1988 JEEP CHEROKEE length

In certain conditions, the pitch of the exhaust gases may
sound like gear whine. At other times, it may be mistaken for a wheel
bearing rumble.
Tires, especially radial and snow, can have a high-pitched
tread whine or roar, similar to gear noise. Also, some non-standard
tires with an unusual tread construction may emit a roar or whine.
Defective CV/universal joints may cause clicking noises or
excessive driveline play that can be improperly diagnosed as drive
axle problems.
Trim and moldings also can cause a whistling or whining
noise. Ensure none of these components are causing the noise before
disassembling the drive axle.
Gear Noise
A "howling" or "whining" noise from the ring and pinion gear
can be caused by an improper gear pattern, gear damage, or improper
bearing preload. It can occur at various speeds and driving
conditions, or it can be continuous.
Before disassembling axle to diagnose and correct gear
noise, make sure that tires, exhaust, and vehicle trim have been
checked as possible causes.
Chuckle
This is a particular rattling noise that sounds like a stick
against the spokes of a spinning bicycle wheel. It occurs while
decelerating from 40 MPH and usually can be heard until vehicle comes
to a complete stop. The frequency varies with the speed of the
vehicle.
A chuckle that occurs on the driving phase is usually caused
by excessive clearance due to differential gear wear, or by a damaged
tooth on the coast side of the pinion or ring gear. Even a very small
tooth nick or a ridge on the edge of a gear tooth is enough the cause
the noise.
This condition can be corrected simply by cleaning the gear
tooth nick or ridge with a small grinding wheel. If either gear is
damaged or scored badly, the gear set must be replaced. If metal has
broken loose, the carrier and housing must be cleaned to remove
particles that could cause damage.
Knock
This is very similar to a chuckle, though it may be louder,
and occur on acceleration or deceleration. Knock can be caused by a
gear tooth that is damaged on the drive side of the ring and pinion
gears. Ring gear bolts that are hitting the carrier casting can cause
knock. Knock can also be due to excessive end play in the axle shafts.
Clunk
Clunk is a metallic noise heard when an automatic
transmission is engaged in Reverse or Drive, or when throttle is
applied or released. It is caused by backlash somewhere in the
driveline, but not necessarily in the axle. To determine whether
driveline clunk is caused by the axle, check the total axle backlash
as follows:
1) Raise vehicle on a frame or twinpost hoist so that drive
wheels are free. Clamp a bar between axle companion flange and a part
of the frame or body so that flange cannot move.
2) On conventional drive axles, lock the left wheel to keep
it from turning. On all models, turn the right wheel slowly until it
is felt to be in Drive condition. Hold a chalk marker on side of tire
about 12" from center of wheel. Turn wheel in the opposite direction
until it is again felt to be in Drive condition.
3) Measure the length of the chalk mark, which is the total

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Application Champion No.
2.5L ...................................................... RC-12LYC









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SPARK PLUG SPECIFICATIONS








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Application Gap: In. (mm) Torque: Ft. Lbs. (N.m\
)
2.5L .................. .035 (.89) ................... 7-15 (9-20\
)









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HIGH TENSION WIRE RESISTANCE
Do not puncture spark plug wires with any type of probe.
Remove spark plug wire and check resistance with an ohmmeter.
ADJUSTMENTS
VALVE ARRANGEMENT
* E-I-I-E-E-I-I-E (Front-to-rear).
VALVE CLEARANCE
All models are equipped with hydraulic lifters, which should
be adjusted to zero lash.
IGNITION COIL WIRE
Remove ignition coil wire from coil and distributor cap.
Check terminals for corrosion and clean if necessary. Check coil wire
resistance. Replace wire if resistance is excessive.
HIGH TENSION WIRE RESISTANCE (OHMS)









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Wire Length (In.) Minimum Maximum\
0-15 ........................ 3000 ........................ 10,000
15-25 ....................... 4000 ........................ 15,000
25-35 ....................... 6000 ........................ 20,000
Over 35 ..................... 8000 ........................ 25,000









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DISTRIBUTOR
All models are equipped with a Renix solid state ignition
module. Renix system uses a TDC sensor mounted near the flywheel. The
distributor consists of a cap and rotor. Its only function is to
distribute high voltage to appropriate spark plug. No adjustments are
required on either system.

inlet line or filter disconnected at carburetor. Disconnect fuel
return line at fuel filter and plug nipple on filter. Make all tests
at idle speed. See FUEL PUMP SPECIFICATIONS TABLE .
FUEL PUMP SPECIFICATIONS TABLE









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Application Pressure Volume
** psi (kg/cm) ( 1) Pts. (L)
4.0L .................... ( 2) 31 (2.1) ............ 1.0 (.47)
4.0L .................... ( 3) 39 (2.6) ............ 1.0 (.47)
4.2L .................. 4.0-5.0 (.28-.35) ......... 1.0 (.47)
( 1) - Volume per 30 seconds.
( 2) - With the vacuum hose connected to the pressure regulator.
( 3) - With the vacuum hose removed from the pressure regulator.









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ADJUSTMENTS
VALVE ARRANGEMENT
* E-I-I-E-I-E-E-I-E-I-I-E (Front-to-rear).
VALVE CLEARANCE
All engines are equipped with hydraulic lifters. Valve
clearance is not adjustable.
IGNITION COIL WIRE
Remove ignition coil wire from coil and distributor cap.
Check terminals for corrosion and clean (if necessary). Check coil
wire resistance. Replace wire if resistance is excessive.
HIGH TENSION WIRE RESISTANCE (OHMS) TABLE









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Wire Length Minimum Maximum
0-15" .................. 3000 ................... 10,000
15-25" ................. 4000 ................... 15,000
25-35" ................. 6000 ................... 20,000
Over 35" ............... 8000 ................... 25,000









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DISTRIBUTOR
4.0L
Information not available from manufacturer.
4.2L
All models are equipped with Motorcraft Solid State Ignition
(SSI) systems. No adjustments are required.

WHEEL A LIG NM EN T S PEC IF IC ATIO NS & P R O CED URES

1988 J e ep C hero ke e
1988 Wheel Alignment
INTRODUCTION
PRE-ALIGNMENT
VEHICLE CHECKS
Prior to making wheel alignment adjustments, check and
adjust the following items:
1) Tire pressure must be inflated to manufacturers
recommended specifications.Tires should be equal in size and type.
Runout must not be excessive. Tires and wheels should be in balance.
2) Wheel bearings must be properly adjusted. Steering
linkage and suspension must not have excessive wear and/or 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 correct ride 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 ride height.
6) Ensure steering wheel spokes are 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.
DESCRIPTION
CAMBER
Camber is the inward or outward tilt of the wheel as viewed
from front of vehicle. Camber is measured from centerline of vehicle.
When wheel is tilted outward at top from centerline of vehicle,
camber is positive. When wheel is tilted inward at top from
centerline of vehicle, camber is negative. Camber is measured in
degrees from vertical.
Fig. 1: Camber Angle
CASTER
Caster is the tilting of front steering axis. This forward

service adjustment. Vehicle must be level, both crosswise and
lengthwise. Camber should be properly adjusted.
2) If camber cannot be brought within limits and steering
axis inclination is correct, steering knuckle is bent. If camber and
steering axis inclination are both incorrect by approximately the
same amount, upper and lower control arms are bent.
3) Replace parts and recheck all wheel alignment
adjustments. Do not attempt to correct by straightening parts.
Fig. 5: Steering Axis Inclination
TORQUE SPECIFICATIONS
WHEEL LUG NUT TORQUE SPECIFICATIONS TABLE








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Application Ft. Lbs. (N.m)
Grand Wagoneer .................................. 85 (115)
All Other Models ................................ 75 (102)









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vehicle is at normal riding height.
* Steering wheel must be centered with wheels in straight ahead
position. If required, shorten one tie rod adjusting sleeve
and lengthen opposite sleeve (equal amount of turns). See
Fig. 2.
* Wheel bearings should have the correct preload and lug nuts
must be tightened to manufacturer's specifications. Adjust
camber, caster and toe-in using this sequence. Follow
instructions of the alignment equipment manufacturer.
CAUTION: Do not attempt to correct alignment by straightening parts.
Damaged parts must be replaced.
Fig. 2: Adjusting Tie Rod Sleeves (Top View)
CAMBER
1) Camber is the tilting of the wheel, outward at either top
or bottom, as viewed from front of vehicle. See Fig. 3.
2) When wheels tilts outward at the top (from centerline of
vehicle), camber is positive. When wheels tilt inward at top, camber
is negative. Amount of tilt is measured in degrees from vertical.

WIR IN G D IA G RAM S YM BO LS

1988 J e ep C hero ke e
WIRING DIAGRAMS
How To Use The Wiring Diagrams
WIRING DIAGRAMS
INTRODUCTION
The wiring diagrams and technical service bulletins,
containing wiring diagram changes, are obtained from the domestic and
import manufacturers. These are checked for accuracy and are all
redrawn into a consistent format for easy use.
All diagrams are arranged with the front of the vehicle at
the left side of the first page and the rear of the vehicle at the
right side of the last page. Accessories are shown near the end of the
diagram.
Components are shown in their approximate location on the
vehicle. Due to the constantly increasing number of components on
vehicles today, it is impossible to show exact locations.
In the past, when cars were simpler, diagrams were simpler.
All components were connected by wires, and diagrams seldom exceeded 4
pages in length. Today some wiring diagrams require more than 16
pages. It would be impractical to expect a service technician to trace
a wire from page 1 across every page to page 16.
Removing some of the wiring maze reduces eyestrain and time
wasted searching across several pages. Today, the majority of diagrams
now follow a much improved format, which permits space for internal
switch details and connector shapes.
Any wires that don't connect directly to their components are
identified on the diagram to indicate where they go. There is a legend
on the first page of each diagram, detailing component location. It
refers you to sub-systems, using grid NUMBERS at the top and bottom of
the page and grid LETTERS on each side. This grid system works in a
manner similar to that of a road map.
HOW TO USE THE WIRING DIAGRAMS
1) On the first page of the diagram, you will find a listing
of major electrical components or systems. Locate the specific
component or system you wish to trace. A grid number and letter will
follow the component's name.
2) Use the grid NUMBERS (arranged horizontally across the top\
and bottom of each page) to find the page of the wiring diagram that
contains the component you're seeking. When you reach this page, use
the grid LETTERS on the side of the page to determine the component's
vertical location.
3) Locate the circuit you need to service. The internals are
shown for switches and relays to assist you in understanding how the
circuit operates.
NOTE: In some of the newer wiring diagram articles in this
product, there is a Legend for the wiring diagrams that has
been created to make locating components easier. For these
articles, there will be a COMPONENT LOCATION MENU title in
the article main menu. These articles will also have the
original legend available on the first graphic.