1988 JEEP CHEROKEE Service Repair Manual

oil capacities service interval horn headlights oil additives TPMS reset

Page 1225 of 1378

JEEP CHEROKEE 1988 Service Repair Manual widening the gap to 1/4-3/8".

Disconnect spark plug wire

and insert test plug. Ground

plug, crank engine, and

check for spark.

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widening the gap to 1/4-3/8".

Disconnect spark plug wire

and insert test plug. Ground

plug, crank engine, and

check for spark.

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GOOD SPARK NO SPARK
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* If plug sparks, driveability * Remove coil wire from the

problem is most likely NOT distributor and attach the

in the ignition system. modified spark plug. Ground

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the plug and crank engine
while checking for spark.
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GOOD SPARK NO SPARK
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* If plug has a good spark, * Proceed to the IGNITION

the problem is in the plug PRIMARY TROUBLE SHOOTING

wires, distributor cap, or CHECK CHART below in this

rotor. Replace components article.

as necessary.
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Ignition Primary Trouble Shooting Chart
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START: Visually inspect primary ignition wires for

broken, frayed, split, or cut wires. Also check

for loose, corroded, or disconnected connectors.

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OK NOT OK
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* Check that battery voltage * Repair or replace damaged

is at least 11.5 volts. components as necessary.

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NOT OK OK
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* Replace or recharge the * Check for battery voltage

battery. at the positive terminal of

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the coil.
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OK NOT OK
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* Check air Gap of the Pick-Up * Check resistance of ballast

coil in the distributor. resistor (if used) for the

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correct resistance value.
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Page 1226 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual �� \ OK NOT OK ��\b$

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OK NOT OK
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* Check Pick-Up coil for * Adjust or replace as

correct resistance value. necessary.

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NOT OK OK
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* Replace Pick-Up coil if * Check control module for

not to specification. good ground connections.

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OK
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* If vehicle fails to run at this point, go to
the appropriate article in the ENGINE
PERFORMANCE section.
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OK NOT OK
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* Check wires from the battery/ * Replace ballast resistor

ignition switch to the coil. if the measured resistance

Also check the coil primary value is not within

and secondary resistance. specification.

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STARTER TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
BASIC STARTER TROUBLE SHOOTING CHART
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CONDITION POSSIBLE CAUSE CORRECTION\
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Starter Fails Dead battery or bad Check battery charge
to Operate connections between and all wires and
starter and battery connections to starter
Ignition switch faulty Adjust or replace
or misadjusted ignition switch
Open circuit between Check and repair wires
starter switch ignition and connections as
terminal on starter relay necessary
Starter relay or starter See Testing in STARTER
defective article

Page 1227 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual Open solenoid pull-in See Testing in STARTER wire article ��\ ��\ ��\ ��$

Open solenoid pull-in See Testing in STARTER
wire article
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Starter Does Not Weak battery or dead Charge or replace
Operate and cell battery as necessary
Headlights Dim
Loose or corroded battery Check that battery
connections connections are clean
and tight
Internal ground in See Testing in STARTER
starter windings article
Grounded starter fields See Testing in STARTERS
Armature rubbing on pole See STARTER article
shoes
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Starter Turns Starter clutch slipping See STARTER article
but Engine
Does Not Rotate
Broken clutch housing See STARTER article
Pinion shaft rusted or See STARTER article
dry
Engine basic timing See Ignition Timing in
incorrect TUNE-UP article
Broken teeth on engine Replace flywheel and
flywheel check for starter pinion
gear damage
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Starter Will Not Faulty overrunning See STARTER article
Crank Engine clutch
Broken clutch housing See STARTER article
Broken flywheel teeth Replace flywheel and
check for starter pinion
gear damage
Armature shaft sheared See STARTER article
or reduction gear teeth
stripped
Weak battery Charge or replace
battery as necessary
Faulty solenoid See On-Vehicle Tests in
STARTER article
Poor grounds Check all ground
connections for
tight and clean
connections
Ignition switch faulty Adjust or replace
or misadjusted ignition switch as
necessary
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Starter Cranks Battery weak or Charge or replace
Engine Slowly defective battery as necessary

Page 1228 of 1378

JEEP CHEROKEE 1988 Service Repair Manual Engine overheated See ENGINE COOLING
SYSTEM article
Engine oil too heavy Check that proper

Engine overheated See ENGINE COOLING
SYSTEM article
Engine oil too heavy Check that proper
viscosity oil
is used
Poor battery-to-starter Check that all
connections between
battery and starter are
clean and tight
Current draw too low or See Bench Tests in
too high STARTER article
Bent armature, loose pole See STARTER article
shoes screws or worn
bearings
Burned solenoid contacts Replace solenoid
Faulty starter Replace starter
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Starter Engages Engine timing too far See Ignition Timing in
Engine Only advanced TUNE-UP article
Momentarily
Overrunning clutch not Replace overrunning
engaging properly clutch. See STARTER
article
Broken starter clutch See STARTER article
Broken teeth on engine Replace flywheel and
flywheel check starter pinion
gear for damage
Weak drive assembly See STARTER article
thrust spring
Weak hold-in coil See Bench Tests in
STARTER article
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Starter Drive Defective point assembly See Testing in STARTER
Will Not Engage article
Poor point assembly ground See Testing in STARTER
article
Defective pull-in coil Replace starter
solenoid
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Starter Relay Dead battery Charge or replace
Does Not Close battery as necessary
Faulty wiring Check all wiring and
connections leading to
relay
Neutral safety switch Replace neutral safety
faulty switch
Starter relay faulty Replace starter relay

Page 1229 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual ��\ ��\ ��\ ��\ ��\ ��\ ��\ �� Starter Drive Starter motor loose on$

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Starter Drive Starter motor loose on Tighten starter
Will Not mountings attach bolts
Disengage
Worn drive end bushing See STARTER article
Damaged engine flywheel Replace flywheel and
teeth starter pinion gear for
damage
Drive yolk return spring Replace return spring
broken or missing
Faulty ignition switch Replace ignition switch
Insufficient clearance Replace starter
between winding leads to solenoid
solenoid terminal and main
contact in solenoid
Starter clutch not Replace starter clutch
disengaging
Ignition starter switch Replace ignition switch
contacts sticking
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Starter Relay Faulty solenoid switch, Check all wiring
Operates but switch connections or between relay and
Solenoid Does Not solenoid or replace
relay or solenoid as
necessary
Broken lead or loose Repair wire or wire
soldered connections connections as
necessary
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Solenoid Plunger Weak battery Charge or replace
Vibrates When battery as necessary
Switch is Engaged
Solenoid contacts Clean contacts or
corroded replace solenoid
Faulty wiring Check all wiring
leading to solenoid
Broken connections inside Repair connections or
switch cover replace solenoid
Open hold-in wire Replace solenoid
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Low Current Draw Worn brushes or weak Replace brushes or
brush springs as
necessary
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High Pitched Whine Distance too great Align starter or check
During Cranking between starter that correct starter
Before Engine pinion and flywheel and flywheel are being
Fires but Engine used
Fires and Cranks
Normally
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High Pitched Distance too small between
Whine After Engine starter pinion and flywheel

Page 1230 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual Fires With Key Flywheel runout contributes released. Engine to the intermittent nature Fires and Cranks Normally ��\ ��\ ��\ ��\$

Fires With Key Flywheel runout contributes
released. Engine to the intermittent nature
Fires and Cranks
Normally
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AIR CONDITIONING & HEAT
AIR CONDITIONING TROUBLE SHOOTING
WARNING: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
BASIC AIR CONDITIONING TROUBLE SHOOTING CHART
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CONDITION POSSIBLE CAUSE\
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Compressor Not Working
Compressor clutch circuit open.

Compressor clutch coil inoperative.

Poor clutch ground connection.

Fan belts loose.

Thermostatic switch inoperative.

Thermostatic switch not adjusted.

Ambient temperature switch open.

Superheat fuse blown.\
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Excessive Noise or Vibration
Missing or loose mounting bolts.

Bad idler pulley bearings.

Fan belts not tightened correctly.

Compressor clutch contacting body.

Excessive system pressure.

Compressor oil level low.

Damaged clutch bearings.

Damaged reed valves.

Damaged compressor.\
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Insufficient or No Cooling;
Compressor Working
Expansion valve inoperative.

Heater control valve stuck open.

Low system pressure.

Blocked condenser fins.

Blocked evaporator fins.

Vacuum system leak.

Vacuum motors inoperative.

Control cables improperly adjusted.

Restricted air inlet.

Mode doors binding.

Blower motor inoperative.

Temperature above system capacity.\
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HEATER SYSTEM TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to

Page 1231 of 1378

JEEP CHEROKEE 1988 Service Repair Manual problem symptoms. For model-specific Trouble Shooting,
refer to DIAGNOSTIC, or TESTING articles available in the
section(s) you are accessing.
BASIC HEATER SYSTEM TROUBLE S

problem symptoms. For model-specific Trouble Shooting,
refer to DIAGNOSTIC, or TESTING articles available in the
section(s) you are accessing.
BASIC HEATER SYSTEM TROUBLE SHOOTING CHART
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CONDITION POSSIBLE CAUSE\
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Insufficient, Erratic,
or No Heat
Low Coolant Level

Incorrect thermostat.

Restricted coolant flow through
heater core.

Heater hoses plugged.

Misadjusted control cable.

Sticking heater control valve.

Vacuum hose leaking.

Vacuum hose blocked.

Vacuum motors inoperative.

Blocked air inlet.

Inoperative heater blower motor.

Oil residue on heater core fins.

Dirt on heater core fins.\
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Too Much Heat
Improperly adjusted cables.

Sticking heater control valve.

No vacuum to heater control valve.

Temperature door stuck open.\
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Air Flow Changes During
Acceleration
Vacuum system leak.

Bad check valve or reservoir.\
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Air From Defroster At All
Times
Vacuum system leak.

Improperly adjusted control cables.

Inoperative vacuum motor.\
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Blower Does Not Operate
Correctly
Blown fuse.

Blower motor windings open.

Resistors burned out.

Motor ground connection loose.

Wiring harness connections loose.

Blower motor switch inoperative.

Blower relay inoperative.

Fan binding or foreign object
in housing.

Fan blades broken or bent.\
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BRAKES
BRAKE SYSTEM TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.

Page 1232 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual BRAKE SYSTEM TROUBLE SHOOTING CHART��\ ��\ ��\ ��\ ��\ ��\ ��\ �� CONDITION$

BRAKE SYSTEM TROUBLE SHOOTING CHART\
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CONDITION POSSIBLE CAUSE CORRECTION\
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Brakes Pull Left
or Right Incorrect tire pressure Inflate tires to proper
pressure
Front end out of alignment See WHEEL ALIGNMENT
Mismatched tires Check tires sizes
Restricted brake lines
or hoses Check hose routing
Loose or malfunctioning
caliper See DISC BRAKES or
BRAKE SYSTEM
Bent shoe or oily linings See DRUM BRAKES or
BRAKE SYSTEM
Malfunctioning rear brakes See DRUM, DISC BRAKES
or BRAKE SYSTEM
Loose suspension parts See SUSPENSION
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Noises Without
Brakes Applied Front linings worn out Replace linings
Dust or oil on drums See DRUM, DISC BRAKES
or rotors or BRAKE SYSTEM
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Noises With
Brakes Applied Insulator on outboard See DISC BRAKES or
shoe damaged BRAKE SYSTEM
Incorrect pads or linings Replace pads or linings
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Brake Rough, Chatters
or Pulsates Excessive lateral runout Check rotor runout
Parallelism not to
specifications Reface or replace rotor
Wheel bearings not adjusted See SUSPENSION
Rear drums out-of-round Reface or replace drums
Disc pad reversed, steel
against rotor Remove and reinstall
pad
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Excessive Pedal
Effort Malfunctioning power unit See POWER BRAKES or
BRAKE SYSTEM
Partial system failure Check fluid and pipes
Worn disc pad or lining Replace pad or lining
Caliper piston stuck or

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