1998 DODGE RAM 1500 air

CONNECTOR NAME/NUMBER COLOR LOCATION FIG.
Data Link Connector - Engine
(Diesel)BK Near T/O for Water In Fuel Sensor N/S
Dome Lamp BK Center of Headliner N/S
Door Ajar Switch-Driver (Base) BK Left Front Door 41
Door Ajar Switch-Left Rear (Base) BK Left Rear Door 43
Door Ajar Switch-Right Rear (Base) BK Right Rear Door 43
Door Lock Motor/Ajar Switch-Driver
(Except Base)BK Left Front Door 41
Door Lock Motor/Ajar Switch-Left
Rear (Except Base)BK Left Rear Door 43
Door Lock Motor/Ajar Switch-
PassengerBK Right Front Door 42
Door Lock Motor/Ajar Switch-Right
Rear (Except Base)BK Right Rear Door 43
Door Lock Switch-Passenger BL In Right Front Door 42
Driver Airbag Squib BK In Steering Column N/S
Driver Blend Door Actuator (Dual
Zone)BK Right Side of HVAC N/S
Driver Door Module C1 BL In Left Front Door 41
Driver Door Module C2 BL In Left Front Door 41
EGR Solenoid Right Front Engine 9
Electric Brake Provision Rear of Engine 22, 24
Engine Control Module C1 BK Left Engine 10
Engine Control Module C2 BK Left Engine 10
Engine Coolant Temperature
SensorBK Near Generator 6
Engine Oil Pressure Switch BK Lower Left Side of Engine 6, 9
Evap/Purge Solenoid BK Left Fender Side Shield 23, 25
Evaporator Temperature Sensor BK Right Side of HVAC N/S
Fog Lamp-Left WT Left Front Facia N/S
Fog Lamp-Right WT Right Front Facia N/S
Fuel Control Actuator (Diesel) BK Left Rear Engine N/S
Fuel Heater (Diesel) BK Left Side Engine 10
Fuel Injector No. 1 BK At Fuel Injector 6
Fuel Injector No. 2 BK At Fuel Injector 3
Fuel Injector No. 3 BK At Fuel Injector 6
Fuel Injector No. 4 BK At Fuel Injector 3
Fuel Injector No. 5 BK At Fuel Injector 6
Fuel Injector No. 6 BK At Fuel Injector 3
Fuel Injector No. 7 BK At Fuel Injector 6
Fuel Injector No. 8 BK At Fuel Injector 3
Fuel Pump Module LT GY At Fuel Tank 50
Fuel Pump Motor (Diesel) BK Left Side Engine 10
Generator BK Front of Engine 6, 9, 10
8W - 91 - 4 8W-91 CONNECTOR/GROUND/SPLICE LOCATIONDR
CONNECTOR/GROUND/SPLICE LOCATION (Continued)

CONNECTOR NAME/NUMBER COLOR LOCATION FIG.
Glove Box Lamp and Switch BK At Glove Box 35, 39
Governor Pressure Sensor BK Left Rear of Transmission N/S
Hands Free Module Right Instrument Panel 39
Headlamp Switch BK Left Side of Instrument Panel 32, 35, 38
Headlamp-Left BL At Headlamp 23, 28, 29
Headlamp-Right BL At Headlamp 1, 21, 26
Heated Seat Cushion - Driver BL Under Driver Seat N/S
Heated Seat Cushion - Passenger BL Under Passenger Seat N/S
Heated Seat Switch-Driver RD Center of Instrument Panel 33, 35, 36
Heated Seat Switch-Passenger BL Center of Instrument Panel 33, 35, 36
Horn Switch WT In Steering Wheel N/S
Horn-High Note BK Left Front Fender 23, 28, 29
Horn-Low Note BK Left Front Fender 23, 29
Idle Air Control Motor BK On Throttle Body 6
Ignition Coil GY Left Rear of Engine N/S
Ignition Switch BK Steering Column 31
Inlet Air Temperature/Pressure
SensorBK Right Side Engine 10
Input Speed Sensor BK At Transmission 15, 16
Instrument Cluster C1 GY Rear of Instrument Cluster 35
Instrument Cluster C2 GY Rear of Instrument Cluster 35
Instrument Cluster C3 WT Rear of Instrument Cluster 35
Intake Air Heater Relay Right Engine Compartment 2
Intake Air Temperature/Manifold
Absolute Pressure Sensor (Diesel)BK Left rear Engine N/S
Intake Air Temperature Sensor BK On Intake Manifold 5
Integrated Power Module C1 BK Left Front Fender 26, 28
Integrated Power Module C2 WT Left Front Fender 26, 28
Integrated Power Module C3 GR Left Front Fender 26, 28
Integrated Power Module C4 WT Left Front Fender 26, 28
Integrated Power Module C5 BK Left Front Fender 26, 28
Integrated Power Module C6 BK Left Front Fender 25, 26, 28
Integrated Power Module C7 GY Left Front Fender 26, 28
Integrated Power Module FCM BK In IPM N/S
Knock Sensor BK Left Rear of Engine 5, 7, 9
License Lamp-Left BK At Rear Bumper 50, 51
License Lamp-Right BK At Rear Bumper 50, 51
Lift Pump Motor BK Near T/O for WIF Sensor N/S
Line Pressure Sensor BK Right Rear of Transmission 15, 18
Lumbar Motor-Driver DK GY At Driver Seat N/S
Lumbar Motor-Passenger BK At Passenger Seat N/S
Manifold Absolute Pressure Sensor GY Left Front of Intake Manifold 6
Mode Door Actuator 1 BK Right Side of HVAC N/S
DR8W-91 CONNECTOR/GROUND/SPLICE LOCATION 8W - 91 - 5
CONNECTOR/GROUND/SPLICE LOCATION (Continued)

CONNECTOR NAME/NUMBER COLOR LOCATION FIG.
Mode Door Actuator 2 BK Right Side of HVAC N/S
Multi-Function Switch BK On Steering Column 31
Natural Vacuum Leak Detection
AssemblyBK Rear of Transmission 18, 50
Output Speed Sensor DB Left Side of Transmission 11, 14, 15, 16
Overdrive Switch WT Center of Instrument Panel 35
Overhead Map/Reading Lamp
(Except Base)NAT Center of Headliner N/S
Oxygen Sensor 1/1 Upstream BK Left Front of Side of Transmission 15, 16, 17, 19
Oxygen Sensor 1/2 Downstream NAT Left Rear of Side of Transmission 15, 16, 17, 19
Oxygen Sensor 2/1 Upstream BK Right Front Side of Transmission 15, 17, 18
Oxygen Sensor 2/2 Downstream BK Right Rear Side of Transmission 15, 17, 18
Park Brake Switch At Park Brake 22, 24
Park/Turn Signal Lamp-Left Front BK At Lamp 23, 28, 29
Park/Turn Signal Lamp-Right Front BK At Lamp 1, 21, 26
Passenger Airbag On/Off Switch Right Side of Instrument Panel 33, 35, 39
Passenger Blend Door Actuator
(Dual Zone)BK Right Side of HVAC N/S
Passenger Lumbar Switch At Passenger Seat N/S
Power Mirror-Left BK At Mirror 41
Power Mirror-Right BK At Mirror 42
Power Outlet RD Center of Instrument Panel 35
Power Outlet-Console BK Center of Instrument Panel N/S
Power Seat Motor-Driver Front
VerticalRD At Driver Seat N/S
Power Seat Motor-Driver Horizontal BK At Driver Seat N/S
Power Seat Motor-Driver Rear
VerticalBK At Driver Seat N/S
Power Seat Switch-Driver BK At Driver Seat N/S
Power Seat Switch-Passenger BK At Passenger Seat N/S
Power Steering Pressure Switch BK Near Power Steering Pump 7
Power Window Circuit Breaker Under Instrument Panel 31, 35, 38
Power Window Motor-Driver BK In Driver Door at Motor 41
Power Window Motor-Left Rear BK In Door at Motor 43
Power Window Motor-Passenger BK In Passenger Door at Motor 42
Power Window Motor-Right Rear BK In Door at Motor 43
Power Window Switch-Left Rear BL In Door 43
Power Window Switch-Passenger Passenger Door 42
Power Window Switch-Right Rear BL In Door 43
Powertrain Control Module C1 BK Right Rear Engine Compartment 4, 8
Powertrain Control Module C2 WT Right Rear Engine Compartment 4, 8
Powertrain Control Module C3 GY Right Rear Engine Compartment 21
Powertrain Control Module C4 GN Right Rear Engine Compartment 4, 8
8W - 91 - 6 8W-91 CONNECTOR/GROUND/SPLICE LOCATIONDR
CONNECTOR/GROUND/SPLICE LOCATION (Continued)

8W-97 POWER DISTRIBUTION
TABLE OF CONTENTS
page page
POWER DISTRIBUTION
DESCRIPTION..........................1
OPERATION............................1
SPECIAL TOOLS
POWER DISTRIBUTION SYSTEMS.........2
CIGAR LIGHTER OUTLET
DESCRIPTION..........................2
OPERATION............................2
DIAGNOSIS AND TESTING - CIGAR LIGHTER
OUTLET.............................2
INTEGRATED POWER MODULE
DESCRIPTION..........................3
OPERATION............................3
REMOVAL.............................3
INSTALLATION..........................4
FRONT CONTROL MODULE
DESCRIPTION..........................5OPERATION............................5
DIAGNOSIS AND TESTING - FRONT
CONTROL MODULE....................5
REMOVAL.............................6
INSTALLATION..........................6
IOD FUSE
DESCRIPTION..........................6
OPERATION............................6
REMOVAL.............................7
INSTALLATION..........................7
POWER OUTLET
DESCRIPTION..........................7
OPERATION............................7
DIAGNOSIS AND TESTING - POWER
OUTLET.............................7
REMOVAL.............................8
INSTALLATION..........................8
POWER DISTRIBUTION
DESCRIPTION
This group covers the various standard and
optional power distribution components used on this
model. The power distribution system for this vehicle
consists of the following components:
²Integrated Power Module (IPM)
²Front Control Module (FCM)
²Power Distribution Center (PDC)
²Power Outlets
²Cigar Lighter Outlets
²Relays
Refer to Wiring Diagrams for complete circuit sche-
matics.
The power distribution system also incorporates
various types of circuit control and protection fea-
tures, including:
²Automatic resetting circuit breakers
²Blade-type fuses
²Cartridge fuses
²Relays
Following are general descriptions of the major
components in the power distribution system. See the
owner's manual in the vehicle glove box for more
information on the features and use of all of the
power distribution system components.
OPERATION
The power distribution system for this vehicle is
designed to provide safe, reliable, and centralized dis-
tribution points for the electrical current required to
operate all of the many standard and optional facto-
ry-installed electrical and electronic powertrain,
chassis, safety, security, comfort and convenience sys-
tems. At the same time, the power distribution sys-
tem was designed to provide ready access to these
electrical distribution points for the vehicle techni-
cian to use when conducting diagnosis and repair of
faulty circuits. The power distribution system can
also prove useful for the sourcing of additional elec-
trical circuits that may be required to provide the
electrical current needed to operate many accessories
that the vehicle owner may choose to have installed
in the aftermarket.
DR8W-97 POWER DISTRIBUTION 8W - 97 - 1

SPECIAL TOOLS
POWER DISTRIBUTION SYSTEMS
CIGAR LIGHTER OUTLET
DESCRIPTION
On models equipped a cigar lighter outlet is
installed to the left of the center stack area in the
lower instrument panel. The cigar lighter outlet is
secured by a snap fit within the bezel.
The cigar lighter outlet, plastic cap and the knob
and heating element unit are available for service
replacement. These components cannot be repaired
and, if faulty or damaged, they must be replaced.
OPERATION
The cigar lighter consists of two major components:
a knob and heating element unit, and the cigar
lighter base or outlet shell. The receptacle shell is
connected to ground, and an insulated contact in the
bottom of the shell is connected to battery current.
The cigar lighter receives battery voltage from a fuse
in the junction block when the ignition switch is in
the Accessory or Run positions.
The cigar lighter knob and heating element are
encased within a spring-loaded housing, which also
features a sliding protective heat shield. When the
knob and heating element are inserted in the outlet
shell, the heating element resistor coil is grounded
through its housing to the outlet shell. If the cigar
lighter knob is pushed inward, the heat shield slides
up toward the knob exposing the heating element,
and the heating element extends from the housing
toward the insulated contact in the bottom of the
outlet shell.
Two small spring-clip retainers are located on
either side of the insulated contact inside the bottom
of the outlet shell. These clips engage and hold the
heating element against the insulated contact longenough for the resistor coil to heat up. When the
heating element is engaged with the contact, battery
current can flow through the resistor coil to ground,
causing the resistor coil to heat.
When the resistor coil becomes sufficiently heated,
excess heat radiates from the heating element caus-
ing the spring-clips to expand. Once the spring-clips
expand far enough to release the heating element,
the spring-loaded housing forces the knob and heat-
ing element to pop back outward to their relaxed
position. When the cigar lighter knob and element
are pulled out of the outlet shell, the protective heat
shield slides downward on the housing so that the
heating element is recessed and shielded around its
circumference for safety.
DIAGNOSIS AND TESTING - CIGAR LIGHTER
OUTLET
For complete circuit diagrams, refer toWiring
Diagrams.
(1) Check the fused B(+) fuse in the integrated
power module. If OK, go to Step 2. If not OK, repair
the shorted circuit or component as required and
replace the faulty fuse.
(2) Turn the ignition switch to the Run position.
Check for battery voltage at the fused B(+) fuse in
the integrated power module. If OK, go to Step 3. If
not OK, repair the open or short as required.
(3) Remove the cigar lighter knob and element
from the cigar lighter outlet shell. Check for continu-
ity between the inside circumference of the cigar
lighter outlet shell and a good ground. there should
be continuity. If OK, go to Step 4. If not OK, go to
Step 5.
(4) Turn the ignition switch to the Run position.
Check for battery voltage at the insulated contact
located at the back of the cigar lighter outlet shell. If
OK, replace the faulty cigar lighter knob and ele-
ment. If not OK, go to Step 5.
(5) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Check for continuity between the ground circuit cav-
ity of the cigar lighter wire harness connector and a
good ground. There should be continuity. If OK, go to
Step 6. If not OK, repair the open ground circuit to
ground as required.
(6) Connect the battery negative cable. Turn the
ignition switch to the Accessory or Run positions.
Check for battery voltage at the fused B(+) circuit
cavity of the cigar lighter wire harness connector. If
OK, replace the faulty cigar lighter outlet. If not OK,
repair the open fused B(+) circuit to the integrated
power module fuse as required.Terminal Pick Kit 6680
8W - 97 - 2 8W-97 POWER DISTRIBUTIONDR
POWER DISTRIBUTION (Continued)

becomes transparent and the fuse that has been
assigned the IOD designation becomes only another
Fused B(+) circuit fuse.
The IOD fuse can be used by the vehicle owner as
a convenient means of reducing battery depletion
when a vehicle is to be stored for periods not to
exceed about thirty days. However, it must be
remembered that disconnecting the IOD fuse will not
eliminate IOD, but only reduce this normal condition.
If a vehicle will be stored for more than about thirty
days, the battery negative cable should be discon-
nected to eliminate normal IOD; and, the battery
should be tested and recharged at regular intervals
during the vehicle storage period to prevent the bat-
tery from becoming discharged or damaged.
REMOVAL
The Ignition-Off Draw (IOD) fuse is disconnected
from Integrated Power Module fuse cavity # 51 when
the vehicle is shipped from the assembly plant.
Dealer personnel must reconnect the IOD fuse when
the vehicle is being prepared for delivery in order to
restore full electrical system operation.
(1) Turn the ignition switch to the Off position.
(2) Remove the Integrated Power Module cover.
(3) Grasp the outer tabs of the IOD fuse holder
unit in fuse cavity # 51 between the thumb and fore-
finger and pull the unit firmly upward.
(4) Install the Integrated Power Module cover.
INSTALLATION
(1) Turn the ignition switch to the Off position.
(2) Remove the Integrated Power Module cover.
(3) To install the IOD fuse, use a thumb to press
the IOD fuse holder unit in fuse cavity # 51 firmly
into the Integrated Power Module.
(4) Install the Integrated Power Module cover.
POWER OUTLET
DESCRIPTION
Two power outlets are utilized on this model. One
in the instrument panel center lower bezel and the
other in the center console. The power outlet bases
are secured by a snap fit within the instrument
panel or trim panel. A plastic protective cap snaps
into the power outlet base when the power outlet is
not being used, and hangs from the power outlet base
mount by an integral bail strap while the power out-
let is in use.The power outlet receptacle unit and the accessory
power outlet protective cap are available for service.
The power outlet receptacle cannot be repaired and,
if faulty or damaged, it must be replaced.
OPERATION
The power outlet base or receptacle shell is con-
nected to ground, and an insulated contact in the
bottom of the shell is connected to battery current.
The power outlet receives battery voltage from a fuse
in the integrated power module at all times.
While the power outlet is very similar to a cigar
lighter base unit, it does not include the two small
spring-clip retainers inside the bottom of the recepta-
cle shell that are used to secure the cigar lighter
heating element to the insulated contact.
DIAGNOSIS AND TESTING - POWER OUTLET
For complete circuit diagrams, refer toWiring
Diagrams.
(1) Check the fused B(+) fuse in the integrated
power module. If OK, go to Step 2. If not OK, repair
the shorted circuit or component as required and
replace the faulty fuse.
(2) Check for battery voltage at the fused B(+) fuse
in the integrated power module. If OK, go to Step 3.
If not OK, repair the open fused B(+) circuit to the
battery as required.
(3) Remove the plastic protective cap from the
power outlet receptacle. Check for continuity between
the inside circumference of the power outlet recepta-
cle and a good ground. There should be continuity. If
OK, go to Step 4. If not OK, go to Step 5.
(4) Check for battery voltage at the insulated con-
tact located at the back of the power outlet recepta-
cle. If not OK, go to Step 5.
(5) Disconnect and isolate the battery negative
cable. Remove the power outlet receptacle from the
instrument panel. Disconnect the wire harness con-
nector from the power outlet receptacle. Check for
continuity between the ground circuit cavity of the
power outlet wire harness connector and a good
ground. There should be continuity. If OK, go to Step
6. If not OK, repair the open ground circuit to ground
as required.
(6) Connect the battery negative cable. Check for
battery voltage at the fused B(+) circuit cavity of the
power outlet wire harness connector. If OK, replace
the faulty power outlet receptacle. If not OK, repair
the open fused B(+) circuit to the integrated power
module fuse as required.
DR8W-97 POWER DISTRIBUTION 8W - 97 - 7
IOD FUSE (Continued)

REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Pull the cigar lighter knob and element out of
the cigar lighter receptacle base, or unsnap the pro-
tective cap from the power outlet receptacle base.
(3) Look inside the cigar lighter or power outlet
receptacle base and note the position of the rectangu-
lar retaining bosses of the mount that secures the
receptacle base to the panel (Fig. 7).
(4) Insert a pair of external snap ring pliers into
the cigar lighter or power outlet receptacle base and
engage the tips of the pliers with the retaining
bosses of the mount.
(5) Squeeze the pliers to disengage the mount
retaining bosses from the receptacle base and, using
a gentle rocking motion, pull the pliers and the
receptacle base out of the mount.
(6) Pull the receptacle base away from the instru-
ment panel far enough to access the instrument
panel wire harness connector.
(7) Disconnect the instrument panel wire harness
connector from the cigar lighter or power outlet
receptacle base connector receptacle.
(8) Remove the cigar lighter or power outlet mount
from the instrument panel.
INSTALLATION
(1) Reconnect the instrument panel wire harness
connector to the cigar lighter or power outlet recep-
tacle base connector receptacle.
(2) Install the cigar lighter or power outlet mount
into the instrument panel.
(3) Align the splines on the outside of the cigar
lighter or power outlet receptacle base connector
receptacle with the grooves on the inside of the
mount.
(4) Press firmly on the cigar lighter or power out-
let receptacle base until the retaining bosses of the
mount are fully engaged in their receptacles.(5) Install the cigar lighter knob and element into
the cigar lighter receptacle base, or the protective cap
into the power outlet receptacle base.
(6) Reconnect the battery negative cable.
Fig. 7 Cigar Lighter and Power Outlet Remove/
Install
1 - KNOB AND ELEMENT
2 - RETAINING BOSSES-ENGAGE PLIERS HERE
3 - BASE
4 - PARTIALLY REMOVED
5 - EXTERNAL SNAP-RING PLIERS
6 - MOUNT
7 - BASE
8W - 97 - 8 8W-97 POWER DISTRIBUTIONDR
POWER OUTLET (Continued)

ENGINE
TABLE OF CONTENTS
page page
ENGINE - 3.7L............................ 1
ENGINE - 4.7L........................... 88ENGINE - 5.7L.......................... 180
ENGINE 5.9L DIESEL..................... 230
ENGINE - 3.7L
TABLE OF CONTENTS
page page
ENGINE - 3.7L
DESCRIPTION..........................3
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - INTRODUCTION............4
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - PERFORMANCE............4
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - MECHANICAL..............6
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - LUBRICATION..............7
DIAGNOSIS AND TESTING - CYLINDER
COMPRESSION PRESSURE..............8
DIAGNOSIS AND TESTING - CYLINDER
COMBUSTION PRESSURE LEAKAGE.......8
STANDARD PROCEDURE
STANDARD PROCEDURE - REPAIR
DAMAGED OR WORN THREADS..........9
STANDARD PROCEDURE - FORM-IN-
PLACE GASKETS AND SEALERS..........9
STANDARD PROCEDURE - ENGINE
GASKET SURFACE PREPARATION........10
REMOVAL.............................10
INSTALLATION.........................11
SPECIFICATIONS
SPECIFICATIONS - 3.7L ENGINE.........12
TORQUE............................16
SPECIAL TOOLS.......................17
AIR CLEANER ELEMENT
REMOVAL.............................21
INSTALLATION.........................21
CYLINDER HEAD - LEFT
DIAGNOSIS AND TESTING - CYLINDER HEAD
GASKET............................21
REMOVAL.............................22
INSTALLATION.........................24
CAMSHAFT(S)
DESCRIPTION.........................25
REMOVAL.............................25INSTALLATION.........................27
CYLINDER HEAD COVER(S)
DESCRIPTION.........................27
REMOVAL.............................28
INSTALLATION.........................28
INTAKE/EXHAUST VALVES & SEATS
DESCRIPTION.........................28
STANDARD PROCEDURE - REFACING......28
REMOVAL.............................29
INSTALLATION.........................30
ROCKER ARM
DESCRIPTION.........................31
REMOVAL.............................31
INSTALLATION.........................31
VALVE GUIDE SEALS
DESCRIPTION.........................32
VALVE SPRINGS
DESCRIPTION.........................32
REMOVAL.............................32
INSTALLATION.........................32
CYLINDER HEAD - RIGHT
DIAGNOSIS AND TESTING - HYDRAULIC
LASH ADJUSTER.....................32
REMOVAL.............................33
INSTALLATION.........................34
CAMSHAFT(S)
DESCRIPTION.........................35
REMOVAL.............................35
INSTALLATION.........................36
CYLINDER HEAD COVER(S)
REMOVAL.............................37
INSTALLATION.........................37
ROCKER ARM
DESCRIPTION.........................37
REMOVAL.............................37
VALVE GUIDE SEALS
DESCRIPTION.........................38
VALVE SPRINGS
DESCRIPTION.........................38
DRENGINE 9 - 1