1988 JEEP CHEROKEE oil dipstick

PLACING SYSTEM IN OPERATION
After component service or replacement has been completed and
all connections have been made, evacuate system throughly with a
vacuum pump. Charge system with proper amount of refrigerant and
perform a leak test. Be sure to check all fittings that have been
opened. After system has been leak tested, make a system performance
check.
SANDEN SD508 5-CYLINDER OIL CHECKING
1) Discharge system using approved refrigerant
recovery/recycling equipment. Remove compressor belt and loosen
mounting bolts. Rotate compressor in brackets until filler plug is at
top. Clean area around filler plug and remove plug slowly. Rotate
front hub plate so notch in lobe is 110 degrees from the bottom. This
rotates ball end of top piston to align with oil fill port and allows
clearance for dipstick. See Fig. 1.
2) Insert compressor dipstick diagonally from right to left
until stop on dipstick contacts filler plug surface. Remove dipstick
and note oil fill level. Each mark on dipstick represents one ounce
of oil. Add oil if necessary to reach 3-4 ounce level.
Fig. 1: Sanden 5-Cylinder Oil Level Checking
YORK - 2-CYLINDER - PURGINE COMPRESSOR

1) Remove gauge set and place caps on service valve ports.
Back-seat the suction service valve to allow refrigerant to enter
compressor.
2) Loosen discharge port valve slightly. Loosen valve port
cap to allow refrigerant to force out air from compressor. Back-seat
the discharge valve and tighten the port cap. Compressor is ready for
service.
YORK - 2-CYLINDER COMPRESSOR OIL CHECKING
1) Operate system for 10 minutes, then stop and isolate
compressor. Loosen filler plug slowly to release any pressure in
crankcase.
2) Use dipstick to check oil level. See Fig. 2. Add oil as
necessary, then install plug with new "O" ring. Purge compressor of
air.
Fig. 2: York A/C Compressor Oil Level Dipstick (Check oil w/ shaft
keyway facing head)
Courtesy of Chrysler Motors.

Information pertaining to Sanden compressors in this article,
will be found in earlier articles under Sankyo compressors.
AMERICAN MOTORS & JEEP WITH 5-CYLINDER COMPRESSOR
Compressor Overhaul
1) After the compressor and system have been run, stop the
engine. Slowly discharge system using approved refrigerant
recovery/recycling equipment. Clean and cool dipstick with R-12.
2) Loosen the compressor mounting bolts, remove the drive
belt, and move the compressor to a bench for easiest and most accurate
measurement. Position the compressor so that the oil fill plug is at
top dead center.
3) Thoroughly clean the oil fill plug and the area around it.
Loosen the fill plug slowly to allow trapped refrigerant pressure to
escape through the loosened threads.
4) The front plate hub has a lobe, which is indexed (notched)\
180
from TDC of the cam rotor. Rotate the hub plate lobe until the
index notch is 110 from bottom center. See Fig. 1. Check this
position by looking through the oil fill hole and noting that the ball
end of the top piston rod lines up with the fill hole.
5) Looking at the front end of the compressor, insert the
dipstick diagonally from upper left to lower left until the dipstick
stop contacts the filler hole surface. Remove dipstick and note oil
level. Oil level should be between the 4th and 6th increment on the
dipstick (3-4 ounces). Add oil as necessary.
Compressor Replacement
If system was opened by a leak or so quickly that oil was
lost, install new compressor with all the oil it contains. If system
was opened slowly and oil was not lost, drain oil from new compressor
and measure. Reinstall 6 ounces of oil back into new compressor prior
to installation.
Component Replacement
If a hose, receiver-drier, condenser, expansion valve or
evaporator core requires replacement, add 1 ounce of new oil for each
new component installed.
Compressor Oil Check
1) Discharge system, using approved refrigerant
recovery/recycling equipment, or isolate compressor. Remove oil filler
plug. Look through oil filler plug hole and rotate clutch front plate
to position piston connecting rod in center of oil filler plug hole.
2) Insert dipstick (J-29642-12) through oil filler plug hole\
to the right of piston connecting rod until dipstick stop contacts the
compressor housing.
3) Remove dipstick and count number of increments covered
with oil. If compressor is properly filled, oil will cover 4-6
increments on the dipstick. Adjust oil level as necessary.

Fig. 1: 5-Cylinder Compressor Oil Check (Use dipstick J-29642-12)
YORK 2-CYLINDER COMPRESSOR SERVICING
JEEP WITH 2-CYLINDER COMPRESSOR

Isolating Compressor
1) Connect manifold gauge set to service valves on
compressor. Close both gauge valves. Open both service valves to the
mid-position.
2) Start engine and operate air conditioning. Turn suction
service valve slowly clockwise toward front-seated position. When
suction pressure is reduced to zero or less, stop engine and quickly
close suction service valve (front-seated).
3) Front-seat the discharge valve. Loosen oil check plug
slowly to release any internal pressure. Service valves can now be
removed from compressor and compressor removed from vehicle (if
necessary). Purge compressor after servicing.
Purging Compressor
1) Remove gauge set and place caps on service valve ports.
Back-seat the suction service valve to allow refrigerant to enter
compressor.
2) Loosen discharge port valve slightly. Loosen valve port
cap to allow refrigerant to force out air from compressor. Back-seat
the discharge valve and tighten the port cap. Compressor is ready for
service.
Compressor Oil Check
1) Operate system for 10 minutes, then stop and isolate
compressor. Loosen filler plug slowly to release any pressure in
crankcase.
2) Use dipstick to check oil level. See Fig. 2. Add oil as
necessary. Install plug with new "O" ring. Purge compressor of air.
Fig. 2: York Compressor Oil Level Dipstick
Check oil with shaft keyway facing head.
SYSTEM SERVICING CAUTIONS

Engine Coolant In coolant overflow bottle.
Engine Oil In oil pan.
Front/Rear Axles On front/rear of differential.
Power Steering In power steering pump
reservoir.
Transfer Case In rear portion of transfer
case.
Transmission On fill plug (M/T) or dipstick\
(A/T).
Windshield Washer On bottom of windshield washer
reservoir.
Fuel Gauge Sending Unit In fuel tank.

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IG NIT IO N S YSTE M - 2 .5 L W /R EN IX E LE C TR O NIC IG NIT IO N

1988 J e ep C hero ke e
Distributors & Ignition Systems
JEEP RENIX ELECTRONIC IGNITION
2.5L TBI: Cherokee, Comanche, Wagoneer, Wrangler
DESCRIPTION
The Renix electronic ignition system consists of a solid-
state Ignition Control Module (ICM), a distributor, a Top Dead Center
(TDC) sensor, and an Electronic Control Unit (ECU).
OPERATION
IGNITION CONTROL MODULE (ICM)
The ignition control module is located in engine compartment,
just left of battery. The ICM consists of a solid-state ignition
circuit and an integrated ignition coil that can be removed and
serviced separately.
Electronic signals from the electronic control unit to the
ICM determine the amount of ignition timing or retard needed to meet
various engine requirements. The electronic control unit provides an
input signal to the ICM. The ICM has only 2 outputs: a tach signal to
the tachometer and diagnostic connector, and a high voltage signal
from the coil to the distributor cap.
TDC SENSOR
The TDC sensor senses TDC and BDC crankshaft positions as
well as engine RPM. Sensor is located on left rear side of engine and
is not adjustable. Sensor is secured by special shouldered bolts to
flywheel/drive plate housing.
TESTING
1) Disconnect ignition coil wire from center tower of
distributor cap. Using insulated pliers, hold coil wire about 1/2" (13
mm) away from engine block. Crank engine and check for spark between
wire and engine block.
2) If spark occurs, reconnect coil wire to distributor cap.
Remove spark plug wire from one spark plug. Using insulated pliers,
hold wire about 1/2" (13 mm) away from engine block.
3) Crank engine and check for spark between wire and engine
block. If spark occurs, check fuel system for problems. If no spark
occurs, check for a defective rotor, distributor cap, or spark plug
wires. Replace parts as necessary.
4) If rotor, cap and wires are okay, check for loose or
corroded connections at coil terminals. If necessary, clean terminals
and wires. Ensure wires are properly seated on coil terminals and not
wedged between coil body and terminal. If okay, go to next step.
5) Check for loose connectors at ICM or ECU. Verify that wire
connectors are firmly plugged into ICM and ECU. Also check for loose
ICM or ECU ground wire connections at oil dipstick bracket. Clean and
tighten if necessary.
6) Load test battery to ensure battery is fully charged.
Replace battery if necessary. If battery is okay, check voltage
between terminals "A" and "B" of ICM connector while cranking engine.
See Fig. 1 .

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.