warning light DODGE RAM 1500 1998 2.G Workshop Manual

INTERNATIONAL VEHICLE
CONTROL & DISPLAY
SYMBOLS
DESCRIPTION - INTERNATIONAL SYMBOLS
The graphic symbols illustrated in the following
International Control and Display Symbols Chart are
used to identify various instrument controls. The
symbols correspond to the controls and displays that
are located on the instrument panel.
FASTENER IDENTIFICATION
DESCRIPTION
The SAE bolt strength grades range from grade 2
to grade 8. The higher the grade number, the greater
the bolt strength. Identification is determined by the
line marks on the top of each bolt head. The actual
bolt strength grade corresponds to the number of line
marks plus 2. The most commonly used metric bolt
strength classes are 9.8 and 10.9. The metric
strength class identification number is imprinted on
the head of the bolt. The higher the class number,
the greater the bolt strength. Some metric nuts are
imprinted with a single-digit strength class on the
nut face. Refer to the Fastener Identification and
Fastener Strength Charts (Fig. 5) and (Fig. 6).
INTERNATIONAL SYMBOLS
1 High Beam 13 Rear Window Washer
2 Fog Lamps 14 Fuel
3 Headlamp, Parking Lamps, Panel Lamps 15 Engine Coolant Temperature
4 Turn Warning 16 Battery Charging Condition
5 Hazard Warning 17 Engine Oil
6 Windshield Washer 18 Seat Belt
7 Windshield Wiper 19 Brake Failure
8 Windshield Wiper and Washer 20 Parking Brake
9 Windscreen Demisting and Defrosting 21 Front Hood
10 Ventilating Fan 22 Rear hood (Decklid)
11 Rear Window Defogger 23 Horn
12 Rear Window Wiper 24 Lighter
DRINTRODUCTION 5

INSTALLATION
(1) Install support plate on axle flange (Fig. 66).
Tighten attaching bolts to 115 N´m (85 ft. lbs.).
(2) Install parking brake cable in the brake lever.
(3) Install the park brake shoes (Refer to 5 -
BRAKES/PARKING BRAKE/SHOES - INSTALLA-
TION). (Fig. 66).
(4) Install axle shaft, (Refer to 3 - DIFFEREN-
TIAL & DRIVELINE/REAR AXLE - 9 1/4/AXLE
SHAFTS - INSTALLATION).
(5) Adjust brake shoes to drum with brake gauge
(Refer to 5 - BRAKES/PARKING BRAKE/SHOES -
ADJUSTMENTS).
(6) Install the rotor (Refer to 5 - BRAKES/HY-
DRAULIC/MECHANICAL/ROTORS - INSTALLA-
TION).
(7) Install the caliper adapter (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/DISC
BRAKE CALIPER ADAPTER - INSTALLATION).
(8) Install the caliper (Refer to 5 - BRAKES/HY-
DRAULIC/MECHANICAL/DISC BRAKE CALIPERS
- INSTALLATION).
(9) Install the wheel and tire assembly (Refer to 22
- TIRES/WHEELS/WHEELS - STANDARD PROCE-
DURE).
PARKING BRAKE
DESCRIPTION
The parking brakes are operated by a system of
cables and levers attached to a primary and second-
ary shoe positioned within the drum section of the
rotor.
The drum-in-hat design utilizes an independent set
of shoes to park the vehicle (Fig. 67).
OPERATION
To apply the parking brake the pedal is depressed.
This creates tension in the cable which pulls forward
on the park brake lever. The lever pushes the park
brake shoes outward and into contact with the drum
section of the rotor. The contact of shoe to rotor parks
the vehicle.
A torsion locking mechanism is used to hold the
pedal in an applied position. Parking brake release is
accomplished by the hand release.
A parking brake switch is mounted on the parking
brake lever and is actuated by movement of the
lever. The switch, which is in circuit with the red
warning light in the dash, will illuminate the warn-
ing light whenever the parking brake is applied.
Parking brake adjustment is controlled by a cable
tensioner mechanism. The cable tensioner, once
adjusted at the factory, should not need further
adjustment under normal circumstances. Adjustment
may be required if a new tensioner, or cables are
installed, or disconnected.
CABLES
REMOVAL
REMOVAL - FRONT PARKING BRAKE CABLE
(1) Raise and support vehicle.
(2) Lockout the parking brake cable (Fig. 69).
(3) Loosen adjusting nut to create slack in front
cable.
(4) Remove the front cable from the cable connec-
tor.
Fig. 66 SUPPORT PLATE WITH BRAKES MOUNTED
1 - SUPPORT PLATE
2 - MOUNTING NUTS
Fig. 67 SUPPORT PLATE WITH BRAKES MOUNTED
1 - SUPPORT PLATE
2 - MOUNTING NUTS
5 - 36 BRAKES - BASEDR
SUPPORT PLATE (Continued)

BRAKES - ABS
TABLE OF CONTENTS
page page
BRAKES - ABS
DESCRIPTION.........................45
OPERATION...........................45
STANDARD PROCEDURE - ABS BRAKE
BLEEDING...........................46
SPECIFICATIONS
TORQUE CHART......................46
FRONT WHEEL SPEED SENSOR
DESCRIPTION.........................47
OPERATION...........................47
REMOVAL.............................48
INSTALLATION.........................48
REAR WHEEL SPEED SENSOR
DIAGNOSIS AND TESTING - REAR WHEEL
ANTILOCK...........................48
REMOVAL.............................48
INSTALLATION.........................48TONE WHEEL
DIAGNOSIS AND TESTING - REAR WHEEL
SPEED SENSOR......................49
HYDRAULIC/MECHANICAL
DESCRIPTION - ELECTRONIC VARIABLE
BRAKE PROPORTIONING...............49
OPERATION - ELECTRONIC VARIABLE
BRAKE PROPORTIONING...............49
HCU (HYDRAULIC CONTROL UNIT)
DESCRIPTION.........................49
OPERATION...........................49
REMOVAL.............................50
INSTALLATION.........................50
R WA L VA LV E
DESCRIPTION.........................50
OPERATION...........................50
REMOVAL.............................51
INSTALLATION.........................51
BRAKES - ABS
DESCRIPTION
The antilock brake system (ABS) is an electroni-
cally operated, three channel brake control system.
The vehicle has Electronic Variable Brake Propor-
tioning (EVBP) designed into the system which elim-
inates the combination/proportioning valve.
The system is designed to prevent wheel lockup
and maintain steering control during braking. Pre-
venting lockup is accomplished by modulating fluid
pressure to the wheel brake units.
The hydraulic system is a three channel design.
The front wheel brakes are controlled individually
and the rear wheel brakes in tandem. The ABS elec-
trical system is separate from other electrical circuits
in the vehicle. A specially programmed controller
antilock brake unit operates the system components.
ABS system major components include:
²Controller Antilock Brakes (CAB)
²Hydraulic Control Unit (HCU)
²Wheel Speed Sensors (WSS)
²ABS Warning Light
OPERATION
Battery voltage is supplied to the CAB. The CAB
performs a system initialization procedure at start
up. A check of the ABS motor is performed at 15miles per hour. Initialization consists of a static and
dynamic self check of system electrical components.
The static and dynamic checks occurs at ignition
start up. During the dynamic check, the CAB briefly
cycles solenoids to verify operation. An audible noise
may be heard during this self check. This noise
should be considered normal. The ABS motor and
pump are then checked at a speed of 15 mile per
hour.
If an ABS component exhibits a fault during ini-
tialization, the CAB illuminates the amber warning
light and registers a fault code in the microprocessor
memory.
The CAB monitors wheel speed sensor inputs con-
tinuously while the vehicle is in motion. However,
the CAB will not activate any ABS components as
long as sensor inputs indicate normal braking.
During normal braking, the master cylinder, power
booster and wheel brake units all function as they
would in a vehicle without ABS. The HCU compo-
nents are not activated.
The purpose of the antilock system is to prevent
wheel lockup. Preventing lockup helps maintain vehi-
cle braking action and steering control.
The antilock CAB activates the system whenever
sensor signals indicate periods of wheel slip.
The antilock system prevents lockup during a
wheel slip condition by modulating fluid apply pres-
sure to the wheel brake units.
DRBRAKES - ABS 5 - 45

PRESSURE TESTER METHOD
The engine should be at normal operating temper-
ature. Recheck the system cold if the cause of coolant
loss is not located during the warm engine examina-
tion.
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING.
Carefully remove the radiator pressure cap from
the filler neck and check the coolant level. Push
down on the cap to disengage it from the stop tabs.
Wipe the inside of the filler neck and examine the
lower inside sealing seat for nicks, cracks, paint, dirt
and solder residue. Inspect the radiator-to- reserve/
overflow tank hose for internal obstructions. Insert a
wire through the hose to be sure it is not obstructed.
Inspect the cams on the outside of the filler neck.
If the cams are damaged, seating of the pressure cap
valve and tester seal will be affected.
Attach pressure tester (7700 or an equivalent) to
radiator filler neck.
Operate the tester pump to apply 103.4 kPa (15
psi) pressure to the system. If the hoses enlarge
excessively or bulges while testing, replace as neces-
sary. Observe the gauge pointer and determine the
condition of the cooling system according to following
criteria:
Holds Steady:If the pointer remains steady for
two minutes, serious coolant leaks are not present in
system. However, there could be an internal leakthat does not appear with normal system test pres-
sure. If it is certain that coolant is being lost and
leaks cannot be detected, inspect for interior leakage
or perform Internal Leakage Test. Refer to INTER-
NAL LEAKAGE INSPECTION.
Drops Slowly:Indicates a small leak or seepage
is occurring. Examine all of the connections for seep-
age or slight leakage with a flashlight. Inspect the
radiator, hoses, gasket edges and heater. Seal the
small leak holes with a Sealer Lubricant (or equiva-
lent). Repair the leak holes and inspect the system
again with pressure applied.
Drops Quickly:Indicates that serious leakage is
occurring. Examine the system for external leakage.
If leaks are not visible, inspect for internal leakage.
Large radiator leak holes should be repaired by a
reputable radiator repair shop.
INTERNAL LEAKAGE INSPECTION
Remove the engine oil pan drain plug and drain a
small amount of engine oil. If coolant is present in
the pan, it will drain first because it is heavier than
oil. An alternative method is to operate engine for a
short period to churn the oil. After this is done,
remove the engine dipstick and inspect for water
globules. Also inspect the transmission dipstick for
water globules and transmission fluid cooler for leak-
age.
WARNING: WITH RADIATOR PRESSURE TESTER
TOOL INSTALLED ON RADIATOR, DO NOT ALLOW
PRESSURE TO EXCEED 145 kPa (21 PSI). PRES-
SURE WILL BUILD UP QUICKLY IF A COMBUSTION
LEAK IS PRESENT. TO RELEASE PRESSURE,
ROCK TESTER FROM SIDE TO SIDE. WHEN
REMOVING TESTER, DO NOT TURN TESTER MORE
THAN 1/2 TURN IF SYSTEM IS UNDER PRESSURE.
Operate the engine without the pressure cap on
the radiator until the thermostat opens. Attach a
Pressure Tester to the filler neck. If pressure builds
up quickly it indicates a combustion leak exists. This
is usually the result of a cylinder head gasket leak or
crack in engine. Repair as necessary.
If there is not an immediate pressure increase,
pump the Pressure Tester. Do this until indicated
pressure is within system range of 110 kPa (16 psi).
Fluctuation of the gauge pointer indicates compres-
sion or combustion leakage into cooling system.
Because the vehicle is equipped with a catalytic
converter,do notshort out cylinders to isolate com-
pression leak.
If the needle on dial of the pressure tester does not
fluctuate, race engine a few times to check for an
abnormal amount of coolant or steam. This would be
emitting from exhaust pipe. Coolant or steam from
Fig. 5 Leak Detection Using Black Light - Typical
1 - TYPICAL BLACK LIGHT TOOL
7 - 6 COOLINGDR
COOLING (Continued)

INSTALLATION
(1) Install fan blade assembly to electrically con-
trolled viscous fan drive. Tighten mounting bolts to
24 N´m (18 ft. lbs.) torque.
(2) Position the fan blade/viscous fan drive to the
vehicle as an assembly.
(3) Install the viscous fan drive assembly onto fan
pulley hub shaft (Fig. 4). Tighten mounting nut to
115 N´m (85 ft. lbs.) torque.
(4) Install upper fan shroud. Make sure the upper
shroud locks into the tabs on the lower radiator.
(5) Install two upper shroud mounting bolts.
Tighten to 11.8 N´m (105 in. lbs.) torque.
(6) Position the electronically controlled viscous
fan drive wiring into the channel in the upper fan
shroud (Fig. 5). Make sure the wiring is not pinched.
(7) Install the lower fan shroud into position and
verify the two locking tabs have seated.
(8) Install two push pin fasteners to lock lower fan
shroud to the main assembly.
NOTE: Verify that the fan drive electrical wire does
not interfere with fan blade travel when the fan
blade is spun by hand.
(9) Connect the wiring harness connector and
install the harness bracket to the upper radiator
shroud.(10) Install the coolant recovery container (Refer to
7 - COOLING/ENGINE/COOLANT RECOVERY
CONTAINER - INSTALLATION).
(11) Connect the battery negative cables.
NOTE:
Viscous Fan Drive Fluid Pump Out Requirement:
After installing a new viscous fan drive, bring the
engine speed up to approximately 2000 rpm and
hold for approximately two minutes. This will
ensure proper fluid distribution within the drive.
ENGINE BLOCK HEATER
DESCRIPTION
WARNING: DO NOT OPERATE ENGINE UNLESS
BLOCK HEATER CORD HAS BEEN DISCONNECTED
FROM POWER SOURCE AND SECURED IN PLACE.
THE POWER CORD MUST BE SECURED IN ITS
RETAINING CLIPS AND ROUTED AWAY FROM
EXHAUST MANIFOLDS AND MOVING PARTS.
An optional engine block heater is available with
all models. The heater is equipped with a power cord.
The cord is attached to an engine compartment com-
ponent with tie-straps. The heater warms the engine
providing easier engine starting and faster warm-up
in low temperatures. The heater is mounted in a core
hole of the engine cylinder block in place of a freeze
plug with the heating element immersed in engine
coolant. The 3.7L/4.7L gas powered engines have the
block heater located to the rear on the right side of
the engine (Fig. 6).
OPERATION
The heater warms the engine coolant providing
easier engine starting and faster warm-up in low
temperatures. Connecting the power cord to a
grounded 110-120 volt AC electrical outlet with a
grounded three wire extension cord provides the elec-
tricity needed to heat the element.
DIAGNOSIS AND TESTING - ENGINE BLOCK
HEATER
If the unit does not operate, possible causes can be
either the power cord or the heater element. Test the
power cord for continuity with a 110-volt voltmeter or
110-volt test light. Test heater element continuity
with an ohmmeter or a 12-volt test light.
CAUTION: To prevent damage, the power cord must
be secured in it's retainer clips and away from any
components that may cause abrasion or damage,
such as linkages, exhaust components, etc.
Fig. 5 Electronically Controlled Viscous Fan Drive
Wiring
1 - UPPER SHROUD
2 - WIRING
3 - GROMMET
7 - 36 ENGINEDR
RADIATOR FAN - 5.9L DIESEL (Continued)

²Engine loads and temperatures are high such as
when towing a trailer.
²Cool silicone fluid within the fan drive unit is
being redistributed back to its normal disengaged
(warm) position. This can occur during the first 15
seconds to one minute after engine start-up on a cold
engine.
LEAKS
Viscous fan drive operation is not affected by small
oil stains near the drive bearing. If leakage appears
excessive, replace the fan drive unit.
VISCOUS DRIVE
If the fan assembly free-wheels without drag (the
fan blades will revolve more than five turns when
spun by hand), replace the fan drive. This spin test
must be performed when the engine is cool.
For the following test, the cooling system must be
in good condition. It also will ensure against exces-
sively high coolant temperature.
WARNING: BE SURE THAT THERE IS ADEQUATE
FAN BLADE CLEARANCE BEFORE DRILLING.
(1) Drill a 3.18-mm (1/8-in) diameter hole in the
top center of the fan shroud.
(2) Obtain a dial thermometer with an 8 inch stem
(or equivalent). It should have a range of -18É-to-
105ÉC (0É-to-220É F). Insert thermometer through the
hole in the shroud. Be sure that there is adequate
clearance from the fan blades.
(3) Connect a tachometer and an engine ignition
timing light. The timing light is to be used as a
strobe light. This step cannot be used on the diesel
engine.(4) Block the air flow through the radiator. Secure
a sheet of plastic in front of the radiator. Use tape at
the top to secure the plastic and be sure that the air
flow is blocked.
(5) Be sure that the air conditioner (if equipped)
and blowe fan is turned off.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR FAN. DO
NOT WEAR LOOSE CLOTHING.
(6) Start the engine and operate at 2400 rpm.
Within ten minutes the air temperature (indicated on
the dial thermometer) should be up to 88É C (190É F).
Fan driveengagementshould start to occur at/be-
tween:
²3.7L Automatic - 93É C - 99ÉC (200É F - 210É F)
²3.7L Manual/4.7L Automatic/5.9L - 85É - 91É C
(185É - 195É F)
²4.7L Manual - 74É - 79É C (165É - 175É F)
²5.7L
²5.9L
²Engagement is distinguishable by a definite
increasein fan flow noise (roaring). The timing light
also will indicate an increase in the speed of the fan.
(7) When viscous drive engagement is verified,
remove the plastic sheet. Fan drivedisengagement
should start to occur at or between:
²3.7L Automatic - 76ÉC - 81ÉC (168É F - 178É F)
²3.7L Manual/4.7L Auto/ 5.9L - 67ÉC - 73ÉC (153É
F - 163É F)
²4.7L Manual - 56ÉC - 62ÉC (133É F - 143É F)
²5.7L
²5.9L
²8.0L engine - 93É to 101É C (190É - 205É F) Min-
imum 73ÉC (163ÉF). A definitedecreaseof fan flow
noise (roaring) should be noticed. If not, replace the
defective viscous fan drive unit.
CAUTION: Some engines equipped with serpentine
drive belts have reverse rotating fans and viscous
fan drives. They are marked with the word
REVERSE to designate their usage. Installation of
the wrong fan or viscous fan drive can result in
engine overheating.
Fig. 32 Viscous Fan Drive - Typical
1 - VISCOUS FAN DRIVE
2 - THERMOSTATIC SPRING
3 - MOUNTING NUT TO WATER PUMP HUB
DRENGINE 7 - 51
FAN DRIVE VISCOUS CLUTCH-GAS ENGINES (Continued)

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)

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)

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 the
Heated 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 notheat, 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
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
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 - 9
HEATED SEAT SYSTEM (Continued)

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 heatedseat 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
inoperative heated seat switch indicator lamps and
the heated seat elements do not heat, proceed. If the
Fig. 4 HEATED SEAT SWITCH
1 - HEATED SEAT SWITCH
2 - LIGHT-EMITTING DIODE (LED) INDICATOR LAMPS
8G - 12 HEATED SEAT SYSTEMDR
HEATED SEAT SWITCH (Continued)