light JEEP CHEROKEE 1988 Service Repair Manual

a good injector will be 60 or more volts.
At Point "E", notice that the trace is now just a few volts
below system voltage and the injector is in the current limiting, or
the "Hold" part of the pattern. This line will either remain flat and
stable as shown here, or will cycle up and down rapidly. Both are
normal methods to limit current flow. Any distortion may indicate
shorted windings.
Point "F" is the actual turn-off point of the driver (and
injector). To measure the millisecond on-time of the injector, measure
between points "C" and "F". Note that we used cursors to do it for us;
they are measuring a 2.56 mS on-time.
The top of Point "F" (second inductive kick) is created by
the collapsing magnetic field caused by the final turn-off of the
driver. This spike should be like the spike on top of point "D".
Point "G" shows a slight hump. This is actually the
mechanical injector pintle closing. Recall that moving an iron core
through a magnetic field will create a voltage surge. The pintle is
the iron core here.
This pintle hump at Point "E" should occur near the end of
the downward slope, and not afterwards. If it does occur after the
slope has ended and the voltage has stabilized, it is because the
pintle is slightly sticking. Some older Nissan TBI systems suffered
from this.
If you see more than one hump it is because of a distorted
pintle or seat. This faulty condition is known as "pintle float".
It is important to realize that it takes a good digital
storage oscilloscope or analog lab scope to see this pintle hump
clearly. Unfortunately, it cannot always be seen.
Fig. 3: Identifying Current Controlled Type Injector Pattern

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WIP ER /W ASH ER S YSTE M

1988 J e ep C hero ke e
1988 Wiper/Washer Systems
JEEP
All Models
DESCRIPTION
Jeep vehicles use a 2-speed electric motor, which is a
compound wound (series and shunt) type. A crank arm, attached
externally to gear shaft, operates linkage which activates wiper
blades.
All models have an optional intermittent feature. All models
use an electric washer system consisting of a motor, reservoir, and
necessary hoses and nozzles.
Some Cherokee and Wagoneer models are equipped with rear
wipers. The rear motor is a single-speed motor with an automatic park
feature. The circuit is protected by a separate 4.5-amp circuit
breaker attached to brake pedal support.
TROUBLE SHOOTING
WIPER INOPERATIVE OR OPERATES AT ONE SPEED ONLY
1) If wiper does not operate on either speed, check for
binding or interference of linkage. If okay, place wiper switch on
"LO" and then on "HI" setting. Connect a test light between terminals
of wiring harness plug that connects to motor.
2) Check for power at White wire with tracer and Black
(ground) wire terminal for low speed. Check between Dk. Blue with
tracer and Black wire terminal for high speed.
3) If light does not glow, check ignition switch, wiper
switch, harness or terminals for open circuits. If light glows, check
for loose or misaligned connection between wiring harness plug and
motor plug. If okay, replace wiper motor.
WIPERS DO NOT PARK
1) Disconnect motor and connect Gray lead to White lead.
Apply 12 volts to Blue lead. Replace motor if it fails to park. If it
parks, turn ignition switch on, and wiper switch to "PARK".
2) Connect a test light to Lt. Green wire with tracer and to
ground at motor plug.
3) Check continuity between Tan wire with tracer and White
wire with tracer.
4) If test light does not glow, check harness connections
between motor and instrument panel switch. If okay, replace panel
switch. If not okay, repair harness connection.
WIPER MOTOR QUITS WHILE WIPING
1) With engine idling and blower motor on high, operate
wipers at high speed setting for 5 cycles consisting of 3 seconds of
water and 57 seconds of drying.
2) If motor struggles to a complete stop, clean glass and
replace blades. Repeat test. If motor stops, test circuit breaker in
panel switch. If motor stopped suddenly in original test, check
circuit breaker. Repeat test. If motor stops, replace motor.

ALL FUNCTIONS OKAY EXCEPT INTERMITTENT WIPE
1) If blades stop and start erratically, test circuit
breaker. If okay, check wiper switch continuity. If continuity is
present, check continuity of wiring between switch, governor and
ground. Repair wiring or replace governor as necessary.
2) If operation is intermittent on low speed only, check for
loose connections at governor by disconnecting governor and connecting
switch directly to instrument panel harness.
3) If all functions except pulse and mist work, replace
governor. If functions are not okay, recheck wiring and replace
governor.
WINDSHIELD WASHER DOES NOT OPERATE
1) If motor runs but does not pump, check fluid level. If
level is okay, check for split, loose, pinched or kinked hoses. Check
for restrictions at nozzles. Check for reversed wire leads to motor.
2) If motor does not run, check for blown fuse. Replace fuse,
if necessary. If fuse is okay, disconnect plug at reservoir and check
for power by connecting a test light across connector terminals.
Energize washer circuit by closing washer and ignition switches.
3) If no power is present, check for open ground wire or
defective wiper/washer switch. Repair or replace as necessary. If
power is present, reconnect plug to motor and check for tight
connection. If motor does not run, replace pump motor.
REMOVAL & INSTALLATION
REAR WIPER SWITCH
Removal & Installation
Remove instrument panel bezel and switch housing panel.
Disconnect switch connector, slightly depress switch mounting tabs and
remove switch. To install, reverse removal procedure.
REAR WIPER MOTOR
Removal & Installation
1) Remove wiper arm from pivot pin by depressing tab and
pulling arm straight out. Disconnect washer hose. Remove pivot pin
retaining nut and interior trim panel. Remove rear wiper motor
attaching screws and remove wiper motor.
2) To install, reverse removal procedure. Wiper blade should
be parallel to window in parked position (3/8-3/4" from bottom of
window) and come no closer than 3/16" to window seal when operated on
a wet window.
WINDSHIELD WIPER MOTOR
Removal & Installation
Remove wiper arm assemblies by lifting blades off windshield
and pulling out tab that locks blade in up position. Remove cowl trim
panel. Disconnect washer hose. Remove cowl mounting bracket attaching
nuts and pivot pin screws. Disconnect wiring harness and remove wiper
motor. To install, reverse removal procedure.

Fig. 2: Identifying Option Symbols
COLOR ABBREVIATIONS IDENTIFICATION
COLOR ABBREVIATIONS








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Color Normal Optional
Black .................. BLK ................... BK
Blue ................... BLU ................... BU
Brown .................. BRN ................... BN
Clear .................. CLR ................... CR
Dark Blue ............ DK BLU ............... DK BU
Dark Green ........... DK GRN ............... DK GN
Green .................. GRN ................... GN
Gray ................... GRY ................... GY
Light Blue ........... LT BLU ............... LT BU
Light Green .......... LT GRN ............... LT GN
Orange ................. ORG ................... OG
Pink ................... PNK ................... PK
Purple ................. PPL ................... PL
Red .................... RED ................... RD
Tan .................... TAN ................... TN

Fig. 8: Diode (Light Emitting)
Fig. 9: Defogger Grid
Fig. 10: Fuse
Fig. 11: Fusible Link
Fig. 12: Ground
Fig. 13: Glow Plug Resistor (In-Line) or Mirror Heater

WIR IN G D IA G RAM S

1988 J e ep C hero ke e
1988 Wiring Diagrams
Jeep
Cherokee & Wagoneer
IDENTIFICATION
COMPONENT LOCATION MENU
COMPONENT LOCATIONS TABLE








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Component Figure No. (Location)
A/C & Htr Systems ............................... 5 (A-D 16-19)
Alternator ............................................ 1 (C 3)
Audio Alarm Module ................................... 7 (D 27)
Back-Up Lt Sw (M/T) .................................. 4 (D 12)
Battery ............................................... 1 (A 2)
Beam Sel Sw .......................................... 6 (E 23)
Brake Warning Sw ..................................... 6 (C 20)
Clock ................................................ 7 (E 27)
Clutch Switch ........................................ 4 (E 15)
Courtesy Lights ................................... 7 (C 24-26)
Cruise Ctrl Sys ................................... 4 (E 12-15)
Diag Conn D1 (2.5L) ................................... 3 (B 9)
Diag Conn D1 (4.0L) ................................... 2 (B 4)
Diag Conn D2 (2.5L) .................................. 3 (B 11)
Diag Conn D2 (4.0L) ................................... 2 (B 7)
DIR Hazard Sw ................................... 6 (D-E 20-21)
Door Switches ........................................ 7 (C 27)
Elect Ctrl Unit (2.5L) ............................. 3 (A 9-10)
Elect Ctrl Unit (4.0L) .............................. 2 (A 4-7)
Engine Compartment Lt ................................. 1 (C 1)
Fog Light Relay ....................................... 1 (D 2)
Fog Light Sw ...................................... 6 (E 21-22)
Fuel Pump Rly (2.5L) .................................. 3 (C 9)
Fuel Pump Rly (4.0L) ................................ 2 (E 5-6)
Fuel Tank Unit ....................................... 6 (B 20)
Fus Links ........................................... 1 (B 2-3)
Fuse Block ...................................... 4 (B-D 12-15)
4WD Switch ..................................... 6 (C 20, D 21)
Gear Sel Sw .......................................... 5 (C 16)
Glove Box Light ...................................... 7 (C 25)
Headlight Delay Module ............................... 6 (E 23)
Headlight Switch .................................. 6 (D 22-23)
Horn Relay ............................................ 1 (C 2)
Ignition Ctrl Mod (2.5L) ............................ 3 (B-C 8)
Ignition Ctrl Module (4.0L) ........................... 2 (E 4)
Ignition Key Warn Sw ................................. 7 (D 26)
Ignition Switch ................................... 4 (A 12-15)
Illum Lights .................................... 7 (C-D 24-25)
Instrument Cluster .............................. 6 (A-C 22-23)
Keyless Entry Module .............................. 7 (B 24-25)
Latch Rly (B+) (4.0L) ............................... 2 (B-C 4)
Power Antenna Rly .................................. 7 (D-E 27)
Power/Comfort Sw ..................................... 5 (D 19)
Power Door Lock Sys ............................. 7 (A-C 24-27)
Power Mirror Sw ................................. 7 (D-E 24-25)
Power Seat Sw ................................... 8 (A-B 28-29)

Power Window Sys ................................ 7 (A-C 24-27)
Radiator Fan Rly (4.0L) ............................. 1 (C 1-2)
Radiator Fan Diode Assy ............................... 1 (C 3)
Radiator Temp Switch .................................. 1 (C 3)
Rear Defogger Unit ................................ 8 (D 28-29)
Rear Wiper/Washer Unit .......................... 8 (B-C 29-30)
Resistor Pack ........................................ 6 (E 21)
Rt Fnt Door Lock/Window Switch .................... 7 (B 26-27)
Starter Solenoid .................................... 1 (A 2-3)
Starter Solenoid Relay ................................ 1 (A 2)
Stop Light Switch .................................... 4 (E 15)
Trailer Towing Harness (Cherokee) ................. 8 (E 28-31)
Trailer Towing Harness (Wagoneer) ................. 8 (A 28-31)
Trans Ctrl Unit ................................. 5 (D-E 16-19)
Upshift Sw (2.5L) .................................... 6 (C 21)
Vanity Lights ........................................ 7 (C 24)
Washer Fluid Level Sw ................................ 3 (D 11)
Wiper/Washer System .............................. 3 (D-E 8-11)









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WIRING DIAGRAMS

Fig. 1: Engine Compartment & Headlights

Fig. 8: Passenger Compartment & Tail Lights