1988 JEEP CHEROKEE Service Repair Manual

ground. Test light should light. Turn defogger switch to "OFF"
position. Test light should not light.
GRID
1) Using a voltmeter with a 0-15 volt range, contact bus bar
connecting grid lines on passenger's side of glass with negative lead
of voltmeter. Contact driver's side bus bar with positive lead.
2) Turn ignition and control switches to "ON" position.
Reading should be 10-14 volts. Lower voltage indicates a poor ground.
Attach negative voltmeter lead to ground. Voltage reading should not
vary.
3) Contact negative lead to passenger's side bus bar. Probe
each grid line at midpoint with positive lead. A 6-volt reading
indicates line is good. A zero volt reading indicates a break between
midpoint and driver's side bus bar line.
4) A 10-14 volt reading indicates a break between midpoint
and passenger's side bus bar line. Move positive lead toward break and
voltage will change when break is crossed.
NOTE: On some Jeep models feed wire and ground wires a reversed.
Fig. 2: Grid Continuity Voltage Drop
RELAY
NOTE: No relay testing is available for Wrangler models.

1) On Grand Wagoneer models, attach negative lead of
voltmeter to ground. Probe Red wire at relay with voltmeter positive
lead. Battery voltage should be indicated. If no voltage is indicated,
operate tailgate window.
2) If window operates, wire between relay and window switch
is open. Probe Orange wire at relay with voltmeter positive lead. No
voltage should be indicated. Turn ignition switch to "ON" position.
Voltmeter should indicate voltage. If not, relay is defective or not
receiving voltage from Purple wire.
3) If relay operates properly, it should remain energized for
8 to 12 minutes before opening. If time period is too short or too
long, relay is defective. If relay did not energize, connect a jumper
wire to a 12-volt source in tailgate and probe Purple relay terminal.
4) If relay "clicks", trace Purple wire for open or short. If
relay does not click, check relay ground. If ground is okay, relay
should be replaced.

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DIF FE R EN TIA L - D AN A T R AC -L O K & P O W ER -L O K

1988 J e ep C hero ke e
1988 Positive Traction Differentials - Dana Power-Lok &
Trac-Lok
Jeep
DESCRIPTION
The limited slip differential uses 2 sets of multiple disc
clutches to control differential action. Dana produces 2 types of
positive traction differentials. The Power-Lok 4-pinion differential
is a split-case type. The Trac-Loc 2-pinion differential is a single-
case type.
OPERATION
When one or both wheels are on a low-traction surface such as
snow, ice or mud, the friction between the clutch plates will transfer
a portion of the usable torque to the wheel with the most traction.
The wheel on ice or snow will have a tendency to operate with the
opposite wheel in a combined driving effort.
AXLE RATIO & IDENTIFICATION
To determine axle ratio, see DRIVE AXLE RATIO IDENTIFICATION
in this section.
LUBRICATION
NOTE: Always use special positive traction differential lubricant
as specified by manufacturer.
DIAGNOSIS & TESTING
DANA 2-PINION TRAC-LOK
1) Drive vehicle to thoroughly warm up lubricant in rear
axle. Place a piece of slick paper over a smooth formica board. Ensure
formica board is on flat and level floor.
Fig. 1: Exploded View of Jeep Single-Case Dana Trac-Lok Differential

Fig. 2: Exploded View of Split Case (4-Pinion)
2) Drive vehicle over formica board until one rear wheel is
in the center of board and paper. Place a block of wood 2" high and a
minimum of 3" wide in front of one of the front wheels.
3) Open throttle gradually attempting to slowly drive vehicle
over block of wood. If paper slips out of position, reposition paper
and repeat test. If vehicle drives over block of wood, axle is
functioning properly.
DANA 4-PINION POWER-LOK
1) With engine off and transmission in "N", raise one wheel
off ground. Block both front and rear wheels of opposite side. Install
adapter tool across 2 wheel studs and attach torque wrench to center
of tool.
2) Observe torque required to continuously turn wheel
smoothly through several revolutions. Repeat test for opposite side.
If differential is okay, torque should be 40-200 ft. lbs. (54-272 N.
m). Disregard breakaway torque. Use rotating torque only.
NOTE: Exploded view of Chrysler Motors Trac-Lok differential was
not available from manufacturer.
REMOVAL & INSTALLATION
See DANA SEMI-FLOATING or FULL-FLOATING AXLE article in this
section.
OVERHAUL
DANA 2-PINION TRAC-LOK
NOTE: For front axle shaft and bearing removal, see articles on
DANA FULL-FLOATING AXLES or 4WD STEERING KNUCKLES in this
section. With the exception of ring gear and differential
side bearings, Chrysler Motors does not recommend disassembly
of differential. If repair is required, manufacturer
recommends replacing entire unit as an assembly.
Disassembly (Jeep)
1) Using 2 screwdrivers, remove pinion snap rings. Using a
brass drift and a hammer, remove pinion shaft from case. Install Step

Plate (J 23781-7) in bottom side gear. Install grease in centering
hole of step plate. Position Rotating Tool (J 23781-3) on step plate
tool. Coat threads of Forcing Screw (J 8646-2) with oil.
2) Insert forcing Screw (J 8646-2) through case and thread
into rotating tool. Thread screw through tool until it contacts
centering hole in step plate. Tighten forcing screw to relieve clutch
pack tension from pinions. Remove pinion thrust washers.
3) Tighten forcing screw until all clutch pack tension is
relieved from pinions. Slide rotating tool pawl so it engages with
side gear teeth. Rotate side gears with rotating tool until pinions
can be removed through case opening.
4) Remove forcing screw, rotating tool, upper side gear and
clutch pack. Remove differential case from axle shaft. Remove
remaining side gear, clutch pack and step plate tool. Remove retainer
clips from clutch packs. Mark clutch packs for reassembly reference.
Using a press, remove differential bearings.
Cleaning & Inspection
Clean all parts and dry with compressed air. If any clutch
plates or discs require replacement, all plates and discs should be
replaced. Replace any worn or damaged components.
NOTE: For adjustment procedures, see DANA SEMI-FLOATING or
FULL FLOATING AXLE articles in this section
Reassembly
1) Lightly lubricate clutch pack discs with axle lubricant.
Assemble clutch pack discs and install retaining clips on ears of
discs. See Fig. 3. Install assembled clutch packs on side gears.
Fig. 3: Typical Clutch Pack Assembly
2) Mount differential case on axle shaft. Install first
clutch pack and side gear in bottom bore of case. Ensure retaining
clips remain seated in case pockets. Install Step Plate (J 8646-2) in

clutch pack just installed.
3) Install remaining side gear and clutch pack in case. Hold
assembly in position and install rotating tool and forcing screw.
Tighten forcing screw and compress clutch packs. Install pinions.
Rotate side gear with tool pawl until each pinion is aligned with
pinion shaft bore.
4) Install pinion thrust washers and pinion shaft. Install
pinion thrust washers and pinion shaft. Install snap rings on pinion
shaft. Remove differential from axle shaft. Remove shaft from vise.
Using Remover (J 22912-01), remove differential bearings. Install end
play shims on each side of case. Reinstall differential bearings.
5) Position ring gear on differential case. Install NEW ring
gear bolts and tighten to 52 ft. lbs. (70 N.m).
DANA 4-PINION POWER-LOK
NOTE: Differential bearings do not need to be removed to overhaul.
Disassembly
1) Mark case halves, pinion mate shafts and ramps for
reassembly reference. Clamp differential assembly in soft-jawed vise
and loosen case half bolts ( DO NOT remove bolts). Position
differential assembly on bench with ring half of case down. Remove
case attaching bolts. Remove cover half of case.
2) Remove pinion mate gear, side gear ring and clutch pack.
Keep parts together for reassembly reference. Remove parts from drive
gear half of case.
Cleaning & Inspection
Clean all parts and dry with compressed air. If any clutch
plates or discs require replacement, it is recommended that all plates
and discs be replaced. Replace any part that is worn or damaged.
Reassembly
NOTE: For adjustment procedures, see DANA SEMI-FLOATING or
FULL FLOATING AXLE articles in this section.
1) Position side gear ring from drive gear half of case on a
pinion flange. Coat clutch plates with Hypoid Gear Lubricant (C6A-Z-
19580-E). Reassemble parts in correct order. See Fig. 1. Install ring
gear half of case over clutch pack and side gear ring. Ensure clutch
plate lugs enter slots in case and case bottoms on clutch pack.
2) Hold assembly together and turn case half upside down.
Install gear in side gear ring. Install mate shaft and pinions on side
gear ring. Align mate shaft and case markings. Install cover half mate
shaft and pinions. Align markings.
3) Install side gear on pinions. Position side gear ring on
side gear and pinions. Assemble clutch pack on side gear. See Fig. 4.
Align clutch plate lugs and install all parts in case. Position cover
half of case over assembly. Align case marks made during disassembly.
4) Lubricate bolt threads with axle lube and install case
bolts. Using both axle shafts, align splines of side gear and side
gear ring. Tighten case bolts to 65-70 ft. lbs. (89-94 N.m).
5) Remove axle shafts. If properly assembled, each pinion
mate cross shaft should be tight on its ramp. If clearance is present,
it should not exceed .010" (.254 mm).

Fig. 4: Power-Lok Differential Clutch Pack Assembly
Courtesy of Ford Motor Co.

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DO OR L O CKS - P O W ER

1988 J e ep C hero ke e
1988 Power Door Locks
JEEP
DESCRIPTION
Jeep vehicles with power door locks use a motor-actuated lock
system, controlled by rocker switches. Operation of switch assembly
controls the actuator motor.
Power door locks are protected by a 30-amp circuit breaker
located in the fuse block. Power door locks will not operate from
outside the vehicle.
TESTING
SWITCH
Using ohmmeter, test switches for continuity. Connect
ohmmeter across terminals as shown. See Fig. 1. Continuity should
exist between terminals in all positions.
Fig. 1: Checking Switch Continuity
Courtesy of Chrysler Motors.
ACTUATOR MOTOR
Connect ammeter to actuator motor terminals. Operate door
switch and note reading. Current draw should not exceed 8 amps at room
temperature. Actuator should complete full travel within one second.
Replace actuator motor if not within specification.
CIRCUIT BREAKER
1) Disconnect harness connector from fuse block. Using test
light, check fuse block harness connection for voltage. If there is no
battery voltage at connection, check for burnt fusible link in engine
compartment.
2) Check circuit breaker continuity if voltage exists. Using
ohmmeter, test circuit breaker for continuity. Replace circuit breaker
if no continuity exists.
3) If circuit breaker tests okay, check for battery voltage
at circuit breaker connection of fuse block with wiring harness
installed. If voltage exists at wiring harness but not at circuit
breaker connection, check fuse block for damage.
REMOVAL & INSTALLATION