1988 JEEP CHEROKEE Service Repair Manual

trunk air suspension overheating radio coolant level navigation system

Page 1249 of 1378

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

\
\
\
\
\
\
\b
\
\
\
\
\

\

OK NOT OK
\b \b
\
\
\

\
\

* 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
\
\
\b

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

Disconnect spark plug wire

and insert test plug. Ground

plug, crank engine, and

check for spark.

\
\
\
\b
\
\
\
\
\
\
\

GOOD SPARK NO SPARK
\
\b \
\b
\
\
\

\
\
\

* 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

\
\
\
\b
the plug and crank engine
while checking for spark.
\
\
\
\b
\
\
\
\
\
\
\

GOOD SPARK NO SPARK
\
\b \
\b
\
\
\

\
\
\

* 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.
\
\
\
\b

\
\
\
\b

Ignition Primary Trouble Shooting Chart
\
\
\
\
\
\

START: Visually inspect primary ignition wires for

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

for loose, corroded, or disconnected connectors.

\
\
\
\
\
\
\b
\
\
\
\
\

\

OK NOT OK
\b \b
\
\
\

\
\
\

* Check that battery voltage * Repair or replace damaged

is at least 11.5 volts. components as necessary.

\
\
\
\b
\
\
\
\b
\
\
\
\
\
\

NOT OK OK
\b \b
\
\
\

\
\
\

* Replace or recharge the * Check for battery voltage

battery. at the positive terminal of

\
\
\
\b
the coil.
\
\
\
\b

Page 1250 of 1378

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

\
\
\
\
\

\
OK NOT OK
\b \b
\
\
\

\
\
\

* Check air Gap of the Pick-Up * Check resistance of ballast

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

\
\
\
\b
correct resistance value.
\
\
\
\b
\
\
\

\

OK NOT OK
\b \b
\
\
\

\
\
\

* Check Pick-Up coil for * Adjust or replace as

correct resistance value. necessary.

\
\
\
\b
\
\
\
\b
\
\
\

\

NOT OK OK
\b \b
\
\
\

\
\
\

* Replace Pick-Up coil if * Check control module for

not to specification. good ground connections.

\
\
\
\b
\
\
\
\b

OK
\b
\
\
\
\
\

* If vehicle fails to run at this point, go to
the appropriate article in the ENGINE
PERFORMANCE section.
\
\
\
\
\
\b
\
\
\
\b
\
\
\
\

\

OK NOT OK
\b \b
\
\
\

\
\
\

* 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.

\
\
\
\b
\
\
\
\b

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
\
\
\
\
\
\
\

CONDITION POSSIBLE CAUSE CORRECTION\
\
\
\
\
\
\

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
\
\
\
\
\
\
\

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
\
\
\
\
\
\
\

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
\
\
\
\
\
\
\

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
\
\
\
\
\
\
\

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
\
\
\
\
\
\
\

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
\
\
\
\
\
\
\

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
\
\
\
\
\
\
\

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
\
\
\
\
\
\
\

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
\
\
\
\
\
\
\

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
\
\
\
\
\
\
\

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
\
\
\
\
\
\
\

Low Current Draw Worn brushes or weak Replace brushes or
brush springs as
necessary

Page 1254 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual ��\ ��\ ��\ ��\ ��\ ��\ ��\ �� High Pitched Whine Distance too great$

\
\
\
\
\
\
\

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
\
\
\
\
\
\
\

High Pitched Distance too small between
Whine After Engine starter pinion and flywheel
Fires With Key Flywheel runout contributes
released. Engine to the intermittent nature
Fires and Cranks
Normally
\
\
\
\
\
\
\

TUNE-UP TROUBLE SHOOTING - GAS ENGINE VEHICLES
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 SPARK PLUG TROUBLE SHOOTING CHARTS
\
\
\
\
\
\
\

CONDITION POSSIBLE CAUSE CORRECTION\
\
\
\
\
\
\

Normal Spark Light Tan or Gray deposits No Action
Plug Condition
Electrode not burned or No Action
fouled
Gap tolerance not changed No Action
\
\
\
\
\
\
\

Cold Fouling or Overrich air/fuel mixture Adjust air/fuel
Carbon Deposits mixture, see ENGINE
PERFORMANCE section
Faulty choke Replace choke
assembly, see ENGINE
PERFORMANCE section
Clogged air filter Clean and/or replace
air filter
Incorrect idle speed or Reset idle speed and/
dirty carburetor or clean carburetor
Faulty ignition wires Replace ignition
wiring
Prolonged operation Shut engine off
at idle during long idle
Sticking valves or worn Check valve train
valve guide seals
\
\
\
\
\
\
\

Wet Fouling Worn rings and pistons Install new rings and
or Oil Deposits pistons

Page 1255 of 1378

JEEP CHEROKEE 1988 Service Repair Manual Excessive cylinder wear Rebore or replace
block
Excessive valve guide Worn or loose bearing

Excessive cylinder wear Rebore or replace
block
Excessive valve guide Worn or loose bearing
clearance
\
\
\
\
\
\
\

Gap Bridged Deposits in combustion Clean combustion
chamber becoming fused chamber of deposits
to electrode
\
\
\
\
\
\
\

Blistered Engine overheating Check cooling system
Electrode
Wrong type of fuel Replace with correct
fuel
Loose spark plugs Retighten spark plugs
Over-advanced ignition Reset ignition timing
timing see ENGINE PERFORMANCE
\
\
\
\
\
\
\

Pre-Ignition or Incorrect type of fuel Replace with correct
Melted Electrodes fuel
Incorrect ignition timing Reset ignition timing
see ENGINE PERFORMANCE
Burned valves Replace valves
Engine Overheating Check cooling system
Wrong type of spark plug, Replace with correct
too hot spark plug, see
ENGINE PERFORMANCE
\
\
\
\
\
\
\

Chipped Severe detonation Check for over-
Insulators advanced timing or
combustion
Improper gapping Re-gap spark plugs
procedure
\
\
\
\
\
\
\

Rust Colored Additives in unleaded Try different fuel
Deposits fuel brand
\
\
\
\
\
\
\

Water In Combus- Blown head gasket or Repair or replace
tion Chamber cracked head head or head gasket
\
\
\
\
\
\
\

NOTE: Before diagnosing an electronic ignition system, ensure that
all wiring is connected properly between distributor, wiring
connector and spark plugs. Ignition problem will show up
either as: Engine Will Not Start or Engine Runs Rough.
BASIC ELECTRONIC IGNITION TROUBLE SHOOTING CHARTS
\
\
\
\
\
\
\

CONDITION POSSIBLE CAUSE CORRECTION\
\
\
\
\
\
\

Engine Won't Open circuit between Repair circuit
Start distributor and bulkhead
connector
Open circuit between Repair circuit
bulkhead connector and

Page 1256 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual ignition switch Open circuit between Repair circuit ignition switch and starter solenoid ��\ ��$

ignition switch
Open circuit between Repair circuit
ignition switch and
starter solenoid
\
\
\
\
\
\
\

Engine Runs Fuel lines leaking or Tighten fitting,
Rough clogged remove restriction
Initial timing incorrect Reset ignition timing
see ENGINE PERFORMANCE
Centrifugal advance Repair distributor
malfunction advance
Defective spark plugs or Replace plugs or plug
wiring wiring
\
\
\
\
\
\
\

Component Failure Spark arc-over on cap, Replace cap, rotor or
rotor or coil or coil
Defective pick-up coil Replace pick-up coil
Defective ignition coil Replace ignition coil
Defective vacuum unit Replace vacuum unit
Defective control module Replace control module
\
\
\
\
\
\
\

BASIC ELECTRONIC IGNITION TROUBLE SHOOTING
CHARTS - USING OSCILLOSCOPE PATTERNS
\
\
\
\
\
\
\

CONDITION POSSIBLE CAUSE CORRECTION\
\
\
\
\
\
\

Firing Voltage Retarded ignition timing Reset ignition
Lines are the Same, timing, see ENGINE
but Abnormally High PERFORMANCE section
Fuel mixture too lean Readjust carburetor,
see ENGINE PERFORMANCE
High resistance in coil Replace coil wire
wire
Corrosion in coil tower Clean and/or replace
terminal coil
Corrosion in distributor Clean and/or replace
coil terminal distributor cap
\
\
\
\
\
\
\

Firing Voltage Fuel mixture too rich Readjust carburetor,
Lines are the Same see ENGINE PERFORMANCE
but Abnormally Low
Breaks in coil wire causing Replace coil wire
arcing
Cracked coil tower causing Replace coil
arcing
Low coil output Replace coil
Low engine compression Determine cause and

Load next 8 pages

Page: < prev 1-10 ... 1217-1224 1225-1232 1233-1240 1241-1248 1249-1256 1257-1264 1265-1272 1273-1280 1281-1288 ... 1384 next >

bulb clock reset transmission auxiliary battery location fuel tank capacity center console