Volvo 850 service & repair manual

TROUBLE SHOOTING – BASIC PROCEDURES

1995 Volvo 850

GENERAL TROUBLE SHOOTING

* PLEASE READ THIS FIRST *

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.

ACCESSORIES & ELECTRICAL

CHARGING 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.
BASIC CHARGING SYSTEM TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION
Vehicle Will Not Dead battery Check battery cells, Start alternator belt tension and alternator output
Loose or corroded battery Check all charging connections system connections
Ignition circuit or switch Check and replace as malfunction necessary

condition, See Belt

Alternator Light	Loose	or worn alternator	Check alternator drive
Stays On With	drive	belt	tension and
Engine Running
			Adjustment in TUNE-UP
			article in the
	Loose	alternator wiring	TUNE-UP section Check all charging

connections system connections
Short in alternator light See Indicator Warning wiring Lights in STANDARD
INSTRUMENTS in the ACCESSORIES & EQUIPMENT section
Defective alternator stator See Bench Tests in or diodes ALTERNATOR article
Defective regulator See Regulator Check in
ALTERNATOR article
Alternator Blown fuse See WIRING DIAGRAMS Light Stays Off
With Ignition
Switch ON
Defective alternator See Testing in
ALTERNATOR article
Defective indicator light See Indicator Warning bulb or socket Lights in STANDARD
INSTRUMENTS in the ACCESSORIES & EQUIPMENT section
Alternator Short in alternator wiring See On-Vehicle Tests Light Stays OFF in ALTERNATOR article With Ignition
Switch ON
Defective rectifier bridge See Bench Tests in
ALTERNATOR article
Lights or Fuses Defective alternator wiring See On-Vehicle Tests Burn Out in ALTERNATOR article Frequently
Defective regulator See Regulator Check in
ALTERNATOR article
Defective battery Check and replace as necessary

Ammeter Gauge Shows Discharge	Loose or worn drive	belt	Check alternator drive belt tension and condition. See Belt Adjustment in TUNE-UP article in the TUNE-UP section
	Defective wiring	Check all wires and wire connections
	Defective alternator or regulator	See Bench Tests and On-Vehicle Tests in ALTERNATOR article
	Defective ammeter, or improper ammeter wiring connection	See Testing in STANDARD INSTRUMENTS in the ACCESSORIES & EQUIPMENT section
Noisy Alternator	Loose drive pulley	Tighten drive pulley attaching nut
	Loose mounting bolts	Tighten all alternator mounting bolts
	Worn or dirty bearings	See Bearing
		Replacement
		ALTERNATOR article

Defective diodes or stator See Bench Test in
ALTERNATOR article

belt tension and

Battery Does	Loose	or	worn drive	belt	Check alternator drive
Stay Charged
	condition. See
	Belt Adjustment in
	appropriate TUNE-UP
	article in the
	TUNE-UP section

Loose or corroded battery Check all charging connections system connections
Loose alternator connections Check all charging system connections
Defective alternator or See On-Vehicle Tests battery and Bench Tests in
ALTERNATOR article
Add-on electrical accessories Install larger exceeding alternator capacity alternator
Battery Defective battery Check alternator Overcharged- output and repair as Uses Too Much necessary
Water
Defective alternator See On-Vehicle Test and Bench Tests in ALTERNATOR article
Excessive alternator voltage Check alternator output and repair as necessary

IGNITION 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.
Ignition Secondary Trouble Shooting Chart
START: Visually inspect Spark Plug Wires, Coil Wires, Plug Wire Boots, Rotor, and Distributor Cap for signs of damage.
OK NOT OK

damaged components

as necessary

* To test secondary ignition	*	Repair or replace
system, modify a Spark Plug
by attaching a ground wire
to the body of the plug and

widening the gap to 1/4-3/8″. Disconnect spark plug wire
and insert test plug. Ground plug, crank engine, and
check for spark.
GOOD SPARK NO SPARK
* 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
the plug and crank engine while checking for spark.

PRIMARY TROUBLE SHOOTING

CHECK CHART below in this

article.

*	GOOD SPARK If plug has a good spark,	*	NO SPARK Proceed to the IGNITION
	the problem is in the plug
	wires, distributor cap, or
	rotor. Replace components
	as necessary.

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.
OK NOT OK

components as necessary.

*	Check	that battery voltage	*	Repair or replace damaged
	is at	least 11.5 volts.

NOT OK OK
* Replace or recharge the * Check for battery voltage battery. at the positive terminal of
the coil.
OK NOT OK
* Check air Gap of the Pick-Up * Check resistance of ballast coil in the distributor. resistor (if used) for the
correct resistance value.
OK NOT OK

necessary.

*	Check Pick-Up coil	for	*	Adjust or replace as
	correct resistance	value.

NOT OK OK
* Replace Pick-Up coil if * Check control module for not to specification. good ground connections.
OK
* If vehicle fails to run at this point, go to the appropriate article in the ENGINE PERFORMANCE section.
OK NOT OK

if the measured resistance

value is not within

specification.

*	Check wires from the battery/	*	Replace ballast resistor
	ignition switch to the coil.
	Also check the coil primary
	and secondary resistance.

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
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 wire	See Testing in STARTER article
Starter Does Not Operate and Headlights Dim	Weak battery or dead cell Loose or corroded battery connections	Charge or replace battery as necessary Check that battery connections are clean and tight
	Internal ground in starter windings	See Testing in STARTER article
	Grounded starter fields	See Testing in STARTERS
	Armature rubbing on pole shoes	See STARTER article
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

See On-Vehicle Tests inSTARTER article

Check all ground connections for tight and clean connections

Charge or replace

battery as necessary

	Faulty solenoid
	Poor grounds
	Ignition switch or misadjusted	faulty	Adjust or replace ignition switch as necessary
Starter Cranks	Battery weak or
Engine Slowly	defective

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

Charge or replace battery as necessary

Check all wiring and connections leading to relay

switch

Starter Relay Does Not Close	Dead battery
	Faulty wiring
	Neutral safety	switch	Replace neutral safety
	faulty

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
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

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 CONDITION POSSIBLE CAUSE
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.
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.
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.

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
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 CONDITION POSSIBLE CAUSE 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.
Too Much Heat Improperly adjusted cables.
Sticking heater control valve.
No vacuum to heater control valve. Temperature door stuck open.
Air Flow Changes During
Acceleration Vacuum system leak.
Bad check valve or reservoir.
Air From Defroster At All
Times Vacuum system leak.
Improperly adjusted control cables. Inoperative vacuum motor.
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.

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.
BRAKE SYSTEM TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION 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
Noises Without
Loose suspension parts See SUSPENSION
Brakes Applied Front linings worn out Replace linings
Noises With
Dust or oil on drums See DRUM, DISC BRAKES
or rotors or BRAKE SYSTEM
Brakes Applied Insulator on outboard See DISC BRAKES or shoe damaged BRAKE SYSTEM
Incorrect pads or linings Replace pads or linings
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
Excessive Pedal
Disc pad reversed, steel
against rotor Remove and reinstall pad
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
sluggish See DISC BRAKES or
BRAKE SYSTEM
Master cylinder piston
stuck See MASTER CYLINDERS
or BRAKE SYSTEM
Brake fade due to incorrect
pads for linings Replace pads or linings
Linings or pads glazed Replace pads or linings
Excessive Pedal
Worn drums Reface or replace drums
Travel Partial brake system failure Check fluid and pipes
Insufficient fluid in
master cylinder See MASTER CYLINDERS or
BRAKE SYSTEM
Air trapped in system See BRAKE BLEEDING or
BRAKE SYSTEM
Rear brakes not adjusted See Adjustments in DRUM BRAKES or BRAKE SYSTEM
Bent shoe or lining See DRUM BRAKES or
BRAKE SYSTEM
Plugged master cylinder cap See MASTER CYLINDERS
or BRAKE SYSTEM
Pedal Travel
Improper brake fluid Replace brake fluid
Decreasing Compensating port plugged See MASTER CYLINDERS
or BRAKE SYSTEM
Swollen cup in master
cylinder See MASTER CYLINDERS
or BRAKE SYSTEM
Master cylinder piston
not returning See MASTER CYLINDERS
or BRAKE SYSTEM
Weak shoe retracting springs See DRUM BRAKES BRAKE SYSTEM
Dragging
Wheel cylinder piston
sticking See DRUM BRAKES or
BRAKE SYSTEM
Brakes Master cylinder pistons
not returning See MASTER CYLINDERS BRAKE SYSTEM
Restricted brake lines
or hoses Check line routing
Incorrect parking brake
adjustment See DRUM BRAKES BRAKE SYSTEM
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
Brakes Grab or
Uneven Braking
Brake pedal not returning See DISC, DRUM BRAKES
freely BRAKE SYSTEM
Action Malfunction of combination See CONTROL VALVE or valve BRAKE SYSTEM
Malfunction of power brake See POWER BRAKE UNITS
unit or BRAKE SYSTEM
Pulsation or
Binding brake pedal See DISC, DRUM BRAKES
or BRAKE SYSTEM
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

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
CONDITION POSSIBLE CAUSE CORRECTION 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
Water Pump Malfunction Replace Water Pump Fan Clutch Malfunction Replace Fan Clutch Retarded Ignition Timing Reset Ignition Timing
Cooling Fan Malfunction Test Cooling Fan/ Circuit
Cooling Fan Motor
Malfunction Test Fan Motor
Cooling Fan Relay
Malfunction Test Fan Relay
Faulty Radiator Cap Replace Radiator Cap Broken/Slipping Fan Belt Replace Fan Belt Restricted Exhaust Repair Exhaust System
Corrosion Impurities In Coolant Clean/Flush System
Coolant Leakage Damaged hose Replace Hose
Leaky Water Pump Replace Water Pump Damaged Radiator Seam Replace/Repair Radiator Leaky Thermostat Cover Replace Thermostat
Cover
Cylinder Head Problem Check Head/Head Gasket
Leaky Freeze Plugs Replace Freeze Plugs
Recovery System Inoperative
Loose and/or Defective
Radiator Cap Replace Radiator Cap
Overflow Tube Clogged
and/or Leaking Repair Tube
Recovery Bottle Vent
Restricted Clean Vent
No Heater Core Flow
Collapsed Heater Hose Replace Heater Hose
Plugged Heater Core Clean/Replace Heater
Core
Faulty Heater Valve Replace Heater Valve

GASOLINE ENGINE – MECHANICAL 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 GASOLINE ENGINE – MECHANICAL TROUBLE SHOOTING CHART CONDITION POSSIBLE CAUSE CORRECTION

	Incorrect ignition timing Leaking valves Worn fuel pump diaphragm or piston	Reset ignition timing, See TUNE-UP Replace valves, See ENGINES Replace diaphragm or piston
Intake Backfire	Improper ignition timing Faulty accelerator pump	Reset ignition timing, See TUNE-UP Replace accelerator
	discharge Improper choke operation Defective EGR valve Fuel mixture too lean Choke valve initial clearance too large	pump Check choke and adjust as required Replace EGR valve Reset air/fuel mixture, See TUNE-UP Reset choke valve initial clearance
Exhaust Backfire	Vacuum leak Faulty vacuum diverter	Inspect and repair vacuum system Replace vacuum diverter
	valve Faulty choke operation Exhaust system leak	valve Check choke and adjust as required repair exhaust system leak
Engine Detonation	Ignition timing too far advanced Faulty ignition system Spark plugs loose or faulty Fuel delivery system clogged EGR valve inoperative PCV system inoperative Vacuum leaks Excessive combustion chamber deposits Leaking, sticking or broken valves	Reset ignition timing, See TUNE-UP Check ignition timing, See TUNE-UP Retighten or replace plugs Inspect lines, pump and filter for clog Replace EGR valve Inspect and/or replace hoses or valve Check vacuum system and repair leaks Remove built-up deposits Inspect and/or replace valves
External Oil	Fuel pump improperly seated	Remove pump, replace
Leakage	or worn gasket	gasket and seat
		properly
	Oil pan gasket broken or	Straighten pan and
	pan bent	replace gasket
	Timing chain cover gasket	Replace timing chain
	broken	cover gasket
	Rear main oil seal worn	Replace rear main oil
		seal
	Oil pan drain plug not	Remove and reinstall
	seated properly	drain plug
	Camshaft bearing drain	Remove restriction
	hole blocked
	Oil pressure sending	Remove and reinstall
	switch leaking	sending switch

Excessive Oil Worn valve stems or guides Replace stems or
Consumption guides, See ENGINES Valve “O” ring seals Replace “O” ring seals, damaged See ENGINES
Plugged oil drain back holes Remove restrictions Improper PCV valve Replace PCV valve operation
Engine oil level too high Remove excess oil Engine oil too thin Replace thicker oil Valve stem oil deflectors Replace oil deflectors damaged
Incorrect piston rings Replace piston rings, See ENGINES
Piston ring gaps not Reinstall piston rings, staggered See ENGINES
Insufficient piston ring Replace rings, See tension ENGINES
Piston ring grooves or oil Replace piston rings, return slots clogged See ENGINES
Piston rings sticking in Replace piston rings, grooves See ENGINES
Piston ring grooves Replace piston and excessively worn rings, See ENGINES Compression rings installed Replace compression upside down rings correctly, See
ENGINES
Worn or scored cylinder Rebore cylinders or walls replace block Mismatched oil ring Replace oil ring expander and rail expander and rail, See
ENGINES
Intake gasket dowels too Replace intake gasket long dowels
Excessive main or connecting Replace main or rod bearing clearance connecting rod
bearings, See ENGINES
No Oil Pressure Low oil level Add oil to proper level Oil pressure sender or Replace sender or gauge gauge broken
Oil pump malfunction Remove and overhaul oil pump, See ENGINES
Oil pressure relief valve Remove and reinstall sticking valve
Oil pump passages blocked Overhaul oil pump, See
ENGINES
Oil pickup screen or tube remove restriction blocked
Loose oil inlet tube Tighten oil inlet tube
Loose camshaft bearings Replace camshaft bearings, See ENGINES
Internal leakage at oil Replace block or passages cylinder head
Low Oil Pressure Low engine oil level Add oil to proper level
Engine oil too thin Remove and replace with thicker oil
Excessive oil pump Reduce oil pump clearance clearance, See ENGINES Oil pickup tube or screen Remove restrictions blocked
Main, rod or cam bearing Replace bearing to clearance excessive reduce clearance, See
ENGINES
High Oil Improper grade of oil Replace with proper oil
Pressure Oil pressure relief valve Eliminate binding stuck closed
Oil pressure sender or Replace sender or gauge gauge faulty
Noisy Main Inadequate oil supply Check oil delivery to
Bearings main bearings
Excessive main bearing Replace main bearings, clearance See ENGINES
Excessive crankshaft end Replace crankshaft, See play ENGINES
Loose flywheel or torque Tighten attaching bolts converter
Loose or damaged vibration Tighten or replace damper vibration damper Crankshaft journals Re-grind crankshaft out-of-round journals
Excessive belt tension Loosen belt tension
Noisy Connecting Excessive bearing clearance Replace bearing, See
Rods or missing bearing ENGINES
Crankshaft rod journal Re-grind crankshaft out-of-round journal
Misaligned connecting rod Remove rod or cap and or cap realign
Incorrectly tightened rod Remove and re-tighten bolts rod bolts
Noisy Pistons Excessive piston-to-bore Install larger pistons, and Rings clearance See ENGINES
Bore tapered or out-of-round Rebore block
Piston ring broken Replace piston rings, See ENGINES
Piston pin loose or seized Replace piston pin, See
ENGINES
Connecting rods misaligned Realign connecting rods Ring side clearance too Replace with larger or loose or tight smaller rings
Carbon build-up on piston Remove carbon
Noisy Valve Worn or bent push rods Replace push rods, See
Train ENGINES
Worn rocker arms or bridged Replace push rods, See pivots ENGINES
Dirt or chips in valve Remove lifters and lifters remove dirt/chips Excessive valve lifter Replace valve lifters, leak-down See ENGINES
Valve lifter face worn Replace valve lifters, See ENGINES
Broken or cocked valve replace or reposition springs springs
Too much valve stem-to-guide Replace valve guides, clearance See ENGINES
Valve bent Replace valve, See
ENGINES
Loose rocker arms Retighten rocker arms, See ENGINES
Excessive valve seat Reface valve seats, See run-out ENGINES

	Missing valve lock Excessively worn camshaft lobes Plugged valve lifter oil holes Faulty valve lifter check ball Rocker arm nut installed upside down Valve lifter incorrect for engine Faulty push rod seat or lifter plunger	Install new valve lock Replace camshaft, See ENGINES Eliminate restriction or replace lifter Replace lifter check ball, See ENGINES Remove and reinstall correctly Remove and replace valve lifters Replace plunger or push rod
Noisy Valves	Improper valve lash Worn or dirty valve lifters Worn valve guides Excessive valve seat or	Re-adjust valve lash, See ENGINES Clean and/or replace lifters Replace valve guides, See ENGINES Reface seats or valve
	face run-out Worn camshaft lobes Loose rocker arm studs Bent push rods Broken valve springs	face Replace camshaft, See ENGINES Re-tighten rocker arm studs, See ENGINES Replace push rods, See ENGINES Replace valve springs, See ENGINES
Burned,Sticking or Broken Valves	Weak valve springs or warped valves Improper lifter clearance Worn guides or improper guide clearance Out-of-round valve seats or improper seat width Gum deposits on valve stems, seats or guides Improper spark timing	Replace valves and/or springs, See ENGINES Re-adjust clearance or replace lifters Replace valve guides, See ENGINES Re-grind valve seats Remove deposits Re-adjust spark timing
Broken Pistons/Rings	Undersize pistons Wrong piston rings Out-of-round cylinder bore	Replace with larger pistons, See ENGINES Replace with correct rings, See ENGINES Re-bore cylinder bore
	Improper connecting rod alignment Excessively worn ring grooves Improperly assembled piston pins Insufficient ring gap clearance Engine overheating Incorrect ignition timing	Remove and realign connecting rods Replace pistons, See ENGINES Re-assemble pin-to -piston, See ENGINES Install new rings, See ENGINES Check cooling system Re-adjust ignition timing, See TUNE-UP
Excessive	Leaks at manifold to	Replace manifold or
Exhaust Noise	head, or to pipe	pipe gasket
	Exhaust manifold	Replace exhaust

cracked or broken manifold, See ENGINES

ENGINE PERFORMANCE

CARBURETOR 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 COLD START SYMPTOMS TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION

Check choke operation, see FUEL SYSTEMS

Check linkage, seeFUEL SYSTEM

Engine Start	Won’t	Choke	not closing
		Choke	linkage bent
Engine	Starts,	Choke	vacuum kick	setting	Check setting and

Then Dies too wide adjust see, FUEL SYSTEMS
Fast idle RPM too low Reset RPM to specif- ication, see TUNE-UP
Fast idle cam index Reset fast idle cam incorrect index, see FUEL
SYSTEMS
Vacuum leak Inspect vacuum system for leaks
Low fuel pump outlet Repair or replace pump, see FUEL SYSTEMS
Low carburetor fuel level Check float setting see FUEL SYSTEM

Engine Quits	Choke vacuum kick setting	Reset vacuum kick
Under Load	incorrect	setting,see FUEL
		SYSTEMS

Fast idle cam index Reset fast idle cam incorrect index, see FUEL
SYSTEM
Incorrect hot fast idle Reset fast idle RPM, speed RPM see TUNE-UP

Engine Starts,	Choke vacuum kick set too	Reset vacuum kick,
Runs Up,Then	narrow	see FUEL SYSTEMS
Idles, Slowly
With Black Smoke	Fast idle cam index	Reset fast idle cam

incorrect index, see FUEL SYSTEMS
Hot fast idle RPM too low Reset fast idle RPM, see TUNE-UP
BASIC HOT START SYMPTOMS TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION Engine Won’t Engine flooded Allow fuel to
Start evaporate
BASIC COLD ENGINE DRIVEABILITY SYMPTOMS TROUBLE SHOOTING CHART CONDITION POSSIBLE CAUSE CORRECTION

Defective choke control switchReplace choke control switch, see FUEL SYSTEMS

Plugged heat crossoverRemove restriction

system

Engine Stalls in Gear	Choke vacuum kick incorrect	setting	Reset choke vacuum kick, see FUEL SYSTEMS
		Fast idle	RPM incorrect	Reset fast idle RPM, see TUNE-UP
		Fast idle incorrect	cam index	Reset fast idle cam see FUEL SYSTEMS
Acceleration or Stall	Sag	Defective switch	choke control	Replace choke control switch
		Choke vacuum kick setting incorrect	Reset choke vacuum kick see, FUEL SYSTEMS
		Float level incorrect (too low)	Adjust float level, FUEL SYSTEMS
		Accelerator pump defective	Repair or replace pump see FUEL SYSTEMS
		Secondary throttles not closed	Inspect lockout adjustment,see FUEL SYSTEMS
Sag or Stall After Warmup
		Defective accelerator pump	Replace pump, see FUEL SYSTEMS
		Float level incorrect (too low)	Adjust float level, see FUEL SYSTEMS
Backfiring &
Black Smoke

BASIC WARM ENGINE DRIVEABILITY SYMPTOMS TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION
Hesitation With Vacuum leak Inspect vacuum lines
Small Amount of
Gas Pedal Movement
Accelerator pump weak or Replace pump, see inoperable FUEL SYSTEMS
Float level setting too low Reset float level, see,FUEL SYSTEMS
Metering rods sticking or Inspect and/or binding replace rods, see
FUEL SYSTEMS
Carburetor idle or transfer Inspect system and system plugged remove restriction
Frozen or binding heated air Inspect heated air inlet door for binding
Hesitation With Defective accelerator pump Replace pump, see Heavy Gas Pedal FUEL SYSTEMS Movement
Metering rod carrier Remove restriction sticking or binding
Large vacuum leak Inspect vacuum system and repair leak
Float level setting too Reset float level, low see FUEL SYSTEMS
Defective fuel pump, lines Inspect pump, lines or filter and filter
Air door setting incorrect Adjust air door setting, see FUEL

DIESEL ENGINE 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.
NOTE: Diesel engines mechanical diagnosis is the same as gasoline engines for items such as noisy valves, bearings, pistons, etc. The following trouble shooting covers only items pertaining to diesel engines.
BASIC DIESEL ENGINE TROUBLE SHOOTING CHART

CONDITION	POSSIBLE CAUSE	CORRECTION
Engine Won’t	Bad battery connections	Check connections
Crank	or dead batteries	and/or replace

batteries
Bad starter connections Check connections or bad starter and/or replace
batteries
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
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
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
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
Air in fuel system Bleed air from system
Incorrect or contaminated Replace fuel fuel
Injector nozzle malfunction Check nozzles, see
FUEL SYSTEMS
Engines Starts Injection pump timing Reset pump timing, see and Idles Rough incorrect FUEL SYSTEMS
W/out Smoke or Engine not fully broken in Put more miles on
Noise, But Clears engine
After Warm-Up Air in system Bleed air from system
Injector nozzle malfunction Check nozzles, see
FUEL SYSTEMS
Engine Idles Blocked fuel filter Replace fuel filter Correctly, Injection pump timing Reset pump timing, see Misfires Above incorrect FUEL SYSTEMS
Idle Incorrect or contaminated Replace fuel fuel
Engine Won’t Fast idle adjustment Reset fast idle, see
Return To Idle incorrect TUNE-UP
Internal injection pump Replace injection pump, malfunction see FUEL SYSTEMS External linkage binding Check linkage and
remove binding
Fuel Leaks On Loose or broken fuel line Check lines and
Ground connections
Internal injection pump Replace injection pump, seal leak see FUEL SYSTEMS
Cylinder Injector nozzles sticking Test injectors, see
Knocking Noise open FUEL SYSTEMS
Very low nozzle opening Test injectors and/or pressure replace
Loss of Engine Restricted air intake Remove restriction
Power EGR valve malfunction Replace EGR valve Blocked or damaged exhaust Remove restriction system and/or replace
components Blocked fuel tank filter Replace filter Restricted fuel filter Remove restriction
and/or replace filter
Block vent in gas cap Remove restriction and/or replace cap
Tank-to-injection pump fuel Check fuel lines and supply blocked connections
Blocked fuel return system Remove restriction
Incorrect or contaminated Replace fuel fuel
Blocked injector nozzles Check nozzle for blockage, see FUEL SYSTEMS
Low compression Check valves, rings, pistons, see ENGINES
Loud Engine Basic timing incorrect Reset timing, see
Noise With Black FUEL SYSTEMS
Smoke EGR valve malfunction Replace EGR valve Internal injection pump Replace injection pump, malfunction see FUEL SYSTEMS

Cooling system leaksBelt slipping or damagedThermostat stuck closedHead gasket leakingCheck cooling system and repair leaks Check tension and/or replace beltRemove and replace thermostat, see ENGINE COOLING Replace head gasket

Injector pump fuel solenoidRemove and check

does not return fuel valvesolenoid and replace

	Incorrect injector pump housing pressure	Check pressure, see FUEL SYSTEMS
Engine Overheating
Oil Light on Idle	at	Low oil pump pressure Oil cooler or line	Check oil pump operation, see ENGINES Remove restriction
		restricted	and/or replace cooler
Engine Won’t
Shut Off
		to OFF position	if needed

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

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

circuit

CONDITION	POSSIBLE CAUSE	CORRECTION
Engine Won’t	Cold start valve inoperative	Test valve and
Start (Cranks
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

	Low fuel pressure	Test pressure regul- ator and fuel pump, check for restricted lines and filters
	No distributor reference pulses	Repair ignition system as necessary
	Open coolant temperature sensor circuit	Test sensor and wiring
	Shorted W.O.T. switch in T.P.S.	Disconnect W.O.T. switch, engine should start
	Defective ECM	Replace ECM
	Fuel tank residual pressure valve leaks	Test for fuel pressure drop after shut down
Hard Starting	Disconnected hot air tube to air cleaner	Reconnect tube and test control valve
	Defective Idle Air Control (IAC) valve	Test valve operation and circuit
	Shorted, open or misadjusted T.P.S.	Test and adjust or replace T.P.S.
	EGR valve open	Test EGR valve and control circuit
	Poor Oxygen sensor signal	Test for shorted or circuit
	Incorrect mixture from PCV system	Test PCV for flow, check sealing of oil filter cap
Poor High Speed Operation	Low fuel pump volume	Faulty pump or restricted fuel lines or filters
	Poor MAP sensor signal	Test MAP sensor, vacuum hose and wiring
	Poor Oxygen sensor signal	Test for shorted or open sensor or circuit
	Open coolant temperature sensor circuit	Test sensor and wiring
	Faulty ignition operation	Check wires for cracks or poor con- nections, test secondary voltage with oscilloscope
	Contaminated fuel	Test fuel for water

or alcohol
Intermittent ECM ground Test ECM ground connection for resistance
Restricted air cleaner Replace air cleaner
Restricted exhaust system Test for exhaust manifold back pressure
Poor MAF sensor signal Check leakage between sensor and manifold

If tester for ALCL hook-up is available check that VSS reading matches speedometer

open sensor or

	Poor	VSS signal
Ping or Knock on	Poor	Knock sensor	signal	Test for shorted or
Acceleration
				circuit

Poor Baro sensor signal Test for shorted or open sensor or circuit
Improper ignition timing See VEHICLE EMISSION CONTROL LABEL (where applicable)
Check for engine Low coolant, loose overheating problems belts or electric
cooling fan inoperative
NOTE: For additional electronic fuel injection trouble shooting information, see the appropriate article in the ENGINE PERFORMANCE section (not all vehicles have Computer Engine Control articles). Information is provided there for diagnosing fuel system problems on vehicles with electronic fuel injection.

IGNITION 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.
Ignition Secondary Trouble Shooting Chart
START: Visually inspect Spark Plug Wires, Coil Wires, Plug Wire Boots, Rotor, and Distributor Cap for signs of damage.
OK NOT OK

damaged components

as necessary

*	To test secondary ignition	*	Repair or replace
	system, modify a Spark Plug
	by attaching a ground wire
	to the body of the plug and
	widening the gap to 1/4-3/8″.
	Disconnect spark plug wire
	and insert test plug. Ground
	plug, crank engine, and
	check for spark.

GOOD SPARK NO SPARK
* 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
the plug and crank engine while checking for spark.

PRIMARY TROUBLE SHOOTING

CHECK CHART below in this

article.

*	GOOD SPARK If plug has a good spark,	*	NO SPARK Proceed to the IGNITION
	the problem is in the plug
	wires, distributor cap, or
	rotor. Replace components
	as necessary.

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.
OK NOT OK

components as necessary.

*	Check	that battery voltage	*	Repair or replace damaged
	is at	least 11.5 volts.

NOT OK OK
* Replace or recharge the * Check for battery voltage battery. at the positive terminal of
the coil.
OK NOT OK
* Check air Gap of the Pick-Up * Check resistance of ballast coil in the distributor. resistor (if used) for the
correct resistance value.
OK NOT OK

necessary.

*	Check Pick-Up coil	for	*	Adjust or replace as
	correct resistance	value.

NOT OK OK

good ground connections.

*	Replace Pick-Up coil if	*	Check control module for
	not to specification.

OK
* If vehicle fails to run at this point, go to the appropriate article in the ENGINE PERFORMANCE section.
OK NOT OK

if the measured resistance

value is not within

specification.

*	Check wires from the battery/	*	Replace ballast resistor
	ignition switch to the coil.
	Also check the coil primary
	and secondary resistance.

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

	Ignition switch faulty or misadjusted	Adjust or replace ignition switch
	Open circuit between starter switch ignition terminal on starter relay	Check and repair wires and connections as necessary
	Starter relay or starter defective	See Testing in STARTER article
	Open solenoid pull-in wire	See Testing in STARTER article
Starter Does Not Operate and Headlights Dim	Weak battery or dead cell Loose or corroded battery connections	Charge or replace battery as necessary Check that battery connections are clean and tight
	Internal ground in starter windings	See Testing in STARTER article
	Grounded starter fields	See Testing in STARTERS
	Armature rubbing on pole shoes	See STARTER article
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 Crank Engine	Faulty overrunning clutch	See STARTER article
	Broken clutch housing	See STARTER article
	Broken flywheel teeth	Replace flywheel and check for starter pinion gear damage
	Armature shaft sheared or reduction gear teeth stripped	See STARTER article
	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
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

Does Not Close	Faulty wiring	battery as necessary Check all wiring and
		connections leading to relay
	Neutral safety switch faulty	Replace neutral safety switch
	Starter relay faulty	Replace starter relay
Starter Drive Will Not Disengage	Starter motor loose on mountings Worn drive end bushing	Tighten starter attach bolts See STARTER article
	Damaged engine flywheel teeth	Replace flywheel and starter pinion gear for damage
	Drive yolk return spring broken or missing	Replace return spring
	Faulty ignition switch	Replace ignition switch
	Insufficient clearance between winding leads to solenoid terminal and main contact in solenoid	Replace starter solenoid
	Starter clutch not disengaging	Replace starter clutch
	Ignition starter switch contacts sticking	Replace ignition switch
Starter Relay Operates but Solenoid Does Not	Faulty solenoid switch, switch connections or	Check all wiring between relay and 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
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

mixture, see ENGINE PERFORMANCE section

Replace choke

Cold Fouling or	Gap tolerance not Overrich air/fuel	changed mixture	No Action Adjust air/fuel
Carbon Deposits
	Faulty 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

pistons

	Prolonged operation at idle	Shut engine during long	off idle
	Sticking valves or worn valve guide seals	Check valve	train
Wet Fouling	Worn rings and pistons	Install new	rings and
or Oil Deposits

Deposits in combustion chamber becoming fused to electrodeClean combustion chamber of deposits

Engine overheatingWrong type of fuelCheck cooling systemReplace with correct

	Excessive cylinder wear	Rebore or replace block
	Excessive valve guide clearance	Worn or loose bearing
Gap Bridged
Blistered Electrode
			fuel
		Loose spark plugs	Retighten spark plugs
		Over-advanced ignition timing	Reset ignition 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 Engine Overheating Wrong type of spark plug,	Replace valves Check cooling system Replace with correct
	too hot	spark plug, see ENGINE PERFORMANCE
Chipped Insulators	Severe detonation	Check for over- advanced timing or combustion
	Improper gapping procedure	Re-gap spark plugs
Rust Colored Deposits	Additives in unleaded fuel	Try different 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

	ignition switch Open circuit between	Repair circuit
	ignition switch and starter solenoid
Engine Runs Rough	Fuel lines leaking or clogged	Tighten fitting, remove restriction
	Initial timing incorrect	Reset ignition timing see ENGINE PERFORMANCE
	Centrifugal advance malfunction	Repair distributor advance
	Defective spark plugs or wiring	Replace plugs or plug wiring
Component Failure	Spark arc-over on cap, rotor or coil	Replace cap, rotor or 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
repair
One or More, But Carburetor idle mixture Readjust carburetor, Not All Firing not balanced see ENGINE PERFORMANCE Voltage Lines are
Higher Than Others EGR valve stuck open Clean and/or replace valve
High resistance in spark Replace spark plug plug wires wires

	Cracked or broken spark plug insulator	Replace spark plugs
	Intake vacuum leak	Repair leak
	Defective spark plugs	Replace spark plugs
	Corroded spark plug terminals	Replace spark plugs
One or More, But Not All Firing Voltage Lines Are Lower Than Others	Curb idle mixture not balanced Breaks in plug wires causing arcing	Readjust carburetor, see ENGINE PERFORMANCE Replace plug wires
	Cracked coil tower causing arcing	Replace coil
	Low compression	Determine cause and repair
	Defective spark plugs	Replace spark plugs
	Corroded spark plugs	Replace spark plugs
Cylinders Not Firing	Cracked distributor cap terminals	Replace distributor cap
	Shorted spark plug wire	Determine cause and repair
	Mechanical problem in engine	Determine cause and repair
	Defective spark plugs	Replace spark plugs
	Spark plugs fouled	Replace spark plugs

BASIC DRIVEABILITY PROBLEMS TROUBLE SHOOTING TABLE CONDITION POSSIBLE CAUSE CORRECTION
Hard Starting Binding carburetor linkage Eliminate binding Binding choke linkage Eliminate binding Binding choke piston Eliminate binding
Restricted choke vacuum Check vacuum lines for blockage

see ENGINE PERFORMANCE

	Worn or dirty needle valve and seat	Clean carburetor, see ENGINE PERFORMANCE
	Float sticking	Readjust or replace float see the ENGINE PERFORMANCE section
	Incorrect choke adjustment	Reset choke adjustment see ENGINE PERFORMANCE
	Defective coil	Replace coil
	Improper spark plug gap	Regap spark plugs
	Incorrect ignition timing	Reset ignition timing see ENGINE PERFORMANCE
Detonation	Over-advanced ignition timing	Reset ignition timing see ENGINE PERFORMANCE
	Defective spark plugs	Replace spark plugs
	Fuel lines clogged	Clean fuel lines
	EGR system malfunction	Check and repair EGR system
	PCV system malfunction	Repair PCV system
	Vacuum leaks	Check and repair vacuum system
	Loose fan belts	Tighten or replace fan belts, see ENGINE PERFORMANCE
	Restricted airflow	Remove restriction
	Vacuum advance malfunction	Check distributor operation
Dieseling	Binding carburetor linkage	Eliminate binding
	Binding throttle linkage	Eliminate blinding
	Binding choke linkage or fast idle cam	Eliminate binding
	Defective idle solenoid	Replace idle solenoid see ENGINE PERFORMANCE
	Improper base idle speed	Reset idle speed, see see ENGINE PERFORMANCE
	Incorrect ignition timing	Reset ignition timing see ENGINE PERFORMANCE
	Incorrect idle mixture setting	Reset idle mixture, see ENGINE PERFORMANCE
Faulty	Incorrect ignition timing	Reset ignition timing
Acceleration

Engine cold and choke too Adjust choke and
lean allow engine to warm- up
Defective spark plugs Replace spark plugs
Defective coil Replace coil

slots, see FUEL

Faulty Low Speed	Clogged idle transfer	slots	Clean idle transfer
Operation

Restricted idle air bleeds Disassemble and clean and passages carburetor, see FUEL
Clogged air cleaner Replace air filter Defective spark plugs Replace spark plugs Defective ignition wires Replace ignition wire
see ENGINE PERFORMANCE
Defective distributor cap Replace distributor cap
Faulty High Speed Incorrect ignition timing Reset ignition timing
Operation see ENGINE PERFORMANCE
Defective distributor Replace advance

	centrifugal advance Defective distributor	mechanism Replace advance unit
	vacuum advance
	Incorrect spark plugs or plug gap	Check gap and/or replace spark plugs
	Faulty choke operation	Check choke and repair as required
	Clogged vacuum passages	Remove restrictions
	Improper size or clogged main jet	Check jet size and clean, see FUEL
	Restricted air cleaner	Check filter and replace as necessary
	Defective distributor cap, rotor or coil	Replace cap, rotor or coil
Misfire at Speeds	All	Defective spark plugs	Replace spark plugs
		Defective spark plug wires	Replace spark plug wires
		Defective distributor cap, rotor, or coil	Replace cap, rotor, or coil
		Cracked or broken vacuum	Replace vacuum hoses
		hoses

Vacuum leaks Repair vacuum leaks
Fuel lines clogged Remove restriction
Hesitation Cracked or broken vacuum Replace vacuum hoses hoses
Vacuum leaks Repair Vacuum leaks Binding carburetor linkage Eliminate binding Binding throttle linkage Eliminate binding Binding choke linkage or Eliminate binding
fast idle cam
Improper float setting Readjust float setting, see FUEL
Cracked or broken ignition Replace ignition wires wires
Rough idle, Incorrect curb idle or fast Reset idle speed, see Missing or idle speed see ENGINE PERFORMANCE Stalling
Incorrect basic timing Reset ignition timing see ENGINE PERFORMANCE
Improper idle mixture Reset idle mixture, adjustment see ENGINE PERFORMANCE
Improper feedback system Check feedback system operation see ENGINE PERFORMANCE
Incorrect spark plug gap Reset spark plug gap, see ENGINE PERFORMANCE
Moisture in ignition Dry components components
Loose or broken ignition Replace ignition wires wires
Damaged distributor cap or Replace distributor or rotor cap or rotor
Faulty ignition coil Replace ignition coil Fuel filter clogged or worn Replace fuel filter Damaged idle mixture screw Replace idle mixture
screw, see FUEL
Improper fast idle cam Reset fast idle cam adjustment adjustment, see TUNE-
see ENGINE PERFORMANCE
Improper EGR valve operation Replace EGR valve Faulty PCV valve air flow Replace PCV valve Choke binding or improper Reset choke or
choke setting eliminate binding

Engine Surges	Vacuum leak Improper float bowl fuel	Repair vacuum leak Reset float
Engine Surges	level	adjustment, see FUEL
Engine Surges	Clogged air bleed or idle passages	Clean carburetor passages, see FUEL
Engine Surges	Clogged or worn air cleaner filter	Replace air filter
Engine Surges	Faulty choke vacuum diaphragm	Replace diaphragm, see ENGINE PERFORMANCE
Engine Surges	Exhaust manifold heat valve inoperative	Replace heat valve
Engine Surges	Improper distributor spark advance	Check distributor operation
Engine Surges	Leaking valves or valve components	Check and repair valvetrain
Engine Surges	Improper carburetor mounting	Remove and remount carburetor
Engine Surges	Excessive play in distributor shaft	Replace distributor
Engine Surges	Loose or corroded wiring connections	Repair or replace as required
Engine Surges	Improper PCV valve airflow	Replace PCV valve
Engine Surges	Vacuum leaks	Repair vacuum leaks
Engine Surges	Clogged air bleeds	Remove restriction
Engine Surges	EGR valve malfunction	Replace EGR valve
Engine Surges	Restricted air cleaner filter	Replace air filter
Engine Surges	Cracked or broken vacuum hoses	Replace vacuum hoses
Engine Surges	Cracked or broken ignition wires	Replace ignition wires
Engine Surges	Vacuum advance malfunction	Check unit and replace as necessary
Engine Surges	Defective or fouled spark plugs	Replace spark plugs
Ping or Spark Knock	Incorrect ignition timing	Reset ignition timing see ENGINE PERFORMANCE
	Distributor centrifugal or vacuum advance malfunction	Check operation and replace as necessary
	Carburetor setting too lean	Readjust mixture

		setting, see ENGINE PERFORMANCE
	Vacuum leak	Eliminate vacuum leak
	EGR valve malfunction	Replace EGR valve
Poor Gasoline Mileage	Cracked or broken vacuum hoses	Replace vacuum hoses
	Vacuum leaks	Repair vacuum leaks
	Defective ignition wires	Replace wires
	Incorrect choke setting	Readjust setting, see ENGINE PERFORMANCE
	Defective vacuum advance	Replace vacuum advance
	Defective spark plugs	Replace spark plugs
	Binding carburetor power piston	Eliminate binding
	Dirt in carburetor jets	Clean and/or replace jets
	Incorrect float adjustment	Readjust float setting, see FUEL
	Defective power valve	Replace power valve, see ENGINE PERFORMANCE
	Incorrect idle speed	Readjust idle speed
Engine Stalls	Improper float level	Readjust float level
	Leaking needle valve and seat	Replace needle valve and seat
	Vacuum leaks	Eliminate vacuum
		leaks

VACUUM PUMP – DIESEL 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.
NOTE: Diesel engines mechanical diagnosis is the same as gasoline engines for items such as noisy valves, bearings, pistons, etc. The following trouble shooting covers only items pertaining to diesel engines.
VACUUM PUMP (DIESEL) TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION

Excessive Noise	Loose pump-to-drive	Tighten	screws
	assembly screws
	Loose tube on pump assembly	Tighten	tube
	Valves not functioning	Replace	valves
Oil Leakage	properly Loose end plug	Tighten	end plug

Bad seal crimp Remove and re-crimp seal

MANUAL TRANSMISSION

MANUAL TRANSMISSION 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.
MANUAL TRANSMISSION/TRANSAXLE TROUBLE SHOOTING Condition Possible Cause
Noisy In Forward Gears .Low gear oil level,
.Loose bell housing bolts,
.Worn bearings or gears
Clunk On Deceleration
(FWD Only) .Loose engine mounts,
.Worn inboard CV joints,
.Worn differential pinion shaft,
.Side gear hub counterbore in case worn oversize
Gear Clash When Shifting
Forward Gears .Clutch Out Of Adjustment,
.Shift linkage damaged or out of adjustment,
.Gears or synchronizers damaged,
.Low gear oil level
Transmission Noisy When
Moving (RWD Only) Quiet In
Neutral With Clutch Engaged .Worn rear outputshaft bearing
Gear Rattle .Worn bearings,
.Wrong gear oil,
.Low gear oil,
.Worn gears
Steady Ticking At Idle
(Increases With RPM) .Broken tooth on gear
Gear Clash When Shifting
Forward Gears .Worn or broken synchronizers
Loud Whine In Reverse .Normal condition (1)
Noise When Stepping On Clutch .Bad release bearing,
.Worn pilot bearing
Ticking Or Screeching As
Clutch Is Engaged .Faulty release bearing,
.Uneven pressure plate fingers
Click Or Snap When Clutch
Is Engaged .Worn clutch fork,
.Worn or broken front bearing retainer
Transmission Shifts Hard .Clutch not releasing,
.Shift mechanism binding,
.Clutch installed backwards
Will Not Shift Into One
Gear, Shifts Into All
Others .Bent shift fork,
.Worn detent balls
Locked Into Gear,
Cannot Shift .Clutch adjustment,
.Worn detent balls
Transmission Jumps Out
Of Gear .Pilot bearing worn,
.Bent shift fork,
.Worn gear teeth or face
.Excessive gear train end play
.Worn synchronizers
.Missing detent ball spring
.Shift mechanism worn or out of adjustment
.Engine or transmission mount bolts loose or out of adjustment
.Transmission not aligned
Shift Lever Rattle .Worn shift lever or detents
.Worn shift forks
.Worn synchronizers sleeve
Shift Lever Hops Under
Acceleration .Worn engine or transmission mounts
(1) – Most units use spur cut gears in reverse and are noisy

POWERTRAIN

CLUTCH 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 CLUTCH TROUBLE SHOOTING CHART

Oil, grease or glaze onDisassemble and clean

Oil or grease on clutchClean or replace clutch

facingsclutch disc

CONDITION Chattering	or	POSSIBLE CAUSE Incorrect clutch adjustment	CORRECTION Adjust clutch
Grabbing
		facings	or replace
		Loose “U” joint flange	See DRIVE AXLES article
		Worn input shaft spline	Replace input shaft
		Binding pressure plate	Replace pressure plate
		Binding release lever	See CLUTCH article
		Binding clutch disc hub	Replace clutch disc
		Unequal pressure plate contact	Replace worn/misaligned components
		Loose/bent clutch disc	Replace clutch disc
		Incorrect transmission alignment	Realign transmission
		Worn pressure plate, disc or flywheel	Replace damaged components
		Broken or weak pressure springs	Replace pressure plate
		Sticking clutch pedal	Lubricate clutch pedal & linkage
		Incorrect clutch disc facing	Replace clutch disc
		Engine loose in chassis	Tighten all mounting bolts
Failure to
Release

Incorrect release lever or See CLUTCH article pedal adjustment
Worn or broken clutch Replace clutch disc facings
Bent clutch disc or Replace damaged pressure plate components
Clutch disc hub binding on Clean or replace clutch input shaft disc and/or input shaft
Binding pilot bearing Replace pilot bearing
Sticking release bearing Replace release bearing sleeve and/or sleeve
Binding clutch cable See CLUTCH article
Defective clutch master Replace master cylinder Defective clutch slave Replace slave cylinder Air in hydraulic system Bleed hydraulic system
Dry or binding clutch Lubricate and align pedal hub components
Floor mat interference Lay mat flat in proper with pedal area

switch

	Dry or pivots	binding ball/fork	Lubricate and align components
	Faulty	clutch cable	Replace clutch cable
Noisy Clutch	Faulty	interlock switch	Replace interlock
Pedal

Self-adjuster ratchet Lubricate or replace noise self-adjuster
Speed control interlock Lubricate or replace switch interlock switch
Clutch Pedal Binding clutch cable See CLUTCH article
Sticks Down
Springs weak in pressure Replace pressure plate plate
Binding in clutch linkage Lubricate and free linkage

Noisy	Dry release bearing	Lubricate or replace release bearing
Noisy	Dry or worn pilot bearing	Lubricate or replace bearing
Noisy	Worn input shaft bearing	Replace bearing
Transmission Click	Weak springs in pressure plate	Replace pressure plate
	Release fork loose on ball stud	Replace release fork and/or ball stud
	Oil on clutch disc damper	Replace clutch disc
	Broken spring in slave	Replace slave cylinder
	cylinder

DRIVE AXLE – NOISE DIAGNOSIS

Unrelated Noises
Some driveline trouble symptoms are also common to the engine, transmission, wheel bearings, tires, and other parts of the vehicle. Ensure cause of trouble actually is in the drive axle before adjusting, repairing, or replacing any of its parts.
Non-Drive Axle Noises
A few conditions can sound just like drive axle noise and have to be considered in pre-diagnosis. The 4 most common noises are exhaust, tires, CV/universal joints and wheel trim rings.
In certain conditions, the pitch of the exhaust gases may sound like gear whine. At other times, it may be mistaken for a wheel bearing rumble.
Tires, especially radial and snow, can have a high-pitched tread whine or roar, similar to gear noise. Also, some non-standard tires with an unusual tread construction may emit a roar or whine.
Defective CV/universal joints may cause clicking noises or excessive driveline play that can be improperly diagnosed as drive axle problems.
Trim and moldings also can cause a whistling or whining noise. Ensure none of these components are causing the noise before disassembling the drive axle.
Gear Noise
A “howling” or “whining” noise from the ring and pinion gear can be caused by an improper gear pattern, gear damage, or improper bearing preload. It can occur at various speeds and driving conditions, or it can be continuous.
Before disassembling axle to diagnose and correct gear noise, make sure that tires, exhaust, and vehicle trim have been checked as possible causes.
Chuckle
This is a particular rattling noise that sounds like a stick against the spokes of a spinning bicycle wheel. It occurs while decelerating from 40 MPH and usually can be heard until vehicle comes to a complete stop. The frequency varies with the speed of the vehicle.
A chuckle that occurs on the driving phase is usually caused by excessive clearance due to differential gear wear, or by a damaged tooth on the coast side of the pinion or ring gear. Even a very small tooth nick or a ridge on the edge of a gear tooth is enough the cause the noise.
This condition can be corrected simply by cleaning the gear tooth nick or ridge with a small grinding wheel. If either gear is damaged or scored badly, the gear set must be replaced. If metal has broken loose, the carrier and housing must be cleaned to remove particles that could cause damage.
Knock
This is very similar to a chuckle, though it may be louder, and occur on acceleration or deceleration. Knock can be caused by a gear tooth that is damaged on the drive side of the ring and pinion gears. Ring gear bolts that are hitting the carrier casting can cause knock. Knock can also be due to excessive end play in the axle shafts.
Clunk
Clunk is a metallic noise heard when an automatic transmission is engaged in Reverse or Drive, or when throttle is applied or released. It is caused by backlash somewhere in the driveline, but not necessarily in the axle. To determine whether driveline clunk is caused by the axle, check the total axle backlash as follows:
1) Raise vehicle on a frame or twinpost hoist so that drive wheels are free. Clamp a bar between axle companion flange and a part of the frame or body so that flange cannot move.
2) On conventional drive axles, lock the left wheel to keep it from turning. On all models, turn the right wheel slowly until it is felt to be in Drive condition. Hold a chalk marker on side of tire about 12″ from center of wheel. Turn wheel in the opposite direction until it is again felt to be in Drive condition.
3) Measure the length of the chalk mark, which is the total
axle backlash. If backlash is one inch or less, drive axle is not the source of clunk noise.
Bearing Whine
Bearing whine is a high-pitched sound similar to a whistle. It is usually caused by malfunctioning pinion bearings. Pinion
bearings operate at drive shaft speed. Roller wheel bearings may whine in a similar manner if they run completely dry of lubricant. Bearing noise will occur at all driving speeds. This distinguishes it from
gear whine, which usually comes and goes as speed changes.
Bearing Rumble
Bearing rumble sounds like marbles being tumbled. It is usually caused by a malfunctioning wheel bearing. The lower pitch is because the wheel bearing turns at only about 1/3 of drive shaft speed.
Chatter On Turns
This is a condition where the entire front or rear of vehicle vibrates when vehicle is moving. The vibration is plainly felt as well as heard. Extra differential thrust washers installed during axle repair can cause a condition of partial lock-up that creates this chatter.
Axle Shaft Noise
Axle shaft noise is similar to gear noise and pinion bearing whine. Axle shaft bearing noise will normally distinguish itself from gear noise by occurring in all driving modes (Drive, cruise, coast and float), and will persist with transmission in Neutral while vehicle is moving at problem speed.
If vehicle displays this noise condition, remove suspect axle shafts, replace wheel seals and install a new set of bearings.
Re-evaluate vehicle for noise before removing any internal components.
Vibration
Vibration is a high-frequency trembling, shaking or grinding condition (felt or heard) that may be constant or variable in level and can occur during the total operating speed range of the vehicle.
The types of vibrations that can be felt in the vehicle can be divided into 3 main groups:
* Vibrations of various unbalanced rotating parts of the vehicle.
* Resonance vibrations of the body and frame structures caused by rotating of unbalanced parts.
* Tip-in moans of resonance vibrations from stressed engine or exhaust system mounts or driveline flexing modes.

DRIVE AXLE – RWD 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. For definitions
of listed noises or sounds, see DRIVE AXLE – NOISE DIAGNOSIS
under POWERTRAIN.
DRIVE AXLE (RWD) TROUBLE SHOOTING
CONDITION POSSIBLE CAUSE CORRECTION
Knocking or Clunking
Differential Side Gear
Clearance Check Clearance
Worn Pinion Shaft Replace Pinion Shaft Axle Shaft End Play Check End Play Missing Gear Teeth Check Differential/
Replace Gear
Wrong Axle Backlash Check Backlash
Misaligned Driveline Realign Driveline
Clinking During Engagement
Side Gear Clearance Check Clearance
Ring and Pinion Backlash Check Backlash Worn/Loose Pinion Shaft Replace Shaft/Bearing Bad “U” Joint Replace “U” Joint Sticking Slip Yoke Lube Slip Yoke
Broken Rear Axle Mount Replace Mount
Loose Drive Shaft Flange Check Flange
Click/Chatter On Turns
Differential Side Gear
Clearance Check Clearance

Change Lubricant

	Wrong Turn On Plates	(1)	Replace Clutch Plates
	Wrong Differential Lubricant (1)
Knock Or Click	Flat Spot on Rear

Wheel Bearing Replace Wheel Bearing
Low Vibration At All Speeds
Faulty Wheel Bearing Replace Wheel Bearing
Faulty “U” Joint Replace “U” Joint Faulty Drive Shaft Balance Drive Shaft Faulty Companion Flange Replace Flange Faulty Slip Yoke Flange Replace Flange
(1) – Limited slip differential only.

FWD AXLE SHAFTS & CV JOINTS 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 FWD AXLE SHAFTS & CV JOINTS TROUBLE SHOOTING CHART CONDITION POSSIBLE CAUSE
Grease Leaks CV boot torn or cracked
Clicking Noise on Cornering Damaged outer CV Clunk Noise on Acceleration Damaged inner CV
Vibration or Shudder Sticking, damaged or worn CV
on Acceleration Misalignment or spring height

STEERING & SUSPENSION

MANUAL STEERING GEAR 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 MANUAL STEERING GEAR TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION

Rattle or Chucking Noise in Rack and Pinion	Rack and pinion mounting bracket loose Lack of/or incorrect lubricant	Tighten all mounting bolts Correct as necessary
Rattle or Chucking Noise in Rack and Pinion	Steering gear mounting bolts loose	Tighten all mounting bolts
Excessive Play	Front wheel bearing improperly adjusted	See FRONT SUSPENSION article
	Loose or worn steering linkage	See STEERING LINKAGE article
	Loose or worn steering gear shift	See MANUAL STEERING GEAR article
	Steering arm loose on gear shaft	See MANUAL STEERING GEAR article
	Steering gear housing bolts loose	Tighten all mounting bolts
	Steering gear adjustment too loose	See MANUAL STEERING GEAR article
	Steering arms loose on	Tighten and check

	knuckles Rack and pinion mounting	steering linkage Tighten all mounting
	loose	bolts
	Rack and pinion out of adjustment	See adjustment in STEERING article
	Tie rod end loose	Tighten and check steering linkage
	Excessive Pitman shaft-to- ball nut lash	Repair as necessary
Poor Returnability	Lack of lubricant in ball joint or linkage	Lubricate and service systems
	Binding in linkage or ball joints	See STEERING LINKAGE and SUSPENSION article
	Improper front end alignment	See WHEEL ALIGNMENT article
	Improper tire pressure	Inflate to proper pressure
	Tie rod binding	Inflate to proper pressure
	Shaft seal rubbing shaft	See STEERING COLUMN article
Excessive Vertical Motion	Improper tire pressure	Inflate to proper pressure
	Tires, wheels or rotors out of balance	Balance tires then check wheels and rotors
	Worn or faulty shock absorbers	Check and replace if necessary
	Loose tie rod ends or steering	Tighten or replace if necessary
	Loose or worn wheel bearings	See SUSPENSION article
Steering Pulls to One Side	Improper tire pressure	Inflate to proper pressure
	Front tires are different sizes	Rotate or replace if necessary
	Wheel bearings not adjusted properly	See FRONT SUSPENSION article
	Bent or broken suspension components	See FRONT SUSPENSION article
	Improper wheel alignment	See WHEEL ALIGNMENT
		article

Brakes dragging See BRAKES article

pressure

Instability	Low or uneven	tire	Inflate to proper
	pressure

Loose or worn wheel See FRONT SUSPENSION
bearings article
Loose or worn idler arm See FRONT SUSPENSION
bushing article
Loose or worn strut See FRONT SUSPENSION
bushings article
Incorrect front wheel See WHEEL ALIGNMENT
alignment article
Steering gear not See MANUAL STEERING
centered GEARS article
Springs or shock Check and replace if necessary
Improper cross shaft See MANUAL STEERING GEARS article

POWER STEERING 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 POWER STEERING TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION Rattle or Pressure hoses touching Adjust to proper

Tighten and check, replace if necessary

fluid

	Worn shaft serrations	See STEERING COLUMN article
Growl in Steering Pump	Excessive pressure in hoses	Restricted hoses, see POWER STEERING GEAR article
	Scored pressure plates	See POWER STEERING GEAR article
	Scored thrust plates or rotor	See POWER STEERING GEAR article
	Extreme wear of cam ring	See POWER article	STEERING	GEAR
Rattle in Steering Pump	Vanes not installed	See POWER article	STEERING	PUMP
	Vanes sticking in rotor	See POWER article	STEERING	PUMP
Swish noise in Pump	Defective flow control valve	See POWER article	STEERING	PUMP
Groan in Steering Pump	Air in fluid	See POWER article	STEERING	PUMP
	Poor pressure hose connection
Squawk When Turning	Damper “O” ring on spool cut	valve	See POWER STEERING PUMP article
Moan or Whine	Pump shaft bearing	scored	Replace bearing and
in Pump

Air in fluid or fluid See POWER STEERING PUMP
level low article
Hose or column grounded Check and replace if necessary
Cover “O” ring missing See POWER STEERING PUMP
or damaged article
Valve cover baffle See POWER STEERING PUMP
missing or damaged article
Interference of See POWER STEERING PUMP
components in pump article
Loose or poor bracket Correct or replace if alignment necessary

article

Hissing When Parking	Internal steering	leakage in gear	Check valved assembly first
Chirp in Steering Pump	Loose or steering	worn power belt	Adjust or replace if necessary
Buzzing When	Noisy pump	See POWER STEERING PUMP
Not Steering

Free play in steering See STEERING COLUMN
shaft bearing article
Bearing loose on shaft See STEERING COLUMN
serrations article

Clicking Noise in Pump	Pump slippers too long	See POWER article	STEERING	PUMP
	Broken slipper springs	See POWER article	STEERING	PUMP
	Excessive wear or nicked rotors	See POWER article	STEERING	PUMP
	Damaged cam contour	See POWER article	STEERING	PUMP
Poor Return Wheel	of	Wheel rubbing against turn signal	See STEERING COLUMN SWITCHES article
		Flange rubbing steering gear adjuster	See STEERING COLUMN article
		Tight or frozen steering shaft bearing	See STEERING COLUMN article
		Steering gear out of adjustment	See POWER STEERING GEAR article
		Sticking or plugged spool valve	See POWER STEERING PUMP article
		Improper front end alignment	See WHEEL ALIGNMENT article
		Wheel bearings worn or loose	See FRONT SUSPENSION article
		Ties rods or ball joints binding	Check and replace if necessary
		Intermediate shaft joints binding	See STEERING COLUMN article
		Kinked pressure hoses	Correct or replace if necessary
		Loose housing head spanner nut	See POWER STEERING GEAR article
		Damaged valve lever	See POWER STEERING GEAR article
		Sector shaft adjusted too tight	See ADJUSTMENTS in POWER STEERING GEAR article
		Worm thrust bearing adjusted too tight	See ADJUSTMENTS in POWER STEERING GEAR article
		Reaction ring sticking	See POWER STEERING GEAR
		in cylinder	article

	Reaction ring sticking in housing head	See POWER STEERING GEAR article
	Steering pump internal leakage	See POWER STEERING PUMP article
	Steering gear-to-column misalignment	See STEERING COLUMN article
	Lack of lubrication in linkage	Service front suspension
	Lack of lubrication in ball joints	Service front suspension
Increased Effort When Turning Wheel Fast	High internal pump leakage Power steering pump belt	See POWER STEERING PUMP article Adjust or replace if
Foaming, Milky Power Steering Fluid, Low Fluid	slipping Low fluid level	necessary Check and fill to
Level or Low Pressure	Engine idle speed to low	proper level Adjust to correct
		setting
	Air in pump fluid system	See POWER STEERING PUMP article
	Pump output low	See POWER STEERING PUMP article
	Steering gear malfunctioning	See POWER STEERING GEAR article
Wheel Surges or Jerks	Low fluid level	Check and fill to proper level
	Loose fan belt	Adjust or replace if necessary
	Insufficient pump pressure	See POWER STEERING PUMP article
	Sticky flow control valve	See POWER STEERING PUMP article
	Linkage hitting oil pan at full turn	Replace bent components
Kick Back or Free Play	Air in pump fluid system	See POWER STEERING PUMP article
	Worn poppet valve in steering gear	See POWER STEERING PUMP article
	Excessive over center lash	See POWER STEERING GEAR article
	Thrust bearing out of	See POWER STEERING GEAR
	adjustment	article

Free play in pot coupling See POWER STEERING PUMP
article
Steering gear coupling See POWER STEERING PUMP
loose on shaft article
Steering disc mounting Tighten or replace if bolts loose necessary
Coupling loose on worm Tighten or replace if shaft necessary
Improper sector shaft See POWER STEERING GEAR
adjustment article
Excessive worm piston See POWER STEERING GEAR
side play article
Damaged valve lever See POWER STEERING GEAR
article
Universal joint loose Tighten or replace if necessary

	Defective rotary valve	See POWER article	STEERING	GEAR
No Power Parking	When	Sticking flow control valve	See POWER article	STEERING	PUMP
		Insufficient pump pressure output	See POWER article	STEERING	PUMP
		Excessive internal pump leakage	See POWER article	STEERING	PUMP
		Excessive internal gear	See POWER	STEERING	PUMP
		leakage	article

Flange rubs against gear See STEERING COLUMN
adjust plug article
Loose pump belt Adjust or replace if necessary
Low fluid level Check and add proper amount of fluid
Engine idle too low Adjust to correct setting
Steering gear-to-column See STEERING COLUMN
misaligned article

No Power, Left Turn	Left turn reaction seal “O” ring worn	See POWER article	STEERING	GEAR
	Left turn reaction seal damaged/missing	See POWER article	STEERING	GEAR
	Cylinder head “O” ring	See POWER	STEERING	PUMP
	damaged	article

No Power,	Column pot coupling	See STEERING COLUMN
Right Turns	bottomed	article

Right turn reaction seal See POWER STEERING GEAR “O” ring worn article
Right turn reaction seal See POWER STEERING GEAR
damaged article
Internal leakage through See POWER STEERING GEAR
piston end plug article
Internal leakage through See POWER STEERING GEAR
side plugs article

incorrectarticle

Lack of Effort in Turning	Left and/or right reaction seal sticking in cylinder head	Replace, see POWER STEERING GEAR article
Wanders to	One	Front end alignment	See WHEEL	ALIGNMENT
Side

Unbalanced steering See POWER STEERING GEAR
gear valve article
Low Pressure Due Flow control valve stuck See POWER STEERING PUMP
to Steering Pump or inoperative article
Pressure plate not flat See POWER STEERING PUMP
against cam ring article
Extreme wear of cam ring Replace and check adjustments
Scored plate, thrust See POWER STEERING PUMP
plate or rotor article
Vanes not installed See POWER STEERING PUMP
properly article
Vanes sticking in rotor See POWER STEERING PUMP
slots article
Cracked/broken thrust or See POWER STEERING PUMP
pressure plate article

STEERING COLUMN 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 STEERING COLUMN TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION

article

Noise in	Coupling pulled apart	See STEERING COLUMNS
Steering

Shifting
Improper gate plate See STEERING COLUMN
adjustment article
Excess Play in Instrument panel bracket Tighten bolts and check
Column bolts loose bracket
Broken weld nut on jacket See STEERING COLUMN
article
Instrument bracket capsule See STEERING COLUMN
sheared article
Column bracket/jacket Tighten bolts and check bolts loose bracket
Steering Locks Release lever mechanism See STEERING COLUMN
in Gear article

SUSPENSION 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 SUSPENSION TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION
Front End Noise Loose or worn wheel See Wheel Bearing Adjustment in SUSPENSION
Worn shocks or shock Replace struts or strut mountings mountings
Worn struts or strut Replace struts or strut mountings mountings
Loose or worn lower control See SUSPENSION
arm
Loose steering gear-to- See STEERING
frame bolts
Worn control arm bushings See SUSPENSION
Ball joints not lubricated Lubricate ball joints & see Ball Joint Checking in SUSPENSION
Front Wheel Tires or wheels out of Check tire balance
Shake, Shimmy, balance or Vibration
Incorrect wheel alignment See WHEEL ALIGNMENT
Drive shaft unbalanced Check drive shaft balance
Loose or worn wheel See WHEEL ALIGNMENT
bearings
Loose or worn tie rod ends See SUSPENSION
Worn upper ball joints See Ball Joint Checking in SUSPENSION
Worn shock absorbers Replace shock absorbers
Worn strut bushings Replace strut bushings
Car Pulls to Mismatched or uneven tires Check tire condition
One Side
Broken or sagging springs See SUSPENSION
Loose or worn strut See SUSPENSION
bushings
Improper wheel alignment See WHEEL ALIGNMENT Improper rear axle Check rear axle
alignment alignment
Power steering gear See STEERING
unbalanced
Front brakes dragging See BRAKES
Abnormal Tire Unbalanced tires Check tire balance & Wear rotation
Sagging or broken springs See SUSPENSION Incorrect front end See WHEEL ALIGNMENT
alignment
Faulty shock absorbers Replace chock absorbers
Scuffed Tires Toe-In incorrect See WHEEL ALIGNMENT Suspension arm bent or See appropriate
twisted SUSPENSION article
Springs Bottom Bent or broken springs See SUSPENSION
or Sag
Leaking or worn shock Replace shock absorbers absorbers
Frame misalignment Check frame for damage

Spring Noises	Loose	“U” Bolts	See	SUSPENSION
	Loose	or worn bushings	See	SUSPENSION
	Worn or missing interliners	See SUSPENSION
Shock Absorber Noise	Loose shock mountings	Check & tighten mountings
	Worn bushings	Replace bushings

Car Leans or	Air in system Undercoating on shocks Loose stabilizer bar	Bleed air from system Remove undercoating See SUSPENSION
Sways on Corners
	Faulty shocks or mountings	Replace shocks or mountings
	Broken or sagging springs	See SUSPENSION
Shock Absorbers Leaking	Worn seals or reservoir tube crimped	See SUSPENSION
Broken Springs	Loose “U” bolts	See SUSPENSION
	Inoperative shock absorbers	Replace shock absorbers

WHEEL ALIGNMENT 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 WHEEL ALIGNMENT TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION
Premature Tire Improper tire inflation Check tire pressure
Wear
Front alignment out of See ALIGNMENT SPECS in tolerance WHEEL ALIGNMENT section
Suspension components worn See SUSPENSION section
Steering system components See STEERING section worn
Improper standing height See WHEEL ALIGNMENT Uneven or sagging springs See SUSPENSION section Bent wheel See WHEEL ALIGNMENT Improper torsion bar See SUSPENSION section
adjustment
Loose or worn wheel See WHEEL BEARING ADJ. bearings in SUSPENSION section
Worn or defective shock Replace shock absorbers
Tires out of balance Check tire balance
Pulls to One Improper tire inflation Check tire pressure
Side
Brake dragging See BRAKE section
Mismatched tires See WHEEL ALIGNMENT Broken or sagging spring See SUSPENSION section Broken torsion bar See SUSPENSION section
Power steering valve not See STEERING section centered
Front alignment out of See WHEEL ALIGNMENT
tolerance section
Defective wheel bearing See WHEEL BEARINGS in
SUSPENSION section
Uneven sway bar links See SUSPENSION section Frame bent Check for frame damage Steering system bushing See STEERING section
worn
Hard Steering Idler arm bushing too tight See STEERING LINKAGE
in STEERING section
Ball joint tight or seized See SUSPENSION section
Steering linkage too tight See STEERING LINKAGE in
STEERING section
Power steering fluid low Add proper amount of fluid
Power steering drive belt See STEERING section loose
Power steering pump See STEERING section defective
Steering gear out of See STEERING section adjustment

	Incorrect wheel alignment	See	WHEEL ALIGNMENT
	Damaged steering gear	See	STEERING section
	Damaged suspension	See	SUSPENSION section
	Bent steering knuckle or supports	See	SUSPENSION section
Vehicle “Wanders”	Strut rod or control arm bushing worn	See	SUSPENSION section
	Loose or worn wheel	See	WHEEL BEARINGS in

bearings SUSPENSION section
Improper tire inflation Check tire pressure
Stabilizer bar missing or See SUSPENSION section defective
Wheel alignment out of See Adjustment in tolerance WHEEL ALIGNMENT section
Broken spring See SUSPENSION section Defective shock absorbers Replace shock absorbers Worn steering & suspension See SUSPENSION section
components
Front End Shimmy Tire out of balance/round Check tire balance Excessive wheel runout See WHEEL ALIGNMENT Insufficient or improper See WHEEL ALIGNMENT
caster section
Worn suspension or steering See SUSPENSION section components
Defective shock absorbers Replace shock absorber
Wheel bearings worn or See WHEEL BEARING ADJ. loose in SUSPENSION section
Power steering reaction See STEERING section
Bracket loose
Steering gear box (rack) See STEERING section mounting loose
Steering gear adjustment See STEERING section loose
Worn spherical joints See SUSPENSION section
Toe-In Not Lower control arm bent See SUSPENSION section
Adjustable
Frame bent Check frame for damage
Camber Not Control arm bent See SUSPENSION section
Adjustable
Frame bent Check frame for damage
Hub & bearing not seated See SUSPENSION section properly

 

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