four wheel drive JEEP CHEROKEE 1988 Service Repair Manual

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* B RAK E S YSTE M U NIF O RM IN SPEC TIO N G UID ELIN ES *

1 988 J e ep C hero ke e
GENERAL INFORMATION
Brake Systems - Motorist Assurance Program
Standards For Automotive Repair
All Makes & Models
CONTENTS
OVERVIEW OF MOTORIST ASSURANCE PROGRAM
OVERVIEW OF SERVICE REQUIREMENTS AND SUGGESTIONS
ACCELEROMETERS (G SENSOR OR LATERAL)
ACCUMULATORS
ANCHOR PINS
ANTI-LOCK BRAKE SYSTEMS
BACKING PLATES
BRAKE FLUID
BRAKE FRICTION MATERIAL
BRAKE PADS
BRAKE PEDALS
BRAKE SHOES
BRAKE SHOE HARDWARE
BRAKE STOPLIGHT SWITCHES
BULB SOCKETS
BULBS AND LEDS
CALIPER HARDWARE
CALIPERS
CONTROLLERS
DIGITAL RATIO AXLE CONTROLLERS AND BUFFERS (DRAC AND DRAB)
DISABLE SWITCHES
DRUMS
ELECTRICAL PUMPS AND MOTORS
ELECTRONIC CONTROLLERS
FLUID
FLUID LEVEL SENSOR SWITCHES
FOUR WHEEL DRIVE SWITCHES
FRICTION MATERIAL
G SENSORS
HOSES
HYDRAULIC MODULATORS
HYDRO-BOOSTERS
HYDRO-ELECTRIC BOOSTERS (POWERMASTER)
IGNITION DISABLE SWITCHES
LATERAL ACCELERATION SWITCHES
LEDS
LENSES
MASTER CYLINDERS
MODULATORS
MOTORS
PARKING BRAKE SWITCHES
PARKING BRAKE SYSTEMS
PADS
PEDAL TRAVEL SWITCHES
PEDALS
POWERMASTER
PUMPS
PRESSURE DIFFERENTIAL SWITCHES
PRESSURE SWITCHES
RELAYS
ROTORS
SELF-ADJUSTING SYSTEMS

hardware.
Attaching hardware threads
damaged ................ A ... Require repair or replacement
of hardware.
Attaching hardware threads
stripped (threads
missing) ............... A ... Require repair or replacement
of hardware.
Code set (if
applicable) ............ A .......... (1) Further inspection
required.
Connector broken ........ A .. Require repair or replacement.
Connector melted ........ A ........... ( 2) Require repair or
replacement.
Connector missing ....... A ................. Require repair.
Contaminated ............ A .. Require repair or replacement.
Inoperative ............. B .. Require repair or replacement.
( 3) Further inspection required.
Leaking ................. A .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Terminal broken ......... A .. Require repair or replacement.
Terminal burned, affecting
performance ............ A ........... ( 2) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.
Wire lead conductors
exposed ................ B .. Require repair or replacement.
Wire lead corroded ...... A .. Require repair or replacement.
Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
( 1) - Refer to manufacturer's diagnostic trouble code procedure
and require repair or replacement of affected component(s).
( 2) - Determine cause and correct prior to repair or replacement
of part.
( 3) - Inoperative includes intermittent operation or out of OEM
specification. Some components may be serviceable. Check
for accepted cleaning procedure.









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FLUID
See BRAKE FLUID.
FLUID LEVEL SENSOR SWITCHES
See SWITCHES.
FOUR WHEEL DRIVE SWITCHES
See SWITCHES.

Condition Code Procedure
Air pressure incorrect .. B .................. Require repair
Bead broken ............. A ............ Require replacement.
Bead leaking, caused
by tire ................ A .. Require repair or replacement.
Bead wire/cord exposed .. A ............ Require replacement.
Cord or belt material
exposed ................ A ............ Require replacement.
Cord ply separations .... A ............ Require replacement.
Directional/asymmetrical
tires mounted
incorrectly ............ B ....... Require remounting and/or
repositioning.
Irregular tread wear,
affecting performance .. 2 ........ (1) Suggest replacement.
Load ratings less
than OEM
specifications ......... B ............ Require replacement.
Mixed tread types (all
season, performance, mud
and snow) on same axle . A ............ Require replacement.
Number of punctures
exceeds manufacturer's
limit .................. B ............ Require replacement.
Out of balance .......... B . Require rebalance of tire/wheel
assembly.
Ply separation .......... A ............ Require replacement.
Pull or lead, caused
by tire ................ A .. Require repair or replacement.
Radial and bias or
bias-belted ply tires
on same axle ........... B .. Require repair or replacement.
Radials are on the front
and not on the rear .... B ........... ( 2) Require repair or
replacement.
Run flat damage ......... A ............ Require replacement.
Shoulder cut ............ A ............ Require replacement.
Shoulder puncture ....... A ............ Require replacement.
Shoulder with plug ...... A ............ Require replacement.
Sidewall bulge .......... A ............ Require replacement.
Sidewall cut ............ A ............ Require replacement.
Sidewall indentation .... .. ......... No service required or
suggested.
Sidewall puncture ....... A ............ Require replacement.
Sidewall with plug ...... A ............ Require replacement.
Speed rating
designations
different
on same axle ........... 2 .. Suggest repair or replacement.
Tire and wheel assembly
has excessive run-out .. B ........... ( 3) Require repair or
replacement of appropriate
part.
Tires with more than
1/4" diameter difference
on a four-wheel drive
vehicle ................ B ............ Require replacement.
Tread area puncture larger
in diameter than
manufacturer's
specifications ......... B ............ Require replacement.
Tread missing pieces

Condition Code Procedure
Air pressure incorrect .. B .................. Require repair
Bead broken ............. A ............ Require replacement.
Bead leaking, caused
by tire ................ A .. Require repair or replacement.
Bead wire/cord exposed .. A ............ Require replacement.
Cord or belt material
exposed ................ A ............ Require replacement.
Cord ply separations .... A ............ Require replacement.
Directional/asymmetrical
tires mounted
incorrectly ............ B ....... Require remounting and/or
repositioning.
Irregular tread wear,
affecting performance .. 2 ........ (1) Suggest replacement.
Load ratings less
than OEM
specifications ......... B ............ Require replacement.
Mixed tread types (all
season, performance, mud
and snow) on same axle . A ............ Require replacement.
Number of punctures
exceeds manufacturer's
limit .................. B ............ Require replacement.
Out of balance .......... B . Require rebalance of tire/wheel
assembly.
Ply separation .......... A ............ Require replacement.
Pull or lead, caused
by tire ................ A .. Require repair or replacement.
Radial and bias or
bias-belted ply tires
on same axle ........... B .. Require repair or replacement.
Radials are on the front
and not on the rear .... B ........... ( 2) Require repair or
replacement.
Run flat damage ......... A ............ Require replacement.
Shoulder cut ............ A ............ Require replacement.
Shoulder puncture ....... A ............ Require replacement.
Shoulder with plug ...... A ............ Require replacement.
Sidewall bulge .......... A ............ Require replacement.
Sidewall cut ............ A ............ Require replacement.
Sidewall indentation .... .. ......... No service required or
suggested.
Sidewall puncture ....... A ............ Require replacement.
Sidewall with plug ...... A ............ Require replacement.
Speed rating
designations
different
on same axle ........... 2 .. Suggest repair or replacement.
Tire and wheel assembly
has excessive run-out .. B ........... ( 3) Require repair or
replacement of appropriate
part.
Tires with more than
1/4" diameter difference
on a four-wheel drive
vehicle ................ B ............ Require replacement.
Tread area puncture larger
in diameter than
manufacturer's
specifications ......... B ............ Require replacement.
Tread missing pieces

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TR AN SFE R C ASE - C O M MAN D T R AC D IA G NO SIS

1988 J e ep C hero ke e
1984-90 Drive Axles - Transfer Case - Electronic Diagnosis
Cherokee, Wagoneer, Wrangler (1987-90)
VACUUM CONTROL SYSTEM
The Command-Trac vacuum switch consists of a vacuum control
switch on the transfer case, an air vent filter, a vacuum shift motor
(located on front axle), a four-wheel drive indicator light and vacuum\
switch, two vacuum check valves and an interconnecting vacuum harness.
See Fig. 1 .
Fig. 1: Command-Trac Vacuum Control System
AXLE SHIFT MOTOR FUNCTIONAL TEST
1) Raise vehicle. Disconnect vacuum harness from axle shift
motor and connect a vacuum pump to vacuum shift motor port. See
Fig. 2 .

2) Apply 15 in. Hg. (51 kPa) of vacuum to front port and
rotate right front wheel to fully disengage outer and intermediate
axle shafts (i.g., into two wheel drive operation).
3) The shift motor should maintain vacuum applied to front
port for a minimum of 30 seconds. If motor does not maintain vacuum,
replace it. If motor does maintain vacuum, proceed to next step.
4) Disconnect vacuum pump from vacuum shift motor front port.
See Fig. 2 . Connect vacuum pump to vacuum shift motor rear port, cap
port for indicator lamp sw., and apply 15 in. Hg (51 kPa) of vacuum to\
rear port.
5) The shift motor should maintain the vacuum applied to rear
port for a minimum of 30 seconds. If shift motor does not maintain
vacuum, replace it. If motor does maintain vacuum, proceed to next
step.
6) Remove cap from port for indicator lamp sw. and determine
if vacuum was present at this port. If vacuum was present, the shift
motor functions normally. If vacuum was not present, proceed to next
step.
7) Apply 15 in. Hg. (51 kPa) of vacuum to shift motor rear
port. Rotate right front wheel as necessary and ensure that outer and
intermediate axle shafts are completely engaged. The axles must be
completely engaged (i.e. into four-wheel drive operation) to open port\
for indicator lamp switch.
8) Determine if vacuum is present at port for indicator lamp
switch again. If vacuum was present at por, shift motor functions
normally. If vacuum was not present at port, replace shift motor.
Fig. 2: Axle Vacuum Shift Motor
AXLE SHIFT MOTOR AND HOUSING REMOVAL & INSTALLATION