1988 JEEP CHEROKEE cooling

same axle to eliminate uneven braking behavior. Always wash drums
after servicing or before installing.
DRUM INSPECTION









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Condition Code Procedure
Balance weight missing .. .. ........ No service suggested or
required.
Bell-mouthed, affecting
performance ............ A ....... Require reconditioning or
replacement.
Cooling fin broken ...... .. ........ No service suggested or
required.
Cracked ................. B ............ Require replacement.
Drum diameter is greater
than OEM "machine to"
specifications but less
than "discard at"
specifications, and the
drum does not require
reconditioning ......... 1 ........ (1) Suggest replacement.
Drum diameter will exceed
OEM "machine to"
specifications after
required
reconditioning ......... B ........ ( 2) Require replacement.
Hard-spotted ............ 2 ....... Suggest reconditioning or
replacement.
Measured diameter is
greater than OEM discard
specifications ......... B ............ Require replacement.
Out-of-round (runout),
affecting performance .. A ....... Require reconditioning or
replacement.
Out-of-round (runout),
exceeding manufacturer's
specifications ......... B ....... Require reconditioning or
replacement.
Scored .................. B ....... Require reconditioning or
replacement.
Surface threaded due to
improper machining ..... B ....... Require reconditioning or
replacement.
Tapered, affecting
performance ............ A ....... Require reconditioning or
replacement.
( 1) - Only applies to vehicles for which OEM "machine to"
specifications exist. If OEM does not supply "machine to"
specifications, the drum may be worn to discard
specifications.
( 2) - If OEM does not supply "machine to" specifications, you
may machine to discard specifications.









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ELECTRICAL PUMPS AND MOTORS
Copied fuel pump conditions from engine UIGs & deleted
pulsator from leaking conditions.
ELECTRICAL PUMP AND MOTOR INSPECTION









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reconditioning ......... B ........ (3) Require replacement.
Surface is rust-pitted .. B ....... Require reconditioning or
replacement of rotor according
to OEM specifications.
Surface is scored ....... B ... ( 4) Require reconditioning or
replacement of rotor according
to OEM specifications.
Thickness variation
(parallelism) exceeds OEM
specifications .......... B ....... Require reconditioning or
replacement of rotor according
to OEM specifications.
( 1) - Examples of severe corrosion are: composite plate
separated from friction surfaces and cooling fins
cracked or missing.
( 2) - Only applies to vehicles for which OEM "machine to"
specifications exist. If OEM does not supply "machine
to" specifications, the rotor may be worn to discard
specifications.
( 3) - If OEM does not supply "machine to" specifications,
you may machine to discard specifications.
( 4) - Scoring is defined as grooves or ridges in the friction
contact surface. Some vehicle manufacturers require
machining when scoring exceeds their allowable
specifications.









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SELF-ADJUSTING SYSTEMS
SELF-ADJUSTING SYSTEM INSPECTION








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Condition Code Procedure
Bent .................... A ... Require repair or replacement
of bent part.
Broken .................. A ... Require repair or replacement
of broken part.
Inoperative ............. A ........... ( 1) Require repair or
replacement of inoperative
parts.
Missing ................. C .......... Require replacement of
missing part.
Star wheel does not turn
freely ................. A .. Require repair or replacement.
( 1) - Inoperative includes intermittent operation.









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SHOE HARDWARE
See BRAKE SHOE HARDWARE .
SHOES
See FRICTION MATERIAL .
SOCKETS
See BULB SOCKETS.
SPEED SENSORS (ELECTRONIC WHEEL AND VEHICLE)

CO M PU TE R R ELE A R N P R O CED URES

1988 J e ep C hero ke e
GENERAL INFORMATION
Computer Relearn Procedures
All Models
* PLEASE READ THIS FIRST *
The following general procedures are to be used if
driveability problems are encountered after power loss or battery has
been disconnected. These procedures may provide an aid in eliminating
these problems.
To reduce the possibility of complaints, after any service
which requires battery power to be disconnected, vehicle should be
road tested.
COMPUTER RELEARN PROCEDURES
Vehicles equipped with engine or transmission computers may
require a relearn procedure after vehicle battery is disconnected.
Many vehicle computers memorize and store vehicle operation patterns
for optimum driveability and performance. When vehicle battery is
disconnected, this memory is lost. The computer will use default data
until new data from each key start is stored. As computer memorizes
vehicle operation for each new key start, driveability is restored.
Vehicle computers may memorize vehicles operation patterns for 40 of
more key starts.
Customers often complain of driveability problems during
relearn stage because vehicle acts differently then before being
serviced. Depending on type and make of vehicle and how it is
equipped, the following complaints (driveability problems) may exist:
* Harsh Or Poor Shift Quality
* Rough Or Unstable Idle
* Hesitation Or Stumble
* Rich Or Lean Running
* Poor Fuel Mileage
These symptoms and complaints should disappear after a number
of drive cycles have been memorized. To reduce the possibility of
complaints, after any service which requires battery power to be
disconnected, vehicle should be road tested. If a specific relearn
procedure is not available, the following procedure may be used:
Automatic Transmission
* Set parking brake, start engine in "P" or "N" position.
Warm-up vehicle to normal operating temperature or until
cooling fan cycles.
* Allow vehicle to idle for one minute in "N" position. Select
"D" and allow engine to idle for one minute.
* Accelerate at normal throttle position (20-50%) until vehicle
shifts into top gear.
* Cruise at light to medium throttle.
* Decelerate to a stop, allowing vehicle to downshift, and use
brakes normally.
* Process may be repeated as necessary.
Manual Transmission

CO OLIN G S YSTE M S PEC IF IC ATIO NS

1988 J e ep C hero ke e
1988 ENGINE COOLING
Jeep Cooling System Specifications
Cherokee, Comanche, Wagoneer, Wrangler, Grand Wagoneer
MAINTENANCE SCHEDULE
Change engine coolant every 12,500 miles or 12 months.
Thereafter change engine coolant at the beginning of every winter
season. Maintain ethylene glycol and water solution at a mixture of
50/50.
COOLING SYSTEM SPECIFICATIONS TABLE









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Application Capacity
Quarts(L)
2.5L
Thermo. Temp.
F (C) ............ 192-198 (89-92)
Rad. Cap PSI ............................... 12-15
Coolant Capacity Qts. (L) ........... ( 1) 10 (9.4)
4.0L
Thermo. Temp.
F (C) ............ 192-198 (89-92)
Rad. Cap PSI ............................... 12-15
Coolant Capacity Qts. (L) .............. 12 (11.3)
4.2L
Thermo. Temp.
F (C) ............ 192-198 (89-92)
Rad. Cap PSI ............................... 12-15
Coolant Capacity Qts. (L) ......... ( 2) 10.5 (9.9)
6.0L
Thermo. Temp.
F (C) ............ 192-198 (89-92)
Rad. Cap PSI ............................... 12-15
Coolant Capacity Qts. (L) .......... 14 (14 (13.2)
( 1) - Without A/C 23 qts. (2.1L) for recovery tank.
( 2) - Includes 1 qt. (.9L) for recovery tank.









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DRIV E B ELT R O UTIN G

1988 J e ep C hero ke e
1983-88 ENGINE COOLING
Jeep Drive Belt Routing
Cherokee, Comanche, Wagoneer, Wrangler, Grand Wagoneer
DESCRIPTION
Two drive belt systems are used on Jeep vehicles. The
conventional V-Belt and the single Serpentine or V-Ribbed belt.
The single (Serpentine or V-Ribbed) drive belt system
has been adopted by several manufacturers as a replacement for
multiple V-Belt systems previously offered. The Serpentine belt
requires a suitable belt tensioner similar to those used to control
timing belt tension.
Use of a tensioner allows engine accessories to be mounted
rigidly on the engine. The single belt drive system has a predicted
life of 100,000 miles before replacement is required.
The belt tensioner has a wide functional range and is
capable of maintaining tension during the expected life of the belt.
Tensioner cannot compensate for extreme belt lengths. Poor tension
control and possible tensioner damage can result from excessive belt
length.
INSPECTION
Inspect belt for fraying. If fraying has occurred, ensure
belt and tensioner are aligned properly. See Fig. 1. If tensioner has
reached its limit of travel, belt is excessively stretched and
replacement of belt is required. If excessive noise is noticed from
tensioner or idler, check for possible bearing failure. Small cracks
in the back of the belt are acceptable. Do not apply "Belt Dressing"
or any other additive to serpentine belt.
Fig. 1: Serpentine Belt Alignment
Courtesy of Ford Motor Co.
DRIVE BELT ROUTING

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.