1988 JEEP CHEROKEE Service Repair Manual

1) Connect a jumper wire between Red lead (Violet on
Cherokee, Comanche and Wagoneer) and switch "UP" terminal. Connect a
second jumper wire between switch ground terminal and "DOWN" terminal.
This will test up operation of switch.
2) If motor runs, connect switch to multiple connector and
operate switch. If motor fails to run, replace switch. Test all
switches in this manner.
3) To test down operation of switch, connect first jumper
wire between Red (Violet) lead and switch "DOWN" terminal, and second
jumper wire between switch ground terminal and "UP" terminal. Repeat
tests on all switches. Results are the same as up test.
Fig. 1: Switch Assembly Check Chart Cherokee & Wagoneer
REMOVAL & INSTALLATION

TAILGATE WINDOW REGULATOR & MOTOR
Removal (Grand Wagoneer)
1) Remove carpet (if equipped) and tailgate access cover.
Remove retainers attaching regulator arms to channel. Disengage
regulator arm pins from channel, and raise glass.
2) Carefully support glass in raised position. Disconnect
wiring harness from safety switch. If regulator attaching screws are
covered by sector gears, place a jumper wire between terminals of
safety switch connector.
NOTE: If regulator attaching screws are accessible, remove
regulator attaching screws and regulator.
3) Place key in tailgate switch and operate motor until
regulator attaching screws are accessible. Hold regulator in this
position, and wedge a screw between meshing teeth.
4) Remove regulator attaching screws and regulator. Using a
large screwdriver, release spring tension from tension bracket. Remove
motor attaching screws and motor.
Installation
To install, reverse removal procedure.
SIDE WINDOW MASTER SWITCH
Removal
1) Disconnect battery negative cable. Remove retaining screws
and escutcheon. Remove switch housing screws.
2) Pull switch out to expose wires. Disconnect terminal plate
from switch. Depress retainer clips through holes in switch housing,
and remove switch.
Installation
To install, reverse removal procedure.
FRONT & REAR DOOR REGULATORS & MOTORS
Removal
1) Raise window half way up. Disconnect battery negative
cable. Remove door trim panel and water shield.
2) Insert a drift punch into hole in door inner panel, or use
masking tape to hold window half way up. Remove regulator arm retainer
clip, and remove arm from bottom window channel.
3) Disconnect wires from motor. Remove inner door panel-to-
regulator nuts and bolts. Remove regulator and motor assembly.
Installation
To install, reverse removal procedure.

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PR E-A LIG NM EN T C HEC KS

1988 J e ep C hero ke e
Wheel Alignment
PRE-ALIGNMENT INSPECTION PROCEDURES
PRE-ALIGNMENT CHECKS
Before making wheel alignment adjustment, perform the
following checks:
1) Tires should be equal in size and runout must not be
excessive. Tires and wheels should be in balance, and inflated to
manufacturer's specifications.
2) Wheel bearings must be properly adjusted. Steering linkage
and suspension must not have excessive looseness. Check for wear in
tie rod ends and ball joints.
3) Steering gear box must not have excessive play. Check and
adjust to manufacturer's specifications.
4) Vehicle must be at curb height with full fuel load and
spare tire in vehicle. No extra load should be on vehicle.
5) Vehicle must be level with floor and with suspension
settled. Jounce front and rear of vehicle several times and allow it
to settle to normal curb height.
6) If steering wheel is not centered with front wheels in
straight-ahead position, correct by shortening one tie rod adjusting
sleeve and lengthening opposite sleeve equal amounts.
7) Ensure wheel lug nuts are tightened to torque
specifications.

PVC & C RAN KCASE V EN TIL A TIO N S YSTE M

1988 J e ep C hero ke e
1987-89 Crankcase Ventilation
PCV AND CCV SYSTEMS
Jeep
DESCRIPTION
Crankcase ventilation systems are designed to prevent
contaminating hydrocarbons from escaping to the atmosphere. This is
accomplished by routing vapors from the crankcase through a
vacuum-controlled ventilating valve (PCV Valve) into the intake
manifold. In the intake manifold, the crankcase vapors mix with the
air/fuel mixture and are burned in the combustion process. PCV systems
are used on all 4.2L and 5.9L engines. 2.5L and 4.0L engines do not
employ PCV systems, instead they are equipped with a Crankcase
Ventilation System (CCV). The CCV system performs the same function as\
a conventional PCV system, but does not use a vacuum controlled valve.
OPERATION
PCV SYSTEM
Air is supplied to the crankcase ventilation system through
a crankcase ventilating filter assembly, located in air cleaner
housing or on rocker arm cover.
When engine is operating, fresh air enters crankcase
ventilation system through the air cleaner and filter.
Air then flows into the rocker arm cover and valve
compartment. It combines with blow-by gas and unburned air/fuel
mixture and burns in combustion chamber. See Fig. 1.
Fig. 1: Typical Crankcase Ventilation System
Ventilator valve is held closed by spring pressure when
engine is not running. See Fig. 2. This prevents accumulation of
hydrocarbon fumes from collecting in intake manifold, which could

result in hard starting.
Fig. 2: Typical PCV Valve & Airflow
When engine is started, manifold vacuum pulls valve open
against spring pressure. As long as there is engine vacuum, the valve
floats, permitting crankcase fumes to enter intake manifold.
A baffle in rocker arm cover prevents oil from being drawn
into intake manifold through ventilator valve.
If the engine backfires, the ventilator valve will close.
This will prevent ignition of fumes in crankcase.
During certain engine operations, more blow-by is created
than ventilator valve can handle. Excess blow-by is returned to air
cleaner and carburetor through rocker arm cover and breather
assembly. It is then burned in the combustion chamber.
A breather assembly acts as separator to keep oil from being
drawn into air cleaner during this operation.
CCV SYSTEM
As stated above, the CCV system performs the same function
as a conventional PCV system, but does not use a vacuum controlled
valve.
A molded vacuum tube connects manifold vacuum to a grommet on
top of the cylinder head cover at the dash panel end. The grommet
contains a metered orifice of a calibrated size that meters the amount
of crankcase vapors drawn out of the engine. A fresh air supply hose
from the air cleaner is also connected to the front of the cylinder
head cover on 4.0L engines and to the rear of the cover on 2.5L
engines.
When the engine is operating, fresh air enters the engine
and mixes with crankcase vapors. Manifold vacuum draws the
vapor/air mixture through the metered orifice and into the intake
manifold. The vapors are consumed during combustion.

Fig. 3: CCV System 2.5L Engine
Fig. 4: CCV System 4.0L Engine
TESTING

To test crankcase ventilation system, start engine and allow
it to reach normal operating temperature. Make sure engine is idling
at normal curb idle, and perform following checks:
1) Remove PCV valve from its mounting. If valve is
functioning properly, hissing noise will be heard as air passes
through it. Strong vacuum should be felt when your finger is placed
over valve inlet.
2) While finger is over inlet, check for presence of vacuum
leaks in hose line and at all connections. Reinstall PCV valve,
remove crankcase air inlet hose at air cleaner.
3) Loosely hold piece of stiff paper over opening at end of
inlet hose. Paper should be sucked against hose opening with
noticeable force after sufficient time has elapsed for crankcase
pressure to lower (usually about a minute). For final check, stop
engine, remove PCV valve and shake it. Metallic clicking noise should
be heard, indicating valve is free.
4) If system passes both engine running and stopped tests,
it is functioning properly. No further tests are required. If it has
failed either test, replace appropriate components and retest. If it
does not pass on second try, clean system.
MAINTENANCE
Engine may idle slow or rough due to clogged ventilator
valve or system. Therefore, never adjust carburetor idle without
first checking valve and system.
If ventilator valve or system becomes clogged, all crankcase
ventilation will stop, and serious engine damage could result.
Although following manufacturers' service procedures give
specific intervals, it is recommended the crankcase ventilation
system be checked more frequently if vehicle is operated under severe
conditions (extreme dust, prolonged idling, trailer hauling or short
trips in cold weather).
PCV VALVE
Replace PCV valve every 30,000 miles. Valve is located on
rocker arm cover of 4-cylinder, 6-cylinder and V6 models and on
intake manifold of V8 models.
FILTER ELEMENT
Clean filter element every 30,000 miles. Filter is located
inside air cleaner of 4-cylinder, 6-cylinder and V6 models and in oil
filler cap of V8 models.

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REC ALL 5 61 - 4 .0 L E N G . F E D . V EH IC LE S - O XYG EN S EN SO R

1988 J e ep C hero ke e
EMISSION RECALL BULLETIN
EMISSIONS RECALL #561 - OXYGEN SENSOR
Model(s): 1987-90 (XJ) Jeep Cherokee, Wagoneer
1987-90 (MJ) Jeep Comanche
Bulletin No.: 561
Date: October, 1993
NOTE: This is an Emission Recall bulletin.
VEHICLES AFFECTED
1987-90 Jeep Cherokee and Wagoneer (XJ); and Comanche (MJ) vehicle\
s
equipped with a 4.0L engine and located outside of California.
SERVICE INFORMATION
Failure of the oxygen sensor on the listed models, may cause a
vehicle to be in violation of Federal Emissions Standards. To correct
the condition, the oxygen sensor must be replaced with an improved
design sensor.
Details of this service action are explained in the following
sections.
SERVICE PROCEDURE VIDEOTAPE
No videotape of the service procedure for this recall will be
provided.
DEALER NOTIFICATION & VEHICLE LIST
INVOLVED DEALERS
Each dealer to whom involved vehicles were invoiced (or the current
dealer at the same street address) will receive a copy of this dealer
recall notification letter and a list of the involved vehicles by
first class mail.
The Vehicle List is arranged in Vehicle Identification Number (VIN)
sequence. Owners known to Chrysler are also listed. The lists are for
dealer reference in arranging for service of involved vehicles.
ALL DEALERS
Each Jeep & Eagle dealer will receive a copy of this dealer recall
notification letter by first class mail.
DIAL SYSTEM FUNCTION 70
All involved vehicles will be entered to DIAL System Function 70 at
the time of recall implementation for dealer inquiry by VIN as needed.
PARTS INFORMATION