Electrical schematic DODGE RAM 1500 1998 2.G Workshop Manual

COOLING SYSTEM DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE READS
LOW1. Has a Diagnostic Trouble Code
(DTC) been set indicating a stuck
open thermostat?1. (Refer to 25 - EMISSIONS
CONTROL - DESCRIPTION) for
On-Board Diagnostics and DTC
information. Replace thermostat if
necessary.
2. Is the temperature sending unit
connected?2. Check the temperature sensor
connector. (Refer to 8 -
ELECTRICAL/INSTRUMENT
CLUSTER - SCHEMATIC -
ELECTRICAL) Repair connector if
necessary.
3. Is the temperature gauge
operating OK?3. Check gauge operation. (Refer to
8 - ELECTRICAL/INSTRUMENT
CLUSTER/ENGINE
TEMPERATURE GAUGE -
DESCRIPTION). Repair as
necessary.
4. Coolant level low in cold ambient
temperatures accompanied with
poor heater performance.4. Check coolant level in the coolant
reserve/overflow tank or degas
bottle and the radiator. Inspect
system for leaks. Repair leaks as
necessary. Refer to the Coolant
section of the manual text for
WARNINGS and CAUTIONS
associated with removing the
radiator cap.
5. Improper operation of internal
heater doors or heater controls.5. Inspect heater and repair as
necessary. (Refer to 24 - HEATING
& AIR CONDITIONING -
DIAGNOSIS AND TESTING) for
procedures.
TEMPERATURE GAUGE READS
HIGH OR THE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST OR LEAKING FROM THE
COOLING SYSTEM1. Trailer is being towed, a steep
hill is being climbed, vehicle is
operated in slow moving traffic, or
engine is being idled with very high
ambient (outside) temperatures and
the air conditioning is on. Higher
altitudes could aggravate these
conditions.1. This may be a temporary
condition and repair is not
necessary. Turn off the air
conditioning and attempt to drive the
vehicle without any of the previous
conditions. Observe the temperature
gauge. The gauge should return to
the normal range. If the gauge does
not return to the normal range,
determine the cause for overheating
and repair. Refer to Possible
Causes (2-18).
2. Is the temperature gauge reading
correctly?2. Check gauge. (Refer to 8 -
ELECTRICAL/INSTRUMENT
CLUSTER - SCHEMATIC -
ELECTRICAL). Repair as
necessary.
DRCOOLING 7 - 11
COOLING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
3. Is the temperature warning
illuminating unnecessarily?3. (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER -
SCHEMATIC - ELECTRICAL).
4. Coolant low in coolant reserve/
overflow tank and radiator?4. Check for coolant leaks and
repair as necessary. (Refer to 7 -
COOLING - DIAGNOSIS AND
TESTING).
5. Pressure cap not installed tightly.
If cap is loose, boiling point of
coolant will be lowered. Also refer
to the following Step 6.5. Tighten cap
6. Poor seals at the radiator cap. 6. (a) Check condition of cap and
cap seals. Refer to Radiator Cap.
Replace cap if necessary.
(b) Check condition of radiator filler
neck. If neck is bent or damaged,
replace radiator (5.9L) or degas
bottle (3.7L, 4.7L).
7. Coolant level low in radiator but
not in coolant reserve/overflow
tank. This means the radiator is not
drawing coolant from the coolant
reserve/overflow tank as the engine
cools (5.9L).7. (a) Check condition of radiator
cap and cap seals. Refer to
Radiator Cap in this Group. Replace
cap if necessary.
(b) Check condition of radiator filler
neck. If neck is bent or damaged,
replace radiator.
(c) Check condition of the hose from
the radiator to the coolant tank. It
should fit tight at both ends without
any kinks or tears. Replace hose if
necessary.
(d) Check coolant reserve/overflow
tank and tanks hoses for blockage.
Repair as necessary.
8. Incorrect coolant concentration 8. Check coolant. (Refer to
LUBRICATION & MAINTENANCE/
FLUID TYPES - DESCRIPTION).
9. Coolant not flowing through
system9. Check for coolant flow at radiator
filler neck with some coolant
removed, engine warm and
thermostat open. Coolant should be
observed flowing through radiator. If
flow is not observed, determine area
of obstruction and repair as
necessary.
10. Radiator or A/C condenser fins
are dirty or clogged.10. Remove insects and debris.
(Refer to 7 - COOLING -
STANDARD PROCEDURE).
7 - 12 COOLINGDR
COOLING (Continued)

The compass unit also will compensate for magne-
tism the body of the vehicle may acquire during nor-
mal use. However, avoid placing anything magnetic
directly on the roof of the vehicle. Magnetic mounts
for an antenna, a repair order hat, or a funeral pro-
cession flag can exceed the compensating ability of
the compass unit if placed on the roof panel. Mag-
netic bit drivers used on the fasteners that hold the
overhead console assembly to the roof header can
also affect compass operation. If the vehicle roof
should become magnetized, the demagnetizing and
calibration procedures found in this section may be
required to restore proper compass operation.
TEMPERATURE DISPLAY
All the available overhead consoles on this model
include Temperature information. The temperature
displays the outside ambient temperature in whole
degrees. The temperature display can be toggled
from Fahrenheit to Celsius by selecting the desired
U.S./Metric option from the customer programmable
features. The displayed temperature is not an instant
reading of conditions, but an average temperature. It
may take the temperature display several minutes to
respond to a major temperature change, such as driv-
ing out of a heated garage into winter temperatures.
When the ignition switch is turned to the Off posi-
tion, the last displayed temperature reading stays in
the electronic control modules, (CMTC, EVIC) mem-
ory. When the ignition switch is turned to the On
position again, the electronic module will display the
memory temperature for one minute; then update the
display to the current average temperature reading
within five minutes.The temperature function is supported by an ambi-
ent temperature sensor. This sensor is mounted out-
side the passenger compartment near the front and
center of the vehicle, and is hard wired to the Front
Control Module (FCM). The FCM sends temperature
status messages to the module over the J1850 PCI
data bus circuit. For more information on the ambi-
ent temperature sensor, refer to Ambient Tempera-
ture Sensor later in this section.
Following are general descriptions of the major
components used in the overhead console. Refer to
Wiring Diagrams for complete circuit schematics.
OPERATION
Refer to the vehicle Owner's Manual for specific
operation of each overhead console and its systems.
DIAGNOSIS AND TESTING - OVERHEAD
CONSOLE
If the problem with the overhead console is an
inaccurate or scrambled display, refer toSELF-DI-
AGNOSTIC TESTlater in this text. If the problem
with the overhead console is incorrect Vacuum Fluo-
rescent Display (VFD) dimming levels, use a DRB
IIItscan tool and the proper Diagnostic Procedures
manual to test for the correct dimming message
inputs being received from the Body Control Module
(BCM) or Front Control Module (FCM) over the
J1850 Programmable Communications Interface
(PCI) data bus circuit. If the problem is a no-display
condition, use the following procedure. For complete
circuit diagrams, refer toOverhead Consolein the
Wiring Diagrams section of the service manual.
(1) Remove the overhead console from the head-
liner (Refer to 8 - ELECTRICAL/OVERHEAD CON-
SOLE - REMOVAL).
(2) Check for battery voltage at the overhead con-
sole electrical connector. Refer to Wiring for connec-
tor information. If OK, go to Step 3. If not OK, Check
for battery voltage at the appropriate B(+) fuse in the
integrated power module, repair the open fused B(+)
circuit as required.
(3) Turn the ignition switch to the On position.
Check the fused ignition switch output circuit(s) at
the overhead console electrical connector. If OK, go to
Step 4. If not OK, repair the open or shorted circuit
as required.
(4) 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 overhead console electrical connector and a
good ground. There should be continuity. If OK, refer
toSELF-DIAGNOSTIC TESTbelow for further
diagnosis of the electronics module and the J1850
PCI data bus circuit. If not OK, repair the open
ground circuit as required.
Fig. 1 DR OVERHEAD CONSOLE ± EVIC
8M - 2 MESSAGE SYSTEMSDR
OVERHEAD CONSOLE (Continued)

INTEGRATED POWER MODULE
DESCRIPTION
The Integrated Power Module (IPM) (Fig. 1) is a
combination of the Power Distribution Center (PDC)
and the Front Control Module (FCM). The IPM is
located in the engine compartment, next to the bat-
tery on this model. The power distribution center
mates directly with the Front Control Module (FCM)
to form the Integrated Power Module Fuse and Relay
Center. The power distribution center (PDC) is a
printed circuit board based module that contains
fuses and relays, while the front control module con-
tains the electronics controlling the integrated power
module and other functions. This integrated power
module connects directly to the battery positive via a
stud located on top of the unit. The ground connec-
tion is via electrical connectors. The integrated power
module provides the primary means of voltage distri-
bution and protection for the entire vehicle.
The molded plastic integrated power module hous-
ing includes a base and cover. The integrated power
module cover is easily opened or removed for service
access by unscrewing the cover retaining nut and has
a fuse and relay layout map integral to the inside
surface of the cover. This integrated power module
housing base and cover are secured in place via bolts
to the left front fender support assembly.
Replaceable components of the integrated power
module assembly are broken down into the followingcomponents: the Power Distribution Center (PDC),
the integrated power module cover, the Front Control
Module (FCM) and the Integrated Power Module
Assembly which includes the power distribution cen-
ter, the cover and FCM.Refer to the Front Con-
trol Module in the Electronic Control Module
sectionof this service manual for information on the
front control module.
OPERATION
All of the current from the battery and the gener-
ator output enters the integrated power module via a
stud on the top of the module. The integrated power
module cover is removed to access the fuses or relays.
Internal connections of all of the power distribution
center circuits is accomplished by a combination of
bus bars and a printed circuit board. Refer to the
Wiring section of the service manual for complete
integrated power module circuit schematics.
REMOVAL
(1) Disconnect the negative and positive battery
cables.
(2) Unsnap cover and remove the B+ terminal nut
from the integrated power module B+ terminal.
Remove the B+ cable from the integrated power mod-
ule.
(3) Disconnect the gray connector from the inte-
grated power module.
Fig. 1 DR INTEGRATED POWER MODULE
1 - POWER DISTRIBUTION CENTER HOUSING
2 - FRONT CONTROL MODULE ELECTRICAL CONNECTOR
Fig. 2 DR INTEGRATED POWER MODULE
1 - COVER RETAINING BOLT
2 - INTEGRATED POWER MODULE RETAINING BOLT
3 - RETAINING SCREW
4 - INTEGRATED POWER MODULE COVER
DR8W-97 POWER DISTRIBUTION 8W - 97 - 3

(8) For columns without tilt remove the bracket to
gain access to the ignition switch mounting screws.
(Fig. 10)
(9) Disconnect the electrical connector at rear of
ignition switch (Fig. 11).
(10) Remove ignition switch mounting screw.
(11) Using a small screwdriver, push on locking
tab and remove switch from steering column.
INSTALLATION
The ignition key must be in the key cylinder for
cylinder removal. The key cylinder must be removed
first before installing ignition switch.
(1) Before installing ignition switch, rotate the slot
in the switch to the ON position.(2) Connect the electrical connector to rear of the
ignition switch. Make sure that locking tabs are fully
seated into wiring connector.
(3) Position switch to column and install the
mounting screw. Tighten screw to 3 N´m (26 in. lbs.).
(4) Install the tilt lever bracket mounting screws.
Tighten screws to 4.5 N´m (40 in. lbs.).
(5) If the column is non-tilt install the bracket.
Tighten screws to 4.5 N´m (40 in. lbs.) (Fig. 10)
(6) Position the wire retainer into the tilt lever
bracket.
(7) Reconnect the lower clockspring connectors.
(8) Install the key cylinder.
(9) Install steering column upper and lower
shrouds.
(10) Enable the airbag system. (Refer to 8 - ELEC-
TRICAL/RESTRAINTS/DRIVER AIRBAG - INSTAL-
LATION).
KEY-IN IGNITION SWITCH
DESCRIPTION
The key-in ignition switch is integral to the igni-
tion switch, which is mounted on the left side of the
steering column. It closes a path to ground for the
Central Timer Module (CTM) when the ignition key
is inserted in the ignition key cylinder and the driver
door ajar switch is closed (driver door is open). The
key-in ignition switch opens the ground path when
the key is removed from the ignition key cylinder.
The ground path is also opened when the driver door
ajar switch is open (driver door is closed).
The key-in ignition switch cannot be repaired and,
if faulty or damaged, the entire ignition switch must
be replaced, (Refer to 19 - STEERING/COLUMN/IG-
NITION SWITCH - REMOVAL).
DIAGNOSIS AND TESTING - IGNITION SWITCH
AND KEY LOCK CYLINDER
ELECTRICAL DIAGNOSIS
For ignition switch electrical schematics, refer to
Ignition Switch in the appropriate section of Electri-
cal Wiring Diagrams.
MECHANICAL DIAGNOSIS (KEY DIFFICULT TO
ROTATE)
(Refer to 19 - STEERING/COLUMN/IGNITION
SWITCH - DIAGNOSIS AND TESTING).
Fig. 10 IGNITION SWITCH WITHOUT TILT
1 - Ignition Switch Mounting Screws
2 - Non-Tilt Mounitng Bracket Screws
Fig. 11 IGNITION SWITCH
1 - Ignition Switch
2 - Ignition Switch Mounting Screws
DRCOLUMN 19 - 11
IGNITION SWITCH (Continued)