1988 JEEP CHEROKEE overheating

Connector missing ....... C ............ Require replacement.
Inoperative ............. A ........ (2) Require replacement.
Insulation overheated ... A ............ Require replacement.
Terminal broken ......... A .. Require repair or replacement.
Terminal burned, affecting
performance ............ A ........... ( 1) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
( 1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Inoperative includes intermittent operation or out of
OEM specification.









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BLOWER SWITCHES
See SWITCHES.
CABIN AIR FILTERS
CABIN AIR FILTER INSPECTION








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Condition Code Procedure
Air flow obstruction .... A ............. Require cleaning or
replacement.
Maintenance intervals ... 3 ............ Suggest replacement.
Missing ................. C ............ Require replacement.









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CIRCUIT BREAKERS
See FUSES, FUSIBLE LINKS AND CIRCUIT BREAKERS .
COMPRESSOR CLUTCH ASSEMBLIES
COMPRESSOR CLUTCH ASSEMBLY INSPECTION








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Condition Code Procedure
Air gap incorrect ....... B .. Require repair or replacement.
Bearing seized .......... A .. Require replacement of bearing
or assembly.
Bearing worn, affecting
performance ............ A .. Require replacement of bearing
or assembly.
Coil shows signs of
overheating ............ 1 .... Suggest replacement of coil.
Connector broken ........ A .. Require repair or replacement.
Connector (Weatherpack
type) leaking .......... A .. Require repair or replacement.
Connector melted,

2) On models with 2-piece shafts, rotate transmission yoke
until trunnion is in horizontal plane. Install front drive shaft with
"U" joint trunnion in vertical plane. Connect bearing support to
crossmember.
3) Ensure that front face of bearing support is perpendicular
(90 degrees) to centerline of drive shaft. Install rear drive shaft
with "U" joint trunnion of slip joint in vertical plane.
4) Set differential pinion yoke trunnion in vertical plane.
Connect rear drive shaft to pinion yoke. If 2-piece shaft is correctly
installed, centerline of trunnions at each end of individual shafts
will be parallel. See Fig. 3.
Fig. 3: Phase Alignment Of 2-Piece Drive Shafts
Trunnion yoke ears on each shaft must be parallel.
DRIVE SHAFT BALANCE TEST
1) Drive shaft imbalance may often be cured by disconnecting
shaft and rotating it 180 degrees in relation to other components.
Test by raising rear wheels off ground, and turning shaft with engine.
NOTE: DO NOT run engine without ram airflow across radiator for
prolonged periods, as overheating of engine or transmission
may occur.
2) On most models, balance testing may be done by marking
shaft in 4 positions, 90 degrees apart. Place marks approximately 6"
forward of weld, at rear end of shaft. Number marks one through 4.
3) Place screw-type hose clamp so clamp head is in number one
position, and rotate shaft with engine. If there is little or no
change, move clamp head to No. 2 position, and repeat test.
4) Continue procedure until vibration is at lowest level. If
no difference is noted with clamp head moved to all 4 positions,
vibrations may not be drive shaft imbalance.
5) If vibration is lessened but not completely gone, place 2
clamps at that point, and run test again. Combined weight of clamps in
one position may increase vibration. If so, rotate clamps 1/2" apart,
above and below best position, and repeat test.
6) Continue to rotate clamps as necessary, until vibration is
at lowest point. If vibration level is still unacceptable, leave rear
clamp(s) in position and repeat procedure at front end of drive shaft.\
If vibration can be eliminated or reduced to acceptable levels using
this test procedure, send drive shaft out to be balanced.

(1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Determine source of contamination, such as engine
coolant, fuel, metal particles, or water. Require
repair or replacement.
( 3) - Inoperative includes intermittent operation or out of
OEM specification. Some components may be serviceable;
check for accepted cleaning procedure.









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ENGINE COOLING SYSTEMS
NOTE: Overheating, poor engine performance, and insufficient
cabin heat can be affected by, but are not limited to,
all of the components in the engine cooling system.
ENGINE COVERS (OIL PAN, VALVE COVER, TIMING COVER)
ENGINE COVER (OIL PAN, VALVE COVER, TIMING COVER) INSPECTION








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Condition Code Procedure
Attaching hardware
incorrect .............. B ............ Require replacement.
Attaching hardware
loose .................. A .. Require repair or replacement.
Attaching hardware
missing ................ C ............ Require replacement.
Baffle loose ............ 2 .. Suggest repair or replacement.
Baffle missing .......... C ............ Require replacement.
Bent, affecting
performance ............ A .. Require repair or replacement.
Bent, not affecting
performance ............ .. ....... No service suggested or
required.
Cracked (not leaking) ... 2 .. Suggest repair or replacement.
Leaking externally ...... A .. Require repair or replacement.
Leaking internally,
causing fluid
contamination .......... A .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Restricted passage ...... A .. Require repair or replacement.
Threads damaged ......... A .. Require repair or replacement.









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ENGINE OIL
ENGINE OIL INSPECTION








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Condition Code Procedure
Contaminated ............ A .. ( 1) Require replacement of oil
and filter.
Level high .............. B ... Determine source of incorrect
level and require repair.
Level low ............... B ... Determine source of incorrect
level and require repair.
Maintenance intervals ... 3 ... Suggest replacement to comply
with vehicle's OEM recommended
service intervals.
( 1) - Determine source of contamination, such as engine coolant,
fuel, metal particles, or water when changing oil. Require

replacement.
Connector missing ....... C ............ Require replacement.
Corroded, affecting
performance ............ A ............ Require replacement.
Corroded, not affecting
performance ............ 2 ............ Suggest replacement.
Distorted ............... .. .... (2) No service suggested or
required.
Inoperative ............. A ........ ( 3) Require replacement.
Oil leaking ............. A ............ Require replacement.
Out of specification .... B ............ Require replacement.
Terminal broken ......... A .. Require repair or replacement.
Terminal burned, affecting
performance ............ A ........... ( 1) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Wire lead conductors
exposed ................ B .. Require repair or replacement.
Wire lead corroded ...... A .. Require repair or replacement.
Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
( 1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Distortion may be the result of overheating; coil should
be tested.
( 3) - Inoperative includes intermittent operation.









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IGNITION CONTROL MODULES (ICM)
IGNITION CONTROL MODULE (ICM) INSPECTION








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Condition Code Procedure
Application incorrect ... B ............ Require replacement.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware
threads damaged ........ A ... Require repair or replacement
of hardware.
Attaching hardware
threads stripped
(threads missing) ...... A ... Require repair or replacement
of hardware.
Code set
(if applicable) ........ A .......... ( 1) Further inspection
required.
Connector broken ........ A .. Require repair or replacement.
Connector (Weatherpack
type) leaking .......... A .. Require repair or replacement.
Connector melted ........ A ........... ( 2) Require repair or
replacement.

loose .................. A ... Require repair or replacement
of injection tube or
replacement of catalytic
converter.
Air injection tube
restricted ............. A ... Require repair or replacement
of injection tube or
replacement of catalytic
converter.
Air injection tube
threads damaged ........ A ... Require repair or replacement
of injection tube or
replacement of catalytic
converter.
Air injection tube
threads stripped
(threads missing) ...... A ... Require repair or replacement
of injection tube or
replacement of catalytic
converter.
Body cracked ............ B .. Require repair or replacement.
Converter empty ......... A .. Require repair or replacement.
Converter fill plug
missing ................ C .. Require repair or replacement.
Converter missing ....... C ............ Require replacement.
Exhaust gases leaking ... A .. Require repair or replacement.
Flanges leaking ......... A ... Require repair or replacement
of flanges.
Inlet pipes cracked ..... B .. Require repair or replacement.
Internal rattle (except
pellet-type) ........... 2 .......... (1) Further inspection
required.
Mounting brackets that
are part of converter
broken ................. A .. Require repair or replacement.
Obvious overheating ..... .. ......... ( 2) Require testing of
converter.
Outlet pipes cracked .... B .. Require repair or replacement.
Pieces of catalyst
material found
downstream ............. 1 ............ Suggest replacement.
Plugged ................. A ........ ( 3) Require replacement.
Testing has determined
that existing converter
has been lead-poisoned,
contaminated, or failed
testing ................ A .. Require repair or replacement.
( 1) - If the converter is breaking up, suggest converter
replacement. If an object has fallen into the converter,
remove the object.
( 2) - Overheating is caused by something other than the
converter. Further diagnosis is required to determine
the cause of the overheating.
( 3) - Determine cause and correct to ensure that new converter
will not become plugged.









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EXHAUST AND TAIL PIPES
NOTE: For pipes with resonators, also see MUFFLERS AND RESONATORS.
EXHAUST AND TAIL PIPE INSPECTION

computers may lose memory data. When battery power is
restored, driveability problems may exist on some vehicles.
These vehicles may require a relearn procedure. See COMPUTER
RELEARN PROCEDURES article in GENERAL INFORMATION section.
REPLACING BLOWN FUSES
Before replacing a blown fuse, remove ignition key, turn off
all lights and accessories to avoid damaging the electrical system. Be
sure to use fuse with the correct indicated amperage rating. The use
of an incorrect amperage rating fuse may result in a dangerous
electrical system overload.
BRAKE PAD WEAR INDICATOR
Indicator will cause a squealing or scraping noise, warning
that brake pads need replacement.
BRAKE WARNING LIGHT
CAUTION: If BRAKE warning light is on with parking brake disengaged
and engine running, there may be a problem in the hydraulic
brake system. Braking effort, brake pedal travel and
stopping distances may increase.
CATALYTIC CONVERTER
To prevent catalytic converter overheating, DO NOT allow
engine to idle for more than 20 minutes.
COMMAND-TRAC (4WD)
CAUTION: NEVER operate a Command-Trac vehicle in 4WD on dry,
hard-surfaced roads for a sustained period. Use 4L only
when needed for added pulling power. Operating vehicle in
4WD mode on such roads will cause stress and possible
damage to components, as well as make shifting difficult.
To reduce shifting effort, drive vehicle in Reverse for a
few feet, or drive off hard-surfaced road momentarily to
allow tire slippage.
FRONT AND REAR DIFFERENTIALS (4WD)
CAUTION: DO NOT use water, steam, kerosene or gasoline for flushing
a differential. ONLY use a flushing oil.
TRAC-LOK DIFFERENTIALS (4WD)
CAUTION: DO NOT flush a rear axle Trac-Lok differential. Trac-Lok
differentials may be cleaned only by disassembling the
unit and wiping the components with clean, lint-free cloth.
CAUTION: NEVER attempt to engage Low range when vehicle is moving
faster than 2-3 MPH, as transfer case damage may result.
GASOLINE CONTAINING ALCOHOL
CAUTION: Exclusive use of gasohol is not recommended. Vehicle test
results have shown that significant fuel system corrosion
can result when gasohol is used exclusively.

Parking Brake cables frozen See DRUM BRAKES
BRAKE SYSTEM
Incorrect installation of
inboard disc pad Remove and replace
correctly
Power booster output
rod too long See POWER BRAKE UNITS
BRAKE SYSTEM
Brake pedal not returning See DISC, DRUM BRAKES
freely BRAKE SYSTEM









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Brakes Grab or
Uneven Braking
Action Malfunction of combination See CONTROL VALVE or
valve BRAKE SYSTEM
Malfunction of power brake See POWER BRAKE UNITS
unit or BRAKE SYSTEM
Binding brake pedal See DISC, DRUM BRAKES
or BRAKE SYSTEM









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Pulsation or
Roughness Uneven pad wear caused by See DISC BRAKES or
caliper BRAKE SYSTEM
Uneven rotor wear See DISC BRAKES or
BRAKE SYSTEM
Drums out-of-round Reface or replace drums









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ENGINE MECHANICAL
COOLING 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.
COOLING SYSTEM TROUBLE SHOOTING









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CONDITION POSSIBLE CAUSE CORRECTION








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Overheating Coolant Leak Fill/Pressure Test
System
A/C Condenser Fins Clogged Remove/Clean Condenser
Radiator Fins Clogged Remove/Clean Radiator
Thermostat Stuck Closed Replace Thermostat
Clogged Cooling System
Passages Clean/Flush Cooling
System

in the section(s) you are accessing.
BASIC GASOLINE ENGINE - MECHANICAL TROUBLE SHOOTING CHART









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CONDITION POSSIBLE CAUSE CORRECTION








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Engine Lopes At Intake manifold-to-head Replace manifold
Idle leaks gasket, See ENGINES
Blown head gasket Replace head gasket,
See ENGINES
Worn timing gears, chain Replace gears, chain or
or sprocket sprocket
Worn camshaft lobes Replace camshaft, See
ENGINES
Overheated engine Check cooling system,
See COOLING
Blocked crankcase vent Remove restriction
valve
Leaking EGR valve Repair leak and/or
replace valve
Faulty fuel pump Replace fuel pump









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Engine Has Low Leaking fuel pump Repair leak and/or
Power replace fuel pump
Excessive piston-to-bore Install larger pistons,
clearance See ENGINES
Sticking valves or weak Check valve train
valve springs components, See ENGINES
Incorrect valve timing Reset valve timing, See
ENGINES
Worn camshaft lobes Replace camshaft, See
ENGINES
Blown head gasket Replace head gasket.
See ENGINES.
Clutch slipping Adjust pedal and/or
replace components, See
ENGINES
Engine overheating Check cooling system,
See COOLING
Auto. Trans. pressure
regulator valve faulty Replace pressure
regulator valve
Auto. Trans. fluid level Add fluid as necessary
too low
Improper vacuum diverter
valve operation Replace vacuum diverter
valve
Vacuum leaks Inspect vacuum system
and repair as required
Leaking piston rings Replace piston rings,
See ENGINES









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Faulty High Low fuel pump volume Replace fuel pump
Speed Operation
Leaking valves or worn Replace valves and/or
springs, See ENGINES
Incorrect valve timing Reset valve timing,See
ENGINES
Intake manifold restricted Remove restriction
Worn distributor shaft Replace distributor









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Faulty Improper fuel pump stroke Remove pump and reset
Acceleration pump stroke