engine JEEP XJ 1995 Service And Repair Manual

Circuit G7 from the vehicle speed sensor provides
an input signal to the PCM. The G7 circuit connects
to cavity 47 of the PCM.
The PCM provides a ground for the vehicle speed
sensor signal (circuit G7) through circuit K4. Circuit
K4 connects to cavity 4 of the PCM.
HELPFUL INFORMATION
²Circuit G7 splices to the speedometer, and daytime
running lights module (DRL).
²Circuit K7 splices to supply 8 volts to the camshaft
position sensor and crankshaft position sensor.
Circuit K4 splices to supply ground for the signals
from the following:
²Heated oxygen sensor
²Camshaft position sensor
²Crankshaft position sensor
²Throttle position sensor
²Manifold absolute pressure sensor
²Engine coolant temperature sensor
²Intake air temperature sensor
HEATED OXYGEN SENSOR
When the fuel pump relay contacts close, they con-
nect circuits A14 and A141. Circuit A141 splices to
supply voltage to the heated oxygen sensor.
Circuit K41 delivers the signal from the heated ox-
ygen sensor to the PCM. Circuit K41 connects to cav-
ity 41 of the PCM.
The PCM provides a ground for the heated oxygen
sensor signal (circuit K41) through circuit K4. Circuit
K4 connects to cavity 4 of the PCM connector.
Circuit Z12 provides a ground for the heater circuit
in the sensor.
Circuit Z12 terminates at the right side of the en-
gine.
HELPFUL INFORMATION
²Circuit A141 also supplies battery voltage to the
fuel pump.
Circuit K4 splices to supply ground for the signals
from the following:
²Heated oxygen sensor
²Camshaft position sensor
²Crankshaft position sensor
²Intake air temperature sensor
²Throttle position sensor
²Manifold absolute pressure sensor
²Engine coolant temperature sensor
²Vehicle speed sensor
CAMSHAFT POSITION SENSOR
The Powertrain Control Module (PCM) supplies 8
volts to the camshaft position sensor (in distributor)
on circuit K7. Circuit K7 connects to cavity 7 of the
PCM.The PCM receives the camshaft position sensor sig-
nal on circuit K44. Circuit K44 connects to cavity 44
of the PCM.
The PCM provides a ground for the camshaft posi-
tion sensor signal (circuit K44) through circuit K4.
Circuit K4 connects to cavity 4 of the PCM.
HELPFUL INFORMATION
²Circuit K7 splices to supply 8 volts to the crank-
shaft position sensor and the vehicle speed sensor.
Circuit K4 splices to supply ground for the signals
from the following:
²Heated oxygen sensor
²Camshaft position sensor
²Crankshaft position sensor
²Intake air temperature sensor
²Throttle position sensor
²Manifold absolute pressure sensor
²Engine coolant temperature sensor
²Vehicle speed sensor
CRANKSHAFT POSITION SENSOR
The Powertrain Control Module (PCM) supplies 8
volts to the crankshaft position sensor on circuit K7.
Circuit K7 connects to cavity 7 of the PCM.
The PCM receives the crankshaft position sensor
signal on circuit K24. Circuit K24 connects to cavity
24 of the PCM.
The PCM provides a ground for the crankshaft po-
sition sensor (circuit K24) through circuit K4. Circuit
K4 connects to cavity 4 of the PCM.
HELPFUL INFORMATION
²Circuit K7 splices to supply 8 volts to the camshaft
position sensor and the vehicle speed sensor.
Circuit K4 splices to supply ground for the signals
from the following:
²Heated oxygen sensor
²Camshaft position sensor
²Crankshaft position sensor
²Intake air temperature sensor
²Throttle position sensor
²Manifold absolute pressure sensor
²Engine coolant temperature sensor
²Vehicle speed sensor
ENGINE COOLANT TEMPERATURE SENSOR
The engine coolant temperature sensor provides an
input to the Powertrain Control Module (PCM) on
circuit K2. From circuit K2, the engine coolant tem-
perature sensor draws up to 5 volts from the PCM.
The sensor is a variable resistor. As coolant temper-
ature changes, the resistance in the sensor changes,
causing a change in current draw. The K2 circuit
connects to cavity 2 of the PCM.
J8W-30 FUEL/IGNITIONÐXJ VEHICLES 8W - 30 - 3

The PCM provides a ground for the engine coolant
temperature sensor signal (circuit K2) through circuit
K4. Circuit K4 connects to cavity 4 of the PCM con-
nector.
HELPFUL INFORMATION
Circuit K4 splices to supply ground for the signals
from the following:
²Heated oxygen sensor
²Camshaft position sensor
²Crankshaft position sensor
²Intake air temperature sensor
²Throttle position sensor
²Manifold absolute pressure sensor
²Engine coolant temperature sensor
²Vehicle speed sensor
THROTTLE POSITION SENSOR
From the Powertrain Control Module (PCM), cir-
cuit K6 supplies 5 volts to the throttle position sen-
sor (TPS). Circuit K6 connects to cavity 6 of the
PCM.
Circuit K22 delivers the TPS signal to the PCM.
Circuit K22 connects to cavity 22 of the PCM.
The PCM provides a ground for the throttle posi-
tion sensor signal (circuit K22) through circuit K4.
Circuit K4 connects to cavity 4 of the PCM.
HELPFUL INFORMATION
Refer to Group 14 for throttle position sensor oper-
ation.
Circuit K6 splices to supply 5 volts to the manifold
absolute pressure sensor.
On vehicles equipped with the 4.0L engine and au-
tomatic transmission, circuit K22 splices to the
transmission control module.
Circuit K4 splices to supply ground for the signals
from the following:
²Heated oxygen sensor
²Camshaft position sensor
²Crankshaft position sensor
²Intake air temperature sensor
²Throttle position sensor
²Manifold absolute pressure sensor
²Engine coolant temperature sensor
²Vehicle speed sensor
MANIFOLD ABSOLUTE PRESSURE SENSOR
From the Powertrain Control Module (PCM), cir-
cuit K6 supplies 5 volts to the manifold absolute
pressure (MAP) sensor. Circuit K6 connects to cavity
6 of the PCM.
Circuit K1 delivers the MAP signal to the PCM.
Circuit K1 connects to cavity 1 of the PCM.
The PCM provides a ground for the MAP sensor
signal (circuit K1) through circuit K4. Circuit K4 con-
nects to cavity 4 of the PCM.
HELPFUL INFORMATION
Refer to Group 14 for MAP sensor operation.
Circuit K6 splices to supply 5 volts to the throttle
position sensor.
Circuit K4 splices to supply ground for the signals
from the following:
²Heated oxygen sensor
²Camshaft position sensor
²Crankshaft position sensor
²Intake air temperature sensor
²Throttle position sensor
²Manifold absolute pressure sensor
²Engine coolant temperature sensor
²Vehicle speed sensor
INTAKE AIR TEMPERATURE SENSOR
The intake air temperature sensor provides an in-
put to the Powertrain Control Module (PCM) on cir-
cuit K21. Circuit K21 connects to cavity 21 of the
PCM.
From circuit K21, the intake air temperature sen-
sor draws voltage from the PCM. The sensor is a
variable resistor. As intake air temperature changes,
the resistance in the sensor changes, causing a
change in current draw.
The PCM provides a ground for the intake air tem-
perature sensor signal (circuit K21) through circuit
K4. Circuit K4 connects to cavity 4 of the PCM.
HELPFUL INFORMATION
Circuit K4 splices to supply ground for the signals
from the following:
²Heated oxygen sensor
²Camshaft position sensor
²Crankshaft position sensor
²Intake air temperature sensor
²Throttle position sensor
²Manifold absolute pressure sensor
²Engine coolant temperature sensor
²Vehicle speed sensor
PARK/NEUTRAL POSITION SWITCH
When closed, the case-grounded park/neutral posi-
tion switch provides a ground path on circuit T41 for
the coil side of the starter motor relay. Circuit A41
from the ignition switch provides battery voltage to
the coil side of the relay.
Circuit T41 splices to cavity 30 of the PCM. The
park/neutral position switch provides an input to the
Powertrain Control Module (PCM).
TORQUE CONVERTER CLUTCH (TCC) SOLENOID
AND RELAY
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.
8W - 30 - 4 8W-30 FUEL/IGNITIONÐXJ VEHICLESJ

Circuit T17 from fuse 3 in the power distribution
center 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 relay, 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 4 in the PDC to circuit
A21.
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.
POWER STEERING PRESSURE SWITCH
The PCM supplies voltage to the power steering
pressure switch on circuit K10. Circuit Z12 provides
ground for the switch. When the switch closes, volt-
age flows through the switch to ground on circuit
Z12. The switch closes during periods of high power
steering pump load and low engine speed; such as
parking maneuvers.
Circuit K10 connects to cavity 10 of the PCM. Cir-
cuit Z12 terminates at the right rear of the engine.
TACHOMETER SIGNAL
The PCM supplies the signal for the tachometer on
circuit G21. Circuit G21 connects to cavity 43 of the
PCM.
MALFUNCTION INDICATOR LAMP (MIL)
The PCM provides ground for the instrument clus-
ter malfunction indicator lamp on circuit G3. The
MIL displays the message CHECK ENGINE when il-
luminated. Circuit F87 provides voltage for the lamp.
DATA LINK CONNECTOR
Circuit F12 supplies battery voltage to the data
link connector. Circuit F12 originates at fuse 11 in
the Power Distribution Center.
Circuit D20 connects to cavity 45 of the PCM. Cir-
cuit D20 is the SCI receive circuit for the PCM.
Circuit D21 connects to cavity 25 of the PCM. Cir-
cuit D21 is the SCI transmit circuit for the PCM.
Circuit Z11 provides ground for the data link con-
nector. Circuit Z11 terminates at the right rear of the
engine. Circuit Z11 also connects to cavity 5 of the
PCM.
HELPFUL INFORMATION
²Circuit Z1 also supplies a ground for the PCM
high current drivers.
²If the system loses ground for the Z11 circuits at
the right rear of the engine, the vehicle will not op-
erate. Check the connection at the ganged-ground cir-
cuit eyelet.
²Circuit F12 splices to supply battery voltage to the
vehicle speed control switch, back-up lamp switch,
A/C compressor clutch relay, windshield washer fluid
level sensor and radiator fan relay (4.0L engines).
BRAKE SWITCH INPUT
Circuit K29 provides the brake switch input to the
PCM. Circuit V40 connects to cavity 29 of the PCM.
POWER (DEVICE) GROUND
Circuit Z12 connects to cavities 11 and 12 of the
PCM. The Z12 circuit provides ground for PCM inter-
nal drivers that operate high current devices like the
injectors and ignition coil.
Internal to the PCM, the power (device) ground cir-
cuit connects to the PCM sensor return circuit (from
circuit K4).
HELPFUL INFORMATION
²The grounding point for circuit Z12 is the right
rear of the engine.
²If the system loses ground for the Z12 circuits at
the rear of the engine, the vehicle will not operate.
Check the connection at the ganged-ground circuit
eyelet.
²On vehicles equipped with the 4.0L engine and au-
tomatic transmission, circuit Z12 splices to provide
ground for the transmission control module.
EXTENDED IDLE SWITCH
On Police Package vehicles, an optional extended
idle switch provides an input to the Powertrain Con-
trol Module (PCM) on circuit K10. Circuit K10 con-
nects to cavity 10 of the PCM. Circuit F60 supplies
battery voltage to the extended idle switch. Circuit
Z1 grounds the switch.
CCD BUS
On vehicles equipped with the 4.0L engine, circuits
D1 and D2 connect the Powertrain Control Module
(PCM) to the CCD Bus. Circuit D1 connects to cavity
26 of the PCM. Circuit D2 connects to cavity 46 of
the PCM. Circuits D1 and D2 are a twisted pair of
wires.
J8W-30 FUEL/IGNITIONÐXJ VEHICLES 8W - 30 - 5

DIAGRAM INDEXÐ2.5L ENGINE
Component Page
Automatic Shut Down Relay.................8W-30-8
Camshaft Position Sensor..................8W-30-10
Crankshaft Position Sensor.................8W-30-11
Data Link Connector......................8W-30-12
Distributor Ignition Coil....................8W-30-12
Engine Coolant Temperature Sensor............8W-30-11
Fuel Injector #1.........................8W-30-9
Fuel Injector #2.........................8W-30-9
Fuel Injector #3.........................8W-30-9
Fuel Injector #4.........................8W-30-9
Fuel Pump Relay........................8W-30-20
Fuel Tank Gauge Level Sending Unit...........8W-30-20
Fuse 2 (PDC)........................8W-30-8, 20
Fuse 6 (PDC)........................8W-30-8, 20
Fuse 11 (PDC).........................8W-30-12
Fuse 14 (PDC)..........................8W-30-8
Heated Oxygen Sensor.....................8W-30-7
Idle Air Control Motor.....................8W-30-7
Ignition Switch.......................8W-30-8, 20
Instrument Cluster....................8W-30-12, 20
Intake Air Temperature Sensor...............8W-30-11
MAP Sensor...........................8W-30-10
Powertrain Control Module........8W-30-7 thru 12, 19, 20
Power Steering Pressure Switch...............8W-30-7
Throttle Position Sensor...................8W-30-10
Vehicle Speed Sensor.....................8W-30-12
DIAGRAM INDEXÐ4.0L ENGINE
Component Page
Automatic Shut Down Relay.................8W-30-14
Camshaft Position Sensor..................8W-30-16
Crankshaft Position Sensor.................8W-30-16
Data Link Connector......................8W-30-18
Distributor Ignition Coil....................8W-30-18
Engine Coolant Temperature Sensor............8W-30-17
Extended Idle Switch.....................8W-30-19
Extended Idle Switch Lamp.................8W-30-19
Fuel Injector #1.........................8W-30-15
Fuel Injector #2.........................8W-30-15
Fuel Injector #3.........................8W-30-15
Fuel Injector #4.........................8W-30-15
Fuel Injector #5.........................8W-30-15
Fuel Injector #6.........................8W-30-15
Fuel Pump Relay........................8W-30-20
Fuel Tank Gauge Level Sending Unit...........8W-30-20
Fuse 2 (PDC).......................8W-30-14, 20
Fuse 3 (Fuse Block)......................8W-30-19
Fuse 5 (PDC)..........................8W-30-19
Fuse 6 (PDC).....................8W-30-14, 19, 20
Fuse 14 (PDC).........................8W-30-14
Fuse 15 (Fuse Block).....................8W-30-19
Fuse 19 (Fuse Block).....................8W-30-19
Headlamp Switch........................8W-30-19
Heated Oxygen Sensor....................8W-30-13
Idle Air Control Motor.....................8W-30-13
Ignition Switch....................8W-30-14, 19, 20
Instrument Cluster.......................8W-30-18
Intake Air Temperature Sensor...............8W-30-17
MAP Sensor...........................8W-30-16
Powertrain Control Module............8W-30-13 thru 20
Throttle Position Sensor...................8W-30-16
Vehicle Speed Sensor.....................8W-30-18
8W - 30 - 6 8W-30 FUEL/IGNITIONÐXJ 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

VEHICLE SPEED CONTROL
VEHICLE SPEED CONTROL
The vehicle speed control system is operated by the
Powertrain Control Module (PCM). Circuit F12 from
fuse 11 in the Power Distribution Center (PDC) sup-
plies battery voltage to the vehicle speed control ON/
OFF switch. Circuit A21 supplies voltage to fuse 11
when the ignition switch is in the START or RUN po-
sitions. In the START or RUN position the ignition
switch connects circuit A21 with circuit A1. Fuse 6 in
the PDC protects circuit A1.
The vehicle speed control ON/OFF switch supplies
voltage to the SET/COAST and RESUME/ACCEL
switches. Both switches send signals to the PCM
(which supplies the ground path for the switches).
The PCM controls the vent and vacuum functions
of the speed control servo on circuits V35 and V36.
Depending on the signal it receives from the vehicle
speed control switches, the PCM either applies vac-
uum to, or vents vacuum from, the servo. Circuit V36
from cavity 33 of the PCM sends the vacuum signal
to the servo. Circuit V35 from cavity 53 sends the
vent signal.
Circuit V32 signals to the PCM that the speed con-
trol switch is in the ON position. The V32 circuit con-
nects to cavity 49 of the PCM. Circuit V32 also
connects to the stop lamp switch.
In the CLOSED position, the stop lamp switch con-
nects circuit V32 with circuit V30 to power the speed
control servo. Circuit Z1 provides ground for the
speed control servo.
Circuit V31 provides the SET/COAST signal to cav-
ity 48 of the PCM. Circuit V33 sends the RESUME/
ACCEL signal to cavity 50 of the PCM.
Circuit K29 connects to cavity 29 of the PCM and
to ground through the stop lamp switch. The stop
lamp switch OPENS when the operator depresses the
brake pedal. The PCM disables speed control when
the stop lamp switch opens. From the stop lamp
switch, circuit Z1 provides ground for circuit K29.
HELPFUL INFORMATION
²Circuit K29 also connects to the ABS control mod-
ule on vehicles with all wheel anti-lock brakes.
²On vehicles with the 4.0L Engine and Automatic
Transmission, Circuit K29 connects to the Transmis-
sion Control Module (TCM).
DIAGRAM INDEX
Component Page
ABS Control Module..................8W-32-4 thru 8
ABS Hydraulic Unit.......................8W-32-6
ABS Power Relay........................8W-32-4
ABS Pump Motor........................8W-32-5
ABS Pump Motor Relay....................8W-32-4
Data Link Connector......................8W-32-8
Diode................................8W-32-6
Fuse 6 (PDC)...........................8W-32-5
Fuse 7 (Fuse Block).......................8W-32-5
Fuse 7 (PDC)...........................8W-32-8
Fuse 8 (PDC)...........................8W-32-5
Fuse 10 (PDC)..........................8W-32-4
Fuse 13 (PDC)..........................8W-32-8
G-Sensor..............................8W-32-8
Ignition Switch..........................8W-32-5
Powertrain Control Module..................8W-32-8
Telltale Connector (Instrument Cluster)...........8W-32-6
Transmission Control Module.................8W-32-8
Wheel Speed Sensors......................8W-32-7
J8W-33 VEHICLE SPEED CONTROLÐXJ VEHICLES 8W - 33 - 1

INSTRUMENT CLUSTER
INDEX
page page
ABS Warning Lamp........................ 2
Brake Warning Lamp....................... 2
Charging System Indicator Lamp............... 3
Cluster Ground............................ 3
Diagram Index............................. 3
Engine Coolant Temperature Gauge............ 1
Engine Coolant Temperature Warning Lamp...... 1
Fuel Gauge.............................. 1
High-Beam Indicator Lamp................... 2
Instrument Cluster......................... 1Low Fuel Warning Lamp..................... 1
Low Washer Fluid Warning Lamp.............. 2
Malfunction Indicator Lamp (MIL)............... 2
Manual Transmission Up-Shift Lamp............ 2
Oil Pressure Gauge........................ 2
Oil Pressure Warning Lamp.................. 2
Seat Belt Indicator Warning Lamp.............. 2
Speedometer............................. 2
Tachometer.............................. 2
Turn Signal Indicator Lamps.................. 2
INSTRUMENT CLUSTER
The instrument cluster contains the gauges and
warning lamps. All gauges have magnetic move-
ments.
When the ignition switch is in the START or RUN
position, circuit A21 feeds circuit F87 through fuse 17
in the fuse block. Circuit A1 from fuse 6 in the Power
Distribution Center (PDC) supplies voltage to circuit
A21. Circuit A1 is HOT at all times.
Circuit F87 connects to the cluster connector to
power the gauges and to the telltale connector to
power the warning lamps.
Circuit E2 from fuse 19 in the fuse block feeds the
illumination lamps. Circuit E2 originates at the head-
lamp switch and continues through fuse 19. The
headlamp switch powers circuit E2 when the parking
lamps or headlamp are ON.
Circuit Z2 provides ground for the indicator lamps
and illumination lamps.
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 F87 connects to the instrument
cluster left connector and supplies voltage for the
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 current
passing through the coils to ground at the sensor.
ENGINE COOLANT TEMPERATURE WARNING
LAMP
Circuit G20 connects the engine coolant tempera-
ture warning lamp to the engine coolant temperature
switch. When the switch closes, battery voltage from
circuit F87 flows through the lamp to ground through
the switch on circuit G20. The engine coolant tem-
perature switch is case grounded to the engine. Cir-cuit F87 connects to the instrument cluster connector
and supplies voltage for the lamp.
Circuit G20 also connects to the warning lamp to
ground when the ignition switch is in the START
position. When the ignition switch is in the START
position, the lamp illuminates for a bulb test.
FUEL GAUGE
The fuel level sensor is a variable resistor. Circuit
G4 connects the fuel level sensor to the fuel gauge in
the instrument cluster. Circuit F87 from fuse 17 in
the fuse block supplies voltage to the fuel gauge. The
fuel level sensor draws voltage from circuit F87
through the fuel gauge on circuit G4. Circuit G4
connects to circuit 57 in the fuel pump module har-
ness. Circuit 57 connects to the fuel level sensor.
Circuit 99 in the fuel pump module harness con-
nects to circuit Z1. Circuit Z1 provides the ground
path for the fuel level sensor. The grounding point for
circuit Z1 is the left side of the cowl panel.
As current flows through the coils in the fuel gauge,
it creates a magnetic field. One of the coils in the
gauge receives fixed current. The other coil is con-
nected to the level sensor. The magnetic field controls
the position of the fuel gauge pointer.
The fuel level sensor contains a variable resistor. As
the position of the float arm on the fuel level sensor
changes, the resistor changes the current flow
through second coil in the fuel gauge. A change in
current flow alters the magnetic field in the fuel
gauge, which changes the pointer position.
LOW FUEL WARNING LAMP
Circuit G4 connects the fuel level sensor to the fuel
gauge. The low fuel level module at the rear of the
gauge monitors resistance in circuit G4. The low fuel
level module powers an light emitting diode (LED)
when the resistance in circuit G4 reaches a calibrated
level. The LED illuminates the Low Fuel indicator.
Refer to Group 8E for additional information.
J8W-40 INSTRUMENT CLUSTERÐXJ VEHICLES 8W - 40 - 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

CHARGING SYSTEM INDICATOR LAMP
The Powertrain Control Module (PCM) illuminates
the charging system indicator lamp by providing
ground for the lamp on circuit G12. Circuit G12 con-
nects to cavity 36 of the PCM. Circuit F87 supplies
battery voltage to the lamp.
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.
CLUSTER GROUND
Circuit Z1 from the instrument cluster left connec-
tor provides ground for the illumination lamps and
indicator lamps.
HELPFUL INFORMATION
²If the warning lamps don't operate, check fuse 14
in the fuse block.
²If the indicator lamps and illumination lamps
don't operate, check fuse 13 in the fuse block.
²Inspect the ground at the instrument panel lower
right reinforcement support.
DIAGRAM INDEX
Component Page
4WD Switch............................8W-40-9
4WD Indicator Lamp......................8W-40-9
ABS Control Module......................8W-40-9
Brake Warning Switch.....................8W-40-10
Chime/Buzzer Module......................8W-40-8
Daytime Running Lamps Module.............8W-40-5, 6
Engine Coolant Temperature Sending Unit.........8W-40-6
Engine Oil Pressure Sending Unit..............8W-40-6
Fuse 3 (PDC)...........................8W-40-8
Fuse 5 (PDC)...........................8W-40-4
Fuse 6 (PDC).........................8W-40-4, 8
Fuse 11 (PDC)..........................8W-40-8
Fuse 16 (PDC)..........................8W-40-8
Fuse 9 (Fuse Block).......................8W-40-8
Fuse 15 (Fuse Block)......................8W-40-4
Fuse 17 (Fuse Block)....................8W-40-4, 8
Fuse 19 (Fuse Block)......................8W-40-4
Headlamp Switch.......................8W-40-4, 5
Headlamp Delay Module....................8W-40-8
Headlamp Dimmer Switch...................8W-40-5
Ignition Switch......................8W-40-4, 8, 10
Instrument Cluster......................8W-40-4, 5
Low Washer Fluid Lamp Switch...............8W-40-8
Park Brake Switch.......................8W-40-10
Powertrain Control Module..................8W-40-6
Remote Keyless Entry Module................8W-40-8
Telltale Connector (Instrument Cluster).....8W-40-7 thru 10
J8W-40 INSTRUMENT CLUSTERÐXJ VEHICLES 8W - 40 - 3

AIR CONDITIONING/HEATER
CONTENTS
page page
A/C-HEATER SYSTEM...................... 1 HEATERSYSTEM......................... 1
GENERAL INFORMATION
This section of the wiring diagrams is divided into
two sub-sections; Heater, and A/C and Heater. When
referring to the circuit descriptions or wiring dia-
grams, ensure that you use the correct sub-section.
HEATER SYSTEM
BLOWER MOTOR
In the RUN or ACCESSORY position, the ignition
switch connects circuit A1 from fuse 6 in the Power
Distribution Center (PDC) to circuit A48. Circuit A48
supplies battery voltage to fuse 5 in the fuse block.
Fuse 5 supplies power to the heat mode switch on
circuit C7.
Circuit C43 from the heat mode switch splices to
supply voltage to the blower motor switch and the
blower motor resistor block. The blower motor switch
sets blower motor speed to HIGH, M1, M2, or LOW.
When the blower motor switch is in the LOW posi-
tion, circuit C43 from the heat mode supplies voltage
to the resistor block. Voltage does not pass through
the blower motor switch in the LOW position.In the M1 position, the blower motor switch sup-
plies voltage to the resistor block on circuit C4. From
circuit C4, voltage passes through three resistors in
the resistor block to the blower motor on circuit C1.
In the M2 position, the blower motor supplies volt-
age to the resistor block on circuit C6. From circuit
C6 voltage flows through two resistors to the blower
motor on circuit C1.
In the HIGH position, the blower motor switch con-
nects directly to the blower motor on circuit C1. Volt-
age does not pass through the resistor block.
Circuit Z1 provides ground for the blower motor.
A/C-HEATER SYSTEM
GENERAL INFORMATION
Several fuses supply power for the air conditioning/
heater system. In the START or RUN positions, the
ignition switch connects circuit A1 from fuse 6 in the
Power Distribution Center (PDC) to circuit A21. Cir-
cuit A21 powers a bus bar in the PDC that feeds cir-
cuit F12 through fuse 11. Circuit F12 feeds the
contact side of the A/C compressor clutch relay and
the coil side of the radiator fan relay (4.0L engine).
In the RUN or ACCESSORY position, the ignition
switch connects circuit A1 from fuse 11 in the PDC to
circuit A48. Circuit A48 supplies battery voltage to
fuse 5 in the fuse block. Fuse 5 supplies power to the
A/C-Heater control switch on circuit C7.
Fuse 13 in the PDC supplies battery voltage to the
contact side of the radiator fan relay on circuit F141.
Circuit A14 from fuse 15 in the PDC powers PDC
fuse 4.
BLOWER MOTOR
In the RUN or ACCESSORY position, the ignition
switch connects circuit A1 from fuse 6 in the PDC to
circuit A48. Circuit A48 supplies battery voltage to
fuse 5 in the fuse block. Fuse 5 supplies power to the
A/C-Heater control switch on circuit C7.
Circuit C43 from the A/C-heater switch splices to
supply voltage to the blower motor switch and the
blower motor resistor block. The blower motor switch
sets blower motor speed to HIGH, M1, M2, or LOW.
When the blower motor switch is in the LOW posi-
tion, circuit C43 from the A/C-Heater switch supplies
voltage to the resistor block. Voltage does not pass
through the blower motor switch in the LOW position
In the M1 position, the blower motor switch sup-
plies voltage to the resistor block on circuit C4. From
circuit C4, voltage passes through three resistors in
the resistor block to the blower motor on circuit C1.
J8W-42 AIR CONDITIONING/HEATERÐXJ VEHICLES 8W - 42 - 1