1988 JEEP CHEROKEE Service Repair Manual

bleeding. Refill clutch master cylinder to level mark on reservoir.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE








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Application Ft. Lbs. (N.m)
Cherokee, Comanche & Wagoneer
Bellhousing-to-Engine Bolts .................... 28 (38)
Clutch Cover Bolts ............................. 23 (31)
Crossmember-to-Sill Bolts ...................... 30 (41)
Flywheel Bolts
4-Cylinder .............................. ( 1) 50 (68)
6-Cylinder ............................ 61-75 (83-102)
Master Cylinder Attaching Nuts ................. 19 (26)
Rear Support-to-Engine Bolt .................... 33 (45)
Slave Cylinder-to-Clutch
Housing Bolts .................................. 16 (22)
Transmission Drain Plug ........................ 27 (37)
Wrangler
Bellhousing-to-Engine Bolts .................... 28 (38)
Clutch Cover Bolts
4-Cylinder .................................... 23 (31)
6-Cylinder .................................... 40 (54)
Crossmember-to-Sill Bolts ...................... 30 (41)
Master Cylinder Attaching Nuts ................. 19 (26)
Rear Support-to-Crossmember Bolts .............. 33 (45)
Transmission Drain Plug ........................ 27 (37)
( 1) - Plus additional 60 degrees turn after reaching
torque specification.









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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

* Place transmission in Neutral position.
* Ensure emergency brake has been set and all accessories
are turned off.
* Start engine and bring to normal operating temperature.
* Allow vehicle to idle in Neutral for one minute.
* Initial relearn is complete: process will be completed during
normal driving.
Some manufacturers identify a specific relearn procedure
which will help establish suitable driveability during relearn stage.
These procedures are especially important if vehicle is equipped with
and electronically controlled automatic transmission or transaxle.
Always complete procedure before returning vehicle to customer.

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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CRUIS E C O NTR O L S YSTE M

1988 J e ep C hero ke e
1988 Cruise Control Systems
JEEP CRUISE COMMAND
All Models
DESCRIPTION & OPERATION
Jeep vehicles use an electro-mechanical servo system. The
system consists of a control module, speed sensor, servo, control
switch assembly, vacuum storage canister, check valve and release
system. Release system consists of a mechanical vacuum vent valve and
brake and clutch (M/T) release switches.
Cruise control switch is an integral part of turn signal
switch lever and consists of 2 separate switches. First is an "ON-OFF"
and "RESUME" slide switch located on flat of directional switch lever.
Second is "SET/COAST" push button switch located at end of
directional switch lever. To engage system, move slide switch to "ON"
position and accelerate to desired speed. Depress and release
"SET/COAST" button on end of switch lever. System will now maintain
selected speed.
System will automatically disengage when brake or clutch
pedal is depressed. It can be re-engaged to previously selected speed
by accelerating to 30 MPH and moving slide switch to "RESUME"
position, then releasing switch.
NOTE: When slide switch is moved to "OFF" position, pre-set speed
of "RESUME" function is canceled from memory and must be
reset when system is reactivated.
Higher speed can be set by pressing on accelerator pedal
until new speed is reached and then pushing "SET/COAST" button. Lower
speed can be obtained by lightly depressing brake pedal, allowing the
vehicle to slow to desired speed and then depressing and releasing
"SET/COAST" button.
CONTROL MODULE
Control module receives input voltage representing vehicle
speed from speed sensor, which is driven by the speedometer cable.
Control module has a low speed circuit that prevents operation at
speeds below 30 MPH. See Fig. 1.
SERVO
Servo is controlled by control module and uses manifold
vacuum to control throttle. Bead-link chain connects servo cable to
throttle linkage. See Fig. 1.
CONTROL SWITCH
Control switch assembly is an integral part of turn signal
switch lever. See Fig. 1.
RELEASE SYSTEM
Release system deactivates cruise control system when brake
or clutch pedal is depressed. Either servo vent valve or mechanical
vacuum vent switch admits atmospheric pressure into servo when brake
pedal is depressed.

Fig. 1: Cruise Control System Components
Courtesy of Chrysler Motors.
TROUBLE SHOOTING
NOTE: Vehicles with computerized engine controls, should be tested
for stored computer codes. Codes and related problems must
be repaired prior to cruise control diagnosis and repair.
For additional information, see COMPUTERIZED ENGINE CONTROLS
section.

SYSTEM WILL NOT ENGAGE
Restricted vacuum hose or no vacuum. Control switch or
control module defective. Speed sensor defective. Clutch or brake
light switch defective or misadjusted. Brake light switch wire
disconnected. Open circuit between brake light switch and brake
lights.
RESUME FEATURE INOPERATIVE
Defective servo ground connection. Defective control switch.
ACCELERATE FUNCTION INOPERATIVE
Accelerate circuit in control module inoperative. Defective
control switch.
SYSTEM RE-ENGAGES WHEN BRAKE PEDAL IS RELEASED
Defective control module. Mechanical vent valve not opening.
Kink in mechanical vent valve hose. Brake light switch defective.
CARBURETOR THROTTLE DOES NOT RETURN TO IDLE POSITION
Improper linkage adjustment.
ROAD SPEED CHANGES 2 MPH OR MORE WHEN SETTING SPEED
Centering adjustment wrong. Servo link misadjusted.
ENGINE ACCELERATES WHEN STARTED
Improper servo chain adjustment. Vacuum hose connections
reversed at servo. Defective servo.
SYSTEM DISENGAGES ON LEVEL ROAD WITHOUT APPLYING BRAKES
Loose wire connection. Loose vacuum hose connection. Servo
linkage broken. Defective brake light switch.
ERRATIC OPERATION
Reverse polarity of system wiring. Defective servo. Defective
control module.
VEHICLE CONTINUES TO ACCELERATE WHEN "SET" BUTTON IS RELEASED
Servo or control module defective.
SYSTEM ENGAGES BUT SLOWLY LOSES SET SPEED
Air leak at connections or in vacuum hoses. Air leak on vent
valve on brake pedal.
ADJUSTMENTS
CONTROL MODULE ADJUSTMENT
NOTE: Control module adjustments are preset by manufacturer. If
other components in system appear to be functioning properly

and cruise control remains inoperative, perform following
adjustments to determine if control module is functional.
1) Remove control module attaching screws or tie straps and
move control module downward for adjustment access. Turn centering
adjustment screw to 10 o'clock position. Turn low speed adjustment
screw to 10 o'clock position. Turn sensitivity adjustment screw fully
clockwise.
CAUTION: Adjustment potentiometers are extremely delicate. Carefully
insert screwdriver and do not push or turn screws
excessively hard. Maximum movement is 3/4 turn.
2) Adjustments are not precisely correct for vehicle, but are
acceptable to determine if control module is functioning. Perform
precise adjustments by road testing vehicle on level road. If
adjustments have no effect on cruise control, replace control module.
3) If actual engagement speed is 2 MPH or more above selected
speed, stop vehicle and turn centering screw 1/16 of a turn
counterclockwise. Recheck engagement speed and adjust as necessary.
4) If engagement speed is 2 MPH or more below selected speed,
turn centering screw 1/16 of a turn clockwise. Recheck engagement
speed and adjust as necessary.
Fig. 2: Control Module Adjustment Screws
Courtesy of Chrysler Motors.
VACUUM VENT VALVE
Depress brake or clutch pedal and hold in depressed position.
Move vacuum vent valve toward bracket on pedal as far as possible.
Release brake or clutch pedal.
TESTING
NOTE: Vehicles with computerized engine controls, should be tested
for stored computer codes. Codes and related problems must
be repaired prior to cruise control diagnosis and repair.
For additional information, see COMPUTERIZED ENGINE CONTROLS
section.
PRELIMINARY INSPECTION
Ensure cruise control wire harness is properly connected to