Battery DODGE RAM 1500 1998 2.G Repair Manual

(6) Disconnect wire harness connector at the inop-
erative speaker. Check for continuity between the
speaker feed (+) circuit cavities of the radio receiver
wire harness connector or if equipped, the amplifier
wire harness connector and the speaker wire harness
connector. Repeat the check between the speaker
return (-) circuit cavities of the radio receiver wire
harness connector and the speaker wire harness con-
nector. In each case, there should be continuity. If
OK, replace the faulty speaker. If not OK, repair the
open speaker feed (+) and/or return (-) circuits(s) as
required.
REMOVAL
FRONT DOOR SPEAKER
(1) Disconnect and isolate the battery negative
cable.
(2) Remove front door trim panel (Refer to 23 -
BODY/DOOR - FRONT/TRIM PANEL - REMOVAL).
(3) Remove speaker mounting screws (Fig. 17).
(4) Disconnect electrical harness connector and
remove speaker.
INSTRUMENT PANEL CENTER SPEAKER
(1) Disconnect and isolate the battery negative
cable.
(2) Remove instrument panel top cover (Refer to
23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL TOP COVER - REMOVAL).
(3) Remove speaker mounting screws (Fig. 18).
(4) Disconnect electrical harness connector and
remove speaker.
INSTRUMENT PANEL END SPEAKER
(1) Disconnect and isolate the battery negative
cable.(2) Remove instrument panel top cover (Refer to
23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL TOP COVER - REMOVAL).
(3) Remove speaker mounting screws (Fig. 19)
(4) Disconnect electrical harness connector and
remove speaker.
REAR CAB SIDE SPEAKER
(1) Disconnect and isolate the battery negative
cable.
(2) Remove B-pillar lower trim (Refer to 23 -
BODY/INTERIOR/B-PILLAR LOWER TRIM -
REMOVAL).
(3) Remove speaker mounting screws (Fig. 20).
(4) Disconnect electrical harness connector and
remove speaker.
REAR DOOR SPEAKER
(1) Disconnect and isolate the battery negative
cable.
Fig. 17 FRONT DOOR SPEAKER
Fig. 18 INSTRUMENT PANEL CENTER SPEAKER
Fig. 19 INSTRUMENT PANEL END SPEAKER
8A - 14 AUDIO/VIDEODR
SPEAKER (Continued)

(2) Remove rear door trim panel (Refer to 23 -
BODY/DOORS - REAR/TRIM PANEL - REMOVAL).
(3) Remove speaker mounting screws (Fig. 21).
(4) Disconnect electrical harness connector and
remove speaker.
INSTALLATION
FRONT DOOR SPEAKER
(1) Connect electrical harness connector and
install speaker.
(2) Install front door trim panel (Refer to 23 -
BODY/DOOR - FRONT/TRIM PANEL - INSTALLA-
TION).
(3) Connect battery negative cable.
INSTRUMENT PANEL CENTER SPEAKER
(1) Connect electrical harness connector and
install speaker.
(2) Install instrument panel top cover (Refer to 23
- BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL TOP COVER - INSTALLATION).
(3) Connect battery negative cable.
INSTRUMENT PANEL END SPEAKER
(1) Connect electrical harness connector and
install speaker.
(2) Install instrument panel top cover (Refer to 23
- BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL TOP COVER - INSTALLATION).
(3) Connect battery negative cable.
REAR CAB SIDE SPEAKER
(1) Connect electrical harness connector and
install speaker.
(2) Install B-pillar lower trim (Refer to 23 - BODY/
INTERIOR/B-PILLAR LOWER TRIM - INSTALLA-
TION).
(3) Connect battery negative cable.
REAR DOOR SPEAKER
(1) Connect electrical harness connector and
install speaker.
(2) Install rear door trim panel (Refer to 23 -
BODY/DOORS - REAR/TRIM PANEL - INSTALLA-
TION).
(3) Connect battery negative cable.
Fig. 20 REAR CAB SIDE SPEAKER
Fig. 21 REAR DOOR SPEAKER
DRAUDIO/VIDEO 8A - 15
SPEAKER (Continued)

CHIME/BUZZER
TABLE OF CONTENTS
page page
CHIME WARNING SYSTEM
DESCRIPTION..........................1
OPERATION............................1DIAGNOSIS AND TESTING - CHIME
WARNING SYSTEM.....................3
CHIME WARNING SYSTEM
DESCRIPTION
A chime warning system is standard factory-in-
stalled equipment on this model. The chime warning
system uses a single chime tone generator that is
integral to the instrument cluster to provide an audi-
ble indication of various vehicle conditions that may
require the attention of the vehicle operator. The
chime warning system includes the following major
components, which are described in further detail
elsewhere in this service information:
²Door Ajar Switch- A door ajar switch is inte-
gral to each door latch. This switch provides an input
to the chime warning system indicating whether the
front doors are open or closed.
²Ignition Switch- A key-in ignition switch is
integral to the ignition switch. The key-in ignition
switch provides an input to the chime warning sys-
tem indicating whether a key is present in the igni-
tion lock cylinder.
²Instrument Cluster- The instrument cluster
contains an integral chime tone generator, integrated
circuitry, a central processing unit and the program-
ming to provide all of the proper chime warning sys-
tem features based upon the monitored inputs. The
instrument cluster circuitry monitors hard-wired
switch inputs, as well as message inputs received
from other vehicle electronic modules on the Pro-
grammable Communications Interface (PCI) data bus
network.
²Headlamp Switch- The headlamp switch pro-
vides an input to the chime warning system indicat-
ing when the exterior lamps are turned On or Off.
²Seat Belt Switch- A seat belt switch is inte-
gral to the driver seat belt buckle-half unit. The seat
belt switch provides an input to the chime warning
system indicating whether the driver seat belt is fas-
tened.
Hard wired circuitry connects many of the chime
warning system components to each other through
the electrical system of the vehicle. These hard wired
circuits are integral to several wire harnesses, which
are routed throughout the vehicle and retained bymany different methods. Refer to the appropriate
wiring information.
The instrument cluster chime warning system cir-
cuitry and the integral chime tone generator cannot
be adjusted or repaired. If the instrument cluster or
the chime tone generator are damaged or faulty, the
instrument cluster must be replaced.
OPERATION
The chime warning system is designed to provide
an audible output as an indication of various condi-
tions that may require the attention or awareness of
the vehicle operator. The chime warning system com-
ponents operate on battery voltage received through
the Ignition-Off Draw (IOD) fuse in the Power Distri-
bution Center (PDC) so that the system may operate
regardless of the ignition switch position.
The chime warning system provides an audible
warning to the vehicle operator under the following
conditions:
²Air Bag Warning- The instrument cluster
chime tone generator will generate a single chime
tone when the airbag indicator is illuminated for an
airbag system fault condition. The instrument cluster
uses airbag indicator lamp-on and lamp-off message
inputs received from the Airbag Control Module
(ACM) over the Programmable Communications
Interface (PCI) data bus indicating that the airbag
indicator should be illuminated for an airbag system
fault condition.
²Door Ajar Warning- The instrument cluster
chime tone generator will generate a single chimes to
announce that the hard wired inputs from the door
ajar switches and the ignition switch as well as an
engine speed message input received from the PCM
over the PCI data bus indicate that a driver or pas-
senger door is opened with the ignition switch in the
On position and vehicle speed present.
²Engine Coolant Temperature High Warning
(Diesel Engine Only)- The instrument cluster
chime tone generator will generate a single chime
tone when the check gauges indicator is illuminated
for a high or critical engine coolant temperature con-
dition. The instrument cluster uses engine coolant
temperature message inputs received from the diesel
DRCHIME/BUZZER 8B - 1

Engine Control Module (ECM) over the PCI data bus
to illuminate the check gauges indicator for a coolant
temperature high condition.
²Fasten Seat Belt Warning- The instrument
cluster chime tone generator will generate repetitive
chimes at a slow rate each time the ignition switch is
turned to the On or Start positions to announce that
the hard wired inputs from the seat belt switch and
the ignition switch indicate that the driver side front
seat belt is not fastened. The chimes will continue to
sound for a duration of about six seconds, until the
driver side front seat belt is fastened, or until the
ignition switch is turned to the Off position, which-
ever occurs first.
²Head/Park Lamps-On Warning- The instru-
ment cluster chime tone generator will generate
repetitive chimes at a slow rate to announce that the
hard wired inputs from the driver door ajar switch,
the ignition switch, and the exterior lighting circuitry
of the headlamp switch indicate that the exterior
lamps are turned On with the driver door opened
and the ignition switch in the Off position. The
chimes will continue to sound until the exterior
lamps are turned Off, the driver door is closed, or the
ignition switch is turned to the On position, or the
battery protection time-out expires, whichever occurs
first.
²Key-In-Ignition Warning- The instrument
cluster chime tone generator will generate repetitive
chimes at a slow rate to announce that the hard
wired inputs from the driver door ajar switch, the
ignition switch, and the key-in ignition circuitry of
the ignition switch indicate that the key is in the
ignition lock cylinder with the driver door opened
and the ignition switch in the Off position. The
chimes will continue to sound until the key is
removed from the ignition lock cylinder, the driver
door is closed, or the ignition switch is turned to the
On position, whichever occurs first.
²Low Fuel Warning- The instrument cluster
chime tone generator will generate one chime tone
when the low fuel indicator is illuminated by the
instrument cluster. The instrument cluster uses a
percent tank full message input received from the
PCM over the PCI data bus indicating that there is
less than about one-eighth tank of fuel remaining to
illuminate the low fuel indicator. This chime feature
will only occur once in an ignition cycle.
²Low Oil Pressure Warning (Diesel Engine
Only)- The instrument cluster chime tone generator
will generate repetitive chimes at a fast rate when
the check gauges indicator is illuminated for a low oil
pressure condition. The instrument cluster uses
engine speed and oil pressure message inputs
received from the diesel Engine Control Module
(ECM) over the PCI data bus indicating that theengine is running and that the oil pressure is low to
illuminate the check gauges indicator. The chimes
will continue to sound for five seconds, until the
engine oil pressure message indicates that the oil
pressure is not low, or until the engine speed mes-
sage indicates that the engine is not running, which-
ever occurs first. This chime tone will only occur once
in an ignition cycle.
²Low Wash Warning- The instrument cluster
chime tone generator will generate one chime tone
when the low washer fluid indicator is illuminated by
the instrument cluster. The instrument cluster uses a
message input received from the Front Control Mod-
ule (FCM) over the PCI data bus indicating that
washer fluid level is low within the washer reservoir.
This chime feature will only occur once in an ignition
cycle.
²Overspeed Warning- The instrument cluster
chime tone generator will generate one chime tone to
announce that a vehicle speed message input
received from the PCM over the PCI data bus indi-
cates that the vehicle speed is above a pre-programed
limit.
²Park Brake Reminder- The instrument clus-
ter chime tone generator will generate ten repetitive
chimes at a slow rate to announce that the hard
wired input from the park brake switch and a vehicle
speed message input received from the PCM over the
PCI data bus indicates that the park brake is applied
and the vehicle is moving. This chime feature will
repeat each time the input conditions are met.
²Sentry Key Immobilizer System ªCustomer
Learnº Mode Announcement- This chime feature
is only active on vehicles equipped with the optional
Sentry Key Immobilizer System (SKIS) and sold in
markets where the optional ªCustomer Learnº pro-
gramming feature is available. The instrument clus-
ter chime tone generator will generate one chime to
announce that a status message input received from
the Sentry Key Immobilizer Module (SKIM) over the
PCI data bus indicates that the SKIS is in the ªCus-
tomer Learnº mode, which is used for programming
additional sentry key transponders.
²Transmission Temperature High Warning
(Automatic Transmission only)- The instrument
cluster chime tone generator will generate repetitive
chimes at a slow rate when the transmission temper-
ature indicator is illuminated for a high or critical
transmission fluid temperature condition. The instru-
ment cluster uses transmission temperature message
inputs received from the Transmission Control Mod-
ule (TCM) over the PCI data bus to illuminate the
indicator for a transmission temperature high condi-
tion.
²Turn Signal On Warning- The instrument
cluster chime tone generator will generate repetitive
8B - 2 CHIME/BUZZERDR
CHIME WARNING SYSTEM (Continued)

chimes at a slow rate to announce that the hard
wired input for the right or left turn signal indicator
as well as vehicle distance and speed message inputs
received from the PCM over the PCI data bus indi-
cate that a turn signal has been active continuously
for 1.6 kilometers (1 mile) with the vehicle speed
greater than 22 kilometers-per-hour (15 miles-per
hour). Vehicles built for markets other than the
United States and Canada have a revised distance
threshold of 4 kilometers for this feature. The chime
will continue until the turn signal input becomes
inactive, the status changes, or until the vehicle
speed message indicates that the speed is less than
22 kilometers-per-hour (15 miles-per-hour), which-
ever occurs first. The hazard warning flashers will
not activate this chime feature.
²Warning Lamp Announcement- The instru-
ment cluster chime tone generator will generate a
single chime when the check gauges indicator is illu-
minated when any critical engine and transmission
systems are out of their operating parameters. The
instrument cluster uses system inputs received over
the PCI data bus to illuminate the check gauges indi-
cator.
The instrument cluster provides chime service for
all available features in the chime warning system.
The instrument cluster relies upon its internal pro-
gramming, hard wired inputs from numerous
switches, and electronic message inputs received
from other electronic modules over the PCI data bus
network. Upon receiving the proper inputs, the
instrument cluster activates the integral chime tone
generator to provide the audible chime to the vehicle
operator. The chime tone generator in the instrument
cluster is capable of producing single chime tones, or
repeated chime tones at two different rates: about
fifty chime tones per minute, or about 180 chime
tones per minute. The internal programming of the
instrument cluster determines the priority of each
chime request input that is received, as well as the
rate and duration of each chime that is to be gener-
ated.
The hard wired chime warning system inputs to
the instrument cluster, as well as other hard wiredcircuits for this system may be diagnosed and tested
using conventional diagnostic tools and procedures.
However, conventional diagnostic methods may not
prove conclusive in the diagnosis of the instrument
cluster or the PCI data bus network. The most reli-
able, efficient and accurate means to diagnose the
instrument cluster and the PCI data bus network
inputs for the chime warning system requires the use
of a DRBIIItscan tool. Refer to the appropriate diag-
nostic information.
DIAGNOSIS AND TESTING - CHIME WARNING
SYSTEM
The chime warning system features driven by hard
wired inputs to the instrument cluster may be diag-
nosed and tested using conventional diagnostic tools
and procedures. However, conventional diagnostic
methods may not prove conclusive in the diagnosis of
the chime warning system features driven by mes-
sage inputs to the instrument cluster over the Pro-
grammable Communications Interface (PCI) data bus
network. The most reliable, efficient and accurate
means to diagnose the instrument cluster and the
PCI data bus network inputs for the chime warning
system requires the use of a DRBIIItscan tool. Refer
to the appropriate diagnostic and 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.
DRCHIME/BUZZER 8B - 3
CHIME WARNING SYSTEM (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
1. Driver door ajar switch
sense circuit open.1. Check for continuity between the driver door
ajar switch sense circuit connector and the
instrument cluster connector. Repair the open
driver door ajar switch sense circuit, if required.
2. Headlamp switch signal
circuit open.2. Check for continuity between the headlamp
switch output circuit connector and the and the
instrument cluster connector. Repair the open
headlamp switch signal circuit, if required.
NO CHIMES AND OTHER
INSTRUMENT CLUSTER
FEATURES ERRATIC OR
DISABLED1. Instrument cluster ground
circuit(s) open.1. Check for continuity between the ground
circuits of the instrument cluster connector and a
good ground. Repair the open ground circuits(s),
if required.
2. Instrument cluster fused
B(+) circuit(s) open.2. Check for battery voltage at the B(+) circuits of
the instrument cluster connector. Repair the open
fused B(+) circuit(s), if required.
3. Instrument cluster fused
ignition switch output
(run-start) circuit open.3. With the ignition switch in the On position,
check for battery voltage at the fused ignition
switch output (run-start) circuit of the instrument
cluster connector. Repair the open fused ignition
switch output (run-start) circuit, if required.
4. Faulty instrument cluster. 4. Replace the faulty instrument cluster, if
required.
NO CHIMES, BUT ALL
OTHER INSTRUMENT
CLUSTER FEATURES OK1. Faulty instrument cluster. 1. Replace the faulty instrument cluster, if
required.
DRCHIME/BUZZER 8B - 5
CHIME WARNING SYSTEM (Continued)

The PCI data bus can be monitored using the
DRBIIItscan tool. It is possible, however, for the bus
to pass all DRBIIIttests and still be faulty if the
voltage parameters are all within the specified range
and false messages are being sent.
CONTROLLER ANTILOCK
BRAKE
DESCRIPTION
The Controler Antilock Brake (CAB) is mounted to
the Hydraulic Control Unit (HCU) and operates the
ABS system (Fig. 1).
OPERATION
The CAB voltage source is through the ignition
switch in the RUN position. The CAB contains a self
check program that illuminates the ABS warning
light when a system fault is detected. Faults are
stored in a diagnostic program memory and are
accessible with the DRB III scan tool. ABS faults
remain in memory until cleared, or until after the
vehicle is started approximately 50 times. Stored
faults arenoterased if the battery is disconnected.
NOTE: If the CAB is being replaced with a new CAB
is must be reprogrammed with the use of a DRB III.
REMOVAL
(1) Remove the negative battery cable from the
battery.
(2) Pull up on the CAB harness connector release
and remove connector.
(3) Remove the CAB mounting bolts.
(4) Remove the pump connector from the CAB.
(5) Remove the CAB from the HCU.
INSTALLATION
NOTE: If the CAB is being replaced with a new CAB
is must be reprogrammed with the use of a DRB III.
(1) Install CAB to the HCU.
(2) Install the pump connector to the CAB.
(3) Install mounting bolts. Tighten to 2 N´m (16 in.
lbs.).
(4) Install the wiring harness connector to the
CAB and push down on the release to secure the con-
nector.
(5) Install negative battery cable to the battery.
DATA LINK CONNECTOR
DESCRIPTION - DATA LINK CONNECTOR
The Data Link Connector (DLC) is located at the
lower edge of the instrument panel near the steering
column.
OPERATION - DATA LINK CONNECTOR
The 16±way data link connector (diagnostic scan
tool connector) links the Diagnostic Readout Box
(DRB) scan tool or the Mopar Diagnostic System
(MDS) with the Powertrain Control Module (PCM).
ENGINE CONTROL MODULE
DESCRIPTION - ECM
The engine control module (ECM) for the 5.9L Die-
sel engine is bolted to the left side of the engine
below the intake manifold.
OPERATION - ECM
The main function of the Engine Control Module
(ECM) is to electrically control the fuel system. The
Powertrain Control Module (PCM)does notcontrol
the fuel system.
The ECM can adapt its programming to meet
changing operating conditions.If the ECM has
been replaced, flashed or re-calibrated, the
ECM must learn the Accelerator Pedal Position
Sensor (APPS) idle voltage. Failure to learn
this voltage may result in unnecessary diagnos-
tic trouble codes. Refer to ECM Removal/Instal-
lation for learning procedures.
The ECM receives input signals from various
switches and sensors. Based on these inputs, the
ECM regulates various engine and vehicle operations
through different system components. These compo-
nents are referred to asECM Outputs.The sensors
and switches that provide inputs to the ECM are
consideredECM Inputs.
Fig. 1 HYDRAULIC CONTROL UNIT
1 - HYDRAULIC CONTROL UNIT
2 - MOUNTING BOLTS
DRELECTRONIC CONTROL MODULES 8E - 3
COMMUNICATION (Continued)

NOTE: ECM Inputs:
²Accelerator Pedal Position Sensor (APPS) Volts
²APPS1 Signal Ð For off engine APPS
²APPS2 Signal Ð For off engine APPS
²APPS idle validation switches #1 and #2
²Battery Temperature
²Battery voltage
²Camshaft Position Sensor (CMP)
²CCD bus (+) circuits
²CCD bus (-) circuits
²Crankshaft Position Sensor (CKP)
²Data link connection for DRB scan tool
²Engine Coolant Temperature (ECT) sensor
²Fuel pressure sensor
²Fan speed (engine cooling fan)
²Ground circuits
²Inlet air temperature sensor/pressure sensor
²Intake air temperature sensor/MAP sensor
²Oil Pressure switch
²Power ground
²Sensor return
²Signal ground
²Water-In-Fuel (WIF) sensor
NOTE: ECM Outputs:
After inputs are received by the ECM, certain sen-
sors, switches and components are controlled or reg-
ulated by the ECM. These are consideredECM
Outputs.These outputs are for:
²CCD bus (+) circuits
²CCD bus (-) circuits
²CKP and APPS outputs to the PCM
²Data link connection for DRB scan tool
²Fan Clutch PWM
²Five volt sensor supply
²Fuel Control Actuator
²Fuel transfer (lift) pump
²Intake manifold air heater relays #1 and #2 con-
trol circuits
²Malfunction indicator lamp (Check engine lamp)
(databus)
²Oil Pressure Swith/warning lamp (databus)
²Wait-to-start warning lamp (databus)
²Water-In-Fuel (WIF) warning lamp (databus)
REMOVAL
The engine control module (ECM) is bolted to a
support bracket near the fuel filter. The support
bracket mounts to the block with four capscrews and
vibration isolators. A ground wire is fastened to the
bracket. The other end of the wire is fastened to the
engine block.
(1) Record any Diagnostic Trouble Codes (DTC's)
found in the ECM.To avoid possible voltage spike damage to the
ECM, ignition key must be off, and both negative
battery cables must be disconnected before unplug-
ging ECM connectors.
(2) Disconnect both negative battery cables at both
batteries.
(3) Remove the 50±way and 60±way connector
bolts at the ECM. Note: The connector bolt is a
female allen head. As bolt is being removed, very
carefully remove connectors from the ECM.
(4) Remove five ECM mounting bolts and remove
ECM from the vehicle (Fig. 2).
INSTALLATION
Do not apply paint to ECM or a poor ground will
result.
(1) Position the ECM to the ECM support bracket
and install the five mounting bolts. Tighten the bolts
to 24 N´m (18 ft. lbs.).
(2) Check pin connectors in ECM, 50±way and
60±way connectors for corrosion or damage. Repair
as necessary.
(3) Clean pins in the 50±way and 60±way electri-
cal connectors with a electrical contact cleaner.
(4) Install the 50±way and 60±way connectors to
ECM. Tighten connector bolts to 3 N´m (27 in. lbs.).
(5) Reconnect both negative battery cables.
(6) Use DRBIIItscan tool to erase any stored com-
panion DTC's from ECM.
Fig. 2 Diesel ECM
1 - ENGINE CONTROL MODULE (ECM)
2 - ECM MOUNTING BOLT
3 - 50-WAY CONNECTOR
4 - SUPPORT PLATE
5 - 60-WAY CONNECTOR
8E - 4 ELECTRONIC CONTROL MODULESDR
ENGINE CONTROL MODULE (Continued)

FRONT CONTROL MODULE
DESCRIPTION
The Front Control Module (FCM) is a micro con-
troller based module located in the left front corner
of the engine compartment. On this model the inte-
grated power module must be positioned aside in
order to access the front control module. The front
control module mates to the power distribution cen-
ter to form the Integrated Power Module (IPM). The
integrated power module connects directly to the bat-
tery and provides the primary means of circuit pro-
tection and power distribution for all vehicle
electrical systems. The front control module controls
power to some of these vehicle systems electrical and
electromechanical loads based on inputs received
from hard wired switch inputs and data received on
the PCI bus circuit (J1850).
For information on theIntegrated Power Mod-
ule Refer to the Power Distribution Sectionof
the service manual.
OPERATION
As messages are sent over the PCI bus circuit, the
front control module reads these messages and con-
trols power to some of the vehicles electrical systems
by completing the circuit to ground (low side driver)
or completing the circuit to 12 volt power (high side
driver). The following functions areControlledby
the Front Control Module:
²Headlamp Power with Voltage Regulation
²Windshield Wiper ªON/OFFº Relay Actuation
²Windshield Wiper ªHI/LOº Relay Actuation
²Windshield Washer Pump Motor
²Fog Lamp Relay Actuation
²Park Lamp Relay Actuation
²Horn Relay Actuation
The following inputs areReceived/Monitoredby
the Front Control Module:
²B+ Connection Detection
²Power Ground
²Ambient Temperature Sensing
²Ignition Switch Run
²Washer Fluid Level Switch
²Windshield Wiper Park Switch
²PCI Bus Circuit
DIAGNOSIS AND TESTING - FRONT CONTROL
MODULE
The front control module is a printed circuit board
based module with a on-board micro-processor. The
front control module interfaces with other electronic
modules in the vehicle via the Programmable Com-
munications Interface (PCI) data bus (J1850). In
order to obtain conclusive testing the Programmable
Communications Interface (PCI) data bus network
and all of the electronic modules that provide inputs
to, or receive outputs from the front control module
must be checked. All PCI (J1850) communication
faults must be resolved prior to further diagnosing
any front control module related issues.
The front control module was designed to be diag-
nosed with an appropriate diagnostic scan tool, such
as the DRB IIIt. The most reliable, efficient, and
accurate means to diagnose the front control module
requires the use of a DRB IIItscan tool and the
proper Body Diagnostic Procedures manual.
Before any testing of the front control module is
attempted, the battery should be fully charged and
all wire harness and ground connections inspected
around the affected areas on the vehicle.
REMOVAL
(1) Disconnect the positive and negative battery
cables from the battery.
(2) Partially remove the integrated power module
from the engine compartment (Refer to 8 - ELECTRI-
CAL/POWER DISTRIBUTION/INTEGRATED
POWER MODULE - REMOVAL).
(3) Remove the front control module retaining
screws.
(4) Using both hands, pull the front control module
straightfrom the integrated power module assembly
to disconnect the 49-way electrical connector and
remove the front control module from the vehicle.
INSTALLATION
(1) Install the front control module on the inte-
grated power module assembly by pushing the
49-way electrical connector straight in.
(2) Install the front control module retaining
screws. Torque the screws to 7 in. lbs.
(3) Install the integrated power module (Refer to 8
- ELECTRICAL/POWER DISTRIBUTION/INTE-
GRATED POWER MODULE - INSTALLATION).
(4) Connect the positive and negative battery
cables.
DRELECTRONIC CONTROL MODULES 8E - 5

HEATED SEAT MODULE
DESCRIPTION
The heated seat module is also known as the Seat
Heat Interface Module. The heated seat module (Fig.
3) is located under the drivers front seat cushion,
where it is secured to a mounting bracket. The
heated seat module has a single connector receptacle
that allows the module to be connected to all of the
required inputs and outputs through the seat wire
harness.
The heated seat module is an electronic micropro-
cessor controlled device designed and programmed to
use inputs from the battery, the two heated seat
switches and the two heated seat sensors to operate
and control the heated seat elements in both front
seats and the two heated seat indicator lamp Light-
Emitting Diodes (LEDs) in each heated seat switch.
The heated seat module is also programmed to per-
form self-diagnosis of certain heated seat system
functions and provide feedback of that diagnosis
through the heated seat switch indicator lamps.
The heated seat module cannot be repaired. If the
heated seat module is damaged or faulty, the entire
module must be replaced.
OPERATION
The heated seat module operates on fused battery
current received from the integrated power module.
Inputs to the module include a resistor multiplexed
heated seat switch request circuit for each of the two
heated seat switches and the heated seat sensor
inputs from the seat cushions of each front seat. In
response to those inputs the heated seat module con-
trols battery current feeds to the heated seat ele-ments and sensors, and controls the ground for the
heated seat switch indicator lamps.
When a heated seat switch (Driver or Passenger) is
depressed a signal is received by the heated seat
module, the module energizes the proper indicator
LED (Low or High) in the switch by grounding the
indicator lamp circuit to indicate that the heated seat
system is operating. At the same time, the heated
seat module energizes the selected heated seat sensor
circuit and the sensor provides the module with an
input indicating the surface temperature of the
selected seat cushion.
The Low heat set point is about 36É C (96.8É F),
and the High heat set point is about 42É C (107.6É F).
If the seat cushion surface temperature input is
below the temperature set point for the selected tem-
perature setting, the heated seat module energizes
an N-channel Field Effect Transistor (N-FET) within
the module which energizes the heated seat elements
in the selected seat cushion and back. When the sen-
sor input to the module indicates the correct temper-
ature set point has been achieved, the module
de-energizes the N-FET which de-energizes the
heated seat elements. The heated seat module will
continue to cycle the N-FET as needed to maintain
the selected temperature set point.
If the heated seat module detects a heated seat
sensor value input that is out of range or a shorted
or open heated seat element circuit, it will notify the
vehicle operator or the repair technician of this con-
dition by flashing the High and/or Low indicator
lamps in the affected heated seat switch. Refer to
Diagnosis and Testing Heated Seat Systemin
Heated Systems for flashing LED diagnosis and test-
ing procedures. Refer toDiagnosis and Testing
Heated Seat Modulein this section for heated seat
module diagnosis and testing procedures.
DIAGNOSIS AND TESTING - HEATED SEAT
MODULE
If a heated seat fails to heat and one or both of the
indicator lamps on a heated seat switch flash, refer
toDiagnosis and Testing Heated Seat Systemin
Heated Seats for the location of flashing LED heated
seat system diagnosis and testing procedures. If a
heated seat heats but one or both indicator lamps on
the heated seat switch fail to operate, test the heated
seat switch. Refer toDiagnosis and Testing
Heated Seat Switchin Heated Seats for heated
seat switch diagnosis and testing procedures. If the
heated seat switch checks OK, proceed as follows.
(1) Check the heated seat element (Refer to 8 -
ELECTRICAL/HEATED SEATS/HEATED SEAT
ELEMENT - DIAGNOSIS AND TESTING).
Fig. 3 Heated Seat Module
1 - MOUNTING TABS (NOT USED ON DR)
2 - HEATED SEAT MODULE
3 - ELECTRICAL CONNECTOR RECEPTACLE
8E - 6 ELECTRONIC CONTROL MODULESDR