1988 JEEP CHEROKEE lock

Installation
1) If needed, use a flat blade screwdriver to turn the oil
pump gear shaft until the slot is slightly past the 11 o'clock
position. See Fig. 26. The oil pump shaft is located down in the
distributor hole.
Fig. 26: Aligning Oil Pump Gear Shaft
Courtesy of Chrysler Motors.
2) Install the rotor.
3) Without engaging the distributor gear into the cam gear
and ensuring the distributor gasket is installed, position the
distributor into the hole in the engine block.
4) Visually line up the hold down ear of the distributor
housing with the hold down clamp hole. See Fig. 27.
Fig. 27: Installing Distributor
Courtesy of Chrysler Motors.
5) Turn the rotor to the 4 o'clock position. See Fig. 28.

Fig. 28: Installing & Aligning Rotor
Courtesy of Chrysler Motors.
6) Carefully slide the distributor into the block until it
seats, keeping the hold down ear aligned to the hole in the block.
7) The rotor should be in the 5 o'clock position with the
trailing edge of the rotor blade lined up with the mark previously
scribed on the distributor housing (number one spark plug wire post
location).
8) install the distributor hold-down clamp bolt and tighten
to 9.5-14 Ft. Lbs. (13-19 N.m).
9) Install the distributor cap. Connect the distributor
electrical connector.
10) Install the electric cooling fan and shroud if
applicable.
11) Connect the negative battery cable.
IGNITION/COIL WIRE REPLACEMENT PRECAUTIONS

Electronic Spark Timing (EST) is used on most computer
controlled systems. The Electronic Control Module (ECM) monitors
information from various engine sensors, computes desired spark
timing, and signals distributor for correct timing change. The HEI
distributor with EST does not have centrifugal advance weights,
springs, or a vacuum advance unit. See Figs. 2 and 3.
HEI & EST WITH ELECTRONIC SPARK CONTROL (ESC)
All fuel injected vehicles are equipped with Electronic Spark
Control (ESC). ESC systems contain a knock sensor mounted in the
engine block. A Blue wire connects the sensor to the ESC module. If
the sensor detects knock, it sends a signal to the module which, in
turn, signals the ECM. The ECM sends a signal to the distributor to
retard spark timing.
Fig. 2: Typical HEI/EST Distributor, Integral coil system shown.
Courtesy of General Motors Corp.
OPERATION

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IN STR UM EN T P A N EL - S TA N DAR D

1988 J e ep C hero ke e
1988 Switches & Instrument Panels
JEEP
DESCRIPTION & OPERATION
Instrument panel is composed of speedometer housing,
tachometer and instrument cluster gauges.
FUEL GAUGE
System consists of a fuel gauge, an in-tank sending unit, and
appropriate wiring. Fuel gauge is grounded through variable resistor
of sending unit. A float attached to a slide rheostat follows fuel
level and varying resistance increases or decreases indicator reading.
TEMPERATURE GAUGE
System consists of gauge and sending unit and appropriate
wiring. The gauge is grounded through variable resistor of sending
unit. Changes in coolant temperature vary resistance in sending unit,
increasing or decreasing indication on gauge.
VOLTMETER
The voltmeter indicates regulated voltage to provide an
indication of charging system's ability to maintain battery charge.
OIL PRESSURE GAUGE
The oil pressure gauge system consists of gauge and a
variable resistance sending unit. Gauge needle, attached to bi-
metallic strip, responds to temperature changes.
REMOVAL & INSTALLATION
INSTRUMENT CLUSTER
Removal & Installation
1) Disconnect negative battery cable. On models with cruise
control, reach behind instrument cluster and disconnect speedometer
cable from speed switch. See Fig. 1.
2) On models without cruise control, raise vehicle on hoist.
Disconnect speedometer cable from transfer case (or transmission) and
at frame rail bracket. Move speedometer cable forward and upward to
provide slack. Lower vehicle.
3) On all models, remove instrument panel bezel screws and
bezel. Remove screws attaching cigarette lighter and switch housings
to instrument panel. Move housings aside.
4) Remove screws attaching cluster to instrument panel and
carefully pull cluster and speedometer toward rear of vehicle.
Disconnect wiring harness connectors.
5) Squeeze speedometer cable locking tabs and disconnect
cable from speedometer. See Fig. 1. Remove instrument cluster. To
install, reverse removal procedure.

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LO CKIN G H UBS - A U TO M ATIC

1988 J e ep C hero ke e
1988 Locking Hubs - Command-Trac & Selec-Trac
Jeep
DESCRIPTION & OPERATION
Command-Trac locking hub is used on Model 30 front axles.
This system can be shifted between 2WD and 4WD high range while
vehicle is moving. The only time vehicle must be stopped to shift into
or out of 4WD is when shifter is in low range. See Fig. 1.
Selec-Trac locking hubs allow full or part time 4WD. Used on
Model 30 front axles, system can be shifted into 2WD or 4WD modes only
when vehicle is stopped. See Fig. 2.
Fig. 1: Command-Trac Vacuum Control System
TROUBLE SHOOTING
SELEC-TRAC SYSTEM
2WD To 4WD
Position mode select switch to "4WD" position while driving
vehicle 2-3 MPH. Axle should ratchet and clunk into position. Transfer
case should shift after axle shifts, accompanied by hissing sound from
mode selector switch.
4WD To 2WD
1) Position mode select switch to "2WD" position. Transfer
case should shift to 2WD and not allow shifting into 4WD or "LO"
range. Axle should shift after transfer case shifts.

2) To determine if front axle has completed a shift out of
4WD into 2WD, position mode select switch back to "4WD" position while
operating vehicle at slow speed. If vehicle shifts into 2WD, axle will
ratchet. If shift is not completed, transfer case will shift into 4WD
and hissing sound will come from mode select switch.
FRONT AXLE SHIFT MOTOR TEST
1) Disconnect vacuum harness from front axle shift motor.
Connect vacuum pump to shift motor front port. Apply 15 in. Hg vacuum
to shift motor. Rotate right front wheel to disengage axle.
2) Shift motor should hold vacuum at least 30 seconds. If
not, replace motor. If motor does hold vacuum, disconnect vacuum pump
from shift motor front port. Connect pump to shift motor rear port and
cap transfer case connecting port. Apply 15 in. Hg vacuum to motor.
3) Shift motor should hold vacuum for at least 30 seconds. If
not, replace motor. If motor does hold vacuum, remove cap from shift
motor transfer case connecting port and check for vacuum. If no vacuum
is present, rotate right front wheel to ensure axle has shifted
completely. Axle must completely shift to open shift motor connecting
port.
4) Recheck vacuum at shift motor transfer case port. If
vacuum is present, transfer case requires diagnosis. Command-Trac uses
Model 207 transfer case. Selec-Trac uses Model 228 transfer case.
REMOVAL & INSTALLATION
LOCKING HUB
Removal
1) Remove cover to outer clutch housing. Remove bearing race
spring assembly. Remove sealing ring and seal bridge retainer. Remove
bearing components.
2) Squeeze tangs of wire retaining ring together with needle-
nose pliers. Pull remaining components of automatic hub from wheel.
Installation
1) Ensure lock ring is in position. Using Bearing Nut Wrench
(J-6893-D), tighten wheel bearing adjusting nut to 50 ft. lbs. (60 N.\
m) to seat bearings.
2) Back off nut and tighten to 35 ft. lbs. (47 N.m) while
rotating hub. Finally, back off nut a maximum of 3/8 turn. Assemble
lock ring (with tab in keyway) over axle shaft, against bearing
adjustment nut.
3) Adjustment nut pin must pass through one of the washer
holes. Tighten outer adjusting nut to 183 ft. lbs. (248 N.m). Align
outer clutch housing splines with splines of wheel hub.
4) Loosen cover screws 3 or 4 turns, and push in on cover to
allow retaining ring to expand into rotor hub groove. Tighten cover
cap screws to 40-50 INCH lbs. (4.5-5.6 N.m).
Fig. 2: Selec-Trac Vacuum Control System
AXLE SHIFT MOTOR & HOUSING

the ENGINE PERFORMANCE section.
Fuel filter should be drained whenever "WATER IN FUEL"
warning light glows. Diesel fuel can damage asphalt and
painted surfaces. Always place a drain pan under fuel filter
to collect contaminated fuel. See Fig. 2.
1) Stop vehicle and turn engine off. Attach a long piece
of tubing to drain cock outlet. Place end of drain hose into
drain pan. Open filter assembly vent valve (Black + shaped
knob) and drain cock.
2) Drain approximately 1/2 pint (.24 Liters) from fuel
filter. Close vent valve and drain cock. Start engine and
check for leaks. If "WATER IN FUEL" warning lamp comes on
again, remove water contaminated fuel from fuel lines and
fuel tank.
WARNING: DO NOT bleed fuel lines on hot engine, as high exhaust
temperatures could cause fire. Use care when bleeding fuel
lines, as fuel is under extreme pressure and could penetrate
skin, causing personal injury. Wear safety goggles and
protective clothing when bleeding fuel lines.
CAUTION: DO NOT drain fuel/water separator when engine is running or
hot. Allow engine to cool before draining. Verify that the
WATER IN FUEL light on instrument panel is OFF.
Fig. 3: Locking Crankshaft at TDC
Courtesy of American Motors/Jeep Corp.

Command-Trac .............................. 2.2 Pts. (1.0L)
Drive Axles (3)
Front ....................................... 2.5 Pts. (1.2L)
Front (Disconnect Housing) ( 4) ............. 5.0 Ozs. (0.15L)
Rear ........................................ 2.5 Pts. (1.2L)
Rear (Trac-Lok) ( 5) ......................... 2.5 Pts. (1.2L)
( 1) - Capacities are recommended or calculated levels. Always use
dipstick (if available) to measure level.
( 2) - Includes 2.3 Qts. for coolant recovery bottle.
( 3) - Fill to bottom of filler plug hole.
( 4) - Add 5 Ozs. of gear lubricant through indicator switch hole.
( 5) - Add 2 Ozs. of Limited-Slip differential lubricant additive
first, then add new fluid.









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WHEEL & TIRE SPECIFICATIONS
WHEEL & TIRE SPECIFICATIONS TABLE








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Wheel Size Tire Size
Cherokee
15x6 & 15x7 (Aluminum Or Steel) ............. P195/75R15
15x6 & 15x7 (Aluminum Or Steel) ............. P205/75R15
15x6 & 15x7 (Aluminum Or Steel) ............. P215/75R15
15x6 & 15x7 (Aluminum Or Steel) ............. P225/75R15
Wagoneer
15x6 (Aluminum/Steel) ....................... P205/75R15
All Models
16-Inch Wheels ...................... Compact Spare Tire









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TIRE REPLACEMENT
CAUTION: Always ensure all 4 tires on the vehicle are the same size,
except when using the temporary spare. The use of
mismatched tires may cause unpredictable handling.
Replacing original tires with tires of a different size may
result in false speedometer and odometer indications.
TIRE INFLATION
The tire specification decal is located in the glove box.
WHEEL TIGHTENING
Tighten the lug nuts firmly in a crisscross pattern as shown
in Fig. 11 . Tighten to 95 ft. lbs (129 N.m). Always position wheel
locking nut opposite valve stem in position indicated. See Fig. 11.
Fig. 11: Wheel Locking Nut Location
Courtesy of American Motors Corp.