1988 JEEP CHEROKEE radiator

2) On models with 2-piece shafts, rotate transmission yoke
until trunnion is in horizontal plane. Install front drive shaft with
"U" joint trunnion in vertical plane. Connect bearing support to
crossmember.
3) Ensure that front face of bearing support is perpendicular
(90 degrees) to centerline of drive shaft. Install rear drive shaft
with "U" joint trunnion of slip joint in vertical plane.
4) Set differential pinion yoke trunnion in vertical plane.
Connect rear drive shaft to pinion yoke. If 2-piece shaft is correctly
installed, centerline of trunnions at each end of individual shafts
will be parallel. See Fig. 3.
Fig. 3: Phase Alignment Of 2-Piece Drive Shafts
Trunnion yoke ears on each shaft must be parallel.
DRIVE SHAFT BALANCE TEST
1) Drive shaft imbalance may often be cured by disconnecting
shaft and rotating it 180 degrees in relation to other components.
Test by raising rear wheels off ground, and turning shaft with engine.
NOTE: DO NOT run engine without ram airflow across radiator for
prolonged periods, as overheating of engine or transmission
may occur.
2) On most models, balance testing may be done by marking
shaft in 4 positions, 90 degrees apart. Place marks approximately 6"
forward of weld, at rear end of shaft. Number marks one through 4.
3) Place screw-type hose clamp so clamp head is in number one
position, and rotate shaft with engine. If there is little or no
change, move clamp head to No. 2 position, and repeat test.
4) Continue procedure until vibration is at lowest level. If
no difference is noted with clamp head moved to all 4 positions,
vibrations may not be drive shaft imbalance.
5) If vibration is lessened but not completely gone, place 2
clamps at that point, and run test again. Combined weight of clamps in
one position may increase vibration. If so, rotate clamps 1/2" apart,
above and below best position, and repeat test.
6) Continue to rotate clamps as necessary, until vibration is
at lowest point. If vibration level is still unacceptable, leave rear
clamp(s) in position and repeat procedure at front end of drive shaft.\
If vibration can be eliminated or reduced to acceptable levels using
this test procedure, send drive shaft out to be balanced.

Mixture Control Solenoid On carburetor, near fuel
line.
Shift Kicker Solenoid On left front wheelwell.









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SWITCHES









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Component Component Location
A/C Low Pressure Switch On top left side of radiator.

EN G IN E C O OLIN G F A N

1988 J e ep C hero ke e
1987-88 ENGINE COOLING
Thermostatically Controlled Electric Fans
Cherokee, Comanche, Wagoneer
DESCRIPTION & OPERATION
On Cherokee, Comanche and Wagoneer models with a 4.0L engine,
A/C and/or heavy duty cooling system, an auxiliary electric fan is
used. The auxiliary fan is controlled by a relay mounted on the left
inner fender panel. A radiator temperature switch attached to the
radiator outlet tank above the lower radiator hose senses engine
coolant temperature.
When coolant temperature is more than 190(0)F (88(0)C), t\
he
radiator coolant temperature switch closes allowing current from the
ignition switch to flow through the fan relay to ground activating the
relay. When relay is activated, battery voltage is supplied to the fan
causing it to operate. When coolant temperature is below 190(0)F
(88(0)C), the radiator coolant temperature switch opens preventing t\
he
relay from being grounded and electric cooling fan from being
energized.
When the A/C (if equipped) is turned on, the Electronic
Control Unit (ECU) grounds the A/C relay coil allowing current to flow\
through it. This activates the A/C relay which then supplies current
to the A/C clutch, fan diode assembly and cooling fan relay. The
cooling fan relay is activated and the fan operates. Whenever the A/C
is used, regardless of engine coolant temperature, the auxiliary
electric cooling fan operates.
TESTING
NOTE: For following tests, refer to fan relay connector terminal
identification and fan controls identification. See Figs. 1
and 2.
With Air Conditioning
1) If electric cooling fan does not work all the time, go to
step 3). If electric cooling fan is inoperative when A/C compressor
operates, start engine and turn A/C on. Disconnect fan relay
connector. Fan relay is located on left inner fender panel.
2) Using a voltmeter, check for voltage at fan relay
connector terminal No. 2. If voltmeter does not read battery voltage,
replace fan diode assembly.
3) Disconnect fan relay connector. Fan relay is located on
left inner fender panel. Using a jumper wire with an in-line 25-amp
fuse, supply battery voltage to fan relay connector terminal No. 4.
4) If fan operates, motor is okay. Go to next step. If fan
motor does not operate, check continuity between fan relay connector
terminal No. 4 and body ground connections. If continuity exists,
replace fan motor. If continuity does not exist, repair open and
retest.
5) Disconnect fan relay connector. Turn ignition switch to
the "RUN" position. Check continuity between fan relay connector
terminal No. 5 and body ground connections. If continuity does not
exist, repair open circuit. If continuity exists, go to next step.
6) Using a jumper wire with an in-line 25-amp fuse, jump
across fan relay connector terminals No. 1 and No. 4. If fan motor
operates, go to next step. If fan motor does not operate, repair fan

relay fuse link.
7) Check for battery voltage at fan relay connector terminal
No. 2. Connect a jumper wire across radiator temperature switch
connector. Radiator temperature switch is located on radiator outlet
tank, above lower radiator hose. If fan does not operate, replace
radiator temperature switch. If fan operates, go to next step.
8) Check for battery voltage at fan relay connector terminal
No. 2. If battery voltage is not present, replace fan diode assembly.
Without Air Conditioning
1) Disconnect fan relay. Fan relay is mounted on left inner
fender panel. Using a jumper wire with an in-line 25-amp fuse, supply
battery voltage to fan relay connector terminal No. 4.
2) If fan operates, motor is okay. Go to next step. If fan
motor does not operate, check continuity between fan relay connector
terminal No. 4 and body ground connections.
If continuity exists, replace fan motor. If continuity does
not exist, repair open and retest.
3) With fan relay connector disconnected, turn ignition
switch to the "RUN" position. Check continuity between fan relay
connector terminal No. 5 and body ground connections. If continuity
does not exist, repair open. If continuity exists, go to next step.
4) Using a jumper wire with a 25-amp in-line fuse, jump
across fan relay connector terminals No. 1 and No. 4. If fan motor
operates, leave jumper wire connected and proceed to next step. If fan
motor does not operate, repair fan relay fuse link.
5) Check for battery voltage at cooling fan relay connector
terminal No. 2. Connect a jumper wire across radiator coolant
temperature switch connector. Radiator coolant temperature switch is
located on radiator outlet tank above lower radiator hose. If fan does
not operate, replace radiator coolant temperature switch.
Fig. 1: Fan Relay Connector Terminal Identification
Courtesy of Chrysler Motors.

Fig. 2: Fan Controls Identification
Courtesy of Chrysler Motors.
REMOVAL & INSTALLATION
AUXILIARY ELECTRIC COOLING FAN
Removal
1) Auxiliary fan is attached to radiator upper crossmember
behind radiator.
2) Remove fan retaining screws from radiator upper
crossmember. Disconnect electric fan connector. Lift fan straight up
out of vehicle.
Disassembly
Components of auxiliary electric cooling fan can be replaced.
However, components cannot be repaired. If an auxiliary cooling fan
component needs repair it must be replaced with the recommended
replacement part only. The auxiliary fan consists of a fan module, fan
module retaining clip, fan shroud, and fan motor.
1) Place assembly on bench with fan blades facing up.
Position an awl between the fan retainer and motor shaft. Pry the
retainer off the motor shaft. Slide fan up off of motor.
2) Unwind fan motor electrical connector from retaining
clips of fan shroud.
3) Remove fan motor mounting screws. Remove fan.
Assembly
1) Attach fan motor to fan shroud with mounting screws. Wind
electrical connector into retaining clips of fan shroud.
The bushing at fan module center has a small groove on the
bottom side of it that fits over the alignment dowel on the fan motor
shaft. The keyway pin of the alignment dowel fits into the groove in
fan motor shaft. A small amount of silicone sealant placed in the
groove of the fan motor shaft holds the alignment dowel in place.

2) Place fan module over motor shaft, align groove in fan
module with dowel on motor shaft. Start fan module retainer onto the
fan motor shaft with open end of the retainer facing the groove in the
shaft. When retainer is completely installed the open end will be on
side opposite the groove. Use needle nose pliers to finish installing
retainer.
Installation
Align lower retaining tabs of fan shroud with slots in
bracket at bottom of radiator and push fan down into position. Tighten
mounting screws to 36 inch lbs. (4.07 N.m). Connect auxiliary cooling
fan electrical connector.
Fig. 3: Auxiliary Fan Removal & Installation

\003
EN G IN E R EM OVA L - 4 -C YL

1988 J e ep C hero ke e
1988 ENGINES
Jeep - Engine Removal - 4-Cylinder
Cherokee, Comanche, Wrangler
4-CYLINDER ENGINES
2.5L
1) Disconnect negative battery cable. Drain cooling system.
Remove air cleaner, lower radiator hose, fan shroud, and engine
compartment light from hood. Scribe hinge locations and remove hood.
Disconnect automatic transmission cooler lines at radiator (if
equipped).
2) Remove upper radiator hose, fan assembly and coolant
recovery hose. Remove radiator and A/C condenser (if equipped). Hold
fan pulley to water pump flange using 5/16" x 1/2" SAE capscrew.
Disconnect heater hoses, throttle linkages, cruise control cable (if
equipped) and Throttle valve rod.
3) Disconnect wires from starter and separate CEC system
wiring harness connector. Disconnect fuel pipe from fuel pump and fuel
return hose from fuel filter. Disconnect hoses from A/C compressor and
power steering pump (if equipped). Drain power steering pump
reservoir. Cap all fittings and hose ends.
4) Remove vacuum check valve from brake booster (if
equipped). Tag and remove all wiring and vacuum lines connected to
engine or accessories. Raise vehicle and remove starter. Disconnect
exhaust pipe from manifold.
5) Remove converter/flywheel housing cover. Remove engine
mount nuts at bracket side. On automatic transmission models, index
mark drive plate and torque converter. Remove drive plate-to-converter
bolts.
6) Remove upper and loosen lower bellhousing-to-engine bolts.
Attach lifting equipment to engine. Raise engine off front mounts,
Place support under bellhousing. Remove remaining bellhousing-to-
engine bolts. Lift engine out of engine compartment.
NOTE: Engine mount pads may be removed from engine brackets to
align engine and transmission during installation.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE








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Application Ft. Lbs. (N.m)
Clutch Housing-to-Block Bolts .................... 55 (75)
Drive Plate-to-Converter ......................... 26 (35)
Flywheel Bolts ............................... ( 1) 50 (68)
Front Support Bracket-to-Block ................... 45 (61)
Front Support Cushion-to-Crossmember ............. 33 (45)
Rear Support Bracket-to-Transmission ............. 33 (45)
Rear Support Cushion-to-Bracket .................. 30 (41)
Starter Motor-to-Block ........................... 33 (45)
( 1) - Tighten an additional 60 degrees.









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\003
EN G IN E R EM OVA L - 6 -C YL

1988 J e ep C hero ke e
1988 ENGINES
Jeep - Engine Removal - 6-Cylinder
Cherokee, Comanche, Wagoneer, Wrangler
6-CYLINDER ENGINES
4.0L
1) Scribe hinge locations, remove engine compartment light
(if equipped) and remove hood. Disconnect battery cables and remove
battery. Drain cooling system.
2) Disconnect wire connectors from alternator, ignition coil
and distributor. Disconnect oil pressure sender wire, starter wires
and fuel injector wiring harness (if equipped). Detach 2 fuel pipe
quick connect couplings at left inner fender panel. Disconnect engine
ground strap and remove air cleaner.
3) Disconnect the vacuum purge hose at fuel vapor canister
tee. Disconnect wire from idle speed actuator and oxygen sensor.
Detach throttle cable from bracket and disconnect throttle valve rod
at bellcrank. Remove upper and lower radiator hoses.
4) On automatic transmission models, disconnect the
transmission fluid cooler tubing. On all models, remove fan shroud and
radiator. Remove fan and spacer or Tempatrol fan assembly. Hold fan
pulley to water pump flange using 5/16" x 1/2" SAE capscrew while
crankshaft is rotated.
5) Disconnect cruise control cable (if equipped). Disconnect\
wires from starter motor solenoid and disconnect CEC system harness.
Remove power brake vacuum check valve from booster (if equipped).
6) Disconnect power steering hoses from steering gear (if
equipped). Drain power steering pump reservoir and plug end of hoses.
Cap all fittings on steering gear and hoses. Raise and support
vehicle. Remove starter. Remove flywheel housing access cover.
7) Remove upper and loosen lower bellhousing-to-engine bolts.
Attach lifting equipment to engine. Raise engine off front mounts.
Place support under bellhousing. Remove remaining bellhousing-to-
engine bolts. Lift engine out of engine compartment.
4.2L
1) Remove battery and drain cooling system. Remove air
cleaner and engine compartment light from hood. Scribe hinge location
and remove hood. Disconnect and plug front fuel line at pump and fuel
return line at frame.
2) Disconnect heater hoses at heater. Label and disconnect
all wiring, lines, linkage and hoses at engine. Remove vacuum switch
assembly bracket from cylinder head cover. Remove both radiator hoses
and automatic transmission oil lines (if equipped) at radiator. Remove\
radiator and shroud.
3) Remove fan and spacer. Use 5/16" x 1/2" SAE bolt to hold
fan pulley to water pump flange. Remove starter and disconnect engine
ground strap. Remove engine mount-to-bracket nuts. Disconnect exhaust
pipe at manifold.
4) Discharge A/C system (if equipped). Disconnect and plug
hose or port openings at compressor. Disconnect hoses at power
steering gear and drain reservoir. Remove power brake vacuum check
valve. Remove bracket bolt for automatic transmission filler tube (if
equipped).
5) Lift and support vehicle. On models with automatic