four wheel drive JEEP CHEROKEE 1995 Service User Guide

TACHOMETER
The tachometer gives an indication of engine speed
in Revolutions-Per-Minute (RPM). With the engine
running, the tachometer receives an engine speed
pulse signal from the Powertrain Control Module
(PCM). An electronic integrated circuit contained
within the tachometer reads and analyzes the pulse
signal. It then adjusts the ground path resistance of
one electromagnet in the gauge to control needle
movement. Frequency values for the pulse signal are
shown in a chart in Specifications.
TRIP ODOMETER
The trip odometer is driven by the same electronic
integrated circuit as the speedometer/odometer. How-
ever, by depressing the trip odometer reset knob on
the face of the speedometer, the trip odometer can be
reset to zero. The trip odometer is serviced only as a
part of the speedometer/odometer gauge assembly.
VOLTMETER
The voltmeter is connected in parallel with the bat-
tery. With the ignition switch ON, the voltmeter in-
dicates battery or generator output voltage,
whichever is greater.
INDICATOR LAMPS
Indicator lamps are located in two areas within the
cluster. Each of these areas is served by a separate
printed circuit and cluster connector. Those lamps in
the gauge area of the cluster share the gauge area
printed circuit and cluster connector A. Those lamps
in the tell-tale area of the cluster use the tell-tale
printed circuit and cluster (tell-tale) connector B.
Up to ten indicator lamps can be found in the tell-
tale area of the cluster. These lamps are arranged in
five stacked rows with two lamps in each row, located
to the driver's side of the main cluster.
ANTI-LOCK BRAKE SYSTEM LAMP
The Anti-Lock Brake System (ABS) lamp is
switched to ground by the ABS module. The module
lights the lamp when the ignition switch is turned to
the START position as a bulb test. The lamp will
stay on for 3 to 5 seconds after vehicle start-up to in-
dicate a system self-test is in process. If the lamp re-
mains on after start-up, or comes on and stays on
while driving, it may indicate that the ABS module
has detected a system malfunction or that the system
has become inoperative. Refer to Group 5 - Brakes
for more information.
BRAKE WARNING LAMP
The brake warning lamp warns the driver that the
parking brake is applied or that the pressures in the
two halves of the split brake hydraulic system are
unequal. With the ignition switch turned ON, batteryvoltage is supplied to one side of the indicator bulb. A
ground path for the bulb is provided by 3 switches.
The bulb will light when:
²the brake warning switch is closed (indicating un-
equal brake system hydraulic pressures possibly due
to brake fluid leakage)
²the ignition switch is in the START position (bulb
test)
²the parking brake switch is closed (parking brake
is applied).
Refer to Group 5 - Brakes for more information.
COOLANT TEMPERATURE WARNING LAMP
The coolant temperature warning lamp lights
whenever engine coolant temperature is too high.
Battery voltage is supplied to one side of the indica-
tor bulb when the ignition switch is turned ON. The
normally open coolant temperature switch is con-
nected to the other side of the bulb. When coolant
temperature is too high, the switch closes. This pro-
vides a ground path for the indicator bulb, which
causes it to light. The lamp is also grounded and
should light with the ignition switch in the START
position as a bulb test.
FOUR-WHEEL DRIVE INDICATOR LAMPS
PART TIME
On vehicles with Command-Trac 4WD, the Part
Time lamp lights when the transfer case is engaged
in the 4H or 4L position. On vehicles with Selec-Trac
4WD, the Part Time lamp lights when the transfer
case is engaged in the4X4PARTTIME or 4 LO po-
sition. Voltage is supplied to one side of the indicator
bulb. A switch in the transfer case is connected to the
other side of the indicator bulb. When the switch is
closed, a path to ground is provided and the indicator
bulb lights.
FULL TIME
The Full Time lamp is only operational on vehicles
equipped with Selec-Trac 4WD. The Full Time lamp
lights when the transfer case is engaged in the4X4
Full Time position. Voltage is supplied to one side of
the indicator bulb. A switch in the transfer case is
connected to the other side of the indicator bulb.
When the switch is closed, a path to ground is pro-
vided and the indicator bulb lights.
GENERATOR WARNING LAMP
The generator warning lamp lights with the igni-
tion switch turned to ON, but should go out when-
ever the engine is running. If the lamp comes on and
stays on while the engine is running, it indicates
that a charging system malfunction exists. One side
of the bulb is connected to ignition-switched battery
feed. The other side of the bulb is switched to ground
by the Powertrain Control Module (PCM).
JINSTRUMENT PANEL AND GAUGESÐXJ 8E - 3

Connect battery negative cable and turn ignition
switch to ON. Lamp should light. If OK, repair open
circuit to brake warning switch. If not OK, replace
bulb.
(5) Turn ignition switch to OFF and remove
jumper wire. Disconnect battery negative cable.
Check for continuity between cavity A (cavity B -
RHD) of brake warning switch connector and a good
ground with ignition switch in START position.
There should be continuity. If not OK, go to next
step.
(6) Turn ignition switch to OFF and remove
jumper wire. Disconnect battery negative cable. Un-
plug ignition switch connector. Check for continuity
between ignition switch connector cavity 3 and a
good ground. There should be no continuity. If OK, go
to next step. If not OK, repair short circuit between
ignition switch and brake warning switch connectors
as required.
(7) Check for continuity between ignition switch
connector cavity 3 and brake warning switch connec-
tor cavity A (cavity B - RHD). There should be conti-
nuity. If OK, go to next step. If not OK, repair open
circuit as required.
(8) Check for continuity between metal steering
column jacket and a good ground. There should be
continuity. If OK, go to next step. If not OK, refer to
Group 19 - Steering to check steering column ground
clip installation.
(9) Turn ignition switch to START position and
hold there. Check for continuity between terminal 3
of ignition switch and a good ground. There should
be continuity. If not OK, replace ignition switch.
(10) Unplug brake warning switch connector.
Check for continuity between parking brake switch
connector and a good ground. There should be no
continuity. If OK, go to next step. If not OK, repair
short circuit as required.
(11) Check for continuity between parking brake
switch connector and cavity B (cavity A - RHD) of
brake warning switch connector. There should be
continuity. If OK, replace parking brake switch. If
not OK, repair open circuit to brake warning switch
as required.
COOLANT TEMPERATURE WARNING LAMP
The diagnosis found here addresses an inoperative
lamp condition. If the problem being diagnosed is re-
lated to lamp accuracy, be certain to confirm that
problem is with lamp and not with cooling system
performance. Actual engine coolant temperature
should be checked with a test gauge or thermometer
before proceeding with lamp diagnosis. Refer to
Group 7 - Cooling System for more information.
(1) Turn ignition switch to START position. Lamp
should light. If OK, go to next step. If not OK, go to
step 3.(2) Turn ignition switch to ON. Disconnect coolant
temperature switch connector (Fig. 1). Jump switch
connector to ground. Lamp should light. If OK, re-
place switch. If not OK, go to next step.
(3) Turn ignition switch to OFF. Disconnect battery
negative cable. Unplug coolant temperature switch
connector. Remove instrument cluster bezel and clus-
ter assembly. Disconnect cluster connector A and
probe cavity A1. Check for continuity to a good
ground. There should be no continuity. If OK, go to
next step. If not OK, repair short circuit to coolant
temperature switch or ignition switch as required.
(4) Connect cluster connector A to cluster. Install a
jumper wire from cavity A1 of cluster connector A to
a good ground. Connect battery negative cable and
turn ignition switch to ON. Lamp should light. If OK,
repair open circuit to coolant temperature switch or
ignition switch as required. If not OK, replace bulb.
FOUR-WHEEL DRIVE INDICATOR LAMPS
(1) Apply parking brake, start engine, vehicle in
4WD Lock or 4WD.
(2) Unplug switch and touch harness side of wire
to ground. Lamp should light. If OK, check switch
operation, replace if bad. If bulb is OK, repair open
to indicator.
GENERATOR WARNING LAMP
(1) Disconnect battery negative cable and unplug
PCM connector. Install a jumper wire between cavity
36 of PCM connector (Fig. 5) and a good ground. Con-
nect battery negative cable and turn ignition switch
to ON. Lamp should light. Unplug jumper wire and
lamp should go off. If OK, refer to Powertrain Diag-
nostic Procedures to check PCM. If not OK, go to
next step.
(2) Turn ignition switch to OFF and disconnect
battery negative cable. Remove instrument cluster
bezel and cluster assembly. Install a jumper wire be-
tween cavity B8 of cluster connector A and a good
ground. Connect battery negative cable and turn ig-
nition switch to ON. Lamp should light. If OK, go to
next step. If not OK, replace bulb.
(3) Turn ignition switch to OFF and disconnect
battery negative cable. Unplug cluster connector A.
Probe cavity B8 of cluster connector A and check for
continuity to a good ground. There should be no con-
tinuity. If OK, go to next step. If not OK, repair short
circuit as required.
(4) Check for continuity between cavity B8 of clus-
ter connector A and cavity 36 of PCM connector.
There should be continuity. If not OK, repair open
circuit as required.
HEADLAMP HIGH BEAM INDICATOR LAMP
(1) Check that headlamp high beams are func-
tional. If OK, go to next step. If not OK, refer to
Group 8L - Lamps for diagnosis of headlamp system.
JINSTRUMENT PANEL AND GAUGESÐXJ 8E - 13

INSTRUMENT PANEL AND GAUGESÐYJ
CONTENTS
page page
INSTRUMENT PANEL AND GAUGESÐYJ..... 22
DIAGNOSIS............................ 23
GENERAL INFORMATION................. 20SERVICE PROCEDURES.................. 31
SPECIFICATIONS........................ 39
GENERAL INFORMATION
Following are general descriptions of major instru-
ment panel components. Refer to Group 8W - Wiring
Diagrams for complete circuit descriptions and dia-
grams.
INSTRUMENT PANEL
Modular instrument panel construction allows all
gauges and controls to be serviced from the front of
the panel. In addition, most instrument panel wiring
and heater components can be accessed without com-
plete instrument panel removal.
Removal of the left instrument cluster bezel allows
access to the main cluster assembly and most
switches. Removal of the center cluster bezel allows
access to the gauge package cluster assembly, the
heater controls, and the radio. Removal of the cluster
assemblies allows access to the individual gauges, il-
lumination and indicator lamp bulbs, printed cir-
cuits, and most wiring.
INSTRUMENT CLUSTERS
The instrument cluster used on YJ (Wrangler) mod-
els consists of two separate assemblies. The main
cluster assembly is located on the left side of the in-
strument panel, centered over the steering column
opening. The gauge package cluster assembly is lo-
cated near the center of the instrument panel. Each
cluster assembly is served by a separate printed cir-
cuit and wiring connector. Some variations of each
cluster exist due to optional equipment and regula-
tory requirements.
The main cluster assembly includes a speedometer/
odometer/trip odometer and a tachometer. It also in-
cludes provisions for the following indicator lamps:
²anti-lock brake system lamp
²brake warning lamp
²headlamp high beam indicator lamp
²malfunction indicator (Check Engine) lamp
²seat belt reminder lamp²turn signal indicator lamps
²upshift indicator lamp.
The gauge package cluster assembly includes a
four-wheel drive indicator lamp and the following
gauges:
²coolant temperature gauge
²fuel gauge
²oil pressure gauge
²voltmeter.
GAUGES
With the ignition switch in the ON or START posi-
tion, voltage is supplied to all gauges through the
two cluster printed circuits. With the ignition switch
in the OFF position, voltage is not supplied to the
gauges. A gauge pointer may remain within the
gauge scale after the ignition switch is OFF. How-
ever, the gauges do not accurately indicate any vehi-
cle condition unless the ignition switch is ON.
All gauges except the odometer are air core mag-
netic units. Two fixed electromagnetic coils are lo-
cated within the gauge. These coils are wrapped at
right angles to each other around a movable perma-
nent magnet. The movable magnet is suspended
within the coils on one end of a shaft. The gauge nee-
dle is attached to the other end of the shaft.
One of the coils has a fixed current flowing through
it to maintain a constant magnetic field strength.
Current flow through the second coil changes, which
causes changes in its magnetic field strength. The
current flowing through the second coil can be
changed by:
²a variable resistor-type sending unit (fuel level,
coolant temperature, or oil pressure)
²changes in electrical system voltage (voltmeter)
²electronic control circuitry (speedometer/odometer,
tachometer).
8E - 24 INSTRUMENT PANEL AND GAUGESÐYJJ

The gauge needle moves as the movable permanent
magnet aligns itself to the changing magnetic fields
created around it by the electromagnets.
COOLANT TEMPERATURE GAUGE
The coolant temperature gauge gives an indication
of engine coolant temperature. The coolant tempera-
ture sending unit is a thermistor that changes elec-
trical resistance with changes in engine coolant
temperature. High sending unit resistance causes
low coolant temperature readings. Low resistance
causes high coolant temperature readings. Sending
unit resistance values are shown in a chart in Spec-
ifications.
FUEL GAUGE
The fuel gauge gives an indication of the level of
fuel in the fuel tank. The fuel gauge sending unit has
a float attached to a swing-arm in the fuel tank. The
float moves up or down within the fuel tank as fuel
level changes. As the float moves, an electrical con-
tact on the swing-arm wipes across a resistor coil,
which changes sending unit resistance. High sending
unit resistance causes high fuel level readings. Low
resistance causes low fuel level readings. Sending
unit resistance values are shown in a chart in Spec-
ifications.
OIL PRESSURE GAUGE
The oil pressure gauge gives an indication of en-
gine oil pressure. The combination oil pressure send-
ing unit contains a flexible diaphragm. The
diaphragm moves in response to changes in engine
oil pressure. As the diaphragm moves, sending unit
resistance increases or decreases. High resistance on
the gauge side of the sending unit causes high oil
pressure readings. Low resistance causes low oil
pressure readings. Sending unit resistance values are
shown in a chart in Specifications.
SPEEDOMETER/ODOMETER
The speedometer/odometer give an indication of ve-
hicle speed and travel distance. The speedometer re-
ceives a vehicle speed pulse signal from the Vehicle
Speed Sensor (VSS). An electronic integrated circuit
contained within the speedometer reads and analyzes
the pulse signal. It then adjusts the ground path re-
sistance of one electromagnet in the gauge to control
needle movement. It also sends signals to an electric
stepper motor to control movement of the odometer
number rolls. Frequency values for the pulse signal
are shown in a chart in Specifications.
The VSS is mounted to an adapter near the trans-
fer case output shaft. The sensor is driven through
the adapter by a speedometer pinion gear. The
adapter and pinion vary with transmission, axle ratio
and tire size. Refer to Group 21 - Transmission and
Transfer Case for more information.
TACHOMETER
The tachometer gives an indication of engine speed
in Revolutions-Per-Minute (RPM). With the engine
running, the tachometer receives an engine speed
pulse signal from the Powertrain Control Module
(PCM). An electronic integrated circuit contained
within the tachometer reads and analyzes the pulse
signal. It then adjusts the ground path resistance of
one electromagnet in the gauge to control needle
movement. Frequency values for the pulse signal are
shown in a chart in Specifications.
TRIP ODOMETER
The trip odometer is driven by the same electronic
integrated circuit as the speedometer/odometer. How-
ever, by depressing the trip odometer reset knob on
the face of the speedometer, the trip odometer can be
reset to zero. The trip odometer is serviced only as a
part of the speedometer/odometer gauge assembly.
VOLTMETER
The voltmeter is connected in parallel with the bat-
tery. With the ignition switch ON, the voltmeter in-
dicates battery or generator output voltage,
whichever is greater.
INDICATOR LAMPS
All indicator lamps, except the four-wheel drive in-
dicator, are located in the main cluster tell-tale area
above the steering column opening. Each of the
lamps is served by the main cluster printed circuit
and cluster connector. The four-wheel drive indicator
lamp is located in the gauge package cluster and is
served by the gauge package printed circuit and clus-
ter connector.
Up to eleven indicator lamps can be found in the
tell-tale area of the main cluster. These lamps are ar-
ranged in two rows, with six lamps in the upper row
and five lamps in the lower row.
ANTI-LOCK BRAKE SYSTEM LAMP
The Anti-Lock Brake System (ABS) lamp is
switched to ground by the ABS module. The module
lights the lamp when the ignition switch is turned to
the START position as a bulb test. The lamp will
stay on for 3 to 5 seconds after vehicle start-up to in-
dicate a system self-test is in process. If the lamp re-
mains on after start-up, or comes on and stays on
while driving, it may indicate that the ABS module
has detected a system malfunction or that the system
has become inoperative. Refer to Group 5 - Brakes
for more information.
BRAKE WARNING LAMP
The brake warning lamp warns the driver that the
parking brake is applied or that the pressures in the
two halves of the split brake hydraulic system are
unequal. With the ignition switch turned ON, battery
JINSTRUMENT PANEL AND GAUGESÐYJ 8E - 25

voltage is supplied to one side of the indicator bulb. A
ground path for the bulb is provided by 3 switches.
The bulb will light when:
²the brake warning switch is closed (indicating un-
equal brake system hydraulic pressures possibly due
to brake fluid leakage)
²the ignition switch is in the START position (bulb
test)
²the parking brake switch is closed (parking brake
is applied).
Refer to Group 5 - Brakes for more information.
FOUR-WHEEL DRIVE INDICATOR LAMP
This lamp lights when the transfer case is engaged
in the 4H or 4L position. Voltage is supplied to one
side of the indicator bulb. A switch on the front axle
disconnect housing is connected to the other side of
the indicator bulb. When the switch is closed, a path
to ground is provided and the indicator bulb lights.
HEADLAMP HIGH BEAM INDICATOR LAMP
The high beam indicator lamp is controlled by the
headlamp dimmer switch. One side of the indicator
bulb is grounded at all times. The other side of the
bulb receives battery feed through the contacts of the
dimmer switch when the turn signal switch lever is
actuated to turn the headlamp high beams on. Refer
to Group 8L - Lamps for more information.
MALFUNCTION INDICATOR LAMP
The CHECK ENGINE or Malfunction Indicator
Lamp (MIL) lights each time the ignition switch is
turned ON, and stays on for 3 seconds as a bulb test.
If the Powertrain Control Module (PCM) receives an
incorrect signal or no signal from certain fuel or
emission system related circuits or components, the
lamp is turned on. This will indicate that the PCM
has recorded a Diagnostic Trouble Code (DTC) in
electronic memory for a circuit or component mal-
function. Refer to Group 14 - Fuel System for more
information.
SEAT BELT REMINDER LAMP
The seat belt reminder lamp lights for 4 to 8 sec-
onds after the ignition switch is turned to the ON po-sition. A timer in the chime/buzzer module controls
ignition-switched battery feed to the lamp. Refer to
Group 8U - Chime/Buzzer Warning Systems for more
information.
TURN SIGNAL INDICATOR LAMPS
The left and right turn signal indicator lamps are
controlled by the turn signal and hazard warning
switches. One side of the bulb for each lamp is
grounded at all times. The other side of the bulb re-
ceives battery feed through the contacts of the turn
signal switch, when the turn signal lever or hazard
warning button are actuated. Refer to Group 8J -
Turn Signal and Hazard Warning Systems for more
information.
UPSHIFT INDICATOR LAMP
Vehicles equipped with manual transmissions have
an optional upshift indicator lamp. Ground feed for
the lamp is switched by the Powertrain Control Mod-
ule (PCM). The lamp lights to indicate when the
driver should shift to the next highest gear for best
fuel economy. The PCM will turn the lamp off after 3
to 5 seconds if the upshift is not performed. The lamp
will remain off until the vehicle stops accelerating
and is brought back to the range of lamp operation,
or until the transmission is shifted into another gear.
The indicator lamp is normally on when the igni-
tion switch is turned ON and is turned off when the
engine is started. The lamp will be turned on during
vehicle operation according to engine speed and load.
CLUSTER ILLUMINATION LAMPS
All cluster illumination lamps receive battery feed
from the instrument lamps fuse in the fuseblock
module through the panel dimmer switch. When the
park or headlamps are on, the cluster illumination
lamps light. Illumination brightness can be adjusted
by rotating the panel dimmer thumb-wheel, which is
next to the headlamp switch.
8E - 26 INSTRUMENT PANEL AND GAUGESÐYJJ

(9) Turn ignition switch to START position and
hold there. Check for continuity between terminal for
circuit G11 of ignition switch and a good ground.
There should be continuity. If not OK, replace igni-
tion switch.
(10) Unplug brake warning switch connector.
Check for continuity between parking brake switch
connector and a good ground. There should be no
continuity. If OK, go to next step. If not OK, repair
short circuit as required.
(11) Check for continuity between parking brake
switch connector and brake warning switch connector
cavity for circuit G11. There should be continuity. If
OK, replace parking brake switch. If not OK, repair
open circuit to brake warning switch as required.
FOUR-WHEEL DRIVE INDICATOR LAMP
(1) Apply parking brake, start engine, vehicle in
4WD Lock or 4WD.
(2) Unplug switch and touch harness side of wire
to ground. Lamp should light. If OK, check switch
operation, replace if bad. If bulb is OK, repair open
to indicator.
HEADLAMP HIGH BEAM INDICATOR LAMP
(1) Check that headlamp high beams are func-
tional. If OK, go to next step. If not OK, refer to
Group 8L - Lamps for diagnosis of headlamp system.
(2) Disconnect battery negative cable. Remove left
instrument cluster bezel and main cluster assembly.
Unplug cluster connector. Connect battery negative
cable. Turn headlamps on and select high beam.
Check for battery voltage at cavity 17 of cluster con-
nector. If OK, replace indicator bulb. If not OK, re-
pair circuit to headlamp dimmer switch as required.
MALFUNCTION INDICATOR LAMP
The diagnosis found here addresses an inoperative
lamp condition. If the lamp comes on and stays on
with engine running, refer to Group 14 - Fuel System
for diagnosis. If no fuel or emission system problem
is found, the following procedure will help locate a
short or open in the lamp circuit.
(1) Disconnect battery negative cable. Unplug PCM
connector. Install a jumper wire from cavity 32 of
PCM connector (Fig. 5) to a good ground. Connect
battery negative cable. Turn ignition switch to ON.
Lamp should light. Remove jumper wire and lamp
should go OFF. If OK, refer to Powertrain Diagnostic
Procedures to check PCM. If not OK, go to next step.
(2) Turn ignition switch to OFF. Disconnect battery
negative cable. Remove left instrument cluster bezel
and main cluster assembly. Install a jumper wire
from cavity 2 of cluster connector to a good ground.
Connect battery negative cable. Turn ignition switch
to ON. Lamp should light. If OK, go to next step. If
not OK, replace bulb.(3) Turn ignition switch to OFF. Disconnect battery
negative cable. Unplug cluster connector. Check for
continuity between cavity 2 of cluster connector and
a good ground. There should be no continuity. If OK,
go to next step. If not OK, repair short circuit to
PCM as required.
(4) Check continuity between cavity 2 of cluster
connector and cavity 32 of PCM connector. There
should be continuity. If not OK, repair open circuit to
PCM as required.
SEAT BELT REMINDER LAMP
(1) Refer to Group 8U - Chime/Buzzer Warning
Systems to check chime/buzzer module operation. If
OK, go to next step. If not OK, replace chime/buzzer
module.
(2) Disconnect battery negative cable. Remove left
instrument cluster bezel and main cluster assembly.
Unplug cluster connector. Check for continuity be-
tween cavity 20 of cluster connector and a good
ground. There should be continuity. If OK, plug clus-
ter connector back into cluster and go to next step. If
not OK, repair open circuit to ground as required.
(3) Connect battery negative cable. Install a
jumper wire between a 12-volt battery feed and cav-
ity 16 of cluster connector. Lamp should light. If OK,
go to next step. If not OK, replace bulb.
(4) Disconnect battery negative cable. Unplug
chime/buzzer module from fuseblock module. Unplug
cluster connector. Check for continuity between cav-
ity 16 of cluster connector and a good ground. There
should be no continuity. If OK, go to next step. If not
OK, repair short circuit to chime/buzzer module as
required.
(5) Check continuity between cavity 16 of cluster
connector and cavity for terminal A3 of chime/buzzer
module (Fig. 7) in fuseblock module. There should be
continuity. If not OK, repair open circuit to chime/
buzzer module as required.
Fig. 7 Chime/Buzzer Module Receptacle
JINSTRUMENT PANEL AND GAUGESÐYJ 8E - 33

VEHICLE SPEED CONTROL SYSTEM
CONTENTS
page page
DIAGNOSIS............................. 2
GENERAL INFORMATION.................. 1SERVICE PROCEDURES................... 9
GENERAL INFORMATION
The vehicle speed control system (Fig. 1) is an
available option on all XJ (Cherokee) models. The
system is electronically controlled and vacuum oper-
ated. Following are general descriptions of the major
components in the vehicle speed control system. Re-
fer to Group 8W - Wiring Diagrams for complete cir-
cuit descriptions and diagrams.
SPEED CONTROL SERVO
The speed control servo is mounted to a bracket on
the right side inner fender shield in the engine com-
partment. The servo unit consists of a solenoid valve
body, a vacuum servo and the mounting bracket. The
PCM controls the solenoid valve body. The solenoid
valve body controls the application and release of
vacuum to the diaphragm of the vacuum servo. The
servo unit cannot be repaired and is serviced only as
a complete assembly.
SPEED CONTROL SWITCH
The speed control switch module is mounted to the
center of the steering wheel below the driver's airbag
module. The PCM monitors the state of the speed
control switches. The individual switches are labeled:
OFF/ON, RESUME/ACCEL, SET/COAST. 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.
STOP LAMP SWITCH
Vehicles with the speed control option use a dual
function stop lamp switch. The switch is mounted in
the same location as the conventional stop lamp
switch, on the brake pedal mounting bracket under
the instrument panel. The PCM monitors the state of
the dual function stop lamp switch. Refer to Group 5
- Brakes for more information on stop lamp switch
service and adjustment procedures.
SERVO CABLE
The speed control servo cable is connected betweenthe speed control vacuum servo diaphragm and the
throttle control linkage. This cable causes the throt-
tle control linkage to open or close the throttle valve
in response to movement of the vacuum servo dia-
phragm.
POWERTRAIN CONTROL MODULE
The speed control electronic control circuitry is in-
tegrated into the Powertrain Control Module (PCM).
The PCM is located in the engine compartment on
the left side inner fender shield. The PCM speed con-
trol functions are monitored by the On-Board Diag-
nostics (OBD). All OBD-sensed systems are
monitored by the PCM. Each monitored circuit is as-
signed a Diagnostic Trouble Code (DTC). The PCM
will store a DTC in electronic memory for any failure
it detects. See Using On-Board Diagnostic System in
this group for more information. The PCM cannot be
repaired and must be replaced if faulty.
VACUUM RESERVOIR
The vacuum reservoir is mounted behind the left
end of the front bumper bar. The reservoir contains a
one-way check valve to trap engine vacuum in the
reservoir. When engine vacuum drops, as in climbing
a grade while driving, the reservoir supplies the vac-
uum needed to maintain proper speed control opera-
tion. The vacuum reservoir cannot be repaired and
must be replaced if faulty.
VEHICLE SPEED SENSOR
The Vehicle Speed Sensor (VSS) is a pulse genera-
tor mounted to an adapter near the transmission
(two-wheel drive) or transfer case (four-wheel drive)
output shaft. The sensor is driven through the
adapter by a speedometer pinion gear. The VSS pulse
signal to the speedometer/odometer is monitored by
the PCM speed control circuitry to determine vehicle
speed and to maintain speed control set speed. Refer
to the appropriate Powertrain Diagnostic Procedures
manual for testing of this component. Refer to Group
14 - Fuel System for service of this component.
JVEHICLE SPEED CONTROL SYSTEM 8H - 1

BULB APPLICATIONÐXJ VEHICLES
GENERAL INFORMATION
The following Bulb Application Table lists the lamp
title on the left side of the column and trade number
or part number on the right.
CAUTION: Do not use bulbs that have a higher can-
dle power than the bulb listed in the Bulb Applica-
tion Table. Damage to lamp can result.
Do not touch halogen bulbs with fingers or other
oily surfaces. Bulb life will be reduced.
EXTERIOR LAMPSÐXJ
Back-up .................................................................1156
Center High Mounted Stoplamp ..........................922
Fog ............................................................................H3
Front Side Marker .................................................194
Headlamp/Sealed Beam....................................H6054
License Plate ..........................................................168
License Plate W/Outside Spare ..............................67
Park/Turn Signal ............................................2057NA
Tail/Stop ................................................................2057
Turn Signal ...........................................................1156
INTERIOR LAMPSÐXJ
Service procedures for most of the lamps in the in-
strument panel, Instrument cluster and switches are
located in Group 8E, Instrument Panel and Gauges.
Some components have lamps that can only be ser-
viced by an Authorized Service Center (ASC) after
the component is removed from the vehicle. Contact
local dealer for location of nearest ASC.
Cargo .......................................................................561
Dome .......................................................................561
Dome/Reading.........................................................906Glove Compartment ...............................................194
Overhead Console ..................................................912
Under Hood ............................................................105
Vanity Mirror ...........................................................74
Underpanel Courtesy.............................................168
INDICATOR LAMPS
Service procedures for most of the lamps in the in-
strument panel, instrument cluster and switches are
located in Group 8E, Instrument Panel and Gauges.
A/C Control ...............................................................74
Airbag ........................................................................74
Anti-lock Brake ........................................................74
Ash Receiver .........................................................1891
Brake Warning .........................................................74
Check Engine ...........................................................74
Cigar Lighter ............................................................53
Diesel Wait ...............................................................74
Fasten Seat Belts ....................................................74
Four Wheel Drive ....................................................74
Generator ................................................................194
Generator/Diesel.......................................................74
Heater Control .........................................................74
High Beam..............................................................194
Illumination ............................................................194
Low Fuel .................................................................194
Low Washer Fluid....................................................74
Radio ......................................................................ASC
Rocker Switch...........................................................37
Seat Belt ...................................................................74
Transfer Case .........................................................658
Transmission Floor Shift.......................................658
Turn Signal.............................................................194
Shift ...........................................................................74
Water In Fuel ...........................................................74
8L - 18 LAMPSÐXJ VEHICLESJ

BULB APPLICATIONÐYJ VEHICLES
GENERAL INFORMATION
The following Bulb Application Table lists the lamp
title on the left side of the column and trade number
or part number on the right.
CAUTION: Do not use bulbs that have a higher can-
dle power than the bulb listed in the Bulb Applica-
tion Table. Damage to lamp can result.
Do not touch halogen bulbs with fingers or other
oily surfaces. Bulb life will be reduced.
EXTERIOR LAMPSÐYJ
Back-up .................................................................1156
Center High Mounted Stoplamp ..........................912
Fog ............................................................................H3
Front Side Marker .................................................194
Headlamp/Sealed Beam....................................H6054
Park/Turn Signal..................................................3157
Tail/Stop ................................................................1157
INTERIOR LAMPSÐYJ
Service procedures for most of the lamps in the in-
strument panel, Instrument cluster and switches are
located in Group 8E, Instrument Panel and Gauges.
Some components have lamps that can only be ser-
viced by an Authorized Service Center (ASC) after
the component is removed from the vehicle. Contact
local dealer for location of nearest ASC.Dome/Cargo .........................................................212-2
Glove Compartment ...............................................194
Under Hood ............................................................105
Underpanel Courtesy...............................................89
INDICATOR LAMPS
Service procedures for most of the lamps in the in-
strument panel, instrument cluster and switches are
located in Group 8E, Instrument Panel and Gauges.
A/C Control ...............................................................74
Anti-lock Brake ........................................................74
Ash Receiver .........................................................1891
Brake Warning .........................................................74
Cigar Lighter ............................................................53
Fasten Seat Belts ....................................................74
Four Wheel Drive ....................................................74
Generator ................................................................194
Hazard.......................................................................74
Heater Control .......................................................194
High Beam..............................................................194
Illumination ............................................................194
Low Coolant..............................................................74
Radio ......................................................................ASC
Rocker Switch...........................................................74
Seat Belt ...................................................................74
Shift ...........................................................................74
Turn Signal.............................................................194
8L - 32 LAMPSÐYJ VEHICLESJ

TRANSMISSION CONTROLS
UPSHIFT LAMP
On vehicles equipped with a manual transmission,
the PCM grounds the up-shift lamp on circuit K54.
Circuit K54 connects to cavity 54 of the PCM.
FOUR-WHEEL DRIVE (4WD) SWITCH
When the 4WD switch closes, circuit Z1 provides
ground for the 4WD indicator lamp in the instrument
cluster. Circuit F87 connects to the instrument clus-
ter and supplies battery voltage to the 4WD indicator
lamp. Circuit 107 connects the indicator lamp to the
4WD switch. Circuit 106 connects the lamp to the in-
strument cluster and circuit F87.
TRANSMISSION CONTROL MODULEÐ4.0L
ENGINE ONLY
Vehicles equipped with the 4.0L engine have elec-
tronically controlled solenoids in the automatic trans-
mission valve body.
The Transmission Control Module (TCM) receives
inputs from the Throttle Position Sensor (TPS) on
circuit K22 and the stop lamp switch on circuit K29.
Circuit K4 connects to the TCM to provide ground for
the TPS signal. The TCM receives the transmission
output speed sensor signal on circuit T505. Circuit
A14 from fuse 2 in the Power Distribution Center
supplies battery voltage to the TCM. Circuit Z12 pro-
vides ground for the TCM.
The TCM powers the S1 solenoid on circuit T510,
the S2 solenoid on circuit T509, and the S3 solenoid
on circuit T508. Circuit Z12 provides ground for the
S1, S2, and S3 solenoids.
TORQUE CONVERTER CLUTCH (TCC) SOLENOID
AND RELAYÐ2.5L ENGINE ONLY
The TCC solenoid is only used on 2.5L engines
with the three-speed automatic transmissions. The
Powertrain Control Module (PCM) operates the TCC
solenoid by energizing the TCC relay.
Circuit T17 from fuse 12 in the Power Distribution
Center (PDC) supplies voltage to the coil and contact
sides of the TCC relay. When the PCM provides a
ground path on circuit K54 for the coil side of the re-
lay, the relay contacts close.
When the relay contacts close, they connect circuit
T17 with circuit T22. Circuit T22 supplies battery
voltage to the case grounded TCC solenoid. Circuit
K54 connects to PCM cavity 54.
HELPFUL INFORMATION
²In the RUN or START position, the ignition switch
connects circuit A1 from fuse 6 in the PDC to circuit
A21.
DIAGRAM INDEX
Component Page
4-WD Indicator Lamp......................8W-31-4
4-WD Indicator Switch.....................8W-31-4
Back-Up Lamp Switch.....................8W-31-3
Fuse 2 (PDC)...........................8W-31-4
Fuse 6 (PDC).........................8W-31-2, 3
Fuse 11 (PDC)..........................8W-31-3
Fuse 12 (PDC)..........................8W-31-2
Ignition Switch........................8W-31-2, 3
Powertrain Control Module..................8W-31-2
Park/Neutral Position Switch.................8W-31-3
TCC Relay.............................8W-31-2
TCC Solenoid...........................8W-31-2
Transmission Control Module.................8W-31-2
J8W-31 TRANSMISSION CONTROLSÐXJ VEHICLES 8W - 31 - 1