1988 JEEP CHEROKEE battery

brake rotor high beam keyless entry inflation pressure child lock ECO mode

Page 1244 of 1378

JEEP CHEROKEE 1988 Service Repair Manual batteries
Bad starter connections Check connections
or bad starter and/or replace

batteries
Bad starter connections Check connections
or bad starter and/or replace
batteries
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Engine Cranks Bad battery connections Check connections
Slowly, Won't or dead batteries and/or replace
Start batteries
Engine oil too heavy Replace engine oil
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Engine Cranks Glow plugs not functioning Check glow plug system,
Normally, But see FUEL SYSTEMS
Will Not Start Glow plug control not Check controller, see
functioning FUEL SYSTEMS
Fuel not injected into Check fuel injectors,
cylinders see FUEL SYSTEMS
No fuel to injection pump Check fuel delivery
system
Fuel filter blocked Replace fuel filter
Fuel tank filter blocked Replace fuel tank
filter
Fuel pump not operating Check pump operation
and/or replace pump
Fuel return system blocked Inspect system and
remove restriction
No voltage to fuel solenoid Check solenoid and
connections
Incorrect or contaminated Replace fuel
fuel
Incorrect injection pump Re-adjust pump timing,
timing see FUEL SYSTEMS
Low compression Check valves, pistons,
rings, see ENGINES
Injection pump malfunction Inspect and/or replace
injection pump
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Engine Starts, Incorrect slow idle Reset idle adjustment,
Won't Idle adjustment see TUNE-UP
Fast idle solenoid Check solenoid and
malfunctioning connections
Fuel return system blocked Check system and remove
restrictions
Glow plugs go off too soon See glow plug diagnosis
in FUEL SYSTEMS
Injection pump timing Reset pump timing, see
incorrect FUEL SYSTEMS
No fuel to injection pump Check fuel delivery
system
Incorrect or contaminated Replace fuel
fuel
Low compression Check valves, piston,
rings, see ENGINES
Injection pump malfunction Replace injection pump,
see FUEL SYSTEMS
Fuel solenoid closes in RUN Check solenoid and
position connections
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Engines Starts/ Incorrect slow idle Reset slow idle, see
Idles Rough W/out adjustment TUNE-UP
Smoke or Noise Injection line fuel leaks Check lines and
connections
Fuel return system blocked Check lines and
connections

Page 1246 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual Incorrect injector pump Check pressure, see housing pressure FUEL SYSTEMS ��\ ��\ ��\ ��$

Incorrect injector pump Check pressure, see
housing pressure FUEL SYSTEMS
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Engine Cooling system leaks Check cooling system
Overheating and repair leaks
Belt slipping or damaged Check tension and/or
replace belt
Thermostat stuck closed Remove and replace
thermostat, see
ENGINE COOLING
Head gasket leaking Replace head gasket
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Oil Light on at Low oil pump pressure Check oil pump
Idle operation, see ENGINES
Oil cooler or line Remove restriction
restricted and/or replace cooler
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Engine Won't Injector pump fuel solenoid Remove and check
Shut Off does not return fuel valve solenoid and replace
to OFF position if needed
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VACUUM PUMP DIAGNOSIS
Excessive Noise Loose pump-to-drive Tighten screws
assembly screws
Loose tube on pump assembly Tighten tube
Valves not functioning Replace valves
properly
Oil Leakage Loose end plug Tighten end plug
Bad seal crimp Remove and re-crimp
seal
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FUEL INJECTION 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 FUEL INJECTION TROUBLE SHOOTING CHART
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CONDITION POSSIBLE CAUSE CORRECTION\
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Engine Won't Cold start valve inoperative Test valve and
Start (Cranks circuit
Normally)
Poor connection;vacuum or Check vacuum and
wiring electrical
connections
Contaminated fuel Test fuel for water
or alcohol
Defective fuel pump relay Test relay and
or circuit wiring
Battery too low Charge and test
battery

Page 1249 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual ��\ ��\ ��\ ��\ ��\ ��\ ��\b ��\ ��\ � ��\$

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OK NOT OK
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* To test secondary ignition * Repair or replace

system, modify a Spark Plug damaged components

by attaching a ground wire as necessary

to the body of the plug and
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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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Page 1250 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual ��\ ��\ ��\ ��\ � ��\ �� \ O$

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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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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

Page 1251 of 1378

JEEP CHEROKEE 1988 Service Repair Manual Ignition switch faulty Adjust or replace
or misadjusted ignition switch
Open circuit between Check and repair wires

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
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

Page 1252 of 1378

JEEP CHEROKEE 1988 Service Repair Manual connections for
tight and clean
connections

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
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

Page 1253 of 1378

JEEP CHEROKEE 1988 Service Repair Manual Does Not Close battery as necessary
Faulty wiring Check all wiring and
connections leadi

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
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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

Page 1289 of 1378

JEEP CHEROKEE 1988 Service Repair Manual Fig. 3: TBI Idle Speed Control (ISC) Motor Adjustment
Courtesy of Chrysler Motors.
4) Connect ISC motor connector. Turn ignition off for 10
seconds. ISC motor should fully extend. Restart en

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