JEEP CHEROKEE 1988 Service Repair Manual

Fig. 22: Single Injector - Known Good - Voltage Pattern
EXAMPLE #5 - CURRENT CONTROLLED DRIVER
These two known-good waveform patterns are from a Chrysler 3.
0L V6 VIN [3]. The first waveform, Fig. 23, is a dual trace pattern
that illustrates how Chrysler uses the rising edge of the engine speed
signal to trigger the injectors. The second waveform, Fig. 24, was
taken during hot idle, closed loop, and no load.

Fig. 23: Injector Bank - Known Good - Voltage Pattern

Fig. 24: Injector Bank - Known Good - Voltage Pattern
EXAMPLE #6 - CURRENT CONTROLLED DRIVER
This known-good pattern from a Ford 3.0L V6 PFI VIN [U]
illustrates that a zener diode inside the computer is used to clamp
the injector's inductive kick to 35-volts on this system. See Fig. 25.

Fig. 25: Injector Bank - Known Good - Voltage Pattern
EXAMPLE #7 - CURRENT CONTROLLED DRIVER
This known-good waveform from a Ford 5.0L V8 CFI VIN [F] was
taken during hot idle, closed loop, and no load. See Fig. 26.

Fig. 26: Single Injector - Known Good - Voltage Pattern
EXAMPLE #8 - CURRENT CONTROLLED DRIVER
These two known-good waveform patterns are from a GM 2.0L In-
Line 4 VIN [1]. Fig. 27 illustrates the 78 volt inductive spike that
indicates a zener diode is not used. The second waveform, Fig. 28, was
taken during hot idle, closed loop, and no load.

Fig. 27: Single Injector - Known Good - Voltage Pattern

Fig. 28: Single Injector - Known Good - Voltage Pattern

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

or backward tilt from vertical is viewed from side of vehicle. When
axis is tilted backward from vertical, caster is said to be positive,
creating a trailing action on front wheels. When axis is tilted
forward, caster is negative, causing a leading action on front wheels.
Fig. 2: Caster Angle
TOE
Toe is the measured difference in inches of distance between
the front edge of the tires and the rear edge of the tires at spindle
height. Toe can be measured in inches or degrees.
ADJUSTMENT
TOE
1) Measure toe with front wheels straight-ahead and steering
wheel locked in a centered position. Adjust toe by loosening clamps
and adjusting sleeve or adjusting ends on right and left tie rods
equally and in opposite directions to maintain steering wheel in
centered position.
2) If steering wheel is not centered to begin with,
determine which tire assembly is toed in or out more than the other

and compensate adjustment more to that side to center steering wheel.
A couple of tries will probably be necessary to properly center
steering wheel.
3) When tightening clamps, make sure that clamp bolts are
positioned so there will be no interference with other parts
throughout entire travel of steering linkage.
Fig. 3: Wheel Toe
To adjust, turn sleeves an equal amount in opposite directions.
TOE-OUT ON TURNS
1) This is a check for bent or damaged parts, and not a
service adjustment. With caster, camber and toe-in properly adjusted,
check toe-out with weight of vehicle on wheels.
2) Use full-floating turn table under each wheel. Turn left
wheel in 20 degrees on scale of turn table and read scale of turn
table on right wheel. Reading should be within 2 degrees of left
wheel. Repeat test for right wheel.
3) Incorrect readings of toe-out generally indicates a bent
steering arm. Replace arm and recheck wheel alignment adjustments. Do
not attempt to correct by straightening parts.