engine JEEP CHEROKEE 1988 Service Repair Manual

Fig. 9: Injector Even Bank w/Normal Current Flow - Current Pattern
EXAMPLE #3 - VOLTAGE CONTROLLED DRIVER
Example #3 is of a Ford 5.0L V8 SEFI. Fig. 10 shows a
waveform of an individual injector at idle with the Lab Scope set on
200 milliamps per division. Notice the dimple in the rising edge. This
dimple indicates the actual opening of the injector (set point)
occurred at 400 milliamps and current peaked at 750 milliamps. This is
a good specification for this engine.
The next waveform pattern in Fig. 11 shows an abnormality
with another injector. With the Lab Scope set on 500 milliamps per
division, you can see that the current waveform indicates a 1200
milliamp draw. This is a faulty injector.
Abnormally low resistance injectors create excessive current
draw, causing rough idle, and possible computer driver damage.
Fig. 10: Single Injector w/Normal Current Flow - Current Pattern

PFI VIN [3]. It is a perfect example of the peak and hold theory. The
waveform shows a 1-amp per division current flow, ramping to 4 amps
and then decreasing to 1-amp to hold the injector open.
Fig. 13: Injector Bank w/Normal Current Flow - Current Pattern
EXAMPLE #6 - CURRENT CONTROLLED DRIVER
This next known-good waveform is from a Ford 5.0L V8 CFI VIN
[F]. See Fig. 14. The pattern, which is set on a 250 milliamps scale,
indicates a 1.25 amp peak draw and a hold at 350 milliamps.
Fig. 14: Single Injector w/Normal Current Flow - Current Pattern
EXAMPLE #7 - CURRENT CONTROLLED DRIVER
The known-good current controlled type waveform in Fig. 15 is
from a GM 2.0L TBI VIN [1]. With the lab scope set at 2 amps per
division, notice that this system peaks at 4 amps and holds at 1 amp.
The next waveform is from the same type of engine, except

Fig. 17: Single Injector w/Normal Current Flow - Current Pattern
VOLTAGE WAVEFORM SAMPLES
EXAMPLE #1 - VOLTAGE CONTROLLED DRIVER
These two known-good waveform patterns are from a Ford 4.6L
V8 VIN [W]. Fig. 18 illustrates the 64 volt inductive kick on this
engine, indicating no clamping is occurring. The second pattern,
Fig. 19 , was taken during hot idle, closed loop, and no load.

Fig. 21: Injector Bank - Known Good - Voltage Pattern
EXAMPLE #4 - CURRENT CONTROLLED DRIVER
From 1984 to 1987, Chrysler used this type injector drive on
their TBI-equipped engines. See Fig. 22 for a known-good pattern.
Instead of the ground side controlling the injector, Chrysler
permanently grounds out the injector and switches the power feed side.
Most systems do not work this way.
These injectors peak at 6 amps of current flow and hold at 1
amp.

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.

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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.

Fig. 1: Identifying Tie-Off Symbols
4) If the wires are not drawn all the way to another
component (across several pages), a reference will tell you their
final destination.
5) Again, use the legend on the first page of the wiring
diagram to determine the grid number and letter of the referenced
component. You can then turn directly to it without tracing wires
across several pages.
6) The symbols shown in Fig. 1 are called tie-offs. The first
tie-off shown indicates that the circuit goes to the temperature
sensor, and is also a ground circuit.
7) The second symbol indicates that the circuit goes to a
battery positive parallel circuit. The third symbol leads to a
particular component and the location is also given.
8) The lines shown in Fig. 2 are called options. Which path
or option to take depends on what engine or systems the vehicle has.

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)

Fig. 1: Engine Compartment & Headlights

Fig. 2: Computer Engine Control (6-Cyl)