1998 DODGE RAM 1500 Brake system

(11) Before starting engine, operate accelerator
pedal to check for any binding.
SWITCH
DESCRIPTION
Two separate switch pods operate the speed control
system. The steering-wheel-mounted switches use
multiplexed circuits to provide inputs to the PCM (to
the ECM for diesel) for ON, OFF, RESUME, ACCEL-
ERATE, SET, DECEL and CANCEL modes. Refer to
the owner's manual for more information on speed
control switch functions and setting procedures.
The individual switches cannot be repaired. If one
switch fails, the entire switch module must be
replaced.
Depending on engine control computer (JTEC
having a 3± plug connector or NGC having a 4±
plug connector), 2 types of switches are used.
Both types of switches are internally and exter-
nally different. The switch used with the NGC
system has an attached pigtail lead. The switch
used with the JTEC system does not have an
attached pigtail lead.
OPERATION
When speed control is selected by depressing the
ON, OFF switch, the PCM(ECM for diesel)allows
a set speed to be stored in its RAM for speed control.
To store a set speed, depress the SET switch while
the vehicle is moving at a speed between approxi-
mately 35 and 85 mph. In order for the speed control
to engage, the brakes cannot be applied, nor can the
gear selector be indicating the transmission is in
Park or Neutral.
The speed control can be disengaged manually by:
²Stepping on the brake pedal
²Depressing the OFF switch
²Depressing the CANCEL switch.
The speed control can be disengaged also by any of
the following conditions:
²An indication of Park or Neutral (auto. trans.)
²The VSS signal increases at a rate of 10 mph
per second (indicates that the co-efficient of friction
between the road surface and tires is extremely low)
²Depressing the clutch pedal (manual trans.).
²Excessive engine rpm (indicates that the trans-
mission may be in a low gear)
²The VSS signal decreases at a rate of 10 mph
per second (indicates that the vehicle may have
decelerated at an extremely high rate)
²If the actual speed is not within 20 mph of the
set speed
Fig. 6 SPEED CONTROL SERVO LOCATION
1 - BATTERY TRAY
2 - MOUNTING LUGS
3 - SERVO
4 - ELEC. CONNEC.
5 - MOUNTING SCREWS (3)
6 - MOUNTING BRACKET
7 - VACUUM LINE
Fig. 7 SERVO CABLE CLIP REMOVE/INSTALL Ð
TYPICAL
1 - SERVO MOUNTING NUTS (2)
2 - SERVO
3 - CABLE RETAINING CLIP
4 - SERVO CABLE AND SLEEVE
DRSPEED CONTROL 8P - 7
SERVO (Continued)

The previous disengagement conditions are pro-
grammed for added safety.
Once the speed control has been disengaged,
depressing the ACCEL switch restores the vehicle to
the target speed that was stored in the PCM's RAM
(ECM for diesel).
NOTE: Depressing the OFF switch will erase the set
speed stored in the PCM's/ECM's RAM.
If, while the speed control is engaged, the driver
wishes to increase vehicle speed, the PCM(ECM for
diesel)is programmed for an acceleration feature.
With the ACCEL switch held closed, the vehicle
accelerates slowly to the desired speed. The new tar-
get speed is stored in the PCM's/ECM's RAM when
the ACCEL switch is released. The PCM/ECM also
has a9tap-up9feature in which vehicle speed
increases at a rate of approximately 2 mph for each
momentary switch activation of the ACCEL switch.
The PCM/ECM also provides a means to decelerate
without disengaging speed control. To decelerate from
an existing recorded target speed, depress and hold
the COAST switch until the desired speed is reached.
Then release the switch. The ON, OFF switch oper-
ates two components: the PCM's/ECM's ON, OFF
input, and the battery voltage to the brake switch.
REMOVAL
Depending on engine control computer (JTEC
having a 3±plug connector or 5.7L V-8 NGC hav-
ing a 4±plug connector), 2 types of switches are
used. Both types of switches are internally and
externally different. The switches used with the
NGC system have attached pigtail leads (Fig. 9).
The switch used with the JTEC system does not
have an attached pigtail lead.
(1) Remove switch mounting screw (Fig. 8). or
(Fig. 9)
(2) Pull switch from steering wheel.
(3) Unplug electrical connector from switch (Fig.
8), or, switch pigtail wire harness from steering
wheel wire harness (Fig. 9) and remove switch.
INSTALLATION
(1) Plug electrical connector into switch (Fig. 8), or
connect pigtail wire harness to steering wheel wire
harness (Fig. 9). Be sure wires are not pinched.
(2) Position switch to steering wheel.
(3) Install switch mounting screw and tighten.
Refer to torque specifications.
Fig. 8 SPEED CONTROL SWITCHES (EXCEPT 5.7L
V-8 ENGINE)
1 - ELECTRICAL CONNECTORS
2 - MOUNTING SCREWS
3 - RIGHT SWITCH
4 - LEFT SWITCH
Fig. 9 SPEED CONTROL SWITCHES (WITH 5.7L V-8
ENGINE)
1 - MOUNTING SCREWS
2 - RIGHT SWITCH
3 - LEFT SWITCH
4 - PIGTAIL LEADS
8P - 8 SPEED CONTROLDR
SWITCH (Continued)

WIRING
TABLE OF CONTENTS
page page
WIRING DIAGRAM INFORMATION....... 8W-01-1
COMPONENT INDEX.................. 8W-02-1
POWER DISTRIBUTION............... 8W-10-1
GROUND DISTRIBUTION.............. 8W-15-1
BUS COMMUNICATIONS.............. 8W-18-1
CHARGING SYSTEM.................. 8W-20-1
STARTING SYSTEM.................. 8W-21-1
FUEL/IGNITION SYSTEM.............. 8W-30-1
TRANSMISSION CONTROL SYSTEM..... 8W-31-1
VEHICLE SPEED CONTROL............ 8W-33-1
REAR WHEEL ANTILOCK BRAKES....... 8W-34-1
ALL WHEEL ANTILOCK BRAKES........ 8W-35-1
VEHICLE THEFT SECURITY SYSTEM..... 8W-39-1
INSTRUMENT CLUSTER............... 8W-40-1
HORN/CIGAR LIGHTER/POWER OUTLET . . 8W-41-1
AIR CONDITIONING.................. 8W-42-1
AIRBAG SYSTEM.................... 8W-43-1
INTERIOR LIGHTING.................. 8W-44-1AUDIO SYSTEM..................... 8W-47-1
REAR WINDOW DEFOGGER............ 8W-48-1
OVERHEAD CONSOLE................. 8W-49-1
FRONT LIGHTING.................... 8W-50-1
REAR LIGHTING..................... 8W-51-1
TURN SIGNALS...................... 8W-52-1
WIPERS............................ 8W-53-1
TRAILER TOW....................... 8W-54-1
NAVIGATION/TELECOMMUNICATION..... 8W-55-1
POWER WINDOWS................... 8W-60-1
POWER DOOR LOCKS................ 8W-61-1
POWER MIRRORS................... 8W-62-1
POWER SEATS...................... 8W-63-1
SPLICE INFORMATION................ 8W-70-1
CONNECTOR PIN-OUTS............... 8W-80-1
CONNECTOR/GROUND/SPLICE
LOCATION........................ 8W-91-1
POWER DISTRIBUTION............... 8W-97-1 DRWIRING 8W - 1

DESCRIPTION - CIRCUIT FUNCTIONS
All circuits in the diagrams use an alpha/numeric
code to identify the wire and it's function. To identify
which circuit code applies to a system, refer to the
Circuit Identification Code Chart. This chart shows
the main circuits only and does not show the second-
ary codes that may apply to some models.
CIRCUIT IDENTIFICATION CODE CHART
CIRCUIT FUNCTION
A BATTERY FEED
B BRAKE CONTROLS
C CLIMATE CONTROLS
D DIAGNOSTIC CIRCUITS
E DIMMING ILLUMINATION
CIRCUITS
F FUSED CIRCUITS
G MONITORING CIRCUITS
(GAUGES)
H OPEN
I NOT USED
J OPEN
K POWERTRAIN CONTROL
MODULE
L EXTERIOR LIGHTING
M INTERIOR LIGHTING
N NOT USED
O NOT USED
P POWER OPTION (BATTERY
FEED)
Q POWER OPTIONS (IGNITION
FEED)
R PASSIVE RESTRAINT
S SUSPENSION/STEERING
T TRANSMISSION/TRANSAXLE/
TRANSFER CASE
U OPEN
V SPEED CONTROL, WIPER/
WASHER
W OPEN
X AUDIO SYSTEMS
Y OPEN
Z GROUNDS
DESCRIPTION - SECTION IDENTIFICATION AND
INFORMATION
The wiring diagrams are grouped into individual
sections. If a component is most likely found in a par-
ticular group, it will be shown complete (all wires,
connectors, and pins) within that group. For exam-
ple, the Auto Shutdown Relay is most likely to be
found in Group 30, so it is shown there complete. It
can, however, be shown partially in another group if
it contains some associated wiring.
Splice diagrams in Section 8W-70 show the entire
splice and provide references to other sections the
splices serves. Section 8W-70 only contains splice dia-
grams that are not shown in their entirety some-
where else in the wiring diagrams.
Section 8W-80 shows each connector and the cir-
cuits involved with that connector. The connectors
are identified using the name/number on the dia-
gram pages.
WIRING SECTION CHART
GROUP TOPIC
8W-01 thru
8W-09General information and Diagram
Overview
8W-10 thru
8W-19Main Sources of Power and
Vehicle Grounding
8W-20 thru
8W-29Starting and Charging
8W-30 thru
8W-39Powertrain/Drivetrain Systems
8W-40 thru
8W-49Body Electrical items and A/C
8W-50 thru
8W-59Exterior Lighting, Wipers and
Trailer Tow
8W-60 thru
8W-69Power Accessories
8W-70 Splice Information
8W-80 Connector Pin Outs
8W-91 Connector, Ground and Splice
Locations
8W - 01 - 6 8W-01 WIRING DIAGRAM INFORMATIONDR
WIRING DIAGRAM INFORMATION (Continued)

DESCRIPTION - CONNECTOR, GROUND AND
SPLICE INFORMATION
CAUTION: Not all connectors are serviced. Some
connectors are serviced only with a harness. A typ-
ical example might be the Supplemental Restraint
System connectors. Always check parts availability
before attempting a repair.
IDENTIFICATION
In-line connectors are identified by a number, as
follows:
²In-line connectors located in the engine compart-
ment are C100 series numbers
²In-line connectors located in the Instrument
Panel area are C200 series numbers.
²In-line connectors located in the body are C300
series numbers.
²Jumper harness connectors are C400 series
numbers.
²Grounds and ground connectors are identified
with a ªGº and follow the same series numbering as
the in-line connectors.
²Splices are identified with an ªSº and follow the
same series numbering as the in-line connectors.
²Component connectors are identified by the com-
ponent name instead of a number. Multiple connec-
tors on a component use a C1, C2, etc. identifier.
LOCATIONS
Section 8W-91 contains connector/ground/splice
location illustrations. The illustrations contain the
connector name (or number)/ground number/splice
number and component identification. Connector/
ground/splice location charts in section 8W-91 refer-
ence the figure numbers of the illustrations.
The abbreviation T/O is used in the component
location section to indicate a point in which the wir-
ing harness branches out to a component. The abbre-
viation N/S means Not Shown in the illustrations
WARNING
WARNINGS - GENERAL
WARNINGSprovide information to prevent per-
sonal injury and vehicle damage. Below is a list of
general warnings that should be followed any time a
vehicle is being serviced.
WARNING: ALWAYS WEAR SAFETY GLASSES FOR
EYE PROTECTION.
WARNING: USE SAFETY STANDS ANYTIME A PRO-
CEDURE REQUIRES BEING UNDER A VEHICLE.WARNING: BE SURE THAT THE IGNITION SWITCH
ALWAYS IS IN THE OFF POSITION, UNLESS THE
PROCEDURE REQUIRES IT TO BE ON.
WARNING: SET THE PARKING BRAKE WHEN
WORKING ON ANY VEHICLE. AN AUTOMATIC
TRANSMISSION SHOULD BE IN PARK. A MANUAL
TRANSMISSION SHOULD BE IN NEUTRAL.
WARNING: OPERATE THE ENGINE ONLY IN A
WELL-VENTILATED AREA.
WARNING: KEEP AWAY FROM MOVING PARTS
WHEN THE ENGINE IS RUNNING, ESPECIALLY THE
FAN AND BELTS.
WARNING: TO PREVENT SERIOUS BURNS, AVOID
CONTACT WITH HOT PARTS SUCH AS THE RADIA-
TOR, EXHAUST MANIFOLD(S), TAIL PIPE, CATA-
LYTIC CONVERTER AND MUFFLER.
WARNING: DO NOT ALLOW FLAME OR SPARKS
NEAR THE BATTERY. GASES ARE ALWAYS
PRESENT IN AND AROUND THE BATTERY.
WARNING: ALWAYS REMOVE RINGS, WATCHES,
LOOSE HANGING JEWELRY AND AVOID LOOSE
CLOTHING.
DIAGNOSIS AND TESTING - WIRING HARNESS
TROUBLESHOOTING TOOLS
When diagnosing a problem in an electrical circuit
there are several common tools necessary. These tools
are listed and explained below.
²Jumper Wire - This is a test wire used to con-
nect two points of a circuit. It can be used to bypass
an open in a circuit.
WARNING: NEVER USE A JUMPER WIRE ACROSS
A LOAD, SUCH AS A MOTOR, CONNECTED
BETWEEN A BATTERY FEED AND GROUND.
²Voltmeter - Used to check for voltage on a cir-
cuit. Always connect the black lead to a known good
ground and the red lead to the positive side of the
circuit.
CAUTION: Most of the electrical components used
in today's vehicles are Solid State. When checking
voltages in these circuits, use a meter with a 10 -
megohm or greater impedance rating.
DR8W-01 WIRING DIAGRAM INFORMATION 8W - 01 - 7
WIRING DIAGRAM INFORMATION (Continued)

8W-21 STARTING SYSTEM
Component Page
Auxiliary Battery.................... 8W-21-3
Battery.......................... 8W-21-2, 3
Clutch Interlock Brake Switch.......... 8W-21-4
Engine Control Module................ 8W-21-4
Fuse 14.......................... 8W-21-2, 3
G104.............................. 8W-21-4
Ignition Switch.................... 8W-21-2, 3Component Page
Integrated Power Module.......... 8W-21-2, 3, 4
Powertrain Control Module............ 8W-21-2
Starter Motor..................... 8W-21-2, 3
Starter Motor Relay................ 8W-21-2, 3
Transfer Case Control Module.......... 8W-21-4
Transmission Range Sensor............ 8W-21-4
DR8W-21 STARTING SYSTEM 8W - 21 - 1

8W-30 FUEL/IGNITION SYSTEM
Component Page
A/C Compressor Clutch Relay............ 8W-30-9, 58
A/C Pressure Transducer......... 8W-30-23, 28, 29, 45
Accelerator Pedal Position Sensor . . . 8W-30-29, 47, 64, 65
Adjustable Pedal Motor................. 8W-30-61
Adjustable Pedal Relay.................. 8W-30-61
Adjustable Pedal Switch................. 8W-30-61
Ambient Temperature Sensor............. 8W-30-30
Auto Shut Down Relay................... 8W-30-4
Battery............................ 8W-30-52
Battery Temperature Sensor............ 8W-30-12, 56
Brake Lamp Switch............. 8W-30-8, 36, 57, 63
Camshaft Position Sensor........ 8W-30-10, 29, 45, 46
Capacitor........................... 8W-30-13
Clockspring..................... 8W-30-8, 36, 59
Coil On Plug No. 1.................. 8W-30-14, 39
Coil On Plug No. 2.................. 8W-30-15, 37
Coil On Plug No. 3.................. 8W-30-14, 39
Coil On Plug No. 4.................. 8W-30-15, 37
Coil On Plug No. 5.................. 8W-30-16, 39
Coil On Plug No. 6.................. 8W-30-13, 37
Coil On Plug No. 7.................. 8W-30-16, 39
Coil On Plug No. 8.................. 8W-30-13, 37
Condenser Fan Relay.................... 8W-30-9
Controller Antilock Brake............ 8W-30-6, 11, 57
Crankshaft Position Sensor............ 8W-30-10, 46
Data Link Connector............... 8W-30-9, 22, 55
Data Link Connector-Engine.............. 8W-30-51
EGR Solenoid................... 8W-30-28, 29, 32
Electronic Throttle Control Module.......... 8W-30-35
Engine Control Module....... 8W-30-42, 43, 44, 45, 46,
47, 48, 49, 50, 51, 52, 53, 54,
55, 56, 57, 58, 59, 60, 62, 63, 64, 65
Engine Coolant Temperature Sensor.... 8W-30-23, 41, 47
Engine Oil Pressure Switch.......... 8W-30-2, 53, 56
EVAP/Purge Solenoid................... 8W-30-12
Front Control Module................... 8W-30-61
Fuel Control Actuator................... 8W-30-50
Fuel Heater......................... 8W-30-60
Fuel Heater Relay..................... 8W-30-60
Fuel Injector No. 1.................. 8W-30-14, 40
Fuel Injector No. 2.................. 8W-30-15, 38
Fuel Injector No. 3.................. 8W-30-14, 40
Fuel Injector No. 4.................. 8W-30-15, 38
Fuel Injector No. 5.................. 8W-30-14, 40
Fuel Injector No. 6.................. 8W-30-15, 38
Fuel Injector No. 7.................. 8W-30-16, 40
Fuel Injector No. 8.................. 8W-30-13, 38
Fuel Injector Pack No. 1................. 8W-30-42
Fuel Injector Pack No. 2............ 8W-30-42, 43, 44
Fuel Injector Pack No. 3................. 8W-30-44
Fuel Pump Module................... 8W-30-3, 58
Fuel Pump Motor...................... 8W-30-48
Fuel Pump Relay....................... 8W-30-3
Fuse 2.............................. 8W-30-4
Fuse 5........................... 8W-30-25, 62
Fuse 12............................ 8W-30-60
Fuse 17............................. 8W-30-3
Fuse 19............................ 8W-30-52
Fuse 23............................. 8W-30-2Component Page
Fuse 36.......................... 8W-30-54, 61
Fuse 40............................ 8W-30-61
Fuse 49............................. 8W-30-4
Fuse 50..................... 8W-30-2, 55, 58, 62
Fusible Link......................... 8W-30-52
G104........................ 8W-30-3, 8, 25, 60
G105............................ 8W-30-56, 58
G107........... 8W-30-2, 7, 15, 18, 19, 20, 21, 30, 32
G114 .............................. 8W-30-53
G120............................ 8W-30-51, 60
G201............................... 8W-30-6
G202.............................. 8W-30-61
Generator......................... 8W-30-7, 51
Idle Air Control Motor................... 8W-30-9
Ignition Switch..................... 8W-30-6, 22
Inlet Air Temperature Sensor............. 8W-30-49
Input Speed Sensor.................... 8W-30-24
Instrument Cluster.................... 8W-30-30
Intake Air Heater Relay No. 1............. 8W-30-56
Intake Air Heater Relay No. 2............. 8W-30-56
Intake Air Temperature Sensor.......... 8W-30-23, 41
Intake Air Temperature/Manifold Absolute
Pressure Sensor..................... 8W-30-50
Integrated Power Module.... 8W-30-2, 3, 4, 9, 25, 52, 54,
55, 58, 60, 61, 62, 64
Knock Sensor........................ 8W-30-31
Knock Sensor-Left..................... 8W-30-33
Knock Sensor-Right.................... 8W-30-33
Lift Pump Motor...................... 8W-30-51
Line Pressure Sensor................... 8W-30-17
Manifold Absolute Pressure Sensor..... 8W-30-23, 29, 41
Natural Vacuum Leak Detection Assembly..... 8W-30-7
Output Speed Sensor................. 8W-30-24, 62
Oxygen Sensor 1/1 Upstream........... 8W-30-20, 21
Oxygen Sensor 1/2 Downstream......... 8W-30-18, 19
Oxygen Sensor 2/1 Upstream........... 8W-30-20, 21
Oxygen Sensor 2/2 Downstream......... 8W-30-18, 19
Oxygen Sensor Downstream Relay........... 8W-30-4
Power Steering Pressure Switch............ 8W-30-7
Powertrain Control Module....... 8W-30-2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19, 20, 21, 22, 23, 24,
25, 26, 27, 28, 29, 30, 31, 32,
33, 35, 36, 37, 38, 39, 40, 41
PTCNo.1 ....................... 8W-30-3, 9, 58
Pto Switch........................... 8W-30-6
Speed Control Servo.................. 8W-30-8, 63
Speed Control Switch-Left............. 8W-30-36, 59
Speed Control Switch-Right............ 8W-30-36, 59
Starter Motor Relay.................. 8W-30-2, 64
Throttle Position Sensor................. 8W-30-17
Tow/Haul Overdrive Switch............. 8W-30-6, 64
Transmission Control Relay............ 8W-30-25, 62
Transmission Range Sensor............... 8W-30-64
Transmission Solenoid Assembly......... 8W-30-54, 62
Transmission Solenoid/TRS Assembly . 8W-30-5, 25, 26, 27
Vacuum Pump........................ 8W-30-58
Vistronic Fan Drive.................... 8W-30-54
Water In Fuel Sensor................ 8W-30-47, 48
DR8W-30 FUEL/IGNITION SYSTEM 8W - 30 - 1

8W-31 TRANSMISSION CONTROL SYSTEM
Component Page
Automatic Day/Night Mirror........... 8W-31-7
Brake Lamp Switch.................. 8W-31-9
Camshaft Position Sensor.............. 8W-31-6
Clockspring........................ 8W-31-10
Clutch Interlock Brake Switch......... 8W-31-11
Data Link Connector................ 8W-31-16
Engine Control Module......... 8W-31-7, 8, 9, 10
Front Control Module................. 8W-31-2
Fuse 5.......................... 8W-31-2, 8
Fuse 38.......................... 8W-31-2, 7
Fuse 43........................... 8W-31-11
Fuse 50............................ 8W-31-8
G104..................... 8W-31-2, 11, 14, 16
G107............................. 8W-31-14
G201........................... 8W-31-3, 10
Input Speed Sensor.................. 8W-31-5
Instrument Cluster................ 8W-31-7, 14
Integrated Power Module....... 8W-31-2, 7, 8, 11Component Page
Line Pressure Sensor................. 8W-31-6
Output Speed Sensor............... 8W-31-5, 8
Powertrain Control Module..... 8W-31-2, 3, 4, 5, 6
Speed Control Servo.................. 8W-31-9
Speed Control Switch-Left............ 8W-31-10
Speed Control Switch-Right........... 8W-31-10
Starter Motor Relay................. 8W-31-11
Tow/Haul Overdrive Switch......... 8W-31-3, 10
Transfer Case Control
Module.............. 8W-31-11, 12, 13, 14, 16
Transfer Case Mode Sensor........ 8W-31-12, 13
Transfer Case Selector Switch......... 8W-31-14
Transfer Case Shift Motor............ 8W-31-16
Transmission Control Relay.......... 8W-31-2, 8
Transmission Range Sensor............ 8W-31-7
Transmission Solenoid Assembly........ 8W-31-8
Transmission Solenoid/TRS Assembly . 8W-31-2, 3, 4
DR8W-31 TRANSMISSION CONTROL SYSTEM 8W - 31 - 1