JEEP CHEROKEE 1988 Service Repair Manual

2. On Wrangler (YJ) vehicles: Support the transmission and remove the
skid plate.
3. Place a block of wood against the rear of the converter and drive
the clamp converter forward to disengage the alignment tab on the
converter pipe from the alignment slot on the muffler.
Fig. 2: Removing Converter and Exhaust Pipe Clamp
NOTE: If the converter does not move forward, it may be necessary to
heat the converter to muffler connection with an oxyacetylene
torch until the metal becomes cherry red.
4. Twist the converter back and forth to separate it from the muffler.
5. Install the new converter into the muffler until the alignment tab
is inserted into the alignment slot.
6. Using the provided gasket, nuts and bolts, attach the converter to
the front exhaust pipe. Do not tighten the bolts.
7. Install and tighten the new exhaust pipe clamp, at the muffler to
converter connection, to 40 ft-lbs (57 N-m).
8. Tighten the converter to front exhaust pipe bolts to 25 ft-lbs
(34 N-m).
9. On Wrangler (YJ) vehicles: Install the skid plate.
10. Lower vehicle.
C. Install Recall Completion Label
1. With a ball point pen, print your dealer code (5 digits) on the
supplied Recall Completion Label.

2. Peel the label from its backing and apply it near the Vehicle
Emissions Control Information Label on the underside of the hood.
D. Complete Proof of Correction Form
1. Complete a Vehicle Emission Recall Proof of Correction Form and
supply it to the vehicle owner.
COMPLETION REPORTING AND REIMBURSEMENT
Claims for vehicles which have been serviced must be submitted on
the DIAL System Claims submitted will be used by Chrysler to record
recall service completions and provide dealer payments.
Use the following labor operation number and time allowance:
Labor
Operation Time
Number Allowance




















Replace oxygen sensor and catalytic converter 25617182 0.8 Hours
Add the cost of the recall parts package plus applicable dealer
allowance to your claim.
PARTS RETURN
Removed catalytic converters must be returned to the Warranty
Material Return Center.
NOTE: See Warranty Policy and Procedure Manual, Chapter 6, Subsection
H for complete recall claim processing and material return
instructions.
VEHICLE NOT AVAILABLE
If a vehicle is not available for service for a known reason, let us
know by filling out the pre-addressed Vehicle Disposition Form portion
of the Owner Notification Form, or describe the reason on a postcard
and mail to:
Chrysler Corporation 429-10-04
P.O. Box 1919
Detroit, Michigan 48231-1919
Following the above procedures will expedite the processing of your
claim.
If you have any questions or need assistance in completing this
action, please contact your Zone Service Office.
Customer Services Field Operations
Chrysler Corporation
CUSTOMER NOTIFICATION LETTER









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EMISSIONS RECALL TO REPLACE YOUR VEHICLE'S
OXYGEN SENSOR AND CATALYTIC CONVERTER
Dear Jeep Vehicle Owner:

Chrysler Corporation has determined that some 1989 and 1990 Jeep
Cherokee, Comanche and Wrangler vehicles equipped with a 2.5L engine,
may be in violation of Federal Emissions Standards.
The Problem is... The oxygen sensor and catalytic convener on your
vehicle (identified on the enclosed form), may be
susceptible to failure. This could result in
hydrocarbon (HC), carbon monoxide (CO) and oxides
of nitrogen (NOx) emission levels above the
allowable limits, which were established to protect
the public health from the dangers of air pollution.
What you must do... * Simply contact your Jeep dealer to schedule
a service appointment. Ask the dealer to hold
parts for your vehicle or order them prior to
your appointment.
* Bring the enclosed Owner Notification Form with
you to your dealer. It tells the dealer what
service is required for your vehicle.
What Chrysler and Chrysler will repair your vehicle free of charge
your dealer will do... (parts and labor). To do this, your dealer will
replace the oxygen sensor and catalytic
converter. The service will take about one hour
but additional time may be required depending on
how service work is scheduled and processed.
If you need help... If you have trouble getting your vehicle
repaired, please call the Chrysler Customer
Center, toll free, at 1-800-853-1403.
A representative will assist you in getting your
vehicle repaired. If you are still unable to
obtain the repair as described in this letter
within a reasonable time, you may also contact
the Manufacturers Operations Division of the
Environmental Protection Agency (6405J), 401 M
Street, S.W., Washington, D.C. 20460.
In order to ensure your full protection under the emission warranty
made applicable to your vehicle under Federal law, and your right to
participate in future recalls, it is recommended that you have your
vehicle serviced as soon as possible. Failure to do so could legally
be determined to be a lack of proper maintenance of your vehicle.
Further, without this repair your vehicle may fail a state or local
emission inspection test.
We're sorry for any inconvenience, but trust that you understand our
interest in clean air and your continuing satisfaction with our
product. Thanks for your attention to this important matter.
Customer Services Field Operations
Chrysler Corporation

EM IS SIO NS S TA N DAR DS

1988 J e ep C hero ke e
1988 EMISSION & TUNE-UP STANDARDS
MANUFACTURING STANDARDS
Federal and state governments have established air quality
standard during the past 20 years. Automobile manufacturers design
their vehicles to conform to standards where the vehicle will be sold
and operated. These standards cover carbon monoxide (CO), hydrocarbons\
(HC) and oxides of nitrogen (NOx).
Federal and California Standards which must be met by
manufacturers are specified in units easily measured in a testing
laboratory. Since 1970, these standards have been in "grams per mile".
This means no vehicle, whether 2-cylinder or V8, may emit more than a
set weight (in grams) of pollutants for each mile travelled. Since
large engines burn more fuel per mile than do small engines, they must
be "cleaner" per gallon burned if they are to meet these standards.
When manufacturers certify vehicle models prior to sale,
the vehicles are placed on a dynamometer and the exhaust gases are
collected in a bag. After the vehicle runs for a specified time, the
gases are analyzed and weighed. Engines and emission systems are
designed so the weight of emissions will be less than the specified
grams per mile standard.
Infra-red exhaust analyzers are commonly used in vehicle test
stations. The analyzer uses a test probe placed in the exhaust stream
to sample the exhaust gases, and measure the percentage of CO and the
parts per million of HC. These are not the same units used by the
manufacturer when the vehicle is certified. The NOx emissions cannot
be measured by an infra-red exhaust analyzer. Laboratory equipment
must be used to determine NOx emissions.
TUNE-UP STANDARDS
The technician must use the proper specifications when
adjusting the vehicle during a tune-up. The first few years of
emission-regulated vehicles were adjusted using an exhaust gas
analyzer which measured CO and HC.
In the past few years, manufacturers have produced much
cleaner running vehicles. The CO (percentage) and HC (ppm) have beco\
me
very low, especially when measured downstream of catalytic converter.
It has become difficult to measure the effect of fuel and ignition
adjustments.
One solution to this problem for vehicles using carburetors
requires the use of artificially-enriched propane adjustments. The
added propane increases or decreases engine RPM for evaluation of
carburetor rich/lean setting. This allows the technician to check
carburetor setting quickly and accurately.
As computer-controlled systems were developed, it became
possible for the vehicles to adjust the air/fuel ratio, ignition
timing and emission control device operation throughout the entire
driving range. These computer control systems use a variety of sensors
that provide the electronic control unit with information on vehicle
speed, altitude of vehicle operation and transmission gear position,
along with engine operating conditions.
Fuel delivery to achieve a lean air/fuel ratio is controlled
by the computer. The computer controls the on/off (duty cycle) time of\
the fuel injector(s) or carburetor mixture control solenoid to achieve\
leanest possible air/fuel ratio while maintaining good driveability.
Although most repair shops have exhaust gas analyzers,
computer-controlled vehicles normally do not have a CO and HC

specification for tuning. An abnormal exhaust gas reading on an
exhaust analyzer may be helpful in diagnosing a problem, but should
not be used as a basis for adjustments.
These procedures and specifications are supplied by the
manufacturer and may not list CO or HC specifications.
STATE TEST STANDARDS
Some states have established standards for allowable
pollutants for used vehicles. These standards are normally given in CO
(percentage) and HC (ppm). Vehicle tail-pipe emissions can be checke\
d
against the standard using an exhaust gas analyzer. Typical standards
for newer vehicles would be 0.5 percent CO and 200 ppm HC. If vehicle
emissions are below this standard, vehicle would pass emissions test.
These standards are used to determine if the vehicle is running
properly, not to be used for tuning or adjusting the engine. If the
vehicle will not pass emission test or is running poorly, use the
manufacturer's diagnostic procedures and specifications for repair.
Test standards may change each year and vary from state to
state, and even by county within each state. It is not possible to
provide an accurate and up-to-date list of emissions standards.
Emission standards can be obtained for your area by contacting your
local county or state office. Remember, the emission standards are
only for test purposes. The manufacturer's adjustment procedures and
specifications must be followed when repairing vehicles.

EN G IN E C O OLIN G F A N

1988 J e ep C hero ke e
1987-88 ENGINE COOLING
Thermostatically Controlled Electric Fans
Cherokee, Comanche, Wagoneer
DESCRIPTION & OPERATION
On Cherokee, Comanche and Wagoneer models with a 4.0L engine,
A/C and/or heavy duty cooling system, an auxiliary electric fan is
used. The auxiliary fan is controlled by a relay mounted on the left
inner fender panel. A radiator temperature switch attached to the
radiator outlet tank above the lower radiator hose senses engine
coolant temperature.
When coolant temperature is more than 190(0)F (88(0)C), t\
he
radiator coolant temperature switch closes allowing current from the
ignition switch to flow through the fan relay to ground activating the
relay. When relay is activated, battery voltage is supplied to the fan
causing it to operate. When coolant temperature is below 190(0)F
(88(0)C), the radiator coolant temperature switch opens preventing t\
he
relay from being grounded and electric cooling fan from being
energized.
When the A/C (if equipped) is turned on, the Electronic
Control Unit (ECU) grounds the A/C relay coil allowing current to flow\
through it. This activates the A/C relay which then supplies current
to the A/C clutch, fan diode assembly and cooling fan relay. The
cooling fan relay is activated and the fan operates. Whenever the A/C
is used, regardless of engine coolant temperature, the auxiliary
electric cooling fan operates.
TESTING
NOTE: For following tests, refer to fan relay connector terminal
identification and fan controls identification. See Figs. 1
and 2.
With Air Conditioning
1) If electric cooling fan does not work all the time, go to
step 3). If electric cooling fan is inoperative when A/C compressor
operates, start engine and turn A/C on. Disconnect fan relay
connector. Fan relay is located on left inner fender panel.
2) Using a voltmeter, check for voltage at fan relay
connector terminal No. 2. If voltmeter does not read battery voltage,
replace fan diode assembly.
3) Disconnect fan relay connector. Fan relay is located on
left inner fender panel. Using a jumper wire with an in-line 25-amp
fuse, supply battery voltage to fan relay connector terminal No. 4.
4) If fan operates, motor is okay. Go to next step. If fan
motor does not operate, check continuity between fan relay connector
terminal No. 4 and body ground connections. If continuity exists,
replace fan motor. If continuity does not exist, repair open and
retest.
5) Disconnect fan relay connector. Turn ignition switch to
the "RUN" position. Check continuity between fan relay connector
terminal No. 5 and body ground connections. If continuity does not
exist, repair open circuit. If continuity exists, go to next step.
6) Using a jumper wire with an in-line 25-amp fuse, jump
across fan relay connector terminals No. 1 and No. 4. If fan motor
operates, go to next step. If fan motor does not operate, repair fan

relay fuse link.
7) Check for battery voltage at fan relay connector terminal
No. 2. Connect a jumper wire across radiator temperature switch
connector. Radiator temperature switch is located on radiator outlet
tank, above lower radiator hose. If fan does not operate, replace
radiator temperature switch. If fan operates, go to next step.
8) Check for battery voltage at fan relay connector terminal
No. 2. If battery voltage is not present, replace fan diode assembly.
Without Air Conditioning
1) Disconnect fan relay. Fan relay is mounted on left inner
fender panel. Using a jumper wire with an in-line 25-amp fuse, supply
battery voltage to fan relay connector terminal No. 4.
2) If fan operates, motor is okay. Go to next step. If fan
motor does not operate, check continuity between fan relay connector
terminal No. 4 and body ground connections.
If continuity exists, replace fan motor. If continuity does
not exist, repair open and retest.
3) With fan relay connector disconnected, turn ignition
switch to the "RUN" position. Check continuity between fan relay
connector terminal No. 5 and body ground connections. If continuity
does not exist, repair open. If continuity exists, go to next step.
4) Using a jumper wire with a 25-amp in-line fuse, jump
across fan relay connector terminals No. 1 and No. 4. If fan motor
operates, leave jumper wire connected and proceed to next step. If fan
motor does not operate, repair fan relay fuse link.
5) Check for battery voltage at cooling fan relay connector
terminal No. 2. Connect a jumper wire across radiator coolant
temperature switch connector. Radiator coolant temperature switch is
located on radiator outlet tank above lower radiator hose. If fan does
not operate, replace radiator coolant temperature switch.
Fig. 1: Fan Relay Connector Terminal Identification
Courtesy of Chrysler Motors.

Fig. 2: Fan Controls Identification
Courtesy of Chrysler Motors.
REMOVAL & INSTALLATION
AUXILIARY ELECTRIC COOLING FAN
Removal
1) Auxiliary fan is attached to radiator upper crossmember
behind radiator.
2) Remove fan retaining screws from radiator upper
crossmember. Disconnect electric fan connector. Lift fan straight up
out of vehicle.
Disassembly
Components of auxiliary electric cooling fan can be replaced.
However, components cannot be repaired. If an auxiliary cooling fan
component needs repair it must be replaced with the recommended
replacement part only. The auxiliary fan consists of a fan module, fan
module retaining clip, fan shroud, and fan motor.
1) Place assembly on bench with fan blades facing up.
Position an awl between the fan retainer and motor shaft. Pry the
retainer off the motor shaft. Slide fan up off of motor.
2) Unwind fan motor electrical connector from retaining
clips of fan shroud.
3) Remove fan motor mounting screws. Remove fan.
Assembly
1) Attach fan motor to fan shroud with mounting screws. Wind
electrical connector into retaining clips of fan shroud.
The bushing at fan module center has a small groove on the
bottom side of it that fits over the alignment dowel on the fan motor
shaft. The keyway pin of the alignment dowel fits into the groove in
fan motor shaft. A small amount of silicone sealant placed in the
groove of the fan motor shaft holds the alignment dowel in place.

2) Place fan module over motor shaft, align groove in fan
module with dowel on motor shaft. Start fan module retainer onto the
fan motor shaft with open end of the retainer facing the groove in the
shaft. When retainer is completely installed the open end will be on
side opposite the groove. Use needle nose pliers to finish installing
retainer.
Installation
Align lower retaining tabs of fan shroud with slots in
bracket at bottom of radiator and push fan down into position. Tighten
mounting screws to 36 inch lbs. (4.07 N.m). Connect auxiliary cooling
fan electrical connector.
Fig. 3: Auxiliary Fan Removal & Installation

Fig. 4: Auxiliary Fan