1998 DODGE RAM 1500 table of contents

CHARGING
TABLE OF CONTENTS
page page
CHARGING
DESCRIPTION.........................19
OPERATION...........................19
DIAGNOSIS AND TESTING - CHARGING
SYSTEM............................19
SPECIFICATIONS
GENERATOR RATINGS.................20
SPECIFICATIONS - TORQUE - GENERATOR
/ CHARGING SYSTEM..................20
BATTERY TEMPERATURE SENSOR
DESCRIPTION.........................21OPERATION...........................21
REMOVAL.............................21
INSTALLATION.........................21
GENERATOR
DESCRIPTION.........................21
OPERATION...........................21
REMOVAL.............................22
INSTALLATION.........................24
VOLTAGE REGULATOR
DESCRIPTION.........................25
OPERATION...........................25
CHARGING
DESCRIPTION
The charging system consists of:
²Generator
²Electronic Voltage Regulator (EVR) circuitry
within the Powertrain Control Module (PCM). Elec-
tronic Control Module (ECM) for diesel engines.
²Ignition switch
²Battery (refer to 8, Battery for information)
²Battery temperature sensor
²Check Gauges Lamp (if equipped)
²Voltmeter (refer to 8, Instrument Panel and
Gauges for information)
²Wiring harness and connections (refer to 8, Wir-
ing Diagrams for information)
OPERATION
The charging system is turned on and off with the
ignition switch. The system is on when the engine is
running and the ASD relay is energized. When the
ASD relay is on, voltage is supplied to the ASD relay
sense circuit at the PCM (ECM Diesel). This voltage
is connected through the PCM (ECM Diesel) and sup-
plied to one of the generator field terminals (Gen.
Source +) at the back of the generator.
The amount of direct current produced by the gen-
erator is controlled by the EVR (field control) cir-
cuitry contained within the PCM (ECM Diesel). This
circuitry is connected in series with the second rotor
field terminal and ground.
A battery temperature sensor, located in the bat-
tery tray housing, is used to sense battery tempera-
ture. This temperature data, along with data from
monitored line voltage, is used by the PCM (ECM
Diesel) to vary the battery charging rate. This isdone by cycling the ground path to control the
strength of the rotor magnetic field. The PCM then
compensates and regulates generator current output
accordingly.
All vehicles are equipped with On-Board Diagnos-
tics (OBD). All OBD-sensed systems, including EVR
(field control) circuitry, are monitored by the PCM
(ECM Diesel). Each monitored circuit is assigned a
Diagnostic Trouble Code (DTC). The PCM will store a
DTC in electronic memory for certain failures it
detects.
The Check Gauges Lamp (if equipped) monitors:
charging system voltage,engine coolant tempera-
ture and engine oil pressure. If an extreme condition
is indicated, the lamp will be illuminated. This is
done as reminder to check the three gauges. The sig-
nal to activate the lamp is sent via the CCD bus cir-
cuits. The lamp is located on the instrument panel.
Refer to 8, Instrument Panel and Gauges for addi-
tional information.
DIAGNOSIS AND TESTING - CHARGING
SYSTEM
The following procedures may be used to diagnose
the charging system if:
²the check gauges lamp (if equipped) is illumi-
nated with the engine running
²the voltmeter (if equipped) does not register
properly
²an undercharged or overcharged battery condi-
tion occurs.
Remember that an undercharged battery is often
caused by:
²accessories being left on with the engine not
running
DRCHARGING 8F - 19

STARTING
TABLE OF CONTENTS
page page
STARTING
DESCRIPTION.........................26
OPERATION...........................26
DIAGNOSIS AND TESTING - STARTING
SYSTEM............................27
SPECIFICATIONS
STARTING SYSTEM...................31
SPECIFICATIONS - TORQUE - STARTING
SYSTEM............................32
STARTER MOTOR
DIAGNOSIS AND TESTING - STARTER
MOTOR .............................32REMOVAL.............................33
INSTALLATION.........................34
STARTER MOTOR RELAY
DESCRIPTION.........................35
OPERATION...........................36
DIAGNOSIS AND TESTING - STARTER RELAY . 36
REMOVAL.............................37
INSTALLATION.........................37
STARTING
DESCRIPTION
The starting system consists of:
²Starter relay
²Starter motor (including an integral starter sole-
noid)
Other components to be considered as part of start-
ing system are:
²Battery
²Battery cables
²Ignition switch and key lock cylinder
²Clutch pedal position switch (manual transmis-
sion)
²Park/neutral position switch (automatic trans-
mission)
²Wire harnesses and connections.
The Battery, Starting, and Charging systems oper-
ate in conjunction with one another, and must be
tested as a complete system. For correct operation of
starting/charging systems, all components used in
these 3 systems must perform within specifications.
When attempting to diagnose any of these systems, it
is important that you keep their interdependency in
mind.
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.Certain starting system components are monitored
by the PCM and may produce a Diagnostic Trouble
Code (DTC). Refer to Diagnostic Trouble Codes in
Emission Control for a list of codes.
OPERATION
The starting system components form two separate
circuits. A high-amperage feed circuit that feeds the
starter motor between 150 and 350 amperes (700
amperes - diesel engine), and a low-amperage control
circuit that operates on less than 20 amperes. The
high-amperage feed circuit components include the
battery, the battery cables, the contact disc portion of
the starter solenoid, and the starter motor. The low-
amperage control circuit components include the igni-
tion switch, the clutch pedal position switch (manual
transmission), the park/neutral position switch (auto-
matic transmission), the starter relay, the electro-
magnetic windings of the starter solenoid, and the
connecting wire harness components.
If the vehicle is equipped with a manual transmis-
sion, it has a clutch pedal position switch installed in
series between the ignition switch and the coil bat-
tery terminal of the starter relay. This normally open
switch prevents the starter relay from being ener-
gized when the ignition switch is turned to the Start
position, unless the clutch pedal is depressed. This
feature prevents starter motor operation while the
clutch disc and the flywheel are engaged. The starter
relay coil ground terminal is always grounded on
vehicles with a manual transmission.
8F - 26 STARTINGDR

HEATED SYSTEMS
TABLE OF CONTENTS
page page
HEATED GLASS........................... 1
HEATED MIRRORS......................... 6HEATED SEAT SYSTEM..................... 7
HEATED GLASS
TABLE OF CONTENTS
page page
HEATED GLASS
DESCRIPTION..........................1
OPERATION............................1
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER SYSTEM...................2
REAR WINDOW DEFOGGER RELAY
DESCRIPTION..........................2
OPERATION............................3REMOVAL.............................3
INSTALLATION..........................4
REAR WINDOW DEFOGGER SWITCH
DESCRIPTION..........................4
OPERATION............................4
REAR WINDOW DEFOGGER GRID
STANDARD PROCEDURE - GRID LINE AND
TERMINAL REPAIR.....................4
HEATED GLASS
DESCRIPTION
CAUTION:Grid lines can be damaged or scraped off
with sharp instruments. Care should be taken in
cleaning glass or removing foreign materials, decals
or stickers. Normal glass cleaning solvents or hot
water used with rags or toweling is recommended.
The rear window defogger system consists of a
back glass with two vertical electrical bus bars linked
by a series of grid lines fired onto the inside surface
of the optional heated rear window.
The rear window defogger system is turned On or
Off by a switch and a timing circuit integral to the
A/C-heater control located at the center of the instru-
ment panel.
Circuit protection is provided by a cartridge fuse
located in the power distribution center (PDC) for the
heated grid circuit, and a fuse located in the fuse
block for the control circuit.
OPERATION
The rear window defogger system is turned on by a
momentary switch located in the A/C-heater control
on the instrument panel. When the rear windowdefogger switch is pressed to the On position, current
is directed through the rear window defogger relay to
the rear defogger grid lines. The heated grid lines
heat the rear glass to help clear the rear window sur-
face of fog or frost.
A yellow indicator above the switch will illuminate
to indicate when the rear window defogger system is
turned on. The A/C-heater control contains the rear
window defogger system control circuitry.
NOTE: The rear window defogger turns off automat-
ically after approximately 10 minutes of initial oper-
ation. Each following activation cycle of the
defogger system will last approximately ten minutes
also.
The rear window defogger system will be automat-
ically turned off after a programmed time interval of
about ten minutes. After the initial time interval has
expired, if the defogger switch is pressed to the On
position again during the same ignition cycle, the
rear window defogger system will automatically turn
off after about ten minutes also.
The rear window defogger system will automati-
cally shut off if the ignition switch is turned to the
Off position, or it can be turned off manually by
pressing the defogger switch a second time.
DRHEATED SYSTEMS 8G - 1

HEATED MIRRORS
TABLE OF CONTENTS
page page
HEATED MIRRORS
DESCRIPTION..........................6OPERATION............................6
HEATED MIRRORS
DESCRIPTION
Electrically heated outside rear view mirrors are
an additional factory-installed option on models that
are equipped with factory-installed dual power mir-
rors and the heated rear window defogger system.
Vehicles with this option can be visually identified by
the International Control and Display Symbol icon
for rear window defogger, which appears on the lower
inboard corner of each outside mirror glass (Fig. 1).
The optional heated mirror system operates in con-
cert with the rear window defogger system, and will
be automatically shut off after a programmed time
interval of about ten minutes. After the initial time
interval has expired, if the defogger switch is turned
on again during the same ignition cycle, the heated
mirror system will automatically shut off after about
ten minutes also.
The heated mirror system will automatically shut
off if the ignition switch is turned to the Off position,
or it can be shut off manually by pressing the rear
window defogger switch a second time.
OPERATION
When the rear window defogger switch is in the
On position, an electric heater grid located behind
the glass of each of the outside rear view mirrors is
energized. When energized, each of these heater
grids produce heat to help clear the outside rear view
mirrors of ice, snow, or fog.
The heated mirror system is controlled by a
momentary rear window defogger switch on the A/C-
heater control. An amber indicator lamp in the
switch will illuminate to indicate when the defogger
system is turned on.If the outside mirror heating grids are both inoper-
ative, refer to DIAGNOSIS AND TESTING - REAR
WINDOW DEFOGGER SYSTEM in his group. If
only one of the outside mirror heating grids is inop-
erative, Refer to 8 - ELECTRICAL/POWER MIR-
RORS - DIAGNOSIS AND TESTING.
The heating grid behind each outside mirror glass
cannot be repaired and, if faulty or damaged, the
entire power mirror unit must be replaced.
Fig. 1 Heated Mirror - Typical
1 - POWER HEATED OUTSIDE REAR VIEW MIRROR
2 - REAR WINDOW DEFOGGER ICON
8G - 6 HEATED MIRRORSDR

HEATED SEAT SYSTEM
TABLE OF CONTENTS
page page
HEATED SEAT SYSTEM
DESCRIPTION..........................7
OPERATION............................8
DIAGNOSIS AND TESTING - HEATED SEAT
SYSTEM.............................8
HEATED SEAT ELEMENT
DESCRIPTION..........................9
OPERATION...........................10
DIAGNOSIS AND TESTING - HEATED SEAT
ELEMENT...........................10
REMOVAL.............................10
INSTALLATION.........................10
HEATED SEAT SENSOR
DESCRIPTION.........................11
OPERATION...........................11
DIAGNOSIS AND TESTING - HEATED SEAT
SENSOR............................11REMOVAL.............................11
HEATED SEAT SWITCH
DESCRIPTION.........................11
OPERATION...........................12
DIAGNOSIS AND TESTING - HEATED SEAT
SWITCH............................12
REMOVAL.............................13
INSTALLATION.........................13
HEATED SEAT MODULE
DESCRIPTION.........................13
OPERATION...........................14
DIAGNOSIS AND TESTING - HEATED SEAT
MODULE............................14
REMOVAL.............................15
INSTALLATION.........................15
HEATED SEAT SYSTEM
DESCRIPTION
Individually controlled, electrically heated front
seats are available as a factory-installed option on
some DR models. Vehicles with this option can be
visually identified by the leather trim seats and two
separate heated seat switches mounted in the lower
center of the instrument panel. The heated seat sys-
tem allows the front seat driver and passenger to
select from two different levels of electrical seat heat-
ing, or no seat heating to suit their individual com-
fort requirements. The heated seat system for this
vehicle includes the following major components,
which are described in further detail later in this sec-
tion:
²Heated Seat Switches- Two heated seat
switches are used per vehicle. One switch is used for
each front seat. The switches are mounted in the
instrument panel, below the radio (Fig. 1). Each
switch also includes two Light-Emitting Diode (LED)
indicator lamps and an incandescent back lighting
bulb.
²Heated Seat Module- also referred to as the
Seat Heat Interface Module (SHIM), this module con-
tains the solid state electronic control and diagnostic
logic circuitry for the heated seat system. One heated
seat module is used per vehicle and is mounted
under the drivers front seat cushion (Fig. 1). Refer to
the Electronic Control Modules section of the servicemanual for additional heated seat module informa-
tion.
²Heated Seat Elements- Four heated seat ele-
ments are used per vehicle. One element is used for
each front seat back and one element and sensor
assembly is used for each front seat cushion (Fig. 1).
The heating elements are integral to the individual
front seat and seat back cushions and cannot be
removed once installed at the factory. Replacement
seat heating elements are available, without having
to replace the entire seat cushion or trim cover. Refer
to the detailed procedure later in this section.
²Heated Seat Sensors- Two heated seat sen-
sors are used per vehicle. One heated seat tempera-
ture sensor is used for each front seat cushion. The
sensors are integral to the individual front seat cush-
ion heating elements (Fig. 1) and cannot be removed
once installed at the factory. Replacement seat heat-
ing elements with the sensors are available, without
having to replace the entire seat cushion or trim
cover. Refer to the detailed procedure later in this
section.
Following are general descriptions and operations
of the major components in the heated seat system.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the heated seat system. Refer toWiringfor the
location of complete heated seat system wiring dia-
grams.
DRHEATED SEAT SYSTEM 8G - 7

HORN
TABLE OF CONTENTS
page page
HORN SYSTEM
DESCRIPTION..........................1
OPERATION............................1
DIAGNOSIS AND TESTING - HORN SYSTEM . . . 1
HORN
DIAGNOSIS AND TESTING - HORN..........1REMOVAL.............................2
INSTALLATION..........................2
HORN SWITCH
DESCRIPTION..........................2
DIAGNOSIS AND TESTING - HORN SWITCH . . . 2
HORN SYSTEM
DESCRIPTION
The dual-note horn system features dual electro-
magnetic horn units. The horn system includes the
following major components:
²Horn- The two horns are located on the left
side of the engine compartment below the Integrated
Power Module (IPM).
²Horn Switch- The horn switch is molded into
the driver airbag trim cover.
OPERATION
The horn system operates on battery current
received through a fuse in the Integrated Power
Module (IPM). The horn system circuit is designed so
that the system will remain operational, regardless
of the ignition switch position.
DIAGNOSIS AND TESTING - HORN SYSTEM
The most reliable, efficient, and accurate
means to diagnose the horn system requires the
use of a DRBIIItscan tool and the proper Diag-
nostic Procedures manual.
Refer to the appropriate wiring information.
In most cases, any problem involving continually
sounding horns can be quickly alleviated by removing
the horn fuse from the Integrated Power Module
(IPM).
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, SEAT BELT TENSIONER, SIDE
AIRBAG, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
HORN
DIAGNOSIS AND TESTING - HORN
The most reliable, efficient, and accurate
means to diagnose the horn system requires the
use of a DRBIIItscan tool and the proper Diag-
nostic Procedures manual. The DRBIIItscan
tool can provide confirmation that the PCI data
bus is functional, that all of the electronic mod-
ules are sending and receiving the proper mes-
sages on the PCI data bus, and that the horns
are being sent the proper hard wired outputs
for them to perform their functions.
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, details of wire
harness routing and retention, connector pin-out
information and location views for the various wire
harness connectors, splices and grounds.
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, SEAT BELT TENSIONER, SIDE
AIRBAG, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
DRHORN 8H - 1

IGNITION CONTROL
TABLE OF CONTENTS
page page
IGNITION CONTROL
DESCRIPTION..........................1
SPECIFICATIONS
SPECIFICATIONS - TORQUE - IGNITION....3
ENGINE FIRING ORDER - 3.7L V-6.........4
ENGINE FIRING ORDER ± 4.7L V-8........4
FIRING ORDER / CABLE ROUTING ± 5.7L
V-8 ENGINE...........................4
SPARK PLUG CABLE RESISTANCE........4
SPARK PLUGS........................4
IGNITION COIL RESISTANCE - 3.7L V-6.....5
IGNITION COIL RESISTANCE - 4.7L V-8.....5
IGNITION COIL RESISTANCE - 5.7L V-8.....5
IGNITION TIMING......................5
AUTOMATIC SHUT DOWN RELAY
DESCRIPTION - PCM OUTPUT.............5
OPERATION
OPERATION - PCM OUTPUT.............5
OPERATION - ASD SENSE - PCM INPUT....5
DIAGNOSIS AND TESTING - ASD AND FUEL
PUMP RELAYS........................5
REMOVAL.............................6
INSTALLATION..........................6
CAMSHAFT POSITION SENSOR
DESCRIPTION..........................7
OPERATION............................7
REMOVAL.............................9
INSTALLATION.........................10IGNITION COIL
DESCRIPTION.........................11
OPERATION...........................12
REMOVAL.............................13
INSTALLATION.........................14
KNOCK SENSOR
DESCRIPTION.........................14
OPERATION...........................14
REMOVAL.............................15
INSTALLATION.........................15
SPARK PLUG
DESCRIPTION.........................17
DIAGNOSIS AND TESTING - SPARK PLUG
CONDITIONS.........................17
REMOVAL.............................19
CLEANING
CLEANING AND ADJUSTMENT...........20
INSTALLATION.........................20
IGNITION COIL CAPACITOR
DESCRIPTION.........................21
OPERATION...........................21
REMOVAL.............................21
INSTALLATION.........................21
SPARK PLUG CABLE
DESCRIPTION.........................21
OPERATION...........................21
REMOVAL.............................22
INSTALLATION.........................22
IGNITION CONTROL
DESCRIPTION
The ignition system is controlled by the Powertrain
Control Module (PCM) on all engines.
3.7L V-6 ENGINE
The 3.7L V-6 engine uses a separate ignition coil
for each cylinder. The one-piece coil bolts directly to
the cylinder head. Rubber boots seal the secondary
terminal ends of the coils to the top of all 6 spark
plugs. A separate electrical connector is used for each
coil.
Because of coil design, spark plug cables (second-
ary cables) are not used. A distributor is not used
with the 3.7L engine.
Two knock sensors (one for each cylinder bank) are
used to help control spark knock.The Auto Shutdown (ASD) relay provides battery
voltage to each ignition coil.
The ignition system consists of:
²6 Spark Plugs
²6 Separate Ignition Coils
²2 Knock Sensors
²Powertrain Control Module (PCM)
²Also to be considered part of the ignition system
are certain inputs from the Crankshaft Position,
Camshaft Position, Throttle Position, 2 knock and
MAP Sensors
4.7L V-8 ENGINE
The 4.7L V-8 engine uses a separate ignition coil
for each cylinder. The one-piece coil bolts directly to
the cylinder head. Rubber boots seal the secondary
terminal ends of the coils to the top of all 8 spark
plugs. A separate electrical connector is used for each
coil.
DRIGNITION CONTROL 8I - 1

INSTRUMENT CLUSTER
TABLE OF CONTENTS
page page
INSTRUMENT CLUSTER
DESCRIPTION..........................2
OPERATION............................6
DIAGNOSIS AND TESTING - INSTRUMENT
CLUSTER...........................10
REMOVAL.............................14
DISASSEMBLY.........................14
ASSEMBLY............................15
INSTALLATION.........................16
ABS INDICATOR
DESCRIPTION.........................17
OPERATION...........................17
AIRBAG INDICATOR
DESCRIPTION.........................18
OPERATION...........................18
BRAKE/PARK BRAKE INDICATOR
DESCRIPTION.........................19
OPERATION...........................19
DIAGNOSIS AND TESTING - BRAKE
INDICATOR..........................20
CARGO LAMP INDICATOR
DESCRIPTION.........................20
OPERATION...........................20
CHECK GAUGES INDICATOR
DESCRIPTION.........................21
OPERATION...........................21
CRUISE INDICATOR
DESCRIPTION.........................22
OPERATION...........................22
DOOR AJAR INDICATOR
DESCRIPTION.........................23
OPERATION...........................23
ENGINE TEMPERATURE GAUGE
DESCRIPTION.........................24
OPERATION...........................24
ETC INDICATOR
DESCRIPTION.........................25
OPERATION...........................25
FUEL GAUGE
DESCRIPTION.........................26
OPERATION...........................26
GEAR SELECTOR INDICATOR
DESCRIPTION.........................27
OPERATION...........................27
HIGH BEAM INDICATOR
DESCRIPTION.........................28
OPERATION...........................28
LAMP OUT INDICATOR
DESCRIPTION.........................29OPERATION...........................29
LOW FUEL INDICATOR
DESCRIPTION.........................30
OPERATION...........................30
MALFUNCTION INDICATOR LAMP (MIL)
DESCRIPTION.........................31
OPERATION...........................31
ODOMETER
DESCRIPTION.........................32
OPERATION...........................32
OIL PRESSURE GAUGE
DESCRIPTION.........................33
OPERATION...........................33
SEATBELT INDICATOR
DESCRIPTION.........................34
OPERATION...........................34
STANDARD PROCEDURE - ENHANCED
SEATBELT REMINDER PROGRAMMING....35
SECURITY INDICATOR
DESCRIPTION.........................35
OPERATION...........................36
SERVICE 4WD INDICATOR
DESCRIPTION.........................36
OPERATION...........................37
SPEEDOMETER
DESCRIPTION.........................37
OPERATION...........................37
TACHOMETER
DESCRIPTION.........................38
OPERATION...........................38
TOW/HAUL INDICATOR
DESCRIPTION.........................39
OPERATION...........................39
TRANS TEMP INDICATOR
DESCRIPTION.........................40
OPERATION...........................40
TURN SIGNAL INDICATOR
DESCRIPTION.........................40
OPERATION...........................41
UPSHIFT INDICATOR
DESCRIPTION.........................41
OPERATION...........................42
VOLTAGE GAUGE
DESCRIPTION.........................42
OPERATION...........................43
WAIT-TO-START INDICATOR
DESCRIPTION.........................44
OPERATION...........................44
DRINSTRUMENT CLUSTER 8J - 1