.
(11) Check the operation of the rear glass heating
grid.
REAR WINDOW DEFOGGER
RELAY
DESCRIPTION
The rear window defogger relay is an electrome-
chanical device that switches fused battery current to
the rear glass heating grid and the Light-Emitting
Diode (LED) indicator of the rear window defogger
switch, when the Body Control Module (BCM) rear
window defogger timer and logic circuitry grounds
the relay coil. The rear window defogger relay is
located in the junction block, under the left end of
the instrument panel in the passenger compartment.
The rear window defogger relay is a International
Standards Organization (ISO) relay. Relays conform-
ing to the ISO specifications have common physical
dimensions, current capacities, terminal patterns,
and terminal functions.
The rear window defogger relay cannot be repaired
or adjusted and, if faulty or damaged, it must be
replaced.
OPERATION
The ISO relay consists of an electromagnetic coil, a
resistor or diode, and three (two fixed and one mov-
able) electrical contacts. The movable (common feed)
relay contact is held against one of the fixed contacts
(normally closed) by spring pressure. When the elec-
tromagnetic coil is energized, it draws the movable
contact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact.
When the electromagnetic coil is de-energized,
spring pressure returns the movable contact to the
normally closed position. The resistor or diode is con-
nected in parallel with the electromagnetic coil in the
relay, and helps to dissipate voltage spikes that are
produced when the coil is de-energized.
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER RELAY
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
RELAY TEST
The rear window defogger relay (Fig. 4) is located
in the junction block, under the left end of the instru-
ment panel in the passenger compartment. Remove
the rear window defogger relay from the junction
block to perform the following tests:
(1) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 2. If not OK, replace the faulty relay.
(2) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75   10 ohms. If OK, go to Step
3. If not OK, replace the faulty relay.
(3) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, refer to theRelay Circuit Test.If
not OK, replace the faulty relay.
RELAY CIRCUIT TEST
(1) The relay common feed terminal cavity (30) is
connected to battery voltage and should be hot at all
times. If OK, go to Step 2. If not OK, repair the open
fused B(+) circuit to the Power Distribution Center
(PDC) fuse as required.
(2) The relay normally closed terminal (87A) is
connected to terminal 30 in the de-energized position,
but is not used for this application. Go to Step 3.
Fig. 4 REAR WINDOW DEFOGGER RELAY
TERMINAL LEGEND
NUMBER IDENTIFICATION
30 COMMON FEED
85 COIL GROUND
86 COIL BATTERY
87 NORMALLY OPEN
87A NORMALLY CLOSED
WJHEATED GLASS 8G - 5
REAR WINDOW DEFOGGER GRID (Continued)

HEATED SEAT SYSTEM
TABLE OF CONTENTS
page page
HEATED SEAT SYSTEM
DESCRIPTION..........................9
OPERATION...........................10
DIAGNOSIS AND TESTING - HEATED SEAT
SYSTEM............................10
DRIVER HEATED SEAT SWITCH
DESCRIPTION.........................11
OPERATION...........................11
DIAGNOSIS AND TESTING - DRIVER HEATED
SEAT SWITCH........................11
REMOVAL.............................12
INSTALLATION.........................13
HEATED SEAT ELEMENT
DESCRIPTION.........................13
OPERATION...........................13
DIAGNOSIS AND TESTING - HEATED SEAT
ELEMENT...........................14REMOVAL.............................14
INSTALLATION.........................14
HEATED SEAT SENSOR
DESCRIPTION.........................15
DIAGNOSIS AND TESTING - HEATED SEAT
SENSOR............................15
REMOVAL.............................15
PASSENGER HEATED SEAT SWITCH
DESCRIPTION.........................15
OPERATION...........................16
DIAGNOSIS AND TESTING - PASSENGER
HEATED SEAT SWITCH.................16
REMOVAL.............................17
INSTALLATION.........................17
HEATED SEAT SYSTEM
DESCRIPTION
Individually controlled driver and passenger side
electrically heated front seats are available factory-
installed optional equipment on this model, when it
is also equipped with the power seat option. The
heated seat system allows both the driver and the
front seat passenger the option to select one of two
seat heating ranges, Low or High, or to turn the indi-
vidual seat heaters Off using the heated seat
switches located in the center lower bezel near the
bottom of the instrument panel center stack (Fig. 1).
The heated seat switch circuit operates on ignition
switched battery current supplied through a fuse in
the junction block, only when the ignition switch is
in the On position.
The heated seat system consists of the following
components :
²Heated seat elements
²Heated seat sensors
²Heated seat module (or memory heated seat
module)
²Heated seat switches.
The heated seat system also relies upon resources
shared with other electronic modules in the vehicle
over the Programmable Communications Interface
(PCI) data bus network. The PCI data bus network
allows the sharing of sensor information. This helps
to reduce wire harness complexity, internal controller
hardware, and component sensor current loads. At
the same time, this system provides increased reli-
ability, enhanced diagnostics, and allows the addition
of many new feature capabilities. For diagnosis of
Fig. 1 HEATED SEAT SWITCHES
1 - HEATED SEAT SWITCHES
WJHEATED SEAT SYSTEM 8G - 9

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