odometer JEEP CHEROKEE 1995 Service User Guide

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

OIL PRESSURE GAUGE
The case grounded oil pressure sensor is a variable
resistor that connects to circuit G6. Circuit G6 con-
nects to the oil pressure gauge.
Circuit F87 connects to the instrument cluster con-
nector and supplies battery voltage to oil pressure
gauge. The gauge uses two coils. Current passing
through the coils creates a magnetic field. Position of
the gauge needle is controlled by the amount of cur-
rent passing through the coils to ground at the sen-
sor.
OIL PRESSURE WARNING LAMP
The case grounded oil pressure switch connects to
circuit G6. Circuit G6 connects to the oil pressure
warning lamp. Circuit F87 connects to the instru-
ment cluster connector and supplies battery voltage
to oil pressure lamp.
When the oil pressure switch close, battery voltage
flows through the warning lamp to ground through
the switch, illuminating the lamp.
TACHOMETER
The tachometer module in the instrument cluster
operates the tachometer. The Powertrain Control
Module (PCM) supplies the signal for the tachometer
on circuit G21. Circuit G21 connects to cavity 43 of
the PCM.
SPEEDOMETER
The speedometer and odometer receive a signal
from the vehicle speed sensor on circuit G7. Circuit
G7 also connects to the Powertrain Control Module
(PCM) at cavity 47.
ABS WARNING LAMP
Circuit F87 provides power for the ABS warning
lamp at the instrument cluster. Ground for the ABS
warning lamp is provided by either the ABS control
module or by the ABS power relay when the relay is
not energized. The ABS control module illuminates
the lamp by providing ground on circuit B205.
Circuit B205 splices to connect to circuit B235
through a diode. When the ABS power relay is not
energized, it connects circuit B235 to circuit Z12. The
ground path for the warning lamp is through the di-
ode to circuit B235, through the ABS power relay to
ground on circuit Z12.
The diode between circuit B205 and B235 prevents
voltage from flowing to the ABS control module when
the ABS power relay switches to supply power on cir-
cuit B235.
MALFUNCTION INDICATOR LAMP (MIL)
The PCM provides ground for the instrument clus-
ter malfunction indicator lamp on circuit G3. Circuit
G3 connects to cavity 32 of the PCM. Circuit F87provides voltage for the lamp. The MIL displays the
message CHECK ENGINE when illuminated.
For information regarding diagnostic trouble code
access using the MIL lamp, refer to Group 14, Fuel
Systems.
LOW WASHER FLUID WARNING LAMP
Circuit G29 connects the low washer fluid switch to
the warning lamp in the instrument cluster. Circuit
F12 supplies battery voltage to the switch.
When the low washer fluid switch closes, it con-
nects circuits G29 and F12. Battery voltage from cir-
cuit F12 powers the low washer fluid lamp. Circuit
Z1 at the instrument cluster provides ground to illu-
minate the warning lamp.
SEAT BELT INDICATOR WARNING LAMP
The seat belt indicator warning lamp is activated
by the chime/buzzer on circuit G11. Circuit G11 sup-
plies power to instrument cluster for the lamp. Cir-
cuit Z1 provides ground for the lamp at the cluster.
The chime/buzzer module powers circuit G11 after
it receives an input on circuit G10 indicating the seat
belt switch is open.
HIGH-BEAM INDICATOR LAMP
Circuit L3 supplies power for the high-beam indi-
cator lamp. The ground path for the lamp is through
circuit Z1. If the vehicle has Daytime Running
Lamps (DRL), the DRL module powers circuit L3
through circuit G465. On vehicles not equipped with
DRL, the headlamp switch powers circuit L3.
Circuit Z1 provides ground for the indicator lamp
at the cluster.
TURN SIGNAL INDICATOR LAMPS
Circuits L61 and L60 power for the turn signal in-
dicator lamps. Circuit L61 powers the left indicator
lamp. Circuit L60 powers the right indicator lamp.
Circuit Z1 provides ground for the lamps.
BRAKE WARNING LAMP
Circuit F87 supplies power to the park brake lamp.
Ground for the park brake lamp is supplied through
the case grounded park brake switch or brake warn-
ing switch on circuit G9. Circuit G9 Connects to cir-
cuit B203. Circuit B203 connects to the brake
warning lamp at the instrument cluster.
MANUAL TRANSMISSION UP-SHIFT LAMP
Circuit F87 supplies power for the manual trans-
mission up-shift lamp. The lamp illuminates when
the Powertrain Control Module (PCM) provides
ground for the lamp on circuit K54. Circuit K54 con-
nects to cavity 54 of the PCM.
8W - 40 - 2 8W-40 INSTRUMENT CLUSTERÐXJ VEHICLESJ

INSTRUMENT CLUSTER
INSTRUMENT CLUSTER
The instrument cluster contains the gauges and
warning lamps. All gauges have magnetic move-
ments.
When the ignition switch is in either the START or
RUN position, circuit A1 from fuse 4 in the Power
Distribution Center (PDC) connects to circuit A21.
Circuit A21 powers fuse 9 in the fuse block. Fuse 9
powers circuit G5. One branch of circuit G5 connects
directly to the combination buzzer. The other branch
of circuit G5 splices to power the gauges, speedome-
ter, tachometer, voltmeter, indicator lamps, and
warning lamps in the instrument cluster.
When the parking lamps or headlamps are ON, the
headlamp switch connects circuit F33 to circuit L7.
Circuit L7 splices to the dimmer switch. Circuit E1
from the dimmer switch powers fuse 10 in the fuse
block when the parking lamps or headlamps are ON.
Circuit E2 from fuse 10 in the fuse block feeds the
illumination lamps in the instrument cluster.
Circuit Z1 provides ground the instrument cluster
illumination lamps, gauges and warning lamps.
HELPFUL INFORMATION
²Circuit G5 also powers the heated rear window,
A/C compressor clutch relay. On Canadian vehicles,
circuit G5 powers the Daytime Running Lamps
(DRL) module.
²Circuit F33 originates at fuse 8 in the fuse block.
Circuit A6 from fuse 3 in the PDC powers fuse 8 in
the fuse block.
ENGINE COOLANT TEMPERATURE GAUGE
Circuit G20 connects the engine coolant tempera-
ture gauge to the engine coolant temperature sensor.
The sensor is a variable resistor and case grounded
to the engine. Circuit G5 connects to the instrument
cluster and supplies voltage for the gauge.
The gauge uses two coils. The first coil has fixed
current flowing through it to maintain magnetic field
strength. Circuit Z1 provides ground for the fixed
current coil. The current level passing through the
second coil is controlled by the variable resistor in
the engine coolant temperature sender. The changing
current varies the magnetic field in the second coil.
Refer to group 8E, Instrument Panel and Gauges
for gauge operation.
FUEL GAUGE
Circuit G4 connects the fuel level sensor to the fuel
gauge in the instrument cluster. Circuit G5 supplies
voltage to the fuel gauge. The fuel level sensor draws
voltage from circuit G5 through the fuel gauge on cir-
cuit G4.The gauge uses two coils. The first coil has fixed
current flowing through it to maintain magnetic field
strength. Circuit Z1 provides ground for the fixed
current coil. The current level passing through the
second coil is controlled by the variable resistor in
the fuel level sensor. The changing current varies the
magnetic field in the second coil.
Circuit Z2 provides the ground path for the fuel
level sensor.
Refer to group 8E, Instrument Panel and Gauges
for gauge operation.
OIL PRESSURE GAUGE
The case grounded oil pressure sending unit is a
variable resistor. The sending unit connects to the oil
pressure gauge on circuit G60.
Circuit G5 connects to the instrument cluster and
supplies battery voltage to the oil pressure gauge.
The gauge uses two coils. The first coil has fixed cur-
rent flowing through it to maintain magnetic field
strength. Circuit Z1 provides ground for the fixed
current coil. The current level passing through the
second coil is controlled by the variable resistor in
the oil pressure sending unit. The changing current
varies the magnetic field in the second coil.
Refer to group 8E, Instrument Panel and Gauges
for gauge operation.
TACHOMETER
The Powertrain Control Module (PCM) provides
the tachometer signal to the electronic tachometer on
circuit G21. Circuit G21 originates at cavity 43 of the
PCM. Circuit Z1 provides ground for the tachometer's
internal logic circuits.
SPEEDOMETER
The electronic speedometer and odometer receive a
signal from the vehicle speed sensor on circuit G7.
Circuit G5 connects to the instrument cluster and
supplies battery voltage to the speedometer. Circuit
Z1 provides ground for the speedometer internal logic
circuits.
Circuit G7 splices to connect to the Powertrain
Control Module (PCM) and if equipped, the Daytime
Running Lamps (DRL) module.
FOUR-WHEEL DRIVE (4WD) INDICATOR LAMP
When the 4WD switch closes, circuit Z1 provides
ground for the 4WD indicator lamp in the instrument
panel. Circuit G5 connects to the instrument cluster
and supplies battery voltage to the 4WD indicator
lamp. Circuit G1 connects the indicator lamp to the
4WD switch.
J8W-40 INSTRUMENT CLUSTERÐYJ VEHICLES 8W - 40 - 1