warning JEEP CHEROKEE 1988 Service User Guide

FUEL PRESSURE REGULATOR
WARNING: Always relieve residual fuel pressure in fuel delivery
system before opening system. To prevent chance of personal
injury, cover fittings with shop towel while disconnecting
fittings.
Removal & Installation
Remove injector fuel rail assembly. Remove 2 pressure
regulator retaining screws. Remove regulator from fuel rail. To
install, reverse removal procedure. Adjust regulator after
installation.
IDLE SPEED STEPPER (ISS) MOTOR
Removal & Installation
1) Disconnect ISS motor connector. Remove ISS motor
retaining screws and ISS motor. To install, reverse removal
procedure. No idle speed adjustment is necessary. Idle speed is
controlled by the Electronic Control Unit (ECU).
THROTTLE POSITION SENSOR
Removal & Installation
Disconnect TPS wire connector. Bend retaining bolts lock
tabs and remove retaining bolts. Remove TPS from throttle plate
assembly. To install, reverse removal procedure. Adjust TPS after
installation. See ADJUSTMENTS in this article.
EGR VALVE
Removal & Installation
Disconnect vacuum hose from EGR valve. Remove bolts which
hold EGR valve to intake manifold. Remove valve and discard gasket.
Clean intake manifold gasket mating surface. To install valve,
reverse removal procedure. Always use new gasket. See Fig. 8.

IDLE SPEED ACTUATOR (ISA) MOTOR
1) Adjust ISA motor plunger to establish initial position of
plunger only if motor has been removed or replaced. Remove air filter
elbow and start engine. Run engine until engine reaches normal
operating temperature. Turn A/C off (if equipped).
2) Connect tachometer leads to diagnostic connector D1,
attaching negative lead to terminal D1-3 and positive lead to
terminal D1-1. See Fig. 4. Turn ignition off. ISA motor plunger
should move to fully extended position.
3) When ISA motor plunger is fully extended, disconnect ISA
motor wiring connector and start engine. Engine speed should be
3300-3700 RPM. If incorrect, turn hex head screw at end of plunger to
provide engine speed of 3500 RPM.
4) Fully retract ISA motor by holding closed throttle (idle)\
switch plunger inward as throttle is opened. Closed throttle switch
plunger should not touch throttle lever in closed position. If
contact is made, check linkage and/or cable for binding or damage.
Repair as necessary.
5) Connect ISA motor wiring harness connector and turn
ignition off for 10 seconds. ISA motor should move to fully extended
position. Start engine. Engine speed should be 3500 RPM for short
period of time and then decrease to normal idle speed.
6) Turn ignition off. Disconnect tachometer. After final
adjustment of ISA motor, use thread penetrating sealant (Loctite 290)
on adjustment screw to prevent movement and maintain adjustment.
NOTE: If adjustment screw must be moved after thread sealant
hardens, loosen threads by heating screw with flameless heat
such as soldering gun. DO NOT use flame or torch type of
heat as damage to ISA motor will result.
FUEL PRESSURE REGULATOR
WARNING: Always relieve residual fuel pressure in fuel delivery
system before opening system. To prevent chance of personal
injury, cover fittings with shop towel while disconnecting
fittings.
1) Replacement fuel pressure regulator must be adjusted to
establish correct pressure. Remove air filter elbow and hose. Connect
tachometer leads to diagnostic connector D1, attaching negative lead
to terminal D1-3 and positive lead to terminal D1-1. See Fig. 4.
Remove screw plug and install fuel pressure test fitting.
NOTE: Fuel pressure test fitting is not included with throttle
body. Fitting (8983 501 572) must be obtained separately.
2) Connect fuel pressure gauge to test fitting. Start engine
and increase speed to approximately 2000 RPM. Turn Torx head screw at
bottom of regulator to set correct pressure. Turning screw inward
increases pressure and turning screw outward decreases pressure. See
Fig. 3 .
3) All models require fuel pressure of 14.5 psi (1.0 kg/cm
).
Install lead sealing ball to cover regulator adjustment
screw after adjusting fuel pressure. Turn ignition off. Remove
measuring equipment and test fitting. Install original plug screw and
air filter assembly.

COOLANT TEMPERATURE SENSOR (CTS)
Removal & Installation
Allow engine to cool down. Disconnect CTS wiring harness.
Remove CTS from intake manifold and rapidly plug hole to prevent
coolant loss. Install replacement CTS and connect CTS wiring harness.
FUEL INJECTOR
WARNING: Always relieve residual fuel pressure in fuel delivery
system before opening system. To prevent chance of personal
injury, cover fittings with shop towel while disconnecting
fittings.
Removal
Remove air cleaner assemby. Remove injector wiring
connector. Remove injector retainer screws and clip. Using small
pliers, carefully grasp center collar of injector between electrical
terminals and carefully remove injector with lifting/twisting motion.
Discard both "O" rings. See Fig. 6.
Installation
1) Using light oil, lubricate new upper and lower "O" rings.
Install "O" rings in housing bore. Install back-up ring over upper
"O" ring. Position replacement injector in fuel body.
2) Center nozzle in lower housing bore and use a
pushing/twisting motion to seat injector. Align wire connectors in
proper orientation. Install retainer clip and screws. Connect
injector wiring. Install air cleaner.
Fig. 6: Fuel Injector & Throttle Body Assembly
Courtesy of Chrysler Motors.
FUEL PRESSURE REGULATOR

Removal & Installation
WARNING: Always relieve residual fuel pressure in fuel delivery
system before opening system. To prevent chance of personal
injury, cover fittings with shop towel while disconnecting
fittings.
With throttle body assembly removed, remove 3 screws holding
fuel pressure regulator in throttle body. Remove fuel pressure
regulator assembly. Note location of components for installation.
Discard gaskets. To install, reverse removal procedure. Adjust
regulator after installation. See ADJUSTMENTS in this article.
IDLE SPEED ACTUATOR (ISA) MOTOR
Removal & Installation
1) Disconnect throttle return spring. Disconnect wiring
harness connector from ISA motor. Remove ISA motor retaining nuts and
remove ISA motor from bracket.
2) To install ISA motor assembly, reverse removal procedure.
Adjust ISA motor after installation. See ADJUSTMENTS in this article.
THROTTLE BODY ASSEMBLY
Removal
1) Remove air inlet duct and adapter plate. Remove throttle
cable and return spring. Disconnect electrical leads from fuel
injector, WOT switch, and ISA motor.
2) Disconnect fuel supply and return lines at throttle body.
See Fig. 7 . Tag and disconnect vacuum hoses. Disconnect TPS wiring.
Remove throttle body assembly. If throttle body assembly is being
replaced, transfer ISA motor and WOT switch bracket assembly to new
unit.
Installation
Install replacement throttle body assembly on manifold using
new gasket. Reconnect all hoses, wires and cable in reverse order of
disassembly. Adjust ISA motor after installation. See ADJUSTMENTS in
this article.
Fig. 7: Intake Manifold & Throttle Body Assembly
Courtesy of Chrysler Motors.
THROTTLE POSITION SENSOR

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).
CAUTIONS & WARNINGS
REPLACING BLOWN FUSES
Before replacing a blown fuse, remove ignition key, turn off
all lights and accessories to avoid damaging the electrical system. Be
sure to use fuse with the correct indicated amperage rating. The use
of an incorrect amperage rating fuse may result in a dangerous

electrical system overload.
BATTERY WARNING
WARNING: When battery is disconnected, vehicles equipped with
computers may lose memory data. When battery power is
restored, driveability problems may exist on some
vehicles. These vehicles may require a relearn procedure.
See the COMPUTER RELEARN PROCEDURES article in GENERAL
INFORMATION section.
ELECTROSTATIC DISCHARGE SENSITIVE (ESD) PARTS
WARNING: Many solid state electrical components can be damaged by
static electricity (ESD). Some will display a warning label,
but many will not. Discharge personal static electricity by
touching a metal ground point on the vehicle prior to
servicing any ESD sensitive component.
HALOGEN BULBS
Halogen bulbs contain pressurized gas which may explode if
overheated. DO NOT touch glass portion of bulb with bare hands. Eye
protection should be worn when handling or working around halogen
bulbs.
RADIATOR CAP
CAUTION: Always disconnect the fan motor when working near the
radiator fan. The fan is temperature controlled and could
start at any time even when the ignition key is in the OFF
position. DO NOT loosen or remove radiator cap when cooling
system is hot.

WARNING: The knock sensor MUST be tightened to the EXACT torque
specified in order to ensure proper operation.
1) Install the knock sensor to the cylinder block. Tighten
the knock sensor to 89 INCH Lbs. (10 Nm).
2) Connect the knock sensor wire connector.
3) Lower vehicle.
ENGINE SPEED SENSOR
Removal
1) Remove engine speed sensor wire connector. See Fig. 21.
2) Remove the engine speed sensor-to-transmission housing
attaching bolts. Remove engine speed sensor from transmission housing.
Fig. 21: Engine Speed Sensor Mounting Bolts
Courtesy of Chrysler Motors.
Installation
1) Install the engine speed sensor to the transmission

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.

BATTERY SPECIFICATIONS
CAUTION: When battery is disconnected, vehicles equipped with
computers may lose memory data. When battery power is
restored, driveability problems may exist on some vehicles.
These vehicles may require a relearn procedure. See COMPUTER
RELEARN PROCEDURES article in the GENERAL INFORMATION
section.
All gasoline engine equipped models use group 58 batteries
with 390 or 475 amp cold crank rating. Models with 2.1L Turbo Diesel
engine use group 24 batteries with a 815 amp cold crank rating.
CAUTIONS & WARNINGS
REPLACING BLOWN FUSES
Before replacing a blown fuse, remove ignition key, turn off
all lights and accessories to avoid damaging the electrical system. Be
sure to use fuse with the correct indicated amperage rating. The use
of an incorrect amperage rating fuse may result in a dangerous
electrical system overload.
BATTERY WARNING
WARNING: When battery is disconnected, vehicles equipped with
computers may lose memory data. When battery power is
restored, driveability problems may exist on some vehicles.
These vehicles may require a relearn procedure. See COMPUTER
RELEARN PROCEDURES article in GENERAL INFORMATION section.
BRAKE PAD WEAR INDICATOR
Indicator will cause a squealing or scraping noise, warning
that brake pads need replacement.
DIESEL FUEL ANTI-FUNGAL ADDITIVES
CAUTION: If fuel contamination due to fungi or other microorganisms is
suspected a fuel additive with a biocide may be used. Follow
the manufacturers dosage as recommended on product label. Use
biocides ONLY when necessary, excessive use can may cause
other fuel system problems.
DIESEL FUEL CONTAMINATION
WARNING: Diesel fuel system may be contaminated with fungi or other
microorganisms. Keep contaminated fuel away from open skin
cuts or sores to prevent skin irritation or infection.
DIESEL FUEL REQUIREMENTS
CAUTION: All diesel engines are to use Diesel Fuel #2 when the outside
temperature is above 20\bF (-7\bC). In temperatures that are
below 20\bF (-7\bC) use Diesel Fuel #1, this will reduce the
chance of the fuel thickening and forming wax.
Note: A Diesel Fuel #1 & #2 combination (Blended Fuel) may be\
used, and is recommended for mild winter driving.

ELECTROSTATIC DISCHARGE SENSITIVE (ESD) PARTS
WARNING: Many solid state electrical components can be damaged by
static electricity (ESD). Some will display a warning label,
but many will not. Discharge personal static electricity by
touching a metal ground point on the vehicle prior to
servicing any ESD sensitive component.
ENGINE OIL
CAUTION: Never use non-detergent or straight mineral oil.
CAUTION: Do not use reclaimed fluid, mineral oil, fluid that was
stored in old or open containers, or fluid inferior to AMC
Standard AM 4101. Be sure to handle the fluid in clean
containers that will not introduce even a slight amount of
foreign liquids or particles. Such contamination of fluid
could lead to hydraulic system failure.
ENGINE OIL FILTER (GASOLINE)
CAUTION: Verify that proper Oil Filter is being used. Filters with
metric threads (M20 x 1.5) must be used with some engines.
Other engines use SAE type (3/4" x 16) threads, and must
use an oil filter with these threads. Possible engine damage
can occur with improper oil filter.
ENGINE OIL FILTER (TURBO DIESEL ONLY)
CAUTION: The engine oil filter has METRIC threads. Use of a filter
with improper threads can result in oil leakage and
possible engine damage. Look for thread size symbol M20x1.5
on filter.
FUEL SYSTEM SERVICE
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.
WARNING: Relieve fuel system pressure prior to servicing any fuel
system component.
HALOGEN BULBS
Halogen bulbs contain pressurized gas which may explode if
overheated. DO NOT touch glass portion of bulb with bare hands. Eye
protection should be worn when handling or working around halogen
bulbs.
RADIATOR CAP
CAUTION: Always disconnect the fan motor when working near the
radiator fan. The fan is temperature controlled and could
start at any time even when the ignition key is in the OFF
position. DO NOT loosen or remove radiator cap when cooling
system is hot.
STARTING FLUID USE (TURBO DIESEL)