1995 JEEP XJ Brake lamp

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

CONNECTOR LOCATIONS
GENERAL INFORMATION
This section provides illustrations identifying com-
ponent and connector locations in the vehicle. A con-nector index is provided. Use the wiring diagrams in
each section for connector number identification. Re-
fer to the index for the proper figure number.
CONNECTOR LOCATIONS
Connector # . Color . Location Fig.
C101......BK ...RTFender Side Shield..........1
C102......BK ...RTFender Side Shield Under PDC . .1
C103......BK ...RTFender Side Shield..........1
C104......BK ...LTSide of Battery on Cowl Panel . . .1
C105 2.5L . . . NAT . . RT Rear of Engine............3
C105 4.0L . . . NAT . . RT Rear of Engine............4
C106......BK ...AtLamp...................1
C107......NAT ..Center of Cowl Panel Near
Map Sensor...............1
C108......BK ...LTKick Panel Above Park Brake . . .8
C109......BK ...Under Drivers Seat............8
C110......BK ...Under I.P.Front of Floor Tunnel....6
C111......BK ...Under I.P.Front of Floor Tunnel....6
C112......BK ...Under I.P. RT of Stop Lamp Switch .7
C113......BK ...LTFender Side Shield..........1
C114......BK ...LTSide Cowl Panel............1
C115......BK ...LTFender Side Shield..........1
C116......BK ...LTFender Side Shield..........1
C117......BK ...LTFender Side Shield..........1
C118......BK ...Bottom of Washer Reservoir......2
C119......BK ...Near Bulkhead Disconnect
2.5L only..........Not Shown
C120 2.5L . . . BK . . . Rear of Generator.............3
C120 4.0L . . . BK . . . Rear of Generator.............5
C121 2.5L . . . BK . . . RT Rear of Engine............3
C121 4.0L . . . BK . . . Rear of Generator.............4
C122......BK ...OnReceiver/Drier.............4
C123 2.5L . . . BK . . . RT Side of Engine Rear of Distributor .3
C123 4.0L . . . BK . . . RT Side of Engine Rear of Distributor .4
C124 2.5L . . . BK . . . At End of Distributor Pig Tail.....3
C124 4.0L . . . BK . . . At End of Distributor Pig Tail.....4
C125......GY ...RTSide of Transmission........5
C126......BK ...LTRear of Transmission.........5
C127......BK ...TopofFuel Tank..............9
C128......BK ...TopofRear Cross-member.......9
C129......BK ...TopofRear Cross-member.......9
C130 2.5L . . . BK . . . On Thermostat Housing.........3
C130 4.0L . . . BK . . . On Thermostat Housing.........4
C131 2.5L . . . BK . . . LT Side of Engine Bottom of Intake .3
C131 4.0L . . . BK . . . LT Side of Engine Bottom of Intake .4
C132 2.5L . . . BK . . . Injector #1.................3
C132 4.0L . . . BK . . . Injector #1.................4
C133 2.5L . . . BK . . . Injector #2.................3
C133 4.0L . . . BK . . . Injector #2.................4
C134 2.5L . . . BK . . . Injector #3.................3
C134 4.0L . . . BK . . . Injector #3.................4
C135 2.5L . . . BK . . . Injector #4.................3
C135 4.0L . . . BK . . . Injector #4.................4Connector # . Color . Location Fig.
C136......BK ...Injector #5.................4
C137......BK ...Injector #6.................4
C138 2.5L . . . BK . . . Center of Dash Panel...........1
C138 4.0L . . . BK . . . Center of Dash Panel...........1
C139......BK ...Under Bulkhead LT Side of I.P.....1
C140 2.5L . . . GY . . . LT Rear of Intake.............3
C140 4.0L . . . GY . . . LT Rear of Intake.............4
C141 2.5L . . . BK . . . Rear of Throttle Body..........3
C141 4.0L . . . BK . . . Rear of Throttle Body..........4
C142 2.5L . . . BK . . . On Throttle Body.............3
C142 4.0L . . . BK . . . On Throttle Body.............4
C143 2.5L . . . BK . . . Rear of Intake...............3
C143 4.0L . . . BK . . . Rear of Intake...............4
C144......BK ...Above Bulkhead Disconnect.......1
C145......GY ...OnPower Steering Pump........3
C146......BK ...AtHeadlamp..........Not Shown
C147......YL ...AtSide Marker Lamp..........2
C148......BK ...AtPark/Turn Lamp......Not Shown
C149......BK ...RTSide Behind Bumper.........2
C150......BK ...LTSide Behind Bumper.........2
C151......BK ...AtPark/Turn Lamp............2
C152......YL ...AtSide Marker Lamp. . . .Not Shown
C153......BK ...AtHeadlamp................2
C154......BK ...LTFender Side Shield..........2
C155......BK ...Direct Connection to Horn.......2
C156......BK ...Bottom of Washer Reservoir......2
C201......BK ...LTSide of I.P...............7
C202......BK ...OnFuse Block...............7
C203......BK ...LTKick Panel................7
C204......BK ...LTKick Panel................7
C205......BK ...LTSide Kick Panel Under I.P......7
C206......BK ...AtSpeaker...........Not Shown
C207......BK ...LTofSteering Column Rear
of Cluster.................7
C208......BK ...LTSide of Steering Column......7
C209......BK ...Rear of Switch...............7
C210......BK ...Rear of Switch...............7
C211......BK ...Base of Steering Column........7
C212......BK ...AtWiper Motor..............7
C213......BK ...RTofSteering Column Under I.P. . .7
C214......BK ...RTSide of Cluster Bezel . .Not Shown
C215......BK ...Base of Steering Column........7
C216......BK ...Base of Steering Column........7
C217......BK ...RTSide of Brake Pedal Support . . .7
C218......BK ...Base of Steering Column........7
C219......BK ...Rear of Switch...............7
C220......BK ...Rear of Switch...............7
C221......BK ...Rear of Switch...............7
J8W-90 CONNECTOR LOCATIONSÐYJ VEHICLES 8W - 90 - 1

SPLICE LOCATIONS
GENERAL INFORMATION
This section provides illustrations identifying the
general location of the splices in this vehicle. A splice
index is provided. Use the wiring diagrams in each
section for splice number identification. Refer to the
index for the proper splice number.
SPLICE LOCATIONS
Splice
NumberLocations Fig.
S101 Near PDC T/O.....................1
S102 Near T/O for Engine Wiring.............1
S103 RT Dash Panel Near T/o for Ground.......1
S104 Near T/O for MAP Sensor..............1
S105 Near T/O for MAP Sensor..............1
S106 Left Side of MAP Sensor..............1
S107 In ABS Wiring T/O Near Grommet........1
S108 In ABS Wiring T/O Near Grommet........1
S109 Above Brake Booster.................1
S110 Rear of Generator...................3
S111 2.5L RT Side of Valve Cover...............4
S111 4.0L RT Side of Valve Cover...............3
S112 Near T/O for PRNDL Switch............5
S113 Between Inj #2 and Inj #3.............3
S114 Near T/O for Throttle Body Wiring........3
S115 Above Bulkhead Connector.............1
S116 Above Bulkhead Connector.............1
S117 Near Data Link T/O..................1
S118 Near Data Link T/O..................1
S119 Near Data Link T/O..................1
S120 4.0L RT Side of Valve Cover...............3
S121 2.5L RT Side of Valve Cover...............4
S122 Near T/O for RT PK/TURN Lamp.........2
S123 Near T/O for RT Fog Lamp.............2
S124 Near T/O for LT Fog Lamp.............2
S125 Near T/O for LT PK/TURN Lamp.........2Splice
NumberLocations Fig.
S126 Near T/O for Headlamp...............2
S127 Near T/O for Headlamp...............2
S128 Near T/O for Headlamp...............2
S129 Near Horn T/O.....................2
S201 Near T/O for Dimmer Switch............7
S202 Near T/O for Dimmer Switch............7
S203 Near T/O for Dimmer Switch............7
S204 Near T/O for Dimmer Switch............7
S205 Near T/O for Wiper Switch.............7
S206 Near T/O for Wiper Switch.............7
S207 Near Panel Illumination T/O.............7
S208 Near Panel Illumination T/O.............7
S209 Near Panel Illumination T/O.............7
S210 Near Panel Illumination T/O.............7
S211 Near T/O for Ignition Switch............7
S212 Near T/O for Ignition Switch............7
S213 Near T/O for Radio..................6
S301 Near T/O for Park Brake Switch..........8
S302 Near T/O for Park Brake Switch..........8
S303 Near Grommet LT Rear Quarter Panel......8
S304 Near LT Rear Tail Lamp T/O............8
S305 RT Rear Quarter Panel Near Tail Lamp.....8
S306 Near T/O for Dome Lamp.......Not Shown
S307 In CHMSL Jumper Harness......Not Shown
S308 In CHMSL Jumper Harness......Not Shown
J8W-95 SPLICE LOCATIONSÐYJ VEHICLES 8W - 95 - 1

(2) Install the upper inner retainer and bushing on
the top of the damper.
(3) Position the upper damper bracket over the
damper and install the stud nut and bolts.
(4) Tighten the stud nut to 23 Nzm (17 ft. lbs.)
torque. Tighten the bracket bolts to 61 Nzm (45 ft.
lbs.) torque.
(5) Install the bushing, upper outer retainer and
damper nut.
(6) Install the bushing, lower outer retainer and
damper nut.
(7) Tighten the upper and lower damper nuts.
(8) Connect negative cable to battery.
ENGINE ASSEMBLYÐXJ VEHICLES
REMOVAL
(1) Disconnect the battery cables. Remove the bat-
tery.
(2) Mark the hinge locations on the hood panel for
alignment reference during installation. Remove the
engine compartment lamp. Remove the hood.
WARNING: THE COOLANT IN A RECENTLY OPER-
ATED ENGINE IS HOT AND PRESSURIZED. USE
CARE TO PREVENT SCALDING BY HOT COOLANT.
CAREFULLY RELEASE THE PRESSURE BEFORE
REMOVING THE RADIATOR DRAIN COCK AND CAP.(3) Remove the radiator drain cock and radiator
cap to drain the coolant. DO NOT waste usable cool-
ant. If the solution is clean, drain the coolant into a
clean container for reuse.
(4) Remove the lower radiator hose.
(5) Remove the upper radiator hose and coolant re-
covery hose (Fig. 15).
(6) Remove the fan shroud (Fig. 15).
(7) Disconnect the transmission fluid cooler tubing
(automatic transmission).
(8) Remove the radiator/condenser (if equipped
with air conditioning).
(9) Remove fan assembly and install a 5/16 x 1/2-
inch SAE capscrew through fan pulley into water
pump flange. This will maintain the pulley and wa-
ter pump in alignment when crankshaft is rotated.
(10) Disconnect the heater hoses (Figs. 16 and 17).
(11) Disconnect the throttle linkages (Fig. 16),
speed control cable (if equipped) and throttle valve
rod.
(12) Disconnect the oxygen sensor wire connector.
(13) Disconnect the wires from the starter motor
solenoid.
(14) Disconnect all fuel injection harness connec-
tions.
(15) Disconnect the quick-connect fuel lines at the
fuel rail and return line by squeezing the two retain-
ing tabs against the fuel tube (Fig. 16). Pull the fuel
tube and retainer from the quick-connect fitting (re-
fer to Group 14, Fuel System for the proper proce-
dure).
(16) Remove the fuel line bracket from the intake
manifold.
(17) Remove the air cleaner assembly (Fig. 18).
(18) If equipped with air conditioning, remove the
service valves and cap the compressor ports.
(19) Remove the power brake vacuum check valve
from the booster, if equipped.
(20) If equipped with power steering (Fig. 18):
Fig. 14 Engine Damper
Fig. 15 Upper Radiator Hose, Coolant Recovery
Hose & Fan Shroud
9 - 18 2.5L ENGINEJ

(14) Install the remaining flywheel housing bolts.
Tighten the bolts to 38 Nzm (28 ft. lbs.) torque.
(15) Install the starter motor and connect the ca-
ble. Tighten the bolts to 45 Nzm (33 ft. lbs.) torque.
(16) Install the oil filter.
(17) Lower the vehicle.
(18) Connect the coolant hoses and tighten the
clamps.
(19) If equipped with power steering:
(a) Remove the protective caps
(b) Connect the hoses to the fittings at the steer-
ing gear. Tighten the nut to 52 Nzm (38 ft. lbs.)
torque.
(c) Fill the pump reservoir with fluid.
(20) Remove the pulley-to-water pump flange
alignment capscrew and install the fan and spacer or
Tempatrol fan assembly.
(21) Tighten the serpentine drive belt according to
the specifications listed in Group 7, Cooling System.
(22) Install the fan shroud and radiator.
(23) Connect the radiator hoses.
(24) Connect the heater hoses.
(25) Connect the throttle valve rod and retainer.
(26) Connect the throttle cable and install the rod.
(27) Install the throttle valve rod spring.
(28) Connect the speed control cable, if equipped.
(29) Connect the oxygen sensor wire connector.
(30) Install the vacuum hose and check valve on
the brake booster.
(31) Connect the coolant temperature sensor wire
connector.
(32) Connect the idle speed actuator wire connec-
tor.
(33) Connect the fuel inlet and return hoses at the
fuel rail. Verify that the quick-connect fitting assem-
bly fits securely over the fuel lines by giving the fuel
lines a firm tug.
(34) Install the fuel line bracket to the intake man-
ifold.
(35) Connect all fuel injection wire connections.
(36) Install the engine ground strap.
(37) Connect the ignition coil wire connector.
(38) Remove the coolant temperature sending unit
to permit air to escape from the block. Fill the cool-
ing system with coolant. Install the coolant tempera-
ture sending unit when the system is filled.
(39) Install the battery and connect the battery ca-
bles.
(40) Install the air cleaner bonnet to the throttle
body.
(41) Install the air cleaner.
(42) Lower the hood and secure in place.
(43) Start the engine and inspect for leaks.
(44) Stop the engine and check the fluid levels.
Add fluid, as required.ENGINE CYLINDER HEAD COVER
A cured gasket is part of the engine cylinder head
cover.
REMOVAL
(1) Disconnect negative cable from battery.
(2) Disconnect the Crankcase Ventilation (CCV)
vacuum hose from engine cylinder head cover (Fig.
1).
(3) Disconnect the fresh air inlet hose from the en-
gine cylinder head cover (Fig. 1).
(4) Remove the engine cylinder head cover mount-
ing bolts.
(5) Remove the engine cylinder head cover.
CLEANING
Remove any original sealer from the cover sealing
surface of the engine cylinder head and clean the
surface using a fabric cleaner.
Remove all residue from the sealing surface using
a clean, dry cloth.
INSPECTION
Inspect the engine cylinder head cover for cracks.
Replace the cover, if cracked.
The original dark grey gasket material should NOT
be removed. If sections of the gasket material are
missing or are compressed, replace the engine cylin-
der head cover. However, sections with minor damage
such as small cracks, cuts or chips may be repaired
with a hand held applicator. The new material must
be smoothed over to maintain gasket height. Allow
the gasket material to cure prior to engine cylinder
head cover installation.
INSTALLATION
(1) If a replacement cover is installed, transfer the
CCV valve grommet the oil filler cap from the origi-
nal cover to the replacement cover.
(2) Install engine cylinder head cover. Tighten the
mounting bolts to 10 Nzm (85 in. lbs.) torque.
Fig. 1 Engine Cylinder Head Cover
9 - 22 2.5L ENGINEJ

(18) Disconnect the oxygen sensor wire connector.
(19) Remove the upper radiator hose and coolant
recovery hose (Fig. 19).
(20) Disconnect lower radiator hoses at the radia-
tor.
(21) Disconnect the coolant hoses from the rear of
the intake manifold and thermostat housing.
(22) Remove the fan shroud screws.
(23) Remove the radiator attaching bolts.
(24) Remove the radiator and fan shroud (Fig. 19).
Refer to Group 7, Cooling System for the proper pro-
cedure.
(25) Remove the fan and spacer or Tempatrol fan
assembly.
(26) Install a 5/16 X 1/2-inch SAE capscrew
through fan pulley into water pump flange. This will
maintain the pulley and water pump in alignment
when crankshaft is rotated.
(27) Remove the power brake vacuum check valve
from the booster, if equipped.
(28) If equipped with power steering (Fig. 19):
(a) Disconnect the hoses from the fittings at the
steering gear.
(b) Drain the pump reservoir.
(c) Cap the fittings on the hoses and steering
gear to prevent foreign objects from entering the
system.
(29) Lift the vehicle and support it with support
stands.
(30) Remove the starter motor.
(31) Remove the flywheel housing access cover.
(32) Remove the engine support cushion-to-bracket
through bolts.
(33) Disconnect the exhaust pipe from the mani-
fold.
(34) Remove the upper flywheel housing bolts and
loosen the bottom bolts.
(35) Lower the vehicle.
(36) Attach a lifting device to the engine.(37) Raise the engine off the front supports.
(38) Place a support stand under the flywheel
housing.
(39) Remove the remaining flywheel housing bolts.
(40) Lift the engine out of the engine compartment
and install on an engine stand.
INSTALLATION
(1) Lift the engine off the stand and lower it into
the engine compartment. For easier installation, it
may be useful to remove the engine support cushions
from the engine support brackets as an aide for
alignment of the engine-to-transmission.
(2) Insert the transmission shaft into the clutch
spline.
(3) Align the flywheel housing with the engine.
(4) Install and finger tighten the flywheel housing
lower bolts.
(5) Install the engine support cushions (if re-
moved).
(6) Remove the support stand from beneath the
flywheel housing.
(7) Lower the engine and engine support cushions
onto the engine compartment brackets. Ensure that
the bolt holes are aligned. Install the bolts and
tighten the nuts.
(8) Remove the engine lifting device.
(9) Raise the vehicle.
(10) Attach the exhaust pipe to the manifold. In-
stall and tighten the nuts to 31 Nzm (23 ft. lbs.)
torque.
(11) Install the flywheel housing access cover.
(12) Install the remaining flywheel housing bolts.
Tighten the bolts to 38 Nzm (28 ft. lbs.) torque.
(13) Install the starter motor and connect the ca-
ble. Tighten the bolts to 45 Nzm (33 ft. lbs.) torque.
(14) Lower the vehicle.
(15) Connect the coolant hoses and tighten the
clamps.
Fig. 18 Fuel Line Quick-Connect Couplings, Air
Cleaner Assembly, Throttle & Speed Control CablesFig. 19 Upper Radiator Hose, Coolant Recovery
Hose, Fan Shroud & Power Steering Pump
J4.0L ENGINE 9 - 63

MULTI-PORT FUEL INJECTION (MFI)ÐCOMPONENT DESCRIPTION/SYSTEM
OPERATION
INDEX
page page
Air Cleaner.............................. 29
Air Conditioning (A/C) Clutch RelayÐPCM Output . 26
Air Conditioning (A/C) ControlsÐPCM Input...... 21
Auto Shutdown (ASD) RelayÐPCM Output...... 26
Automatic Shutdown (ASD) SenseÐPCM Input . . . 21
Battery VoltageÐPCM Input................. 21
Brake SwitchÐPCM Input................... 22
Camshaft Position SensorÐPCM Input......... 22
Crankshaft Position SensorÐPCM Input........ 22
Data Link ConnectorÐPCM Input............. 22
Data Link ConnectorÐPCM Output............ 27
EMR LampÐPCM Output................... 27
Engine Coolant Temperature SensorÐPCM Input . 23
Extended Idle SwitchÐPCM Input............. 23
Fuel InjectorsÐPCM Output................. 27
Fuel Pressure Regulator.................... 33
Fuel Pump RelayÐPCM Output.............. 27
Fuel Rail................................ 33
General Information....................... 19
Generator FieldÐPCM Output................ 27
Generator LampÐPCM Output............... 27
Idle Air Control (IAC) MotorÐPCM Output....... 27
Ignition Circuit SenseÐPCM Input............. 23
Ignition CoilÐPCM Output................... 28Intake Manifold Air Temperature SensorÐ
PCM Input............................. 22
Malfunction Indicator LampÐPCM Output....... 28
Manifold Absolute Pressure (MAP) SensorÐPCM
Input................................. 23
Open Loop/Closed Loop Modes of Operation..... 30
Oxygen (O2S) SensorÐPCM Input............ 24
Park/Neutral SwitchÐPCM Input.............. 24
Power Ground........................... 24
Power Steering Pressure SwitchÐPCM Input.... 24
Powertrain Control Module (PCM)............. 20
Radiator Fan RelayÐPCM Output............. 28
SCI ReceiveÐPCM Input................... 24
SCI TransmitÐPCM Output.................. 29
Sensor ReturnÐPCM Input.................. 25
Shift IndicatorÐPCM Output................. 29
Speed ControlÐPCM Input.................. 25
Speed ControlÐPCM Output................. 29
TachometerÐPCM Output................... 29
Throttle Body............................ 33
Throttle Position Sensor (TPS)ÐPCM Input...... 25
Torque Converter Clutch RelayÐPCM Output.... 29
Vehicle Speed SensorÐPCM Input............ 25
GENERAL INFORMATION
All 2.5L 4-cylinder and 4.0L 6-cylinder engines are
equipped with sequential Multi-Port Fuel Injection
(MFI). The MFI system provides precise air/fuel ra-
tios for all driving conditions.
The Powertrain Control Module (PCM) operates
the fuel system. The PCM was formerly referred to
as the SBEC or engine controller. The PCM is a pre-
programmed, dual microprocessor digital computer. It
regulates ignition timing, air-fuel ratio, emission con-
trol devices, charging system, speed control, air con-
ditioning compressor clutch engagement and idle
speed. The PCM can adapt its programming to meet
changing operating conditions.
Powertrain Control Module (PCM) Inputsrep-
resent the instantaneous engine operating conditions.
Air-fuel mixture and ignition timing calibrations for
various driving and atmospheric conditions are pre-
programmed into the PCM. The PCM monitors and
analyzes various inputs. It then computes engine fuel
and ignition timing requirements based on these in-
puts. Fuel delivery control and ignition timing will
then be adjusted accordingly.
Other inputs to the PCM are provided by the brake
light switch, air conditioning select switch and the
speed control switches. All inputs to the PCM are
converted into signals.
Electrically operated fuel injectors spray fuel inprecise metered amounts into the intake port directly
above the intake valve. The injectors are fired in a
specific sequence by the PCM. The PCM maintains
an air/fuel ratio of 14.7 to 1 by constantly adjusting
injector pulse width. Injector pulse width is the
length of time that the injector opens and sprays fuel
into the chamber. The PCM adjusts injector pulse
width by opening and closing the ground path to the
injector.
Manifold absolute pressure (air density) and engine
rpm (speed) are the primary inputs that determine
fuel injector pulse width. The PCM also monitors
other inputs when adjusting air-fuel ratio.
Inputs That Effect Fuel Injector Pulse Width:
²Exhaust gas oxygen content
²Engine coolant temperature
²Manifold absolute pressure (MAP)
²Engine speed
²Throttle position
²Battery voltage
²Air conditioning selection
²Transmission gear selection (automatic transmis-
sions only)
²Speed control
The powertrain control module (PCM) adjusts igni-
tion timing by controlling ignition coil operation. The
ignition coil receives battery voltage when the igni-
tion key is in the run or starter position. The PCM
JFUEL SYSTEM COMPONENT DESCRIPTION/SYSTEM OPERATION 14 - 19

MULTI-PORT FUEL INJECTION (MFI)ÐCOMPONENT REMOVAL/INSTALLATION
INDEX
page page
Accelerator Pedal and Throttle Cable........... 58
Air Cleaner Element....................... 59
Air Cleaner Housing....................... 58
Air Conditioning (A/C) Clutch Relay............ 58
Automatic Shutdown (ASD) Relay............. 59
Brake Switch............................ 59
Camshaft Position Sensor................... 60
Crankshaft Position Sensor.................. 60
Engine Coolant Temperature Sensor........... 60
Fuel Filter............................... 60
Fuel Injector............................. 60
Fuel Pressure Regulator.................... 61
Fuel Pump Module........................ 61
Fuel Pump Relay......................... 61
Fuel Rail Assembly........................ 62
Fuel System Pressure Release Procedure....... 62
Fuel Tank Pressure Relief/Rollover Valve........ 62Fuel Tanks.............................. 62
Fuel Tubes/Lines/Hoses and Clamps........... 62
Idle Air Control (IAC) Motor.................. 62
Ignition Coil............................. 62
Intake Manifold........................... 63
Intake Manifold Air Temperature Sensor......... 60
Manifold Absolute Pressure (Map) Sensor....... 63
Oxygen (O2S) Sensor...................... 63
Park Neutral Switch....................... 63
Power Steering Pressure SwitchÐ2.5L
Engine Only............................ 63
Powertrain Control Module (PCM)............. 64
Quick-Connect Fittings..................... 64
Throttle Body............................ 64
Throttle Position Sensor (TPS)............... 65
Torque Converter Clutch Relay............... 65
Vehicle Speed Sensor...................... 66
ACCELERATOR PEDAL AND THROTTLE CABLE
Refer to the Accelerator Pedal and Throttle Cable
section of this group for removal/installation proce-
dures.
AIR CONDITIONING (A/C) CLUTCH RELAY
The A/C clutch relay is located in the power distri-
bution center (PDC) (Figs. 1 or 2). For location of this
relay within the PDC, refer to label on PDC cover.
AIR CLEANER HOUSING
REMOVAL
(1) Unlock clean air hose clamp (Figs. 3 or 4) at air
cleaner cover. To unlock the clamp, attach adjustablepliers to clamp and rotate pliers as shown in figure
5. Remove clean air hose at cover.
(2) Disconnect vacuum lines at air cleaner housing.
(3) YJ Models: Release the three over-center type
clamps securing the housing to the housing bracket.
XJ Models: Remove the housing cover and remove air
cleaner element. Remove two bolts and one nut.
(4) Release the air cleaner housing from the ambi-
ent air inlet and remove housing from vehicle.
INSTALLATION
(1) Position air cleaner housing to body and ambi-
ent air inlet.
(2) YJ Models: Lock the three over-center type
clamps securing the housing to the housing bracket.
XJ Models: Install two bolts and one nut to housing.
Install air cleaner element and cover.
(3) Install vacuum lines to housing.
Fig. 1 PDCÐYJ Models
Fig. 2 PDCÐXJ Models
14 - 58 FUEL SYSTEM COMPONENT REMOVAL/INSTALLATIONJ