1900 MITSUBISHI DIAMANTE clutch

I TROUBLESHOOTING II-3
Condition Section/hem Number
2-A, 1
2-A, 2
2-A, 3 Transmission shifts erratically
Transmission will not engage
Transmission will not downshift during heavy acceleration
Transmission grinds going into forward gears while driving
Transmission jumps out of gear
Transmission difficult to shift
Transmission leaks fluid 2-B, 1 2-C, 2
2-B, 2
2-B, 3 2-C, 2
2-B, 4
2-C,l
2-c,2
2-c,3
2-c,4
2-c,5
2-C,6 Clutch slips on hills or during sudden acceleration
Clutch will not disengage, difficult to shift
Clutch is noisy when the clutch pedal is pressed
Clutch pedal extremely difficult to press
Clutch pedal remains down when pressed
Clutch chatters when engaging
2-D, 1
2-D, 2 Differential makes a low pitched rumbling noise
Differential makes a howling noise
All Wheel and Four Wheel Drive Vehicles Leaks fluid from seals or vent after being driven
Makes excessive noise while driving
Jumps out of gear 2-E, 1
2-E, 2
2-E, 3
Rear Wheel, All Wheel and Four Wheel Drive Vehicles Clunking noise from center of vehicle shifting from forward to reverse
,Excessive vibration from center of vehicle when accelerating 2-F, l
2-F,2
All Wheel and Four Wheel Drive Vehicles , Front or rear wheel makes a clicking noise
Front or Rear wheel vibrates with increased speed 2-G,l
2-G,2
Front Wheel Drive Vehicles Front wheel makes a clicking noise
Rear wheel makes a clicking noise 2-G,3
2-G,4
Rear Wheel Drive Vehicles Front or rear wheel makes a clicking
Rear wheel shudders or vibrates noise 2-G,5
2-G,6
2-H, 1; 2-C, 1; 3-A, 9
2-H, 2; 2-C, 1; 3-A, 9 Burning odor from center of vehicle when accelerating
Engine accelerates, but vehicle does not gain speed
Brakes pedal pulsates or shimmies when pressed 3-A-l
Brakes make a squealing noise CI
3-A, 2
Brakes make a grinding noise
Vehicle pulls to one side during.braking
Brake pedal feels spongy or has excessive brake pedal travel
Brake pedal feel is firm, but brakes lack sufficient stopping power or fade 3-A, 3
3-A, 4
3-A, 5
3-A, 6

II-6 TROUBLESHOOTING
DIAGhUSTIC PROCEDURES
Gasoline Engines
1. Engine turns over, but wilt not start
a. Check fuel level in fuel tank, add fuel if empty.
b. Check battery condition and state of charge. If voltage and load test below specifica-
tion, charge or replace battery.
c. Check battery terminal and cable condition and tightness. Clean terminals and replace
damaged, worn or corroded cables.
d. Check fuel delivery system. If fuel is not reaching the fuel injectors, check for a loose
electrical connector or defective fuse, relay or fuel pump and replace as necessary.
e. Engine may have excessive wear or mechanical damage such as low cylinder cranking
pressure, a broken camshaft drive system, insufficient valve clearance or bent valves.
f. Check for fuel contamination such as water in the fuel. During winter months, the wa-
ter may freeze and cause a fuel restriction. Adding a fuel additive may help, however
the fuel system may require draining and purging with fresh fuel.
g. Check for ignition system failure. Check for loose or shorted wires or damaged igni-
tion system components. Check the spark plugs for excessive wear or incorrect elec-
trode gap. If the problem is worse in wet weather, check for shorts between the spark
plugs and the ignition coils.
h. Check the engine management system for a failed sensor or control module.
2. Engine does not turn over when attempting to start
a. Check the battery state of charge and condition. If the dash lights are not visible or
very dim when turning the ignition key on, the battery has either failed internally or
discharged, the battery cables are loose, excessively corroded or damaged, or the al-
ternator has failed or internally shorted, discharging the battery. Charge or replacethe
battery, clean or replace the battery cables, and check the alternator output.
b. Check the operation of the neutral safety switch. On automatic transmission vehicles,
try starting the vehicle in both Park and Neutral. On manual transmission vehicles, de-
press the clutch pedal and attempt to start. On some vehicles, these switches can be
adjusted. Make sure the switches or wire connectors are not loose or damaged. Re-
place or adjust the switches as necessary.
c. Check the starter motor, starter solenoid or relay, and starter motor cables and wires.
Check the ground from the engine to the chassis. Make sure the wires are not loose,
damaged, or corroded. If battery voltage is present at the starter relay, try using a re-
mote starter to start the vehicle for test purposes only. Replace any damaged or cor-
roded cables, in addition to replacing any failed components.
d. Check the engine for seizure. If the engine has not been started for a long period of
time, internal parts such as the rings may have rusted to the cylinder walls. The engine
may have suffered internal damage, or could be hydro-locked from ingesting water.
Remove the spark plugs and carefully attempt to rotate the engine using a suitable
breaker bar and socket on the crankshaft pulley. If the engine is resistant to moving, or
moves slightly and then binds, do not force the engine any further before determining
the problem.
3. Enpine stalls immediately when started
a. Check the ignition switch condition and operation. The electrical contacts in the run
position may be worn or damaged. Try restarting the engine with all electrical acces-
sories in the off position. Sometimes turning the key on an off will help in emergency
situations, however once the switch has shown signs of failure, it should be replaced
as soon as possible.
b. Check for loose, corroded, damaged or shorted wires for the ignition system and re-
pair or replace.
c. Check for manifold vacuum leaks or vacuum hose leakage and repair or replace parts
as necessary.
d. Measure the fuel pump delivery volume and pressure. Low fuel pump pressure can
also be noticed as a lack of power when accelerating. Make sure the fuel pump lines
are not restricted. The fuel pump output is not adjustable and requires fuel pump re-
placement to repair.
e. Check the engine fuel and ignition management system. Inspect the sensor wiring and
electrical connectors. A dirty, loose or damaged sensor or control module wire can
simulate a failed component.
f. Check the exhaust system for internal restrictions.
4. Starter motor spins, but does not engage
a. Check the starter motor for a seized or binding pinion gear.
b. Remove the flywheel inspection plate and check for a damaged ring gear.
5. Engine is difficult to start when Gold
a. Check the battery condition, battery state of charge and starter motor current draw. Re-
place the battery if marginal and the starter motor if the current draw is beyond specifi-
cation. b. Check the battery cable condition. Clean the battery terminals and replace corroded or
damaged cables.
c. Check the fuel system for proper operation. A fuel pump with insufficient fuel pressure
or clogged injectors should be replaced.
d. Check the engine’s tune-up status. Note the tune-up specifications and check for items
such as severely worn spark plugs; adjust or replace as needed. On vehicles with
manually adjusted valve clearances, check for tight valves and adjust to specification.
e. Check for a failed coolant temperature sensor, and replace if out of specification.
f. Check the operation of the engine management systems for fuel and ignition; repair or
replace failed components as necessary.
6. En#ine is ditticutt to start when hot
a. Check the air filter and air intake system. Replace the air filter if it is dirty or contami-
nated. Check the fresh air intake system for restrictions or blockage.
b. Check for loose or deteriorated engine grounds and clean, tighten or replace as
needed.
c. Check for needed maintenance. Inspect tune-up and service related items such as
spark plugs and engine oil condition, and check the operation of the engine fuel and
ignition management system.
Diesel Engines
1. Engine turns over but won’t start
a. Check engine starting procedure and restart engine.
b. Check the glow plug operation and repair or replace as necessary.
c. Check for air in the fuel system or fuel filter and bleed the air as necessary.
d. Check the fuel delivery system and repair or replace as necessary.
e. Check fuel level and add fuel as needed.
f. Check fuel quality. If the fuel is contaminated, drain and flush the fuel tank.
g. Check engine compression. If compression is below specification, the engine may
need to be renewed or replaced.
h. Check the injection pump timing and set to specification.
i. Check the injection pump condition and replace as necessary.
j. Check the fuel nozzle operation and condition or replace as necessary.
2. Engine does
hot turn over when attempting to start
a. Check the battery state of charge and condition. If the dash lights are not visible or
very dim when turning the ignition key on, the battery has either failed internally or
discharged, the battery cables are loose, excessively corroded or damaged, or the al-
ternator has failed or internally shorted, discharging the battery. Charge or replace the
battery, clean or replace the battery cables, and check the alternator output.
b. Check the operation of the neutral safety switch. On automatic transmission vehicles,
try starting the vehicle in both Park and Neutral. On manual transmission vehicles, de-
press the clutch pedal and attempt to start. On some vehicles, these switches can be
adjusted. Make sure the switches or wire connectors are not loose or damaged. Re-
place or adjust the switches as necessary.
c. Check the starter motor, starter solenoid or relay, and starter motor cables and wires.
Check the ground from the engine to the chassis. Make sure the wires are not loose,
damaged, or corroded. If battery voltage is present at the starter relay, try using a re-
mote starter to start the vehicle for test purposes only. Replace any damaged or cor-
roded cables, in addition to replacing any failed components.
d. Check the engine for seizure. If the engine has not been started for a long period of
time, internal parts such as the rings may have rusted to the cylinder walls. The engine
may have suffered internal damage, or could be hydro-locked from ingesting water.
Remove the injectors and carefully attempt to rotate the engine using a suitable
breaker bar and socket on the crankshaft pulley. If the engine is resistant to moving, or
moves slightly and then binds, do not force the engine any further before determining
the cause of the problem.
3. Engine stalls afier starting
a. Check for a restriction in the fuel return line or the return line check valve and repair as
necessary.
b. Check the glow plug operation for turning the glow plugs off too soon and repair as
necessary.
c. Check for incorrect injection pump timing and reset to specification.
d. Test the engine fuel pump and replace if the output is below specification.
e. Check for contaminated or incorrect fuel. Completely flush the fuel system and replace
with fresh fuel.
f. Test the engine’s compression for low compression. If below specification, mechanical
repairs are necessary to repair.
g. Check for air in the fuel. Check fuel tank fuel and fill as needed.
h. Check for a failed injection pump. Replace the pump, making sure to properly set the
pump timing.

TROUBLESHOOiNG 11-7
4. Starter motor spins, but does not engage
a. Check the starter motor for a seized or binding pinion gear.
b. Remove the flywheel inspection plate and check for a damaged ring gear.
Gasoline Engines
1. Engine runs poor/y, hesiiates
a. Check the engine ignition system operation and adjust if possible, or replace defective
parts.
b. Check for restricted fuel injectors and replace as necessary.
c. Check the fuel pump output and delivery. Inspect fuel lines for restrictions. If the fuel
pump pressure is below specification, replace the fuel pump.
d. Check the operation of the engine management system and repair as necessary.
2. Enfline lacks power
a. Check the engine’s tune-up status. Note the tune-up specifications and check for items
such as severely worn spark plugs; adjust or replace as needed. On vehicles with
manually adjusted valve clearances, check for tight valves and adjust to specification.
b. Check the air filter and air intake system. Replace the air filter if it is dirty or contami-
nated. Check the fresh air intake system for restrictions or blockage.
c. Check the operation of the engine fuel and ignition management systems. Check the
sensor operation and wiring. Check for low fuel pump pressure and repair or replace
components as necessary.
d. Check the throttle linkage adjustments. Check to make sure the linkage is fully open-
ing the throttle. Replace any worn or defective bushings or linkages.
e. Check for a restricted exhaust system. Check for bent or crimped exhaust pipes, or in-
ternally restricted mufflers or catalytic converters. Compare inlet and outlet tempera-
tures for the converter or muffler. If the inlet is hot, but outlet cold, the component is
restricted.
f. Check for a loose or defective knock sensor. A loose, improperly torqued or defective
knock sensor will decrease spark advance and reduce power. Replace defective knock
sensors and install using the recommended torque specification.
g. Check for engine mechanical conditions such as low compression, worn piston rings,
worn valves, worn camshafts and related parts. An engine which has severe mechani-
cal wear, or has suffered internal mechanical damage must be rebuilt or replaced to re-
store lost power.
h. Check the engine oil level for being overfilled. Adjust the engine’s oil level, or change
the engine oil and filter, and top off to the correct level.
i. Check for an intake manifold or vacuum hose leak. Replace leaking gaskets or worn
vacuum hoses.
j. Check for dragging brakes and replace or repair as necessary.
k. Check tire air pressure and tire wear. Adjust the pressure to the recommended set-
tings. Check the tire wear for possible alignment problems causing increased rolling
resistance, decreased acceleration and increased fuel usage.
I. Check the octane rating of the fuel used during refilling, and use a higher octane rated
fuel.
3. Poor fuel economy
a. Inspect the air filter and check for any air restrictions going into the air filter housing.
Replace the air filter if it is dirty or contaminated.
b. Check the engine for tune-up and related adjustments. Replace worn ignition parts,
check the engine ignition timing and fuel mixture, and set to specifications if possible.
c. Check the tire size, tire wear, alignment and tire pressure. Large tires create more
rolling resistance, smaller tires require more engine speed to maintain a vehicle’s road
speed. Excessive tire wear can be caused by incorrect tire pressure, incorrect wheel
alignment or a suspension problem. All of these conditions create increased rolling
resistance, causing the engine to work harder to accelerate and maintain a vehicle’s
speed.
d. Inspect the brakes for binding or excessive drag. A sticking brake caliper, overly ad-
justed brake shoe, broken brake shoe return spring, or binding parking brake cable or
linkage can create a significant drag, brake wear and loss of fuel economy. Check the
brake system operation and repair as necessary.
4. Engine runs on (diesels) when turned off
a. Check for idle speed set too high and readjust to specification.
b. Check the operation of the idle control valve, and replace if defective.
c. Check the ignition timing and adjust to recommended settings.
Check for defective
sensors or related components and replace if defective.
d. Check for a vacuum leak at the intake manifold or vacuum hose
and replace defective
gaskets or hoses.
e. Check the engine for excessive carbon build-up in the combustion chamber. Use a
recommended decarbonizing fuel additive or disassemble the cylinder head to remove
the carbon.
f. Check the operation of the engine fuel management system and replace defective sen-
sors or control units.
g. Check the engine operating temperature for overheating and repair as necessary. 5. Engine knocks and pinfls during heavy accele/ation, and on steep hills
a. Check the octane rating of the fuel used during refilling, and use a higher octane rated
fuel.
b. Check the ignition timing and adjust to recommended settings. Check for defective
sensors or related components and replace if defective.
c. Check the engine for excessive carbon build-up in the combustion chamber. Use a
recommended decarbonizing fuel additive or disassemble the cylinder head to remove
the carbon.
d. Check the spark plugs for the correct type, electrode gap and heat range. Replace worn
or damaged spark plugs. For severe or continuous high speed use, install a spark plug
that is one heat range colder.
e. Check the operation of the engine fuel management system and replace defective sen-
sors or control units.
f. Check for a restricted exhaust system. Check for bent or crimped exhaust pipes, or in-
ternally restricted mufflers or catalytic converters. Compare inlet and outlet tempera-
tures for the converter or muffler. If the inlet is hot, but outlet cold, the component is
restricted.
6. Engine atxelerates, but vehicle does not gain speed
a. On manual transmission vehicles, check for causes of a slipping clutch. Refer to the
clutch troubleshooting section for additional information.
b. On automatic transmission vehicles, check for a slipping transmission” Check the
transmission fluid level and condition. If the fluid level is too high, adjust to the cor-
rect level. If the fluid level is low, top off using the recommended fluid type. If the fluid
exhibits a burning odor, the transmission has been slipping internally. Changing the
fluid and filter may help temporarily, however in this situation a transmission may re-
quire overhauling to ensure long-term reliability.
Diesel Engines
1. Engine runs pOOr!y a. Check the injection pump timing and adjust to specification.
b. Check for air in the fuel lines or leaks, and bleed the air from the fuel system.
c. Check the fuel filter, fuel feed and return lines for a restriction and repair as necessary.
d. Check the fuel for contamination, drain and flush the fuel tank and replenish with fresh
fuel.
2. Enfline lacks power
a. Inspect the air intake system and air filter for restrictions and, if necessary, replace the
air filter.
b. Verify the injection pump timing and reset if out of specification.
c. Check the exhaust for an internal restriction and replace failed parts.
d. Check for a restricted fuel filter and, if restricted, replace the filter.
e. Inspect the fuel filler cap vent. When removing the filler cap, listen for excessive hiss-
ing noises indicating a blockage in the fuel filler cap vents, If the filler cap vents are
blocked, replace the cap.
f. Check the fuel system for restrictions and repair as necessary.
g. Check for low engine compression and inspect for external leakage at the glow plugs
or nozzles. If no external leakage is noted, repair or replace the engine.
ENGINE PERFORMANCE TROUBLESHOOTING HINTS When troubleshooting an engine running or performance condition, the mechanical
condition of the engine should be determined before lengthy troubleshooting procedures
are performed.
The engine fuel management systems in fuel injected vehicles rely on electronic sen-
sors to provide information to the engine control unit for precise fuel metering. Unlike
carburetors, which use the incoming air speed to draw fuel through the fuel metering jets
in order to provide a proper fuel-to-air ratio, a fuel injection system provides a specific
amount of fuel which is introduced by the fuel injectors into the intake manifold or intake
port, based on the information provided by electronic sensors.
The sensors monitor the engine’s operating temperature, ambient temperature and the
amount of air entering the engine, engine speed and throttle position to provide informa-
tion to the engine control unit, which, in turn, operates the fuel injectors by electrical
pulses. The sensors provide information to the engine control unit using low voltage
electrical signals. As a result, an unplugged sensor or a poor electrical contact could
cause a poor running condition similar to a failed sensor.
When troubleshooting a fuel related engine condition on fuel injected vehicles, care-
fully inspect the wiring and electrical connectors to the related components. Make sure
the electrical connectors are fully connected, clean and not physically damaged. If neces-
sary, clean the electrical contacts using electrical contact cleaner. The use of cleaning
agents not specifically designed for electrical contacts should not be used, as they could
leave a surface film or damage the insulation of the wiring.
The engine electrical system provides the necessary electrical power to operate the ve-
hicle’s electrical accessories, electronic control units and sensors. Because engine man-
agement systems are sensitive to voltage changes, an alternator which over or under-
charges could cause engine running problems or component failure. Most alternators
utilize internal voltage regulators which cannot be adjusted and must be replaced indi-
vidually or as a unit with the alternator.

II-10 TROUBLESHOOTING
1. Transmission grinds going into forward gears while driving
a. Check the clutch release system. On clutches with a mechanical or cable linkage,
check the adjustment. Adjust the clutch pedal to have 1 inch (25mm) of free-play at
the pedal.
b. If the clutch release system is hydraulically operated, check the fluid level and, if low,
top off using the recommended type and amount of fluid. ,
c. Synchronizers worn. Remove transmission and replace synchronizers.
d. Synchronizer sliding sleeve worn. Remove transmission and replace sliding sleeve.
e. Gear engagement dogs worn or damaged. Remove transmission and replace gear.
2. Transmission jumps out of gear
a. Shift shaft detent springs worn. Replace shift detent springs.
b. Synchronizer sliding sleeve worn. Remove transmission and replace sliding sleeve.
c. Gear engagement dogs worn or damaged. Remove transmission and replace gear.
d. Crankshaft thrust bearings worn. Remove engine and crankshaft, and repair as neces-
sary.
3. Transmission difficult to shift
a. Verify the clutch adjustment and, if not properly adjusted, adjust to specification.
b. Synchronizers worn. Remove transmission and replace synchronizers.
c. Pilot bearing seized. Remove transmission and replace pilot bearing.
d. Shift linkage or bushing seized. Disassemble the shift linkage, replace worn or dam-
aged bushings, lubricate and reinstall.
4. Transmission leaks fluid
a. Check the fluid level for an overfilled condition. Adjust the fluid level to specification.
b. Check for a restricted transmission vent or breather tube. Clear the blockage as neces-
sary and check the fluid level. If necessary, top off with the recommended lubricant.
c. Check for a porous casting, leaking seal or gasket. Replace defective parts and top off
the fluid level with the recommended lubricant.
1. Clutch slips on hills or during sudden acceleration
a. Check for insufficient clutch pedal free-play. Adjust clutch linkage or cable to allow
about 1 inch (25mm) of pedal free-play.
b. Clutch disc worn or severely damaged. Remove engine or transmission and replace
clutch disc.
c. Clutch pressure plate is weak. Remove engine or transmission and replace the clutch
pressure plate and clutch disc.
d. Clutch pressure plate and/or flywheel incorrectly machined. If the clutch system has
been recently replaced and rebuilt, or refurbished parts have been used, it is possible
that the machined surfaces decreased the clutch clamping force. Replace defective
parts with new replacement parts.
2. Clutch will not disengage, difficult to shift
a. Check the clutch release mechanism. Check for stretched cables, worn linkages or
failed clutch hydraulics and replace defective parts. On hydraulically operated clutch
release mechanisms, check for air in the hydraulic system and bleed as necessary.
b. Check for a broken, cracked or fatigued clutch release arm or release arm pivot. Re-
place defective parts and properly lubricate upon assembly.
c. Check for a damaged clutch hub damper or damper spring. The broken parts tend to
become lodged between the clutch disc and the pressure plate. Disassemble clutch
system and replace failed parts.
d. Check for a seized clutch pilot bearing. Disassemble the clutch assembly and replace
the defective parts.
e. Check for a defective clutch disc. Check for warpage or liningthicknesses larger than
original equipment.
3. Clutch is noisy when the clutch pedal is pressed
a. Check the clutch pedal stop and pedal free-play adjustment for excessive movement
and adjust as necessary.
b. Check for a worn or damaged release bearing. If the noise ceases when the pedal is re-
leased, the release bearing should be replaced.
c. Check the engine crankshaft axial play. If the crankshaft thrust bearings are worn or
damaged, the crankshaft will move when pressing the clutch pedal. The engine must
be disassembled to replace the crankshaft thrust bearings.
4. Clutch pedal extremely difficult to press
a. Check the clutch pedal pivots and linkages for binding. Clean and lubricate linkages.
b. On cable actuated clutch systems, check the cable routing and condition. Replace
kinked, frayed, damaged or corroded cables and check cable routing to avoid sharp
bends. Check the engine ground strap for poor conductivity. If the ground strap is
marginal, the engine could try to ground itself via the clutch cable, causing premature
failure. c. On mechanical linkage clutches, check the linkage for binding or misalignment. Lubri-
cate pivots or linkages and repair as necessary.
d. Check the release bearing guide tube and release fork for a lack of lubrication. Install a
smooth coating of high temperature grease to allow smooth movement of the release
bearing over the guide tube.
5. Clutch pedal remains down when pressed
a, On mechanical linkage or cable actuated clutches, check for a loose or disconnected
link.
b. On hydraulically actuated clutches, check the fluid level and check for a hydraulic leak
at the clutch slave or master cylinder, or hydraulic line. Replace failed parts and bleed
clutch hydraulic system. If no leakage is noted, the clutch master cylinder may have
failed internally. Replace the clutch master cylinder and bleed the clutch hydraulic sys-
tem.
6. clutch chatters when engaging
a. Check the engine flywheel for warpage or surface variations and replace or repair as
necessary.
b. Check for a warped clutch disc or damaged clutch damper hub. Remove the clutch
disc and replace.
c. Check for a loose or damaged clutch pressure plate and replace defective components.
NOTE: The clutch is actuated either by a mechanical linkage, cable or a
clutch hydraulic system. The mechanical linkage and cable systems may
require the clutch pedal free-play to be adjusted as the clutch disc wears. A
hydraulic clutch system automatically adjusts as the clutch wears and, with
the exception of the clutch pedal height, no adjustment is possible.
1. Differential makes a low pitched rumbling noise
a. Check fluid level type and amount. Replace the fluid with the recommended type and
amount of lubricant.
b. Check the differential bearings for wear or damage. Remove the bearings, inspect the
drive and driven gears for wear or damage, and replace components as necessary.
2. Differential makes a howling noise
a. Check fluid level type and amount. Replace the fluid with the recommended type and
amount of lubricant.
b. Check the differential drive and driven gears for wear or damage, and replace compo-
nents as necessary.
All Wheel and Four Wheel Drive Vehicles
1. Leaks fluid from seals or vent after being driven
a. Fluid level overfilled. Check and adjust transfer case fluid level.
b. Check for a restricted breather or breather tube, clear and check the fluid level and top
off as needed.
c. Check seal condition and replace worn, damaged, or defective seals. Check the fluid
level and top off as necessary.
2. Makes excessive noise while driving
a. Check the fluid for the correct type of lubricant. Drain and refill using the recom-
mended type and amount of lubricant.
b. Check the fluid level. Top off the fluid using the recommended type and amount of lu-
bricant.
c. If the fluid level and type of lubricant meet specifications, check for internal wear or
damage. Remove assembly and disassemble to inspect for worn, damaged, or defec-
tive components.
3. Jumps out of gear
a. Stop vehicle and make sure the unit is fully engaged.
b. Check for worn, loose or an improperly adjusted linkage. Replace and/or adjust link-
age as necessary.
c. Check for internal wear or damage. Remove assembly and disassemble to inspect for
worn, damaged, or defective components.
Rear Wheel, All Wheel and Four Wheel Drive Vehicles
1. Clunking noise from center of Vehicle shifting from forward to reverse
a. Worn universal joint. Remove driveshaft and replace universal joint.
2. Excessive vibration from center of vehicle when accelerating
a. Worn universal joint. Remove driveshaft and replace universal joint.

TROUBLESHOOTlNGll-11
b. Driveshaft misaligned. Check for collapsed or damaged engine and transmission
mounts, and replace as necessary.
c. Driveshaft bent or out of balance. Replace damaged components and reinstall.
d. Driveshaft out of balance. Remove the driveshaft and have it balanced by a competent
professional, or replace the driveshaft assembly.
NOTE: Most driveshafts are linked together by universal joints; however,
some manufacturers use Constant Velocity (CV) joints or rubber flex cou-
plers.
All Wheel and Four Wheel Drive Vehicles
1. Front or rear wheel makes a clicking noise
a. Check for debris such as a pebble, nail or glass in the tire or tire tread. Carefully re-
move the debris. Small rocks and pebbles rarely cause a puncture; however, a sharp
object should be removed carefully at a facility capable of performing tire repairs.
b. Check for a loose, damaged or worn Constant Velocity (CV) joint and replace if defec-
tive.
2. Front or rear wheel vibrates wlth Increased speed
a. Check for a bent rim and replace, if damaged.
b. Check the tires for balance or internal damage and replace if defective.
c. Check for a loose, worn or damaged wheel bearing and replace if defective.
d. Check for a loose, damaged or worn Constant Velocity (CV) joint and replace if defec-
tive.
Front Wheel Drive Vehicles
3. Front wheel makes a c&kin@ noise
a. Check for debris such as a pebble, nail or glass in the tire or tire tread. Carefully re-
move the debris. Small rocks and pebbles rarely cause a puncture; however, a sharp
object should be removed carefully at a facility capable of performing tire repairs.
b. Check for a loose, damaged or worn Constant Velocity (CV) joint and replace if defec-
tive. 4. Rear wheel makes a clicking noise
a. Check for debris such as a pebble, nail or glass in the tire or tire tread. Carefully re-
move the debris. Small rocks and pebbles rarely cause a puncture; however, a sharp
object should be removed carefully at a facility capable of performing tire repairs.
Rear Wheel Drive Vehicles
5. Front or rear wheel makes a clicking noise
a. Check for debris such as a pebble, nail or glass in the tire or tire tread. Carefully re-
move the debris. Small rocks and pebbles rarely cause a puncture; however, a sharp
object should be removed carefully at a facility capable of performing tire repairs.
6. Rear wheel shudders or vibrates
a. Check for a bent rear wheel or axle assembly and replace defective components.
b. Check for a loose, damaged or worn rear wheel bearing and replace as necessary.
1. Burning odor from center of vehicle when accelerating
a. Check for a seizing brake hydraulic component such as a brake caliper. Check the
caliper piston for surface damage such as rust, and measure for out-of-round wear
and caliper-to-piston clearance. For additional information on brake related odors, re-
fer to section 3-A, condition number 9.
b. On vehicles with a manual transmission, check for a slipping clutch. For possible
causes and additional information, refer to section Z-C, condition number 1.
c. On vehicles with an automatic transmission, check the fluid level and condition, Top
off or change the fluid and filter using the recommended replacement parts, lubricant
type and amount. If the odor persists, transmission removal and disassembly will be
necessary.
2. Engine accelerates, but vehicle does not gain speed
a. On vehicles with a manual transmission, check for a slipping or damaged clutch. For
possible causes and additional information refer to section Z-C, condition number 1.
b. On vehicles with an automatic transmission, check the fluid level and condition. Top
off or change the fluid and filter using the recommended replacement parts, lubricant
type and amount. If the slipping continues, transmission removal and disassembly will
be necessary.
1. Brake pedal pulsates or shimmies when pressed
a. Check wheel lug nut torque and tighten evenly to specification.
b. Check the brake rotor for trueness and thickness variations. Replace the rotor if it is
too thin, warped, or if the thickness varies beyond specification. Some rotors can be
machined: consult the manufacturer’s specifications and recommendations before us-
ing a machined brake rotor.
c. Check the brake caliper or caliper bracket mounting bolt torque and inspect for loose-
ness. Torque the mounting bolts and inspect for wear or any looseness, including
worn mounting brackets, bushings and sliding pins.
d. Check the wheel bearing for looseness. If the bearing is loose, adjust if possible, oth-
erwise replace the bearing.
2. Brakes make a squealing noise
a. Check the brake rotor for the presence of a ridge on the outer edge; if present, remove
the ridge or replace the brake rotor and brake pads.
b. Check for debris in the brake lining material, clean and reinstall.
c. Check the brake linings for wear and replace the brake linings if wear is approaching
the lining wear limit.
d. Check the brake linings for glazing. Inspect the brake drum or rotor surface and re-
place, along with the brake linings, if the surface is not smooth or even.
e. Check the brake pad or shoe mounting areas for a lack of lubricant or the presence of
surface rust. Clean and lubricate with a recommended high temperature brake grease.
3. Brakes make a flrindinfl noise
a. Check the brake linings and brake surface areas for severe wear or damage. Replace
worn or damaged parts.
b. Check for a seized or partially seized brake causing premature or uneven brake wear,
excessive heat and brake rotor or drum damage. Replace defective parts and inspect
the wheel bearing condition, which could have been damaged due to excessive heat.
4. Vehicle pulls to one side during braking
a. Check for air in the brake hydraulic system. Inspect the brake hydraulic seals, fluid
lines and related components for fluid leaks. Remove the air from the brake system by bleeding the brakes. Be sure to use fresh brake fluid that meets the manufacturers rec-
ommended standards.
b. Check for an internally restricted flexible brake hydraulic hose. Replace the hose and
flush the brake system.
c. Check for a seizing brake hydraulic component such as a brake caliper. Check the
caliper piston for surface damage such as rust, and measure for out-of-round wear
and caliper-to-piston clearance. Overhaul or replace failed parts and flush the brake
system.
d. Check the vehicle’s alignment and inspect for suspension wear. Replace worn bush-
ings, ball joints and set alignment to the manufacturers specifications.
e. If the brake system uses drum brakes front or rear, check the brake adjustment. Inspect
for seized adjusters and clean or replace, then properly adjust.
5. Brake pedal feels spongy or has excessive travel
a. Check the brake fluid level and condition. If the fluid is contaminated or has not been
flushed every two years, clean the master cylinder reservoir, and bleed and flush the
brakes using fresh brake fluid that meets the manufacturers recommended standards.
b. Check for a weak or damaged flexible brake hydraulic hose. Replace the hose and
flush the brake system.
c. If the brake system uses drum brakes front or rear, check the brake adjustment. Inspect
for seized adjusters and clean or replace, then properly adjust.
6. Brake pedal feel is firm, but brakes lack sufficient stopping power or
fade
a. Check the operation of the brake booster and brake booster check valve: Replace worn
or failed parts.
b. Check brake linings and brake surface areas for glazing and replace worn or damaged
parts.
c. Check for seized hydraulic parts and linkages, and clean or replace as needed.
7. Vehicle has excessive front end dive or locks rear brakes too easily
a. Check for worn, failed or seized brake proportioning valve and replace the valve.
b. Check for a seized, disconnected or missing spring or linkage for the brake propor-
tioning valve. Replace missing parts or repair as necessary.

II-16 TROUBLESHOOTING
c. Gauge sending unit defective. Replace gauge sending unit.
d. Gauge or sending unit improperly installed. Verify installation and wiring, and repair
1. Speedometer does not work
a. Check the speed sensor pickup and replace as necessary.
b. Check the wiring between the speed sensor and the speedometer for corroded termi-
nals, loose connections or broken wires and clean or repair as necessary.
c. Install a known good speedometer to test for proper operation. If the substituted
speedometer functions properly, replace the speedometer assembly.
2. Speedometer works intermittently
a. Check the wiring between the speed sensor and the speedometer for corroded termi-
nals, loose connections or broken wires and clean or repair as necessary.
b. Check the speed sensor pickup and replace as necessary. as necessary.
2. Gauge operates enatica//y
a. Checkfor ioose, shorted, damaged or corroded electrical connections or wiring and
repair as necessary.
b. Check gauge sending units and replace as necessary.
3. Gauge operates fully pegged
a. Sending unit-to-gauge wire shorted to ground.
b. Sending unit defective; replace sending unit.
c. Gauge or sending unit not properly grounded.
d. Gauge or sending unit improperly installed. Verify installation and wiring, and repair
as necessary.
I. Gauge does not register
a. Check for a missing or blown fuse and replace as necessary.
b. Check for an open circuit in the gauge wiring. Repair wiring as necessary.
I. No air coming from air conditioner vents
a. Check the air conditioner fuse and replace as necessary.
b. Air conditioner system discharged. Have the system evacuated, charged and leak
tested by an MVAC certified technician, utilizing approved recovery/recycling equip-
ment. Repair as necessary.
c. Air conditioner low pressure switch defective. Replace switch.
d. Air conditioner fan resistor pack defective. Replace resistor pack.
e. Loose connection, broken wiring or defective air conditioner relay in air conditioning*
electrical circuit. Repair wiring or replace relay as necessary.
2. Air conditioner blows warm air
a. Air conditioner system is discharged. Have the system evacuated, charged and leak
tested by an MVAC certified technician, utilizing approved recovery/recycling equip-
ment. Repair as necessary.
b. Air conditioner compressor clutch not engaging. Check compressor clutch wiring,
electrical connections and compressor clutch, and repair or replace as necessary.
3. Water collects on the interior floor when the air conditioner is used
a. Air conditioner evaporator drain hose is blocked. Clear the drain hose where it exits
the passenger compartment.
b. Air conditioner evaporator drain hose is disconnected. Secure the drain hose to the
evaporator drainage tray under the dashboard.
4. Air conditioner has a moldy odor when used
a. The air conditioner evaporator drain hose is blocked or partially restricted, allowing
condensation to build up around the evaporator and drainage tray. Clear the drain
hose where it exits the passenger compartment.
,
1. Blower motor does not operate
a. Check blower motor fuse and replace as necessary.
b. Check blower motor wiring for loose, damaged or corroded contacts and repair as
necessary.
c. Check blower motor switch and resistor pack for open circuits, and repair or replace
as necessary.
d. Check blower motor for internal damage and repair or replace as necessary.
2. Heater blows cool air
a. Check the engine coolant level. If the coolant level is low, top off and bleed the air
from the cooling system as necessary and check for coolant leaks.
b. Check engine coolant operating temperature. If coolant temperature is below specifica-
tion, check for a damaged or stuck thermostat.
c. Check the heater control valve operation. Check the heater control valve cable or vac-
uum hose for proper installation. Move the heater temperature control from hot to cold
several times and verify the operation of the heater control valve. With the engine at
normal operating temperature and the heater temperature control in the full hot posi-
tion, carefully feel the heater hose going into and exiting the control valve. If one
heater hose is hot and the other is much cooler, replace the control valve.
3. Heater steams the windshield when used
a. Check for a loose cooling system hose clamp or leaking coolant hose near the engine
firewall or under the dash area, and repair as necessary.
b. Check for the existence of a sweet odor and fluid dripping from the heater floor vents,
indicating a failed or damaged heater core. Pressure test the cooling system with the
heater set to the fully warm position and check for fluid leakage from the floor vents. If
leakage is verified, remove and replace the heater core assembly.
NOTE: On some vehicles, the dashboard must be disassembled and re-
moved to access the heater core.

GLOSSARY 1149
GENERATOR: A device which produces direct current (DC) necessary to
charge the battery. OVERHEAD CAMSHAFT (OHC): An engine configuration in which the
camshaft is mounted on top of the cylinder head and operates the valve either
directly or by means of rocker arms.
HEAT RANGE: A term used to describe the ability of a spark plug to carry
away heat. Plugs with longer nosed insulators take longer to carry heat off
effectively.
HUB: The center part of a wheel or gear.
HYDROCARBON (HC): Any chemical compound made up of hydrogen
and carbon. A major pollutant formed by the engine as a by-product of
combustion.
HYDROMETER: An instrument used to measure the specific gravity of a so-
lution.
INCH POUND (inch Ibs.; sometimes in. lb. or in. Ibs.): One twelfth
.
of a foot pound.
INDUCTION: A means of transferring electrical energy in the form of a mag-
netic field. Principle used in the ignition coil to increase voltage.
INJECTOR: A device which receives metered fuel under relatively low pres-
sure and is activated to inject the fuel into the engine under relatively high
pressure at a predetermined time.
INPUT SHAFT: The shaft to which torque is applied, usually carrying the dri-
ving gear or gears.
INTAKE MANIFOLD: A casting of passages or pipes used to conduct air or
a fuel/air mixture to the cylinders.
JOURNAL: The bearing surface within which a shaft operates.
KEY: A small block usually fitted in a notch between a shaft and a hub to pre-
vent slippage of the two parts.
MANIFOLD: A casting of passages or set of pipes which connect the cylin-
ders to an inlet or outlet source.
MASTER CYLINDER: The primary fluid pressurizing device in a hydraulic
system. In automotive use, it is found in brake and hydraulic clutch systems
and is pedal activated, either directly or, in a power brake system, through the
power booster.
MODULE: Electronic control unit, amplifier or igniter of solid state or inte-
grated design which controls the current flow in the ignition primary circuit
based on input from the pick-up coil. When the module opens the primary cir-
cuit, high secondary voltage is induced in the coil.
NEEDLE BEARING: A bearing which consists of a number (usually a large
number) of long, thin rollers.
OHM: The unit used to measure the resistance of conductor-to-electrical flow.
One ohm is the amount of resistance that limits current flow to one ampere in
a circuit with one volt of pressure.
OHMMETER: An instrument used for measuring the resistance, in ohms, in
an electrical circuit.
OUTPUT SHAFT: The shaft which transmits torque from a device, such as a
transmission. OVERHEAD VALVE (OHV): An engine configuration in which all of the
valves are located in the cylinder head
and the camshaft is located in the cylin-
der block. The camshaft operates the valves via lifters and pushrods.
OXIDES OF NITROGEN (NOx): Chemical compounds of nitrogen produced
as a byproduct of combustion. They combine with hydrocarbons to produce
smog.
OXYGEN SENSOR: Used with a feedback system to sense the presence of
oxygen in the exhaust gas and signal the computer which can use the voltage
signal to determine engine operating efficiency and adjust the air/fuel ratio.
PINION: The smaller of two gears. The rear axle pinion drives the ring gear
which transmits motion to the axle shafts.
PISTON RING: An open-ended ring which fits into a groove on the outer di-
ameter of the piston. Its chief function is to form a seal between the piston and
cylinder wall. Most automotive pistons have three rings: two for compression
sealing; one for oil sealing.
PRELOAD: A predetermined load placed on a bearing during assembly or by
adjustment.
PRESS FIT: The mating of two parts under pressure, due to the inner diam-
eter of one being smaller than the outer diameter of the other, or vice versa;
an interference fit.
PRIMARY CIRCUIT: The low voltage side of the ignition system which con-
sists of the ignition switch, ballast resistor or resistance wire, bypass, coil,
electronic control unit and pick-up coil as well as the connecting wires and
harnesses.
RACE: The surface on the inner or otiter ring of a bearing on which the balls,
needles or rollers move.
REGULATOR: A device which maintains the amperage and/or voltage levels
of a circuit at predetermined values.
RELAY: A switch which automatically opens and/or closes a circuit.
RESISTANCE: The opposition to the flow of current through a circuit or elec-
trical device, and is measured in ohms. Resistance is equal to the voltage di-
vided by the amperage.
RESISTOR: A device, usually made of wire, which offers a preset amount of
resistance in an electrical circuit.
RING GEAR: The name given to a ring-shaped gear attached to a differential
case, or affixed to a flywheel or as part of a planetary gear set.
ROLLER BEARING: A bearing made up of hardened inner and outer races
between which hardened steel rollers move.
ROTOR: (1.) The disc-shaped part of a disc brake assembly, upon which the
brake pads bear; also called, brake disc. (2.) The device mounted atop the dis-
tributor shaft, which passes current to the distributor cap tower contacts.

II-20 GLOSSARY
SECONDARY CIRCUIT: The high voltage side of the ignition system, usu-
ally above 20,000 volts. The secondary includes the ignition coil, coil wire,
distributor cap and rotor, spark plug wires and spark plugs.
SENDING UNIT: A mechanical, electrical, hydraulic or electromagnetic de-
vice which transmits information to a gauge.
SENSOR: Any device designed to measure engine operating conditions or
ambient pressures and temperatures. Usually electronic in nature and designed
to send a voltage signal to an on-board computer, some sensors may oper-
ate as a simple on/off switch or they may provide a variable voltage signal
(like a potentiometer) as conditions or measured parameters change.
SHIM: Spacers of precise, predetermined thickness used between parts to es-
tablish a proper working relationship.
SLAVE CYLINDER: In automotive use, a device in the hydraulic clutch sys-
tem which is activated by hydraulic force, disengaging the clutch.
SOLENOID: An electrically operated, magnetic switching device.
SPARK PLUG: A device screwed into the combustion chamber of a spark ig-
nition engine. The basic construction is a conductive core inside of a ceramic
insulator, mounted in an outer conductive base. An electrical charge from the
spark plug wire travels along the conductive core and jumps a preset air gap
to a grounding point or points at the end of the conductive base. The resul-
tant spark ignites the fuel/air mixture in the combustion chamber.
SPLINES: Ridges machined or cast onto the outer diameter of a shaft or in-
ner diameter of a bore to enable parts to mate without rotation.
TACHOMETER: A device used to measure the rotary speed of an engine,
shaft, gear, etc., usually in rotations per minute.
THERMOSTAT: A valve, located in the cooling system of an engine, which
is closed when cold and opens gradually in response to engine heating, con-
trolling the temperature of the coolant and rate of coolant flow.
TOP DEAD CENTER (TDC): The point at which the piston reaches the top
of its travel on the compression stroke.
TORQUE: Measurement of turning or twisting force, expressed as foot-pounds
or inch-pounds.
TORQUE CONVERTER: A turbine used to transmit power from a driving
member to a driven member via hydraulic action, providing changes in drive
ratio and torque. In automotive use, it links the driveplate at the rear of the en-
gine to the automatic transmission. TRANSDUCER: A device that changes energy from one form to another. For
example, a transducer in a microphone changes sound energy to electrical en-
ergy. In automotive air-conditioning controls used in automatic temperature
systems, a transducer changes an electrical signal to a vacuum signal, which
operates mechanical doors.
TRANSISTOR: A semi-conductor component which can be actuated by a
small voltage to perform an electrical switching function.
TUNE-UP: A regular maintenance function, usually associated with the re-
placement and adjustment of parts and components in the electrical and fuel
systems of a vehicle for the purpose of attaining optimum performance.
TURBOCHARGER: An exhaust driven pump which compresses intake air
and forces it into the combustion chambers at higher than atmospheric pres-
sures The increased air pressure allows more fuel to be burned and results
in increased horsepower being produced.
.
VACUUM ADVANCE: A device which advances the ignition timing in re-
sponse to increased engine vacuum.
VACUUM GAUGE: An instrument used for measuring the existing vacuum
in a vacuum circuit or chamber. The unit of measure is inches (of mercury in
a barometer).
VALVE: Devices that can open or close fluid passages in a hydraulic system
and are used for directing fluid flow and controlling pressure.
VALVE CLEARANCE: The measured gap between the end of the valve stem
and the rocker arm, cam lobe or follower that activates the valve.
VISCOSITY: The ability of a fluid to flow. The lower the viscosity rating, the
easier the fluid will flow. 10 weight motor oil will flow much easier than 40
weight motor oil.
VOLTMETER: An instrument used for measuring electrical force in units
called volts. Voltmeters are always connected parallel with the circuit being
tested.
WHEEL CYLINDER: Found in the automotive drum brake assembly, it is a
device, actuated by hydraulic pressure, which, through internal pistons, pushes
the brake shoes outward against the drums.