1998 DODGE RAM 1500 Ignition control

TRANSFER CASE CONTROL MODULE C1 (ELECTRIC 4x4) - 16 WAY
CAV CIRCUIT FUNCTION
A1 D25 20VT/DB PCI BUS
A2 - -
A3 - -
A4 G92 20VT/OR 4WD LOW INDICATOR
A5 G91 20VT/WT 4WD HIGH INDICATOR
A6 K977 20BR/WT MODE SELECT
A7 T885 20YL/GY MODE SENSOR GROUND
A8 Z905 18BK GROUND
A9 - -
A10 - -
A11 - -
A12 G95 20VT/BR NEUTRAL INDICATOR
A13 G2 20BR/WT IGNITION SWITCH SENSE
A14 D200 20WT/LG MODE SENSOR D
A15 - -
A16 Z905 20BK GROUND
TRANSFER CASE CONTROL MODULE C2 (ELECTRIC 4x4) - 16 WAY
CAV CIRCUIT FUNCTION
B1 D202 20WT/VT MODE SENSOR B
B2 D201 20WT/DG MODE SENSOR A
B3 - -
B4 - -
B5 - -
B6 T41 20YL/DB TRS T41 SENSE
B7 - -
B8 T313 20YL/LG 5 VOLT MODE SENSOR SUPPLY
B9 - -
B10 D203 20WT/BR MODE SENSOR C
B11 - -
B12 - -
B13 - -
B14 - -
B15 - -
B16 T322 20DG/GY 5 VOLT SELECTOR SWITCH SUPPLY
8W - 80 - 100 8W-80 CONNECTOR PIN-OUTSDR

TRANSFER CASE CONTROL MODULE C3 (ELECTRIC 4x4)-4WAY
CAV CIRCUIT FUNCTION
A Z905 16BK GROUND
B A34 16RD/WT FUSED B(+)
C T315 16YL/BR SHIFT MOTOR CONTROL A
D T316 16YL/GY SHIFT MOTOR CONTROL B
TRANSFER CASE MODE SENSOR-6WAY
CAV CIRCUIT FUNCTION
1 D200 20WT/LG MODE SENSOR D
2 T313 20YL/LG 5 VOLT MODE SENSOR SUPPLY
3 D202 20WT/VT MODE SENSOR B
4 T885 20YL/GY MODE SENSOR GROUND
5 D201 20WT/DG MODE SENSOR A
6 D203 20WT/BR MODE SENSOR C
TRANSFER CASE SELECTOR SWITCH - 12 WAY
CAV CIRCUIT FUNCTION
1 T322 20DG/GY 5 VOLT SELECTOR SWITCH SUPPLY
2 G2 20BR/WT IGNITION SWITCH SENSE
3- -
4 G95 20VT/BR NEUTRAL INDICATOR
5 K977 20BR/WT MODE SELECT
6 E11 20OR/DB PANEL LAMPS DRIVER
7 F21 20PK/DG FUSED IGNITION SWITCH OUTPUT (RUN-START)
8 G92 20VT/OR 4WD LOW INDICATOR
9 G91 20VT/WT 4WD HIGH INDICATOR
10 - -
11 Z905 20BK GROUND
12 - -
TRANSFER CASE SHIFT MOTOR-2WAY
CAV CIRCUIT FUNCTION
1 T316 16YL/GY SHIFT MOTOR CONTROL B
2 T315 16YL/BR SHIFT MOTOR CONTROL A
DR8W-80 CONNECTOR PIN-OUTS 8W - 80 - 101

TRANSMISSION RANGE SENSOR-6WAY
CAV CIRCUIT FUNCTION
1 L10 18WT/GY FUSED IGNITION SWITCH OUTPUT (RUN)
2 T117 20DG/YL TRANS RANGE SENSOR ELECTRONIC CLUSTER 5
VOLT SUPPLY
3- -
4 L1 18WT/LG BACKUP LAMP FEED
5 T917 20YL/TN TRANS RANGE SENSOR ELECTRONIC CLUSTER MUX
6 T41 20YL/DB PARK NEUTRAL POSITION SWITCH SENSE (T41)
6 T41 18YL/DB PARK NEUTRAL POSITION SWITCH SENSE (T41)
TRANSMISSION SOLENOID ASSEMBLY (48RE)-8WAY
CAV CIRCUIT FUNCTION
1 T16 18YL/OR TRANSMISSION CONTROL RELAY OUTPUT
2 F856 18YL/PK 5 VOLT SUPPLY
3 K900 20DB/DG SENSOR GROUND
3 K900 18DB/DG SENSOR GROUND
4 T38 18YL/BR GOVERNOR PRESSURE SENSOR SIGNAL
5 T118 18DG GOVERNOR PRESSURE SOLENOID CONTROL
6 T9 18DG/TN 3-4 SHIFT SOLENOID
7 T75 18YL/LB TORQUE CONVERTER CLUTCH SOLENOID CONTROL
8 T54 18DG/OR TRANSMISSION TEMPERATURE SENSOR SIGNAL
TRANSMISSION SOLENOID/TRS ASSEMBLY (NGC) - 23 WAY
CAV CIRCUIT FUNCTION
1 L10 18WT/GY FUSED IGNITION SWITCH OUTPUT (RUN)
2 T20 18DG/WT L/R SOLENOID CONTROL
3- -
4 T41 20YL/DB TRS T41 SENSE
5 T42 18DG/YL TRS T42 SENSE
6 L1 18WT/LG BACKUP LAMP FEED
7 T60 18YL/GY OVERDRIVE SOLENOID CONTROL
8 T3 18DG/DB TRS T3 SENSE
9 T1 18DG/LB TRS T1 SENSE
10 T16 18YL/OR TRANSMISSION CONTROL RELAY OUTPUT
11 T48 18BR/YL 4C PRESSURE SWITCH SENSE
12 T140 18YL/GY PRESSURE CONTROL SOLENIOD CONTROL
13 T4 18DG/LB TRS T2 SENSE
14 T50 18YL/TN LOW/REVERSE PRESSURE SWITCH SENSE
15 T147 18DG/YL 2C PRESSURE SWITCH SENSE
16 T9 18DG/TN OVERDRIVE PRESSURE SWITCH SENSE
17 T59 18YL/LB UNDERDRIVE SOLENOID CONTROL
18 T29 18YL/WT UNDERDRIVE PRESSURE SWITCH SENSE
19 T259 18YL/DG 4C SOLENOID CONTROL
20 T219 18YL/LG 2C SOLENOID CONTROL
21 T118 18DG MS SOLENOID CONTROL
22 K900 18DB/DG SENSOR GROUND
23 T54 18DG/OR TRANSMISSION TEMPERATURE SENSOR SIGNAL
8W - 80 - 102 8W-80 CONNECTOR PIN-OUTSDR

VACUUM PUMP (DIESEL)-4WAY
CAV CIRCUIT FUNCTION
1- -
2 F202 20PK/GY FUSED IGNITION SWITCH OUTPUT (RUN-START)
3- -
4 Z936 18BK GROUND
VISTRONIC FAN DRIVE (DIESEL)-6WAY
CAV CIRCUIT FUNCTION
1 K160 18BR/OR PARK LOCKOUT SOLENOID CONTROL
2 K900 18DB/DG SENSOR GROUND
3 K161 18BR/LB FAN SPEED SENSOR
4- -
5 F856 18YL/PK 5 VOLT SUPPLY
6 F504 20GY/PK FUSED IGNITION SWITCH OUTPUT (RUN)
WASHER FLUID LEVEL SWITCH-2WAY
CAV CIRCUIT FUNCTION
1 Z932 20BK GROUND
2 W1 20BR/TN WASHER FLUID SWITCH SENSE
WASHER PUMP MOTOR-FRONT - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 Z945 20BK GROUND
2 W10 20BR WASHER PUMP MOTOR CONTROL
WATER IN FUEL SENSOR-2WAY
CAV CIRCUIT FUNCTION
A K914 18RD/WT (A/T) SENSOR GROUND
A K914 18BR/WT (M/T) SENSOR GROUND
B G123 18VT/LG WATER IN FUEL SENSOR SIGNAL
DR8W-80 CONNECTOR PIN-OUTS 8W - 80 - 103

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)

(3) Connect the electrical connectors by pushing
straight on and rotating the connector arm inboard,
until the connector is firmly locked in place on the
module assembly.
(4) Grasp the integrated power module with two
hands and install the assembly on the battery tray
(Fig. 5).
(5) Install the integrated power module retaining
bolt and screw.
(6) Connect the gray connector on the integrated
power module housing.
(7) Install the B+ terminal cable and nut on the
integrated power module B+ terminal. Snap the
cover in place.
(8) Connect the negative and positive battery
cables.
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). Theintegrated 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
Fig. 5 INTEGRATED POWER MODULE MOUNTING
TABS
1 - INTEGRATED POWER MODULE MOUNTING HOLES
2 - BATTERY TRAY ASSEMBLY
3 - FRONT CONTROL MODULE
DR8W-97 POWER DISTRIBUTION 8W - 97 - 5
INTEGRATED POWER MODULE (Continued)

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.
IOD FUSE
DESCRIPTION
All vehicles are equipped with an Ignition-Off
Draw (IOD) fuse that is disconnected within the Inte-
grated Power Module when the vehicle is shipped
from the factory. Dealer personnel are to reconnect
the IOD fuse in the Integrated Power Module as part
of the preparation procedures performed just prior to
new vehicle delivery.
A laser printed fuse layout map is integral to the
Integrated Power Module cover to ensure proper fuse
identification. The IOD fuse is a 20 ampere mini
blade-type fuse, located in fuse cavity # 51 (Fig. 6).
The fuse is secured within a black molded plastic
fuse holder and puller unit that serves both as a tool
for disconnecting and reconnecting the fuse in its
Integrated Power Module cavity, and as a fuse holder
that conveniently stores the fuse in the same Inte-
grated Power Module cavity after it has been discon-
nected.
CIRCUITS INCLUDED WITH IOD FUSE
²Cluster (CCN)
²Diagnostic Connector
²Map Lamps
²Glove Box Lamp
²Courtesy Lamps
²Radio
²Underhood Lamp
OPERATION
The term ignition-off draw identifies a normal con-
dition where power is being drained from the battery
with the ignition switch in the Off position. The IOD
fuse feeds the memory and sleep mode functions for
some of the electronic modules in the vehicle as well
as various other accessories that require battery cur-
rent when the ignition switch is in the Off position.
The only reason the IOD fuse is disconnected is to
reduce the normal IOD of the vehicle electrical sys-
tem during new vehicle transportation and pre-deliv-
ery storage to reduce battery depletion, while still
allowing vehicle operation so that the vehicle can be
loaded, unloaded and moved as needed by both vehi-
cle transportation company and dealer personnel.
The 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. Once the vehicle is pre-
pared for delivery, the IOD function of this fuse
Fig. 6 IOD FUSE LOCATION
1 - IOD FUSE
8W - 97 - 6 8W-97 POWER DISTRIBUTIONDR
FRONT CONTROL MODULE (Continued)

DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - INTRODUCTION
Engine diagnosis is helpful in determining the
causes of malfunctions not detected and remedied by
routine maintenance.
These malfunctions may be classified as either per-
formance (e.g., engine idles rough and stalls) or
mechanical (e.g., a strange noise).
(Refer to 9 - ENGINE - DIAGNOSIS AND TEST-
ING) - PERFORMANCE and (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)ÐMECHANICAL for
possible causes and corrections of malfunctions.
(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY -
DIAGNOSIS AND TESTING) and (Refer to 14 -
FUEL SYSTEM/FUEL INJECTION - DIAGNOSIS
AND TESTING) for the fuel system diagnosis.Additional tests and diagnostic procedures may be
necessary for specific engine malfunctions that can
not be isolated with the Service Diagnosis charts.
Information concerning additional tests and diagno-
sis is provided within the following diagnosis:
²Cylinder Compression Pressure Test (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING).
²Cylinder Combustion Pressure Leakage Test
(Refer to 9 - ENGINE - DIAGNOSIS AND TEST-
ING).
²Engine Cylinder Head Gasket Failure Diagnosis
(Refer to 9 - ENGINE/CYLINDER HEAD - DIAGNO-
SIS AND TESTING).
²Intake Manifold Leakage Diagnosis (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
DIAGNOSIS AND TESTING).
DIAGNOSIS AND TESTING - ENGINE DIAGNOSIS - PERFORMANCE
CONDITION POSSIBLE CAUSE CORRECTION
ENGINE WILL NOT START 1. Weak battery 1. Charge or replace as necessary.
2. Corroded or loose battery
connections.2. Clean and tighten battery
connections. Apply a coat of light
mineral grease to the terminals.
3. Faulty starter. 3. (Refer to 8 - ELECTRICAL/
STARTING - DIAGNOSIS AND
TESTING).
4. Faulty coil or control unit. 4. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/IGNITION
COIL - REMOVAL).
5. Incorrect spark plug gap. 5. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/SPARK PLUG
- CLEANING).
6. Incorrect right bank cam timing. 6. Refer to engine timing in this
section.
7. Dirt or water in fuel system. 7. Clean system and replace fuel
filter.
8.Faulty fuel pump, relay or wiring. 8.Repair or replace as necessary.
9. Faulty cam or crank sensor 9. Refer to Ignition system.
ENGINE STALLS OR ROUGH IDLE 1. Vacuum leak. 1. Inspect intake manifold and
vacuum hoses, repair or replace as
necessary.
2. Faulty crank position sensor 2. Replace crank position sensor.
3. Faulty coil. 3. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/IGNITION
COIL - REMOVAL).
9 - 4 ENGINE - 3.7LDR
ENGINE - 3.7L (Continued)