1988 JEEP CHEROKEE instrument panel

Remove retaining clip and cable self-adjusting clip from blend-air
door lever at bottom of blower housing. Remove cable by squeezing tabs
with needle nose pliers. Do not break housing.
INSTALLATION
To install, connect cable self-adjusting clip to blend-air
door lever, then snap cable into position. Install retaining clip onto
blend-air door lever. Route cable to A/C-heater control panel and
connect. Install control panel.
REMOVAL & INSTALLATION (WRANGLER)
1) Disconnect cables from vent doors. Disconnect cables from
heater control panel levers. Remove cables by squeezing tabs with
needle nose pliers.
2) Connect and adjust cables as described in ADJUSTMENTS
section of this article
HEATER CORE R & I
REMOVAL & INSTALLATION (CHEROKEE & COMANCHE)
1) Disconnect battery ground. Drain cooling system.
Disconnect heater hoses at heater core inlet and outlet tubes.
Disconnect blower motor wires and vent tube. Remove console (if
equipped). Remove lower instrument panel.
2) Disconnect electrical connectors from blower motor
resistors. Disconnect vacuum hose at vacuum motor. Cut plastic
retaining strap holding blower housing to heater core housing.
3) Disconnect and remove heater control cable. Detach clip at
rear of blower housing flange and remove retaining screws. Remove
housing mounting nuts from studs on engine compartment side of dash
panel. Remove right kick panel.
4) Remove instrument panel support bolt. Gently pull on right
side of dash, then rotate housing downward and toward rear of vehicle
to disengage housing studs from dash panel. Remove blower housing.
Detach retaining screws and remove heater core by pulling it straight
out of housing.
5) To install, reverse removal procedure. Ensure seal is
cemented in place to prevent movement when blower assembly is
installed. Connect heater hoses and fill cooling system.
REMOVAL & INSTALLATION (WRANGLER)
1) Disconnect battery ground. Drain about 2 quarts of coolant
from radiator. Disconnect heater hoses at heater core inlet and outlet
tubes. Disconnect vent door cables. Disconnect blower motor wires.
Disconnect defroster duct.
2) Remove nuts attaching heater housing studs to engine
compartment side of dash panel. Remove heater housing assembly by
tilting it downward, to disengage it from defroster duct.
3) Pull heater housing rearward and out from under instrument
panel. Remove heater housing cover from heater housing assembly.
Remove heater core from housing.
HEATER SYSTEM OPREATION CHART & VACUUM DIAGRAM
HEATER SYSTEM OPERATION TABLE







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MODE       

Fig. 3: Ignition Control Module Connector Identification
Courtesy of Chrysler Motors.
Terminal "B" of Connector No. 1 is grounded at the engine oil
dipstick bracket along with the ECU ground wire and Oxygen (O2) sensor\
ground.
The tachometer output signal wire of the ICM is connected to
Pin No. 1 of the "D1" Diagnostic connector. The wire is routed to the
diagnostic connector through a short section of the ECU harness, the
engine, and the instrument panel harness. This type of routing
eliminates any potential electrical interference from occurring in the
various ECU circuitry.
Ignition firing signals from ECU terminal "27" are
transmitted through terminal "B" of Connector No. 2 on the ICM. the
ignition signal from the ECU is received by the ICM in the form of a 5
volt square wave. As the leading edge of the wave contacts the
ignition circuitry in the ICM, the ICM charges the coil primary
windings.
When coil saturation occurs, the module circuitry opens the
primary windings to collapse the magnetic field in the windings. This
induces the coil secondary windings which is then transmitted to the
spark plug via the coil wire, distributor cap, and rotor.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
The MAP sensor reacts to absolute pressure in the intake
manifold and provides an input signal to the ECU. As the engine load
changes, manifold pressure varies, which causes the MAP sensor
resistance to change, resulting in a different input voltage to the
ECU. The input voltage level supplies the ECU with information
relating to ambient barometric pressure during engine start-up or
regarding engine load while the engine is running. The ECU calculates
this information and adjusts the air-fuel mixture accordingly.
The MAP sensor is mounted under the hood on the firewall and
is connected to the throttle body with a vacuum hose. See Fig. 4.

housing with 2 shoulder bolts. Tighten the engine speed sensor
shoulder bolts.
2) Connect the engine speed sensor wire connector.
ELECTRONIC CONTROL UNIT (ECU)
Removal
NOTE: The ECU is located below the instrument panel, between
the steering column and the A/C-Heater housing. See
Fig. 22. Three screws mount the ECU to a bracket.
1) Disconnect the negative battery cable.
2) Remove the 3 ECU attaching screws. See Fig. 23.
3) Disconnect the ECU wiring harness connector.
4) Remove the ECU.
Fig. 22: Location of ECU
Courtesy of Chrysler Motors.

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IN STR UM EN T P A N EL - S TA N DAR D

1988 J e ep C hero ke e
1988 Switches & Instrument Panels
JEEP
DESCRIPTION & OPERATION
Instrument panel is composed of speedometer housing,
tachometer and instrument cluster gauges.
FUEL GAUGE
System consists of a fuel gauge, an in-tank sending unit, and
appropriate wiring. Fuel gauge is grounded through variable resistor
of sending unit. A float attached to a slide rheostat follows fuel
level and varying resistance increases or decreases indicator reading.
TEMPERATURE GAUGE
System consists of gauge and sending unit and appropriate
wiring. The gauge is grounded through variable resistor of sending
unit. Changes in coolant temperature vary resistance in sending unit,
increasing or decreasing indication on gauge.
VOLTMETER
The voltmeter indicates regulated voltage to provide an
indication of charging system's ability to maintain battery charge.
OIL PRESSURE GAUGE
The oil pressure gauge system consists of gauge and a
variable resistance sending unit. Gauge needle, attached to bi-
metallic strip, responds to temperature changes.
REMOVAL & INSTALLATION
INSTRUMENT CLUSTER
Removal & Installation
1) Disconnect negative battery cable. On models with cruise
control, reach behind instrument cluster and disconnect speedometer
cable from speed switch. See Fig. 1.
2) On models without cruise control, raise vehicle on hoist.
Disconnect speedometer cable from transfer case (or transmission) and
at frame rail bracket. Move speedometer cable forward and upward to
provide slack. Lower vehicle.
3) On all models, remove instrument panel bezel screws and
bezel. Remove screws attaching cigarette lighter and switch housings
to instrument panel. Move housings aside.
4) Remove screws attaching cluster to instrument panel and
carefully pull cluster and speedometer toward rear of vehicle.
Disconnect wiring harness connectors.
5) Squeeze speedometer cable locking tabs and disconnect
cable from speedometer. See Fig. 1. Remove instrument cluster. To
install, reverse removal procedure.

the ENGINE PERFORMANCE section.
Fuel filter should be drained whenever "WATER IN FUEL"
warning light glows. Diesel fuel can damage asphalt and
painted surfaces. Always place a drain pan under fuel filter
to collect contaminated fuel. See Fig. 2.
1) Stop vehicle and turn engine off. Attach a long piece
of tubing to drain cock outlet. Place end of drain hose into
drain pan. Open filter assembly vent valve (Black + shaped
knob) and drain cock.
2) Drain approximately 1/2 pint (.24 Liters) from fuel
filter. Close vent valve and drain cock. Start engine and
check for leaks. If "WATER IN FUEL" warning lamp comes on
again, remove water contaminated fuel from fuel lines and
fuel tank.
WARNING: DO NOT bleed fuel lines on hot engine, as high exhaust
temperatures could cause fire. Use care when bleeding fuel
lines, as fuel is under extreme pressure and could penetrate
skin, causing personal injury. Wear safety goggles and
protective clothing when bleeding fuel lines.
CAUTION: DO NOT drain fuel/water separator when engine is running or
hot. Allow engine to cool before draining. Verify that the
WATER IN FUEL light on instrument panel is OFF.
Fig. 3: Locking Crankshaft at TDC
Courtesy of American Motors/Jeep Corp.

1 - 25 Amp
Rear Washer/Wiper
2 - 15 Amp
Radio, Cigarette Lighter
3 - 25 Amp
Blower Motor
4 - 20 Amp
Turn Signal, Back-Up Lights, Rear Window Defogger Relay
5 - 10 Amp
Dome Light, Courtesy Lights, Glove Box Light, Cargo Light,
Radio Memory, Power Mirrors, Teltak Connector
6 - 15 Amp
Hazard Warning System, Stoplights
7 - 10 Amp
Parking Lights, Headlight Warning Chime/Buzzer, Instrument
Panel Light Dimmer
8 - 7.5 Amp
Gauges, Instrument Cluster, Seat Belt Warning,
Headlight Delay, Chime Module, Overhead Console
9 - 5 Amp
Instrument Panel Illumination
10 - 25 Amp
Rear Window Defogger
11 - 30 Amp (Circuit Breaker)
Power Door Locks, Power Seats, Trailer Towing Wiring Harness
12 - 10 Amp
ETR Radio, Power Antenna
13 - Not Used (1984-87)
7.5 Amp (1988)
Transmission Control Unit
14 - 25 Amp
Headlight Delay, Horns, Security Alarm
15 - 5.5 Amp (Circuit Breaker)
Front Wiper
16 - 30 Amp (Circuit Breaker)
Power Windows
17 - 10 Amp
Clock, Security Alarm (IGN)

PO W ER W IN DO W S

1988 J e ep C hero ke e
1988 Power Windows
JEEP SIDE & TAILGATE WINDOWS
Cherokee, Comanche, Grand
Wagoneer, Wagoneer
DESCRIPTION
All models have a tape-driven window regulator system in the
side doors, and a mechanical regulator in rear door of Grand Wagoneer.
On Grand Wagoneer, the tailgate window operates on 2 circuits, from an
instrument panel switch or an external key switch at the tailgate.
Side windows are operated by individual switches at each door, or by a
complete set of control switches at the instrument panel or drivers
door. The system is protected by a 30 amp circuit breaker in the fuse
panel.
TESTING
NOTE: Ensure instrument panel tailgate switch is properly grounded
as motor grounds through switch. The electric tailgate and
defogger switch are serviced as an assembly.
INSTRUMENT PANEL TAILGATE SWITCH
Grand Wagoneer
1) Turn ignition on. Using a 12-volt test light, connect one
end of test light to ground and probe Red wire. If test light does not
glow, repair feed circuit.
2) If test light glows, probe Brown wire with switch in "UP"
position. If test light does not glow, replace switch. If test light
glows, move switch to "DOWN" position and probe Tan wire. If test
light does not glow, replace switch. If test light glows, check
tailgate window switch.
TAILGATE WINDOW SWITCH
Grand Wagoneer
1) Using a 12-volt test light, connect one end of test light
to ground and probe Red wire of tailgate window switch. If test light
does not glow, repair feed circuit.
2) If test light glows, probe Tan wire. Turn tailgate switch
to "DOWN" position. If test light does not glow, replace switch. If
test light glows, probe Brown wire. Turn tailgate switch to "UP"
position.
3) If test light does not glow, replace switch. If test light
glows, check tailgate window safety switch.
TAILGATE WINDOW SAFETY SWITCH
Grand Wagoneer
1) Using a 12-volt test light, connect one end of test light
to ground and probe Brown wire of safety switch. Turn tailgate switch
to "UP" position. If test light glows, voltage is present at switch.
If test light does not glow, check feed circuit and repair as
necessary.
2) Probe Brown wire. Turn tailgate switch to "UP" position
and close safety switch. If test light does not glow, replace switch.

at road speeds, it may indicate that the ABS system has detected a
malfunction or has become inoperative. The system reverts to standard
non-anit-lock brakes. If both Red BRAKE light and Amber CHECK ANTI-
LOCK light are on, have vehicle serviced immediately.
Fig. 1: Instrument Panel Interior Controls
Courtesy of Chrysler Motors.
Fig. 2: Dash Gauges & Warning Lights (Gasoline Engines)
Courtesy of Chrysler Motors.