(6) Remove upper radiator support retaining bolts
and remove radiator support.
(7) Remove the fan shroud (Fig. 13) and electric
cooling fan.
(8) Disconnect the transmission fluid cooler tubing
(automatic transmission).
(9) Disconnect radiator fan switch wire connector.
(10)Vehicles with Air Conditioning:
(a) Discharge the A/C condenser.
(b) Remove the service valves and cap the com-
pressor ports.
(11) Remove the radiator or radiator and con-
denser (if equipped with A/C).
(12) Remove the fan assembly from the idler pul-
ley.
(13) Disconnect the heater hoses at the engine
thermostat housing and water pump (Figs. 13 and
14).
(14) Disconnect the throttle linkages (Fig. 15).
(15) Disconnect the speed control cable (if
equipped)Ð(Fig. 15).(16) Disconnect the line pressure cable (if equipped
with automatic transmission).
(17) Disconnect injection system wire harness con-
nector at the dash panel.
(18) Disconnect the distributor electrical connec-
tion and the oil pressure switch connector.
(19) Perform the Fuel System Pressure Release
procedure (refer to Group 14, Fuel System).
(20) 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. 15). Pull the fuel
tube and retainer from the quick-connect fitting (re-
fer to Group 14, Fuel System for the proper proce-
dure).
(21) Remove the fuel line bracket from the intake
manifold.
(22) Remove the air cleaner assembly (Fig. 16).
(23) Remove the power brake vacuum check valve
from the booster, if equipped.
(24) If equipped with power steering (Fig. 16):
(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.
(25) Identify, tag and disconnect all necessary wire
connectors and vacuum hoses.
(26) Raise and support the vehicle.
(27) Disconnect the wires from the starter motor
solenoid.
(28) Remove the starter motor.
Fig. 13 Upper Radiator Hose, Coolant Recovery
Hose, Fan Shroud & Heater hoses
Fig. 14 Heater Hoses (RH Drive Vehicle)
Fig. 15 Accelerator Cable, Speed Control Cable,
Automatic Transmission Control Cable & Quick-
Connect Fuel Lines
9 - 60 4.0L 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
(16) Remove the pulley-to-water pump flange
alignment capscrew and install the fan and spacer or
Tempatrol fan assembly.
(17) Tighten the serpentine drive belt according to
the specifications listed in Group 7, Cooling System.
(18) Install the fan shroud and radiator (refer to
Group 7, Cooling System for the proper procedure).
(19) Connect the radiator hoses.
(20) Connect the throttle valve rod and retainer.
(21) Connect the throttle cable and install the rod.
(22) Install the throttle valve rod spring.
(23) Connect the speed control cable, if equipped.
(24) Connect the oxygen sensor wire connector.
(25) Install the vacuum hose and check valve on
the brake booster.
(26) Connect the coolant temperature sensor wire
connector.
(27) Connect the idle speed actuator wire connec-
tor.
(28) 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.
(29) Install the fuel line bracket to the intake man-
ifold.
(30) Connect all fuel injection wire connections.
(31) Install the engine ground strap.
(32) Connect the ignition coil wire connector.
(33) 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.
(34) 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.
(35) Install the battery and connect the battery ca-
bles.
(36) Install the air cleaner bonnet to the throttle
body.
(37) Install the air cleaner.
(38) Lower the hood and secure in place.
(39) Start the engine and inspect for leaks.
(40) 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 and oil filler cap from the origi-
nal cover to the replacement cover.
(2) Install engine cylinder head cover. Tighten the
mounting bolts to 13 Nzm (115 in. lbs.) torque.
(3) Connect the CCV hoses (Fig. 1).
(4) Connect negative cable to battery.
Fig. 1 Engine Cylinder Head Cover
9 - 64 4.0L ENGINEJ
provides a ground for the ignition coil. The coil dis-
charges when the PCM supplies a ground. By switch-
ing the ground path on and off, the PCM regulates
ignition timing.
The sensors and switches that provide inputs to
the powertrain control module (PCM) comprise the
Engine Control System. It is also comprised of the
PCM Outputs (engine control devices that the are op-
erated by the PCM).
SYSTEM DIAGNOSIS
The powertrain control module (PCM) tests many
of its own input and output circuits. If a Diagnostic
Trouble Code (DTC) is found in a major system, this
information is stored in the PCM memory. Refer to
On-Board Diagnostics in the MFI SystemÐGeneral
Diagnosis section of this group for DTC information.
POWERTRAIN CONTROL MODULE (PCM)
The PCM operates the fuel system. The PCM was
formerly referred to as the SBEC or engine control-
ler. The PCM is a pre-programmed, dual microproces-
sor digital computer. It regulates ignition timing, air-
fuel ratio, emission control devices, charging system,
speed control, air conditioning compressor clutch en-
gagement and idle speed. The PCM can adapt its
programming to meet changing operating conditions.
On XJ models, the PCM is located in the engine
compartment next to the air cleaner (Fig. 1). On YJ
models, the PCM is located in the engine compart-
ment behind the windshield washer fluid reservoir
(Fig. 2).
The PCM receives input signals from various
switches and sensors. Based on these inputs, the
PCM regulates various engine and vehicle operations
through different system components. These compo-
nents are referred to as PCM Outputs. The sensors
and switches that provide inputs to the PCM are con-
sidered PCM Inputs.The PCM adjusts ignition timing based upon in-
puts it receives from sensors that react to: engine
rpm, manifold absolute pressure, coolant tempera-
ture, throttle position, transmission gear selection
(automatic transmission), vehicle speed and the
brake switch.
The PCM adjusts idle speed based on inputs it re-
ceives from sensors that react to: throttle position,
vehicle speed, transmission gear selection, coolant
temperature and from inputs it receives from the air
conditioning clutch switch and brake switch.
Based on inputs that it receives, the PCM adjusts
ignition coil dwell. The PCM also adjusts the gener-
ator charge rate through control of the generator
field and provides speed control operation.
Powertrain Control Module (PCM) Inputs:
²Generator output
²A/C request (if equipped with factory A/C)
²A/C select (if equipped with factory A/C)
²Auto shutdown (ASD) sense
²Intake manifold air temperature sensor
²Battery voltage
²Brake switch
²Engine coolant temperature sensor
²Crankshaft position sensor
²Ignition circuit sense (ignition switch in run posi-
tion)
²Manifold absolute pressure sensor
²Overdrive/override switch
²Oxygen sensor
²Park/neutral switch (auto. trans. only)
²SCI receive (DRB scan tool connection)
²Speed control resume switch
²Speed control set switch
²Speed control on/off switch
²Camshaft position sensor signal
²Throttle position sensor
²Vehicle speed sensor
²Sensor return
²Power ground
Fig. 1 PCM LocationÐXJ Models
Fig. 2 PCM LocationÐYJ Models
14 - 20 FUEL SYSTEM COMPONENT DESCRIPTION/SYSTEM OPERATIONJ
²Remove windshield washer reservoir from fender
inner panel (Fig. 39).
²Remove the hood ajar switch, if equipped, from
fender (Fig. 40 and 41).
²Remove the Power Distribution Center (PDC), the
coolant recovery bottle and speed servo from fender
the inner panel (Fig. 42, 43 and 44).
Fig. 41 Hood Ajar Switch Removal/Installation
Fig. 42 Power Distribution Center and Vapor
Canister
Fig. 43 Coolant Recovery Bottle
Fig. 39 Coolant Recovery Bottle, Windshield Washer
Fluid Reservoir & Hood Support Rod
Fig. 40 Hood Ajar Switch, Speed Servo & A/C
Receiver/Drier
23 - 16 EXTERIOR COMPONENTSÐXJJ
²Install the retainers to attach the fender liner to
the fender inner panel.
²Install the rivets to attach the flare to the air de-
flector (Figs. 48 and 50). and
²Install the screws to attach the flare to the fender.
Tighten the screws to 1 Nzm (13 in-lbs) torque.
(8) Connect the front lamp wire harness connectors
to the engine wire harness connectors (Fig. 52).
(9) Install the front lamps.
(10) Install the front bumper.
(11) Install the wheel, remove the support and
lower the vehicle.
(12) Right fender only: install the hood support rod
on the fender inner panel.
(13) Install the hood bumper on the fender inner
panel.(14) Right fender only: install the Daytime Run-
ning Light (DRL) module on fender inner panel.
(15) Right fender only: install the A/C Receiver/
Drier on the fender inner panel.
(16) Right fender only: install the vapor canister
on the fender inner panel. Tighten the vapor canister
screws to 5 Nzm (45 in-lbs) torque.
(17) Right fender only: install the PDC, coolant re-
covery bottle and speed servo on the fender inner
panel.
(18) Right fender only: install the hood ajar switch,
if equipped. Tighten the screws to 2 Nzm (15 in-lbs)
torque.
(19) Right fender only: install the windshield
washer fluid reservoir on the inner panel.
(20) Right fender only: install the battery tray and
battery on the inner panel.
(21) Right fender only: if equipped, install the ra-
dio antenna. Tighten the nut/escutcheon to 4.5 Nzm
(40 in-lbs) torque. Tighten the power antenna bracket
screws to 2 Nzm (20 in-lbs) torque.
REAR WHEELHOUSE FLARES AND LINERSÐXJ
REMOVAL
(1) Remove the flare and liner lower screws (Fig.
53 and 54).
(2) Remove the nuts that attach the liner to the
wheelhouse.
(3) Remove the liner from the wheelhouse.
(4) Remove the push-nuts that attach the flare re-
tainers to the wheelhouse (Fig. 55).
(5) Remove the flare and retainers from the wheel-
house.
INSTALLATION
(1) Position the flare and retainers at the wheel-
house.
(2) Install the push-nuts to attach the flare retain-
ers to the wheelhouse.
(3) Position the liner in the wheelhouse.
Fig. 50 Fender Flare & Retainers
Fig. 51 Fender Liner and Retainers
Fig. 52 Front Lamp Wire Harness Connectors
JEXTERIOR COMPONENTSÐXJ 23 - 19
²Remove the horn from the fender inner panel (Fig.
7).
²Remove the windshield washer fluid reservoir and
coolant reserve bottle from the fender inner panel
(Fig. 8 and 9).(4) Right fender:
²Remove the jack and related tools from the jack
storage tray (Fig. 10).
²Remove the jack storage tray and A/C receiver/
drier from the fender inner panel (Fig. 11).
Fig. 7 Horn Removal/Installation
Fig. 8 Windshield Washer Fluid Reservoir
Fig. 9 Coolant Reserve Bottle
Fig. 10 Jack and Related Tools
Fig. 11 Jack Storage Tray and A/C Receiver/Drier
23 - 112 EXTERIOR COMPONENTSÐYJJ
(8) Left fender:
²Install the air cleaner housing and support bracket
on the fender inner panel.
²Install the horn on the fender inner panel.
²Install the windshield washer fluid reservoir and
coolant reserve bottle on the fender inner panel.
(9) Right fender:
²Install the jack storage tray and A/C receiver/drier
on the fender inner panel.
²Install the jack and related tools in the jack stor-
age tray (Fig. 17).
FENDER FLAREÐYJ
REMOVAL
(1) Remove the side marker lamp lens and discon-
nect the wire harness bulb socket.(2) Remove the serrated retainers, screws and
plastic nuts that attach the flare to the front fender
or rear wheelhouse (Fig. 18 and 19).
(3) Remove the flare and clean the contact surface
on the body.
(4) Inspect the flare serrated retainers and plastic
nuts. Replace any hardware that is loose or damaged.
INSTALLATION
(1) Clean the contact surface on the flare and posi-
tion it on the front fender or wheelhouse.
(2) Install the flare serrated retainers, screws and
nuts. Tighten the screw at the lower molding to 11
Nzm (96 in-lbs) torque. Tighten the upper screws to
11 Nzm (96 in-lbs) torque.
Fig. 16 Fender Splash Shields
Fig. 17 Jack Installation
Fig. 18 Front Fender Flare and Side Step Molding
Fig. 19 Rear Flare and license Plate Bracket
23 - 114 EXTERIOR COMPONENTSÐYJJ