JEEP CHEROKEE 1988 Service Repair Manual

throttle body. Connect Exerciser Tool (Part No. 8980 002 646) into
ISS motor. See Fig. 6.
3) Connect Red clip to battery positive cable. Connect
Black clip to battery negative cable. Red light on exerciser tool
will illuminate when properly connected. Start engine.
NOTE: When switch on exerciser tool is in "High" or "Low"
position, light on exerciser tool will flash indicating
voltage pulses are being sent to ISS motor.
4) Move exerciser tool switch to "High" position. Engine
speed should increase. Move switch to "Low" position. Engine speed
should decrease. If engine speed increases or decreases while using
exerciser tool, ISS motor is functioning properly.
5) Disconnect exerciser tool and reconnect ISS motor
connector. If engine speed does not change, turn ignition off and
remove ISS motor from throttle body.
6) With ignition off, switch exerciser tool between "High"
and "Low" positions. Check movement of ISS motor pintle. Pintle
should move in and out. If pintle does not move, replace ISS motor.
7) Start engine and test new ISS motor for proper
operation. If pintle operates properly, check ISS motor bore in
throttle body for blockage and clean as necessary. Reinstall ISS
motor into throttle body.
Fig. 6: ISS Motor Test Connector
Courtesy of Chrysler Motors.
Fuel Injector Test

See FUEL INJECTOR TEST PROCEDURE chart in this article.
REMOVAL & INSTALLATION
COOLANT TEMPERATURE SENSOR (CTS)
Removal & Installation
Drain cooling system. Remove air cleaner assembly.
Disconnect CTS wire connector. Remove CTS from engine block. Install
replacement CTS and connect CTS wire connector. Install air cleaner
assembly. Fill cooling system.
OXYGEN SENSOR
Removal & Installation
Raise and support vehicle. Disconnect O2 sensor wire
connector. Remove O2 sensor from exhaust manifold. Install O2 sensor
and tighten to 30 ft. lbs. (41 N.m). Connect O2 sensor wire connector
and lower vehicle.
KNOCK SENSOR
Removal & Installation
Raise and support vehicle. Disconnect knock sensor wire
connector. Remove knock sensor from cylinder block. Install knock
sensor and connect knock sensor wire connector. Lower vehicle.
SPEED SENSOR
Removal & Installation
Disconnect speed sensor wire connector. Remove 2 speed
sensor retaining bolts at transmission housing. Install speed sensor
and connect speed sensor wire connector.
STARTER MOTOR RELAY
Removal & Installation
Disconnect negative battery cable. Identify, tag and
disconnect wiring to relay. Remove relay retaining screws and remove
relay from inner fender panel. Install replacement relay and connect
relay wires. Connect negative battery cable. Test relay operation.
MANIFOLD AIR/FUEL TEMPERATURE (MAT) SENSOR
Removal & Installation
Disconnect wire connector from MAT sensor. Remove MAT sensor
from intake manifold. To install, reverse removal procedure.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
Removal & Installation
Disconnect wire connector, vacuum hose, and retaining nuts
from MAP sensor. Remove sensor from firewall. To install, reverse
removal procedure.
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
Disconnect fuel lines from fuel rail assembly. Disconnect
injector wire harness connector. Remove fuel rail retaining bolts.
Remove vacuum hose from fuel pressure regulator valve. Remove fuel
injector retaining clips and remove fuel injectors. See Fig. 7. On
models with (A/T), it may be necessary to remove throttle pressure
cable and bracket to remove fuel rail assembly.
NOTE: O-rings must be replaced before fuel lines are reassembled.
Installation
Install fuel injectors into fuel rail assembly and install
retaining clips. Position fuel rail onto manifold while lining up
injectors with holes in intake manifold. Secure injector retaining
bolts. Connect injector wire connectors to proper injectors. Install
fuel lines into fuel rail assembly. Connect vacuum hose to pressure
regulator. Install throttle pressure bracket and cable (A/T).
Fig. 7: Fuel Rail Assembly
Courtesy of Chrysler Motors.

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.

Fig. 8: EGR Valve
Courtesy of Chrysler Motors.
EGR SOLENOID

Disconnect solenoid vacuum hoses. Disconnect solenoid wiring
connector. Remove solenoid retaining bolts and solenoid. To install
valve, reverse removal procedure.
ECU CONNECTOR PIN IDENTIFICATION 24-PIN CONNECTOR MPFI TABLE
\
\
\
\
\
\
\

Terminal No. Wire Function
A1 .................................................. Injector No. 3
A2 .................................................. Injector No. 6
A3 .................................................. Injector No. 2
A4 .................................................. Injector No. 4
A5 ................................................. Fuel Pump Relay
A6 ........................................................ Not Used
A7 ............................................. Oxygen Sensor Relay
A8 ..................................................... Shift Light
A9 ..................................................... Latch Relay
A10 ............................................. EGR/Evap. Solenoid
A11 ....................................................... Not Used
A12 ...................................................... A/C Relay
B1 .................................................. Injector No. 1
B2 .................................................. Injector No. 5
B3 ........................................................... AIS A
B4 .......................................................... AIS A1
B5 ........................................................... AIS C
B6 .......................................................... AIS C1
B7 .................................................. Battery (Pos.)\
B8 ........................................................ Ignition
B9 ........................................................ Not Used
B10 ............................................... Latched B (Pos.)\
B11 ......................................................... Ground
B12 ......................................................... Ground
\
\
\
\
\
\
\

Fig. 9: Multi-Point Injection ECU Connector
Courtesy of Chrysler Motors.
ECU CONNECTOR PIN IDENTIFICATION 32-PIN CONNECTOR MPFI TABLE
\
\
\
\
\
\
\

Terminal No. Wire Function
C1 ............................................. Speed Sensor (Pos.)\
C2 ..................................................... A/C Request
C3 ........................................................... Start
C4 ...................................................... P/N Switch
C5 .................................................... Sync. (Neg.)\

C6 ...................................................... MAP Sensor
C7 ...................................................... TPS Sensor
C8 ................................................ Air Temp. Sensor
C9 ........................................................ Not Used
C10 ........................................... Coolant Temp. Sensor
C11 ............................................... Injection Supply
C12 ................................................. TX Serial Data
C13 ....................................................... Not Used
C14 ...................................... MAP Sensor Supply Voltage
C15 ............................................. TPS Supply Voltage
C16 ................................................... Sync. (Pos.)\
D1 ............................................. Speed Sensor (Neg.)\
D2 ...................................................... A/C Select
D3 ................................................... Sensor Ground
D4 ........................................................ Not Used
D5 ........................................................ Not Used
D6 ........................................................ Not Used
D7 ........................................................ Not Used
D8 ............................................. Knock Sensor Ground
D9 ............................................. Oxygen Sensor Input
D10 ................................................ Injector Supply
D11 ................................................. RX Serial Data
D12 ....................................................... Not Used
D13 .................................................... Spark/Dwell
D14 ....................................................... Not Used
D15 ....................................................... Not Used
D16 ................................................... Knock Sensor
\
\
\
\
\
\
\

Fig. 10: Multi-Point Injection Diagnostic Connector
Courtesy of Chrysler Motors.

Fig. 11: Comanche Multi-Point Fuel Injection Wiring Diagram
(Wiring Diagram Not Available for Cherokee & Wagoneer Models)

Fig. 12: Throttle Position Sensor Test Procedure Chart (M/T)

Fig. 13: Fuel Injector Test Procedure Chart