1988 JEEP CHEROKEE change wheel

ECU signal line and the other end connected to ground. As throttle
valve angle changes, a return voltage is sent back to the ECU through
the third wire. Output voltage to the ECU is about one volt when
throttle valve is at idle position, and about 5 volts when throttle
valve is at wide open throttle.
A dual TPS is used on automatic transmission equipped models.
The additional sensor provides throttle position information to the
transmission.
Knock Sensor
A knock sensor is mounted on the lower left side of block,
just above the oil pan. This sensor detects abnormal engine vibration
due to "detonation" and/or "pre-ignition". The knock sensor supplies
detonation information to the ECU. The ECU then alters ignition timing
as needed to maintain maximum timing under most operating conditions.
Park/Neutral (P/N) Switch
The P/N switch is mounted in automatic transmission equipped
vehicles. The switch indicates when the transmission is in Park or
Neutral.
Speed Sensor
The speed sensor is a nonadjustable sensor attached to the
flywheel/drive plate housing with special shoulder bolts. This sensor
provides Top Dead Center (TDC) and engine speed information to the ECU\
by counting the flywheel teeth as they pass during engine operation.
The flywheel has a large trigger tooth and notch located 12 small
teeth before each TDC position. See Fig. 2.
Fig. 2: Design of Speed Sensor
When a small tooth and notch pass the magnetic core of the
sensor, the concentration and collapse of the magnetic field created
induces a small voltage spike into the sensor pick-up coil windings.

closer to pinion gear. If backlash is too low, move ring gear away
from pinion gear.
3) To change backlash readings, move shims from one side of
differential case to other. When backlash adjustment is completed,
check tooth contact pattern. See GEAR TOOTH CONTACT PATTERNS in this
section. Pattern should be correct if assembly and adjustments have
been done properly.
4) When differential is complete and correctly adjusted,
install new cover gasket and cover. Tighten cover bolts to 30-40 ft.
lbs. (41-54 N.m). Fill assembly with hypoid lubricant.
AXLE ASSEMBLY SPECIFICATIONS TABLE









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Application Specifications In. (mm)
Pinion Gear Depth (Nominal Dimension)
Model 44 ................................. 2.625 (66.68)
Model 60 & 61 ............................ 3.125 (79.38)
Model 70 & 80 ............................ 3.500 (88.90)
Ring Gear Backlash ................... .004-.009 (.10-.23)
Side Bearing Preload .......................... .015 (.38)
INCH lbs. (N.m)
Pinion Bearing Preload
New Bearings ........................... 20-40 (2.3-4.5)
Used Bearings .......................... 10-20 (1.1-2.3)









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TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE








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Applications Ft. Lbs. (N.m)
Axle Flange-to-Hub Bolt
Model 44 ...................................... 35 (48)
Models 60 & 61 ................................ 55 (75)
Model 70 & 80 ................................ 85 (115)
Pinion Shaft Flange Nut
Models 44 & 70 .............................. 210 (285)
Models 60 & 61 .............................. 270 (367)
Model 80 ............................ 440-500 (597-678)
Ring Gear-to-Case Bolt
Model 44 ...................................... 55 (75)
Models 60, 61, & 70 ......................... 110 (149)
Model 80 ............................ 145-165 (196-223)
Side Bearing Cap Bolt ........................... 80 (108)
Front Axle
Cherokee, Comanche, & Wagoneer
Axle Shaft Nut ............................. 175 (237)
Disconnect Housing Bolt ...................... 10 (14)
Hub-to-Knuckle Bolt ......................... 75 (102)
Lower Control Arm Bolt ..................... 133 (180)
Lower Shock Mount Bolt ....................... 14 (19)
Drive Shaft Bolt ............................. 14 (19)
Stabilizer Bar Link Bolt ..................... 70 (95)
Tie Rod Nut ............................ 25-45 (34-61)
Upper Control Arm Bolt ....................... 37 (50)
Wheel Lug Nut ............................... 75 (102)
Grand Wagoneer
Leaf Spring "U" Bolt Nut ................... 100 (136)
Lower Shock Mount Bolt ....................... 45 (61)

2) On models with 2-piece shafts, rotate transmission yoke
until trunnion is in horizontal plane. Install front drive shaft with
"U" joint trunnion in vertical plane. Connect bearing support to
crossmember.
3) Ensure that front face of bearing support is perpendicular
(90 degrees) to centerline of drive shaft. Install rear drive shaft
with "U" joint trunnion of slip joint in vertical plane.
4) Set differential pinion yoke trunnion in vertical plane.
Connect rear drive shaft to pinion yoke. If 2-piece shaft is correctly
installed, centerline of trunnions at each end of individual shafts
will be parallel. See Fig. 3.
Fig. 3: Phase Alignment Of 2-Piece Drive Shafts
Trunnion yoke ears on each shaft must be parallel.
DRIVE SHAFT BALANCE TEST
1) Drive shaft imbalance may often be cured by disconnecting
shaft and rotating it 180 degrees in relation to other components.
Test by raising rear wheels off ground, and turning shaft with engine.
NOTE: DO NOT run engine without ram airflow across radiator for
prolonged periods, as overheating of engine or transmission
may occur.
2) On most models, balance testing may be done by marking
shaft in 4 positions, 90 degrees apart. Place marks approximately 6"
forward of weld, at rear end of shaft. Number marks one through 4.
3) Place screw-type hose clamp so clamp head is in number one
position, and rotate shaft with engine. If there is little or no
change, move clamp head to No. 2 position, and repeat test.
4) Continue procedure until vibration is at lowest level. If
no difference is noted with clamp head moved to all 4 positions,
vibrations may not be drive shaft imbalance.
5) If vibration is lessened but not completely gone, place 2
clamps at that point, and run test again. Combined weight of clamps in
one position may increase vibration. If so, rotate clamps 1/2" apart,
above and below best position, and repeat test.
6) Continue to rotate clamps as necessary, until vibration is
at lowest point. If vibration level is still unacceptable, leave rear
clamp(s) in position and repeat procedure at front end of drive shaft.\
If vibration can be eliminated or reduced to acceptable levels using
this test procedure, send drive shaft out to be balanced.

mounted on throttle body and senses angle of throttle blade opening.
A voltage signal of up to 5 volts at wide open throttle is
produced by TPS. Voltage varies with throttle angle changes. This
signal is transmitted to ECU where it is used to adjust air/fuel
ratio during acceleration, deceleration, idle, and wide open throttle
conditions.
A dual TPS is used on models with automatic transmissions.
This dual TPS not only provides ECU with input voltages but also
supplies automatic transmission control unit with input signals
relative to throttle position.
Knock Sensor
Knock sensor (detonation sensor) is located on lower left
side of cylinder block just above oil pan. Knock sensor picks up
detonation vibration from engine and converts it to an electrical
signal for use by ECU.
ECU uses this information to determine when a change in
ignition timing is required. Knock sensor allows for engine operation
on either "premium" unleaded or "regular" unleaded fuel.
When knock occurs, ECU retards ignition timing in one or
more cylinders until detonation is eliminated.
Speed Sensor
Speed sensor is secured by special shouldered bolts to
flywheel/drive plate housing. Speed sensor is nonadjustable and
preset at factory. Speed sensor senses TDC and engine speed by
detecting flywheel teeth as they pass pick-up coil during engine
operation. See Fig. 2.
Flywheel has a large trigger tooth and notch located 12
small teeth before each TDC position. When a small tooth and notch
pass the magnetic core in sensor, concentration and collapse of the
magnetic field created induces a small voltage spike into sensor
pick-up coil windings. These small voltage spikes are sent to ECU,
allowing ECU to count the teeth as they pass sensor.
When a large tooth and notch pass magnetic core in sensor,
increased concentration and collapse of the magnetic field induces a
higher voltage spike than smaller teeth. Higher spike indicates to
ECU that a piston will soon be at TDC position, 12 teeth later.
Ignition timing for cylinder is either advanced or retarded by ECU
based upon "sensor input".
Fig. 2: Speed Sensor Operation
Courtesy of Chrysler Motors.
Engine Switches
Several switches provide operating information to ECU. These

Coolant temperature sensor is installed in intake manifold
water jacket to provide coolant temperature input signal for ECU.
During cold engine operation, ECU will make mixture richer, make up
for fuel condensation in cold intake manifold, increase idle speed
during warm-up period, increase ignition advance and keep EGR system
inoperative until engine warms up.
THROTTLE POSITION SENSOR (TPS)
Throttle position sensor provides ECU with input signal, up
to about 5 volts, to indicate throttle position. This allows ECU to
control air/fuel mixture according to throttle position. TPS is
mounted on throttle body assembly.
WIDE OPEN THROTTLE (WOT) SWITCH
WOT switch provides an input signal to ECU when engine is at
wide open throttle. The ECU enriches air/fuel mixture. The WOT switch
is located on the side of throttle body.
CLOSED THROTTLE (IDLE) SWITCH
Idle switch is integral with ISA motor and provides voltage
signal to ECU. ECU will signal ISA motor to change throttle stop
angle in response to engine operating conditions.
UPSHIFT INDICATOR LIGHT
On vehicles equipped with a manual transmission, ECU
controls upshift indicator light. Indicator light is normally
illuminated when ignition is turned on without engine running.
Indicator light is turned off when engine is started.
Indicator light will be illuminated during engine operation
in response to engine load and speed. If transmission is not shifted,
ECU will turn light off after 3 to 5 seconds. A switch located on
transmission prevents indicator light from being illuminated when
transmission is shifted to highest gear.
ENGINE SPEED SENSOR
Engine speed sensor is attached to bellhousing. It senses
and counts teeth on flywheel gear ring as they pass during engine
operation. Signal from speed sensor provides ECU with engine speed
and crankshaft angle. On flywheel gear ring, large trigger tooth and
notch is located 90 degrees before each TDC point. Each trigger tooth
is followed by 12 smaller teeth and notches before TDC point is
reached.
As each of 12 small teeth and notches pass magnetic core in
speed sensor, concentration and collapse of magnetic field induces
slight voltage (spike) in sensor pick-up coil winding. See Fig. 2.
Larger trigger teeth and notches induce higher voltage (spike) in
sensor pick-up coil winding. These voltage spikes enable ECU to count
teeth as they pass speed sensor.
Higher voltage spike (from larger tooth and notch) indicates
to ECU that piston will be at TDC position after 12 smaller voltage
spikes have been counted. ECU will then either advance or retard
ignition timing depending upon remaining sensor inputs.

stream See Fig. 6. The MAT sensor provides an input voltage to the
ECU. As the temperature of the air-fuel stream in the manifold varies,
resistance changes, resulting in a different input voltage to the ECU.
Fig. 6: Location of Manifold Air Temperature (MAT) Sensor
Courtesy of Chrysler Motors.
ENGINE SPEED SENSOR (CRANKSHAFT POSITION SENSOR - CPS)
The engine speed sensor is attached to the flywheel cover
housing and provides an input signal to the ECU relating to crankshaft
speed, angle, and position. See Fig. 7. The ECU converts crankshaft
speed input into engine RPM and converts crankshaft angle to piston

* Cold Climate Operation
* Towing Or Heavily Loading
* Severe Dust Conditions
* Sustained High Speed Operation
* Off-Road Driving
* Hot Weather, Stop-And-Go Driving
* Extensive Idling Conditions (Taxi Or Delivery Type Service)
Normal Service
* Driven More Than 10 Miles Daily
* No Severe Service Operating Conditions
CAMSHAFT TIMING BELT REPLACEMENT INFORMATION (TURBO-DIESEL)
CAUTION: Failure to replace a faulty camshaft timing belt may result
in serious engine damage.
The condition of camshaft drive belts should always be
checked on vehicles which have more than 50,000 miles. Although some
manufacturers do not recommend belt replacement at a specified
mileage, others require it at 60,000-100,000 miles. A camshaft drive
belt failure may cause extensive damage to internal engine components
on most engines, although some designs do not allow piston-to-valve
contact. These designs are often called "Free Wheeling".
Many manufacturers changed their maintenance and warranty
schedules in the mid-1980's to reflect timing belt inspection and/or
replacement at 50,000-60,000 miles. Most service interval schedules
reflect these changes.
Belts or components should be inspected and replaced if any
of the following conditions exist:
* Cracks Or Tears In Belt Surface
* Missing, Damaged, Cracked Or Rounded Teeth
* Oil Contamination
* Damaged Or Faulty Tensioners
* Incorrect Tension Adjustment
SERVICE LABOR TIMES
SERVICE LABOR TIMES TABLE (HOURS)








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( 1) 30,000 60,000
Application Mile Service Mile Service
2.1L (Turbo Diesel)
Automatic Transmission ........... 4.3 ................ 4.5
Manual Transmission .............. 3.6 ................ 3.8
2.5L
Automatic Transmission ........... 5.6 ................ 3.5
Manual Transmission .............. 4.9 ................ 3.5
2.8L
Automatic Transmission ........... 5.8 ................ 3.7
Manual Transmission .............. 5.1 ................ 3.7
4.0L
Automatic Transmission ........... 5.7 ................ 3.6
Manual Transmission .............. 5.0 ................ 3.6
( 1) - Add .8 hr. for vehicles equipped with 4WD.









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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)