differential JEEP CHEROKEE 1988 Service Owner's Guide

See DIFFERENTIAL AND FINAL DRIVE ASSEMBLIES .
LINES
See HOSES, LINES AND TUBES .
LINKAGES (EXTERNAL)
LINKAGE (EXTERNAL) INSPECTION








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Condition Code Procedure
Components missing ...... C .. Require replacement of missing
components.
Linkage bent, affecting
performance ............ A ... Require repair or replacement
of linkage.
Linkage bent, not
affecting performance .. 2 ... Suggest repair or replacement
of linkage.
Linkage binding, affecting
performance ............ A ... Require repair or replacement
of linkage.
Linkage binding, not
affecting performance .. 1 ... Suggest repair or replacement
of linkage.
Linkage broken .......... A ... Require repair or replacement
of linkage.
Linkage loose, affecting
performance ............ A ... Require repair or replacement
of linkage.
Linkage loose, not
affecting performance .. 1 ... Suggest repair or replacement
of linkage.
Linkage missing ......... C ............ Require replacement.
Linkage noisy ........... 2 .. Suggest repair or replacement.
Out of adjustment ....... B .. Require repair or replacement.
Worn to the extent that it
no longer performs its
intended function ...... A .. Require repair or replacement.









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LOCKING HUB ASSEMBLIES
LOCKING HUB ASSEMBLY INSPECTION








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Condition Code Procedure
Inoperative ............. A ........... ( 1) Require repair or
replacement.
Loose ................... A .. Require repair or replacement.
Seized in any position .. A .. Require repair or replacement.
( 1) - Inoperative includes intermittent operation.









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LOCKING HUB CONTROL KNOBS
LOCKING HUB CONTROL KNOB INSPECTION








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Condition Code Procedure

Engine Coolant In coolant overflow bottle.
Engine Oil In oil pan.
Front/Rear Axles On front/rear of differential.
Power Steering In power steering pump
reservoir.
Transfer Case In rear portion of transfer
case.
Transmission On fill plug (M/T) or dipstick\
(A/T).
Windshield Washer On bottom of windshield washer
reservoir.
Fuel Gauge Sending Unit In fuel tank.

Automatic Load Leveling Sw. On compressor bracket, in
engine compartment.
Back-Up Light Sw. (Man. Trans.) On left side of transmission
case.
Back-Up/Neutral Sw. (Auto. Trans.) On left side of transmission
case.
Brake/Stop Light (Cruise) Switch On brake pedal bracket.
Brake Warning Switch On brake pressure differential
valve, below master cylinder.
Closed Throttle (Idle) Switch An integral part of ISA motor.\
Command Track Switch On left side of transmission.
Parking Brake Switch Under center console, at base
of parking brake lever.

than .010" (.25 mm) from tip. Chamfer sharp edge of reground valve
tip. Recheck valve stem installed height.
VALVE STEM OIL SEALS
Valve stem oil seals must be installed on valve stem. See
Fig. 2 . Seals are needed due to pressure differential at the ends of
valve guides. Atmospheric pressure above intake guide, combined with
manifold vacuum below guide, causes oil to be drawn into the cylinder.
Exhaust guides also have pressure differential created by
exhaust gas flowing past the guide, creating a low pressure area. This
low pressure area draws oil into the exhaust system.
Replacement (On Vehicle)
Mark rocker arm or overhead cam components for location.
Remove rocker arm components or overhead cam components. Components
must be installed in original location. Remove spark plugs. Valve stem
oil seals may be replaced by holding valves against seats using air
pressure.
Air pressure must be installed in cylinder using an adapter
for spark plug hole. An adapter can be constructed by welding air hose
connection to spark plug body with porcelain removed.
Install adapter in spark plug hole. Apply a minimum of 140
psi (9.8 kg/cm
) to adapter. Air pressure should hold valve closed. If
air pressure does not hold valve closed, check for damaged or bent
valve. Cylinder head must be removed for service.
Using valve spring compressor, compress valve springs. Remove
valve locks. Carefully release spring compressor. Remove retainer or
rotator and valve spring. Remove valve stem oil seal.
If oversized valves have been installed, oversized oil seals
must be used. Coat valve stem with engine oil. Install protective
sleeve over end of valve stem. Install new oil seal over valve stem
and seat on valve guide. Remove protective sleeve. Install spring
seat, valve spring and retainer or rotator. Compress spring and
install valve locks. Remove spring compressor. Ensure valve locks
are fully seated.
Install rocker arms or overhead cam components. Tighten all
bolts to specification. Adjust valves if required. Remove adapter.
Install spark plugs, valve cover and gasket.
VALVE SPRING INSTALLED HEIGHT
Valve spring installed height should be checked during
reassembly. Measure height from lower edge of valve spring to the
upper edge. DO NOT include valve spring seat or retainer. Distance
must be within specifications. If valves and/or seats have been
ground, a valve spring shim may be required to correct spring height.
See Fig. 12 .
Fig. 12: Measuring Valve Spring Installed Height - Typical
This Graphic For General Information Only

\003
FU EL IN JE C TIO N S YSTE M - T B I

1 988 J e ep C hero ke e
1988 Electronic Fuel Injection
JEEP/RENIX THROTTLE BODY INJECTION
2.5L Cherokee, Comanche, Wagoneer, Wrangler
DESCRIPTION
The Throttle Body Injection (TBI) system is a single
injector system that introduces fuel into throttle body from above
throttle plate. Fuel injector, located within throttle body, is
controlled by the Electronic Control Unit (ECU).
The ECU is a sealed microprocessor that receives input
signals from several sensors and other related engine components.
Based on these inputs, ECU generates output signals that control and
adjust air/fuel mixture and ignition timing as necessary for proper
engine performance.
ECU also controls engine idle speed, emission control
systems, upshift indicator light (manual transmission only), and A/C
compressor clutch.
OPERATION
ELECTRONIC CONTROL UNIT (ECU)
On Cherokee, Comanche and Wagoneer, ECU is located under
instrument panel, above accelerator pedal. On Wrangler, ECU is
located behind glove box. Input information from various engine
sensors to ECU is used to determine engine operating conditions and
needs. Battery voltage input is used to ensure that correct output
voltage is supplied by ECU during fluctuations in battery voltage.
FUEL INJECTOR
Fuel injector is mounted in throttle body so that fuel is
injected into incoming airflow. When injector solenoid is energized,
armature and plunger move upward against spring. Check ball above
injector nozzle moves off seat and opens small orifice at end of
injector.
Fuel supplied to injector is forced around ball and through
orifice, resulting in fine spray of fuel. Volume of fuel injected is
dependent only on length of time that injector is energized by ECU,
as fuel pressure is constant at injector. During cold engine starts,
extra fuel is supplied so richer mixture will aid in starting.
FUEL PRESSURE REGULATOR
Fuel pressure regulator is integral part of throttle body.
Pressure regulator has a spring chamber that is vented to same
pressure as tip of injector. Because differential pressure between
injector nozzle and spring chamber is same, only the length of time
that injector is energized controls volume of fuel injected.
Fuel pump delivers more fuel than is required by engine.
Excess fuel goes to fuel tank from pressure regulator via fuel return
hose. Fuel pressure regulator function is mechanical and ECU does not
control it.
FUEL PUMP

Fig. 1: Drive Axle Gear Tooth Patterns
ADJUSTMENTS
GEAR BACKLASH & PINION SHIM CHANGES
NOTE: Backlash is adjusted by either moving shims from one side of
differential case to the other or by turning adjusting nuts
on which side bearing races ride. Changing of pinion shims
alters the distance from face of pinion of centerline of
ring gear.
1) With no change in backlash, moving pinion further from
ring gear moves drive pattern toward heel and top of tooth, and moves
coast pattern toward toe and top of tooth.
2) With no change in backlash, moving pinion closer to ring
gear moves drive pattern toward toe and bottom of tooth, and moves
coast pattern toward heel and bottom of tooth.
3) With no change in pinion shim thickness, an increase in
backlash moves ring gear further from pinion. Drive pattern moves
toward heel and top of tooth, and coast pattern moves toward heel and
top of tooth.
4) With no change in pinion shim thickness, decrease in

Brake Caliper Bushings ....... GE 661 or DOW 111 Silicone Grease
Caliper Slide Pins .......... GE 661 or DOW 111 Silicone Grease
Wheel Bearings ............ Multi-Purpose NLGI Grade 2EP, GC-LB
Drive Shaft U-Joints ...... Multi-Purpose NLGI Grade 2EP, GC-LB
Steering Linkage (4)( 5) ... Multi-Purpose NLGI Grade 2EP, GC-LB
Ball Joints ( 4)( 6) ........ Multi-Purpose NLGI Grade 2EP, GC-LB
Engine Oil Filter (Diesel) ( 7) .... AMC/Jeep (P/N 8983 002 656)
Weatherstrip ......................... Silicone Spray Lubricant
( 1) - SAE 10W-30 SH/CD is preferred.
( 2) - Add 2 Ozs. (59 ml) of Limited-Slip differential lubricant
additive when changing fluid.
( 3) - For vehicles operating under heavy-duty towing conditions,
use SAE 75W-140 Synthetic lube.
NOTE: Before using SAE 75W-140 Synthetic the old fluid must be
DRAINED and FLUSHED with clean mineral based (non-synthetic)
axle lubricant. Then refill with new synthetic lube.
( 4) - Use low pressure grease gun to prevent seal damage.
( 5) - Fill until lubricant squeezes out from the base of seals.
( 6) - Fill ball joint until seal starts to swell.
( 7) - Use of AMC/Jeep Oil Filter is RECOMMENDED.









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FLUID CAPACITIES
FLUID CAPACITIES TABLE








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Application Quantity ( 1)
A/C System R-12 Refrigerant Capacity ............... 36-40 Ozs.
Automatic Transmission
1984-86 (904 HD)
Fluid Change .............................. 4.0 Qts. (3.8L)
Overhaul (Dry Fill) ....................... 8.0 Qts. (7.6L)
1987-88
Fluid Change .............................. 4.0 Qts. (3.8L)
Overhaul (Dry Fill) ....................... 8.5 Qts. (8.0L)
Cooling System ( 2)
4-Cylinder ................................. 10.0 Qts. (9.5L)
6-Cylinder ................................ 12.0 Qts. (11.4L)
4-Cylinder Turbo Diesel (1985-87) ........... 9.0 Qts. (8.5L)
Engine Oil
4-Cylinder .................................. 4.0 Qts. (3.8L)
6-Cylinder .................................. 6.0 Qts. (5.7L)
4-Cylinder Turbo Diesel (1985-87) ........... 5.5 Qts. (8.5L)
Fuel Tank
Standard ................................. 13.5 Gals. (51.1L)
Optional ................................... 20 Gals. (75.7L)
Manual Transmission ( 3)
AX4 (AISIN) ................................. 7.4 Pts. (3.5L)
T4 (Borg-Warner) ............................ 3.9 Pts. (1.8L)
AX5 (AISIN) ................................. 7.0 Pts. (3.3L)
T5 (Borg-Warner) ............................ 4.5 Pts. (2.1L)
Transfer Case
1985-86
Selec-Trac (229 Full-Time) ................ 6.0 Pts. (2.8L)
Command-Trac (Part-Time 207) .............. 4.5 Pts. (2.1L)
1987
Selec-Trac ................................ 2.5 Pts. (1.2L)
Command-Trac .............................. 2.2 Pts. (1.0L)
1988
Selec-Trac ................................ 3.0 Pts. (1.4L)

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.

computers may lose memory data. When battery power is
restored, driveability problems may exist on some vehicles.
These vehicles may require a relearn procedure. See COMPUTER
RELEARN PROCEDURES article in GENERAL INFORMATION section.
REPLACING BLOWN FUSES
Before replacing a blown fuse, remove ignition key, turn off
all lights and accessories to avoid damaging the electrical system. Be
sure to use fuse with the correct indicated amperage rating. The use
of an incorrect amperage rating fuse may result in a dangerous
electrical system overload.
BRAKE PAD WEAR INDICATOR
Indicator will cause a squealing or scraping noise, warning
that brake pads need replacement.
BRAKE WARNING LIGHT
CAUTION: If BRAKE warning light is on with parking brake disengaged
and engine running, there may be a problem in the hydraulic
brake system. Braking effort, brake pedal travel and
stopping distances may increase.
CATALYTIC CONVERTER
To prevent catalytic converter overheating, DO NOT allow
engine to idle for more than 20 minutes.
COMMAND-TRAC (4WD)
CAUTION: NEVER operate a Command-Trac vehicle in 4WD on dry,
hard-surfaced roads for a sustained period. Use 4L only
when needed for added pulling power. Operating vehicle in
4WD mode on such roads will cause stress and possible
damage to components, as well as make shifting difficult.
To reduce shifting effort, drive vehicle in Reverse for a
few feet, or drive off hard-surfaced road momentarily to
allow tire slippage.
FRONT AND REAR DIFFERENTIALS (4WD)
CAUTION: DO NOT use water, steam, kerosene or gasoline for flushing
a differential. ONLY use a flushing oil.
TRAC-LOK DIFFERENTIALS (4WD)
CAUTION: DO NOT flush a rear axle Trac-Lok differential. Trac-Lok
differentials may be cleaned only by disassembling the
unit and wiping the components with clean, lint-free cloth.
CAUTION: NEVER attempt to engage Low range when vehicle is moving
faster than 2-3 MPH, as transfer case damage may result.
GASOLINE CONTAINING ALCOHOL
CAUTION: Exclusive use of gasohol is not recommended. Vehicle test
results have shown that significant fuel system corrosion
can result when gasohol is used exclusively.

 Automatic Transmission .......................... Dexron-IIE ATF 

Brake Master Cylinder .......... DOT 3 (SAE J-1703F) Brake Fluid 

Engine Coolant ........... Alugard 340-2 & Water (50/50 Mixture) 

Engine Oil (
1) 

Gasoline Engine 

Temperature Range 

Above 30
F (-1
C) ........ SAE 20W-40 Or 20W-50 API SH/CD 

Above 0
F (-18
C) ......... SAE 10W-30 Or 10W-40 API SH/CD 

Less Than 60
F (16
C) ............... SAE 5W-30 API SH/CD 

Drive Axles ................................ SAE 75W-90 API GL-5 

Drive Axles (Trac-Lok) (
2) ................ SAE 80W-140 API GL-5 

Drive Axles (Trailer Towing) .............. SAE 80W-140 API GL-5 

Hydraulic Clutch ............... DOT 3 (SAE J-1703F) Brake Fluid 

Manual Transmission ........................ SAE 75W-90 API GL-5 

Parking Brake Cable Guides ................. NLGI Grade 2, GC-LB 

Door & Hood Hinges ............................ Light Engine Oil 

Manual Steering Box ............... Multi-Purpose NLGI Grade 2EP 

Power Steering Pump ....................... Power Steering Fluid 

Transfer Case ................................... Dexron-IIE ATF 

Brake Caliper Bushings ........ GE 661 or DOW 111 Silicone Grease 

Caliper Slide Pins ........... GE 661 or DOW 111 Silicone Grease 

Wheel Bearings .................. Multi-Purpose NLGI Grade GC-LB 

Drive Shaft U-Joints .............. Multi-Purpose NLGI Grade 2EP 

Steering Linkage (
4)( 5) .................... NLGI Grade 2, GC-LB 

Ball Joints (
4)( 6) ......................... NLGI Grade 2, GC-LB 

Weatherstrip .......................... Silicone Spray Lubricant 

Wheel Lug Nut Torque ...................... 95 ft. lbs. (129 N.m) 



(
1) - SAE 10W-30 SH/CD is preferred. 

(
2) - Add 4 ozs. (118 ml) of Limited-Slip differential lubricant 

additive when changing fluid. 

(
3) - For vehicles operating under heavy-duty towing conditions, 

use SAE 75W-140 Synthetic lube. 

NOTE: Before using SAE 75W-140 Synthetic the old fluid must 

be DRAINED and FLUSHED with clean mineral based axle 

lubricant. Then refill with new synthetic lube. 

(
4) - Use low pressure grease gun to prevent seal damage. 

(
5) - Fill until lubricant squeezes out from the base of seals. 

(
6) - Fill ball joint until seal starts to swell. 










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Fluid Capacities 










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Application ( 1) Quantity 



Automatic Transmission 

1984-86 (904 HD) 

Fluid Change ............................... 4.0 Qts. (3.8L) 

Overhaul (Dry Fill) ........................ 8.0 Qts. (7.6L) \


1987-88 

Fluid Change ............................... 4.0 Qts. (3.8L) 

Overhaul (Dry Fill) ........................ 8.5 Qts. (8.0L) \


Cooling System (
2) 

4-Cylinder .................................. 10.0 Qts. (9.5L) 

6-Cylinder ................................. 12.0 Qts. (11.4L) 

Engine Oil 

4-Cylinder ................................... 4.0 Qts. (3.8L) 

6-Cylinder ................................... 6.0 Qts. (5.7L) 

Fuel Tank 

Standard .................................. 13.5 Gals. (51.1L) 

Optional .................................... 20 Gals. (75.7L) 

Manual Transmission (
3) 

AX4 (AISIN) .................................. 7.4 Pts. (3.5L) \


T4 (Borg-Warner) ............................. 3.9 Pts. (1.8L) \