Back JEEP CHEROKEE 1995 Service Repair Manual

STARTING SYSTEM
STARTING SYSTEM
AUTOMATIC TRANSMISSIONS
Circuit A0 from the battery is double crimped at
the positive battery post. One branch of circuit A0
(battery positive cable) connects to the engine starter
motor. The other A0 branch supplies voltage to the
bus bar in the Power Distribution Center (PDC).
The PDC supplies battery voltage to the engine
starter motor solenoid on circuit T40 when the coil
side of the engine starter motor relay energizes. Cir-
cuit A1 from the fuse 4 in the PDC supplies battery
voltage to the contact side of the starter motor relay.
The ignition switch supplies battery voltage to the
coil side of the starter motor relay on circuit A41
when the key is moved to the START position and
the Park/Neutral position switch is closed. Ground
for the coil side of the starter motor relay is supplied
by the case grounded Park/Neutral position switch.
Circuit T41 connects the coil side of the relay to the
Park/Neutral position switch.
When the starter motor relay energizes and the
contacts close, circuit T40 supplies battery voltage to
the starter motor solenoid. Circuit A0 from the bat-
tery supplies voltage to the starter motor when the
solenoid energizes.
MANUAL TRANSMISSIONS
Circuit A0 from the battery is double crimped at
the positive battery post. One branch of circuit A0
(battery positive cable) connects to the battery
starter motor. The other A0 branch supplies voltage
to the bus bar in the Power Distribution Center
(PDC).The PDC supplies battery voltage to the engine
starter motor solenoid on circuit T40 when the coil
side of the engine starter motor relay energizes. Cir-
cuit A1 from the fuse 4 in the PDC supplies battery
voltage to the contact side of the starter motor relay.
The ignition switch supplies battery voltage to the
coil side of the starter motor relay on circuit A41
when the key is moved to the START position. Cir-
cuit T41 from the coil side of the relay connects to a
Z2 jumper wire in the back-up lamp switch. Circuit
Z2 provides ground for the starter motor relay.
When the starter motor relay energizes and the
contacts close, circuit T40 supplies battery voltage to
the starter motor solenoid. Circuit A0 from the bat-
tery supplies voltage to the starter motor when the
solenoid energizes.
HELPFUL INFORMATION
²The Park/Neutral switch closes when the trans-
mission is in either the PARK or NEUTRAL posi-
tions.
²Circuit T41 also connects to cavity 30 of the Pow-
ertrain Control Module (PCM). This input tells the
PCM the operator is starting the vehicle.
DIAGRAM INDEX
Component Page
Engine Starter Motor......................8W-21-2
Engine Starter Motor Relay..................8W-21-2
Ignition Switch..........................8W-21-2
Park/Neutral Position Switch.................8W-21-2
Power Distribution Center (PDC)...............8W-21-2
Powertrain Control Module (PCM)..............8W-21-2
Fuse 4 (PDC)...........................8W-21-2
J8W-21 STARTING SYSTEMÐYJ VEHICLES 8W - 21 - 1

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
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 (MAP) 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
²Manifold absolute pressure sensor
²Engine coolant temperature sensor
²Vehicle speed sensor
MANIFOLD ABSOLUTE PRESSURE (MAP) 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
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
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 Powertrain
Control Module (PCM). The park/neutral position
switch provides an input to the (PCM).
HELPFUL INFORMATION
²In the START position, the ignition switch con-
nects circuit A1 from the Power Distribution Center
(PDC) to circuit A41. Fuse 4 in the fuse block pro-
tects circuits A1 and A41.
²The Park/Neutral position switch and back-up
lamp switch are molded together.
POWER STEERING PRESSURE SWITCH
The Powertrain Control Module (PCM) supplies
voltage to the power steering pressure switch on cir-
cuit K10. Circuit Z1 provides ground for the switch.
When the switch closes, voltage flows through the
8W - 30 - 4 8W-30 FUEL/IGNITIONÐYJ VEHICLESJ

AIR CONDITIONING AND HEATER
GENERAL INFORMATION
On vehicles built with the 2.5L engine, the electri-
cal system has provisions for dealer installed air con-
ditioning. The provisions consist of two connectors
which include circuitry for:
²Circuit C1 - Ignition feed
²Circuit C21 - Blower motor switch
²Circuit C91 - A/C request signal
²Circuit C20 - A/C select signal
²Circuit C13 - Ground for coil side of A/C compres-
sor clutch relay
²Circuit G5 - Battery voltage for coil side of A/C
compressor clutch relay
A/C COMPRESSOR
When the ignition switch is in the RUN position it
connects circuit A1 from fuse 4 in the Power Distri-
bution Center (PDC) to circuit A22. Circuit A22 sup-
plies battery voltage to fuse 12 in the fuse block.
Fuse 12 powers circuit C1.
Circuit C1 supplies battery voltage to the A/C
blower switch. Circuit C21 connects the A/C blower
switch to the A/C low pressure switch.
When the operator selects A/C operation, the A/C
blower switch provides the A/C request signal to cav-
ity 27 of the Powertrain Control Module (PCM) on
circuit C91. At the same time, the blower switch sup-
plies voltage through the A/C thermostat to circuit
C21.
Circuit C21 supplies voltage to the A/C low pres-
sure switch. When the A/C low pressure switch
closes, circuit C20 provides battery voltage to the
contact side of the A/C compressor clutch relay and
provides the A/C select signal to the PCM. Circuit
C20 is double crimped at the contact side of the re-
lay. The C20 circuit branch from the relay supplies
the A/C select input to cavity 28 of the PCM.
After receiving the A/C request signal, the PCM en-
ergizes the A/C compressor clutch relay by providing
ground for the coil side of the relay on circuit C13.
Circuit C13 connects to cavity 34 of the PCM.
Circuit G5 from fuse 9 in the fuse block supplies
voltage to the coil side of the relay. In the START or
RUN positions the ignition switch connects circuit A1
from fuse 4 in the PDC with circuit A21. Circuit A21
connects to the fuse block bus bar that powers circuit
C5 through fuse 9.
When the PCM energizes the A/C compressor
clutch relay, the relay switches from its normally
grounded position to connect circuit C20 to circuit
C3. Circuit C3 supplies voltage to the case grounded
A/C compressor clutch.
HELPFUL INFORMATION
²Circuit G5 is double crimped at the coil side of the
A/C compressor clutch relay. The G5 branch from the
relay continues to the back-up lamp switch.
²Circuit Z1 provides ground for the A/C compressor
clutch relay when the relay is in its normally
grounded position.
A/C-HEATER BLOWER MOTOR
When the ignition switch is in the RUN position it
connects circuit A1 from fuse 4 in the Power Distri-
bution Center (PDC) to circuit A22. Circuit A22 sup-
plies battery voltage to fuse 12 in the fuse block.
Fuse 12 powers circuit C1.
Circuit C1 supplies battery voltage to the A/C
blower switch. In the LOW position, the A/C blower
switch supplies voltage to the low speed brush of the
blower motor. In the MEDIUM position, the switch
supplies voltage to the medium speed bush of the
blower motor. In the HIGH position, the switch sup-
plies voltage to the high speed brush of the blower
motor.
The blower motor has a field jumper. The ground
circuit for the blower motor connects to the cigar
lighter. Circuit Z1 provides ground for the blower mo-
tor and the cigar lighter.
HELPFUL INFORMATION
²Check fuse 4 in the PDC.
²Check fuse 12 in the fuse block.
DIAGRAM INDEX
Component Page
A/C Compressor Clutch.....................8W-42-4
A/C Compressor Clutch Relay................8W-42-4
A/C Thermostat..........................8W-42-5
Blower Motor...........................8W-42-5
Blower Motor Switch......................8W-42-5
Fuse 4 (PDC).........................8W-42-4, 6
Fuse 7 (Fuse Block).......................8W-42-6
Fuse 9 (Fuse Block).....................8W-42-4, 6
Fuse 12 (Fuse Block)....................8W-42-4, 6
Ignition Switch........................8W-42-4, 6
Powertrain Control Module.................8W-42-4, 6
8W - 42 - 2 8W-42 AIR CONDITIONING/HEATERÐYJ VEHICLESJ

REAR LIGHTING
TAIL LAMPS AND LICENSE PLATE LAMPS
Circuit A6 in the Power Distribution Center (PDC)
connects to a bus bar in the fuse block. The fuse
block bus bar powers circuit F33. Circuit F33 con-
nects to the headlamp switch. Fuse 3 in the PDC
protects circuit A3. Fuse 8 in the fuse block protects
circuit F33.
The headlamp switch has three positions: ON,
PARK (parking lamps) and OFF, plus a dimmer
switch. When the headlamp switch is in the PARK or
ON position, the switch connects circuit F33 to cir-
cuit L7. From the headlamp switch, circuit L7
branches to power the front parking lamps and rear
tail and license plate lamps. The lamps are case
grounded.
HELPFUL INFORMATION
²If the vehicle is equipped with factory installed fog
lamps, circuit L7 splices to feed the park lamp relay.
²Jumper harnesses connect the tail, stop, turn sig-
nal lamp to the body harness.
²Check fuse 3 in the PDC.
²Check fuse 8 in the fuse block.
²Circuit L7 also feeds the radio, if equipped.
STOP LAMPS AND CHMSL LAMPS
Circuit A6 from fuse 3 in the Power Distribution
Center (PDC) supplies voltage to the fuse block bus
bar. The bus bar powers circuit F32 through fuse 3 in
the fuse block. Circuit F32 connects to the stop lamp
switch.
When the operator depresses the brake pedal, the
stop lamp switch closes, and connects circuit F32 to
circuit L50. Circuit L50 connects to the CHMSL
lamps and turn signal/hazard flasher. Circuit Z1 pro-
vides ground for the CHMSL lamps. The turn signal/
hazard flasher supplies current to the L62 and L63
circuits. Circuit L62 powers the right stop lamp. Cir-
cuit L63 powers the left stop lamp. The stop lamps
are case grounded.
HELPFUL INFORMATION
²Circuits L50 and Z1 pass through contacts in the
rear door before reaching the CHMSL lamps.
²Check fuse 3 in the PDC.²Check fuse 3 in the fuse block.
²Check for continuity across the stop lamp switch
when it is closed.
²If the vehicle is equipped with anti-lock brakes,
circuit L50 connects to the ABS module.
BACK-UP LAMPS
In the START or RUN position, the ignition switch
connects circuit A1 from fuse 4 in the Power Distri-
bution Center (PDC) to circuit A21. Circuit A21 feeds
a bus bar in the fuse block that powers circuit G5
through fuse 9.
Circuit G5 splices to supply power to the back-up
lamp switch. On automatic transmission vehicles, the
back-up lamp switch is part of an assembly that in-
cludes the PARK/NEUTRAL position switch.
When the operator puts the transmission in Re-
verse, the back-up lamp switch connects circuit G5 to
circuit L1. Circuit L1 feeds the case grounded
back-up lamps.
HELPFUL INFORMATION
²Check fuse 4 in the PDC.
²Check fuse 9 in the fuse block.
²Check for continuity across the back-up lamp
switch when it is closed.
DIAGRAM INDEX
Component Page
ABS Control Module......................8W-51-3
Back-Up Lamps..........................8W-51-4
Back-Up Lamp Switch.....................8W-51-2
Center High Mounted Stop Lamps (CHMSL).......8W-51-3
Fuse 3 (Fuse Block).......................8W-51-2
Fuse 3 (PDC)...........................8W-51-2
Fuse 4 (PDC)...........................8W-51-2
Fuse 9 (Fuse Block).......................8W-51-2
Fuse 8 (Fuse Block).......................8W-51-2
Headlamp Switch.........................8W-51-2
Ignition Switch..........................8W-51-2
Powertrain Control Module..................8W-51-3
Stop Lamp Switch........................8W-51-3
Tail, Stop, and Turn Signal Lamps.............8W-51-4
J8W-51 REAR LIGHTINGÐYJ VEHICLES 8W - 51 - 1