JEEP CHEROKEE 1988 Service Repair Manual

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.

Fig. 23: Location of ECU Mounting Screws
Courtesy of Chrysler Motors.
Installation
1) Connect the ECU wiring harness connector.
2) While holding the ECU in position, attach the 3 ECU
attaching screws. See Fig. 23.
3 Connect the negative battery cable.
DISTRIBUTOR

Removal
1) Disconnect the battery negative cable.
2) On vehicles equipped with A/C, remove the electrical
cooling fan and shroud assembly from the radiator to allow room to
rotate the engine with a socket and ratchet using the vibration damper
bolt.
3) Scribe a mark on the distributor housing below the left
side (past) the number one spark plug wire post of the distributor cap\
for reassembly reference for No 1 cylinder firing position.
4) Remove the distributor cap.
5) Turn the engine in a clockwise direction until the rotor
is approaching the scribed mark on the distributor housing. Then
slowly turn the engine until the timing mark on the crankshaft
vibration damper lines up with zero on the front cover timing scale.
See Fig. 24 .
NOTE: The timing mark is located on the edge of the vibration
damper closest to the front cover.
Fig. 24: View of Crankshaft Vibration Damper Timing Marks
Courtesy of Chrysler Motors.
6) Align the trailing edge of the rotor blade with the mark
previously scribed on the distributor housing. See Fig. 25.

Fig. 25: Aligning Rotor & Distributor Cap for Removal
Courtesy of Chrysler Motors.
7) Remove the distributor hold-down bolt and clamp.
8) Remove the distributor from the engine.

Installation
1) If needed, use a flat blade screwdriver to turn the oil
pump gear shaft until the slot is slightly past the 11 o'clock
position. See Fig. 26. The oil pump shaft is located down in the
distributor hole.
Fig. 26: Aligning Oil Pump Gear Shaft
Courtesy of Chrysler Motors.
2) Install the rotor.
3) Without engaging the distributor gear into the cam gear
and ensuring the distributor gasket is installed, position the
distributor into the hole in the engine block.
4) Visually line up the hold down ear of the distributor
housing with the hold down clamp hole. See Fig. 27.
Fig. 27: Installing Distributor
Courtesy of Chrysler Motors.
5) Turn the rotor to the 4 o'clock position. See Fig. 28.

Fig. 28: Installing & Aligning Rotor
Courtesy of Chrysler Motors.
6) Carefully slide the distributor into the block until it
seats, keeping the hold down ear aligned to the hole in the block.
7) The rotor should be in the 5 o'clock position with the
trailing edge of the rotor blade lined up with the mark previously
scribed on the distributor housing (number one spark plug wire post
location).
8) install the distributor hold-down clamp bolt and tighten
to 9.5-14 Ft. Lbs. (13-19 N.m).
9) Install the distributor cap. Connect the distributor
electrical connector.
10) Install the electric cooling fan and shroud if
applicable.
11) Connect the negative battery cable.
IGNITION/COIL WIRE REPLACEMENT PRECAUTIONS

Removal & Installation
Using care, disconnect the spark plug and coil wire boots and
wires. Twist the boot one half turn and pull on the boot to disconnect
the wire.
When replacing the spark plug and coil wires, carefully route
the wires correctly and secure them in their proper channels
retainers.
Failure to route the wires properly can cause the radio to
reproduce ignition noise, cross ignition of the plugs, or can short
circuit the wires to ground.
OVERHAUL
STATOR REPLACEMENT
Disassembly
1) Remove the distributor as specified in DISTRIBUTOR under
REMOVAL & INSTALLATION above in this article.
2) Remove the distributor rotor.
3) Position the distributor in a vise.
4) Remove the distributor gear from the shaft using a small
punch and a hammer to drive out the retaining roll pin. See Fig. 29.
5) Remove the distributor shaft from the distributor housing.
6) Remove the stator retaining screw.
NOTE: Mark the location of the stator position for reassembly
reference.
Fig. 29: Removing Distributor Gear Retaining Roll Pin
Courtesy of Chrysler Motors.
7) Remove stator harness by pushing the grommet through the
distributor housing. Remove stator assembly. See Fig. 30.

Fig. 30: Location of Stator Retaining Screw
Courtesy of Chrysler Motors.
Reassembly
1) Install stator assembly and the stator retaining screw.
2) Position the stator assembly harness through the
distributor housing and push the grommet into position.
3) Install distributor shaft into the distributor housing. If
the shaft is equipped with seals, ensure that they are in place and
not damaged.

4) Install the distributor gear washer and distributor gear
onto the shaft.
5) Install the distributor gear retaining pin.
6) Install the distributor rotor.
7) Install the distributor as specified in DISTRIBUTOR under
REMOVAL & INSTALLATION above in this article.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS








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Application Ft. Lbs. (N.m)
Coolant Temperature Sensor ....................... 21 (28)
Distributor Hold-Down Clamp Bolt .......... 9.5-14 (13-19)
Manifold Air Temperature Sensor .................. 21 (28)
INCH Lbs. (N.m)
Knock Sensor ..................................... 89 (10)









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IG NIT IO N S YSTE M - 4 .0 L W /H EI/E ST/E SC ( D ELC O -R EM Y)

1 988 J e ep C hero ke e
Distributors & Ignition Systems
HEI, HEI/EST & HEI/EST/ESC IGNITION SYSTEM
Jeep 4.0L
DESCRIPTION
HIGH ENERGY IGNITION (HEI)
The Delco-Remy High Energy Ignition system is a self-
contained unit. It consists of ignition coil, spark plugs, distributor
assembly and primary and secondary wiring. The distributor housing
contains an electronic control module, pick-up coil, pole piece, timer
core, rotor, capacitor for radio noise suppression and timing advance
mechanisms. Most applications house the ignition coil assembly within
the distributor cap. See Fig. 1.
Fig. 1: Delco-Remy HEI System Circuit Diagram
Courtesy of General Motors Corp.
HEI WITH ELECTRONIC SPARK TIMING (EST)