SUSPENSION AND STEERING SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
FRONT END NOISE 1. Loose or worn wheel bearing. 1. Replace wheel bearing.
2. Loose or worn steering or sus-
pension components.2. Tighten or replace components as nec-
essary.
3. Loose or worn steering or sus-
pension components.3. Tighten or replace components as nec-
essary.
EXCESSIVE PLAY IN
STEERING1. Loose or worn wheel bearing. 1. Replace wheel bearing.
2. Loose or worn steering or sus-
pension components.2. Tighten or replace components as nec-
essary.
3. Loose or worn steering gear. 3. Replace steering gear.
FRONT WHEELS SHIMMY 1. Loose or worn wheel bearing. 1. Replace wheel bearing.
2. Loose or worn steering or sus-
pension components.2. Tighten or replace components as nec-
essary.
3. Tires worn or out of balance. 3. Replace or balance tires.
4. Alignment. 4. Align vehicle to specifications.
VEHICLE INSTABILITY 1. Loose or worn wheel bearing. 1. Replace wheel bearing.
2. Loose or worn steering or sus-
pension components.2. Tighten or replace components as nec-
essary.
3. Tire pressure. 3. Adjust tire pressure.
4. Alignment. 4. Align vehicle to specifications.
EXCESSIVE STEERING
EFFORT1. Loose or worn steering gear. 1. Replace steering gear.
2. Column coupler binding. 2. Replace coupler.
3. Tire pressure. 3. Adjust tire pressure.
4. Alignment. 4. Align vehicle to specifications.
VEHICLE PULLS TO ONE
SIDE1. Tire pressure. 1. Adjust tire pressure.
2. Tire. 2. Criss-Cross Front Tires.
3. Alignment. 3. Align vehicle to specifications.
4. Loose or worn steering or sus-
pension components.4. Tighten or replace components as nec-
essary.
5. Radial tire lead. 5. Rotate or replace tire as necessary.
6. Brake pull. 6. Repair brake as necessary.
7. Weak or broken spring. 7. Replace spring.
STANDARD PROCEDURE - TOE ADJUSTMENT
CAMBER AND CASTER ARE NOT ADJUSTABLE
(TOE ONLY)..
The wheel toe position adjustment is the final
adjustment.
(1) Start the engine and turn wheels both ways
before straightening the wheels. Secure the steering
wheel with the front wheels in the straight-ahead
position.(2) Loosen the tie rod jam nuts.
NOTE: Each front wheel should be adjusted for
one-half of the total toe position specification. This
will ensure the steering wheel will be centered
when the wheels are positioned straight-ahead.
(3) Adjust the wheel toe position by turning the
inner tie rod as necessary.
2 - 18 WHEEL ALIGNMENTVA
DRIVELINE VIBRATION
Drive Condition Possible Cause Correction
Propeller Shaft Noise 1) Undercoating or other foreign
material on shaft.1) Clean exterior of shaft and wash
with solvent.
2) Loose U-joint clamp screws. 2) Install new clamps and screws
and tighten to proper torque.
3) Loose or bent U-joint yoke or
excessive runout.3) Install new yoke.
4) Incorrect driveline angularity. 4) Measure and correct driveline
angles.
5) Rear spring center bolt not in
seat.5) Loosen spring u-bolts and seat
center bolt.
6) Worn U-joint bearings. 6) Install new U-joint.
7) Propeller shaft damaged or out
of balance.7) Installl new propeller shaft.
8) Broken rear spring. 8) Install new rear spring.
9) Excessive runout or unbalanced
condition.9) Re-index propeller shaft, test,
and evaluate.
10) Excessive drive pinion gear
shaft runout.10) Re-index propeller shaft and
evaluate.
11) Excessive axle yoke deflection. 11) Inspect and replace yoke if
necessary.
12) Excessive transfer case
runout.12) Inspect and repair as neces-
sary.
Universal Joint Noise 1) Loose U-joint clamp screws. 1) Install new clamps and screws
and tighten to proper torque.
2) Lack of lubrication. 2) Replace as U-joints as neces-
sary.
PROPELLER SHAFT BALANCE
NOTE: Removing and indexing the propeller shaft
180É relative to the yoke may eliminate some vibra-
tions.
If propeller shaft is suspected of being out of bal-
ance, verify with the following procedure:
(1) Place vehicle in netrual.
(2) Raise and support the vehicle by the axles as
level as possible.
(3) Clean all foreign material from propeller shaft
and universal joints.
(4) Inspect propeller shaft for missing balance
weights, broken welds, and bent areas.
NOTE: If propeller shaft is bent, it must be replaced.
(5) Inspect universal joints for wear, properly
installed and correct alignment with the shaft.
(6) Check universal joint clamp screws torque.
(7) Remove wheels and tires. Install wheel lug
nuts to retain the brake drums/rotors.(8) Mark and number propeller shaft six inches
from the pinion yoke end at four positions 90É apart.
(9) Run and accelerate the vehicle until vibration
occurs. Note intensity and speed the vibration
occurred. Stop the engine.
(10) Install a screw clamp at position 1 (Fig. 1).
3 - 2 PROPELLER SHAFTVA
(3) During road test, make normal and firm brake
stops in 25-40 mph range. Note faulty brake opera-
tion such as low pedal, hard pedal, fade, pedal pulsa-
tion, pull, grab, drag, noise, etc.
(4) Attempt to stop the vehicle with the parking
brake only and note grab, drag, noise, etc.
PEDAL FALLS AWAY
A brake pedal that falls away under steady foot
pressure is generally the result of a system leak. The
leak point could be at a brake line, fitting, hose, or
caliper/wheel cylinder. If leakage is severe, fluid will
be evident at or around the leaking component.
Internal leakage (seal by-pass) in the master cylin-
der caused by worn or damaged piston cups, may
also be the problem cause.
An internal leak in the ABS or RWAL system may
also be the problem with no physical evidence.
LOW PEDAL
If a low pedal is experienced, pump the pedal sev-
eral times. If the pedal comes back up worn linings,
rotors, drums, or rear brakes out of adjustment are
the most likely causes. The proper course of action is
to inspect and replace all worn component and make
the proper adjustments.
SPONGY PEDAL
A spongy pedal is most often caused by air in the
system. However, thin brake drums or substandard
brake lines and hoses can also cause a spongy pedal.
The proper course of action is to bleed the system,
and replace thin drums and substandard quality
brake hoses if suspected.
HARD PEDAL OR HIGH PEDAL EFFORT
A hard pedal or high pedal effort may be due to
lining that is water soaked, contaminated, glazed, or
badly worn. The power booster or check valve could
also be faulty.
PEDAL PULSATION
Pedal pulsation is caused by components that are
loose, or beyond tolerance limits.
The primary cause of pulsation are disc brake
rotors with excessive lateral runout or thickness vari-
ation, or out of round brake drums. Other causes are
loose wheel bearings or calipers and worn, damaged
tires.
NOTE: Some pedal pulsation may be felt during
ABS activation.
BRAKE DRAG
Brake drag occurs when the lining is in constant
contact with the rotor or drum. Drag can occur at one
wheel, all wheels, fronts only, or rears only.Drag is a product of incomplete brake shoe release.
Drag can be minor or severe enough to overheat the
linings, rotors and drums.
Minor drag will usually cause slight surface char-
ring of the lining. It can also generate hard spots in
rotors and drums from the overheat-cool down pro-
cess. In most cases, the rotors, drums, wheels and
tires are quite warm to the touch after the vehicle is
stopped.
Severe drag can char the brake lining all the way
through. It can also distort and score rotors and
drums to the point of replacement. The wheels, tires
and brake components will be extremely hot. In
severe cases, the lining may generate smoke as it
chars from overheating.
Common causes of brake drag are:
²Seized or improperly adjusted parking brake
cables.
²Loose/worn wheel bearing.
²Seized caliper or wheel cylinder piston.
²Caliper binding on corroded bushings or rusted
slide surfaces.
²Loose caliper mounting.
²Drum brake shoes binding on worn/damaged
support plates.
²Mis-assembled components.
²Long booster output rod.
If brake drag occurs at all wheels, the problem
may be related to a blocked master cylinder return
port, or faulty power booster (binds-does not release).
BRAKE FADE
Brake fade is usually a product of overheating
caused by brake drag. However, brake overheating
and resulting fade can also be caused by riding the
brake pedal, making repeated high deceleration stops
in a short time span, or constant braking on steep
mountain roads. Refer to the Brake Drag information
in this section for causes.
BRAKE PULL
Front brake pull condition could result from:
²Contaminated lining in one caliper
²Seized caliper piston
²Binding caliper
²Loose caliper
²Rusty caliper slide surfaces
²Improper brake pads
²Damaged rotor
A worn, damaged wheel bearing or suspension
component are further causes of pull. A damaged
front tire (bruised, ply separation) can also cause
pull.
A common and frequently misdiagnosed pull condi-
tion is where direction of pull changes after a few
stops. The cause is a combination of brake drag fol-
lowed by fade at one of the brake units.
VABRAKES - BASE 5 - 3
As the dragging brake overheats, efficiency is so
reduced that fade occurs. Since the opposite brake
unit is still functioning normally, its braking effect is
magnified. This causes pull to switch direction in
favor of the normally functioning brake unit.
An additional point when diagnosing a change in
pull condition concerns brake cool down. Remember
that pull will return to the original direction, if the
dragging brake unit is allowed to cool down (and is
not seriously damaged).
REAR BRAKE GRAB OR PULL
Rear grab or pull is usually caused by improperly
adjusted or seized parking brake cables, contami-
nated lining, bent or binding shoes and support
plates, or improperly assembled components. This is
particularly true when only one rear wheel is
involved. However, when both rear wheels are
affected, the master cylinder or proportioning valve
could be at fault.
BRAKES DO NOT HOLD AFTER DRIVING THROUGH DEEP
WATER PUDDLES
This condition is generally caused by water soaked
lining. If the lining is only wet, it can be dried by
driving with the brakes very lightly applied for a
mile or two. However, if the lining is both soaked and
dirt contaminated, cleaning and/or replacement will
be necessary.
BRAKE LINING CONTAMINATION
Brake lining contamination is mostly a product of
leaking calipers or worn seals, driving through deep
water puddles, or lining that has become covered
with grease and grit during repair. Contaminated lin-
ing should be replaced to avoid further brake prob-
lems.
WHEEL AND TIRE PROBLEMS
Some conditions attributed to brake components
may actually be caused by a wheel or tire problem.
A damaged wheel can cause shudder, vibration and
pull. A worn or damaged tire can also cause pull.
Severely worn tires with very little tread left can
produce a grab-like condition as the tire loses and
recovers traction. Flat-spotted tires can cause vibra-
tion and generate shudder during brake operation. A
tire with internal damage such as a severe bruise,
cut, or ply separation can cause pull and vibration.
BRAKE NOISES
Some brake noise is common with rear drum
brakes and on some disc brakes during the first few
stops after a vehicle has been parked overnight or
stored. This is primarily due to the formation of trace
corrosion (light rust) on metal surfaces. This light
corrosion is typically cleared from the metal surfacesafter a few brake applications causing the noise to
subside.
BRAKE SQUEAK / SQUEAL
Brake squeak or squeal may be due to linings that
are wet or contaminated with brake fluid, grease, or
oil. Glazed linings and rotors with hard spots can
also contribute to squeak. Dirt and foreign material
embedded in the brake lining will also cause squeak/
squeal.
A very loud squeak or squeal is frequently a sign of
severely worn brake lining. If the lining has worn
through to the brake pads in spots, metal-to-metal
contact occurs. If the condition is allowed to continue,
rotors can become so scored that replacement is nec-
essary.
BRAKE CHATTER
Brake chatter is usually caused by loose or worn
components, or glazed/burnt lining. Rotors with hard
spots can also contribute to chatter. Additional causes
of chatter are out-of-tolerance rotors, brake lining not
securely attached to the shoes, loose wheel bearings
and contaminated brake lining.
THUMP / CLUNK NOISE
Thumping or clunk noises during braking are fre-
quentlynotcaused by brake components. In many
cases, such noises are caused by loose or damaged
steering, suspension, or engine components. However,
calipers that bind on the slide surfaces can generate
a thump or clunk noise.
STANDARD PROCEDURE
STANDARD PROCEDURE - MANUAL BLEEDING
Use approved brake fluid (Refer to LUBRICATION
& MAINTENANCE/FLUID TYPES - DESCRIP-
TION). Use fresh, clean fluid from a sealed container
at all times.
(1) Remove reservoir filler caps and fill reservoir.
(2) If calipers, or wheel cylinders were overhauled,
open all caliper and wheel cylinder bleed screws.
Then close each bleed screw as fluid starts to drip
from it. Top off master cylinder reservoir once more
before proceeding.
(3) Attach one end of bleed hose to bleed screw
and insert opposite end in glass container partially
filled with brake fluid (Fig. 1). Be sure end of bleed
hose is immersed in fluid.
5 - 4 BRAKES - BASEVA
COOLING
TABLE OF CONTENTS
page page
COOLING
OPERATION - COOLING SYSTEM...........1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - PRELIMINARY
CHECKS.............................1COOLING SYSTEM.....................2
ACCESSORY DRIVE.......................5
ENGINE.................................9
COOLING
OPERATION - COOLING SYSTEM
The cooling system regulates engine operating tem-
perature. It allows the engine to reach normal oper-
ating temperature as quickly as possible. It also
maintains normal operating temperature and pre-
vents overheating.
The cooling system also provides a means of heat-
ing the passenger compartment and cooling the auto-
matic transmission fluid (if equipped). The cooling
system is pressurized and uses a centrifugal water
pump to circulate coolant throughout the system.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - PRELIMINARY
CHECKS
ENGINE COOLING SYSTEM OVERHEATING
Establish what driving conditions caused the com-
plaint. Abnormal loads on the cooling system such as
the following may be the cause:
²PROLONGED IDLE
²VERY HIGH AMBIENT TEMPERATURE
²SLIGHT TAIL WIND AT IDLE
²SLOW TRAFFIC
²TRAFFIC JAMS
²HIGH SPEED OR STEEP GRADES
Driving techniques that avoid overheating are:
²Idle with A/C off when temperature gauge is at
end of normal range.²Increasing engine speed for more air flow is rec-
ommended.
TRAILER TOWING:
Consult Trailer Towing section of owners manual.
Do not exceed limits.
AIR CONDITIONING; ADD - ON OR AFTER MARKET:
A maximum cooling package should have been
ordered with vehicle if add-on or after market A/C is
installed. If not, maximum cooling system compo-
nents should be installed for model involved per
manufacturer's specifications.
RECENT SERVICE OR ACCIDENT REPAIR:
Determine if any recent service has been per-
formed on vehicle that may effect cooling system.
This may be:
²Engine adjustments (incorrect timing)
²Slipping engine accessory drive belt(s)
²Brakes (possibly dragging)
²Changed parts. Incorrect water pump or pump
rotating in wrong direction due to belt not correctly
routed
²Reconditioned radiator or cooling system refill-
ing (possibly under filled or air trapped in system).
NOTE: If investigation reveals none of the previous
items as a cause for an engine overheating com-
plaint, (Refer to 7 - COOLING - DIAGNOSIS AND
TESTING)
VACOOLING 7 - 1
COOLING SYSTEM
COOLING SYSTEM DIAGNOSIS - DIESEL ENGINE
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATUREGAUGE READS
LOW1. Vehicle is equipped with a
heavy duty cooling system.1. None. System operating norma-
ly.
2. Temperature gauge not connect-
ed2. Connect gauge.
3. Temperature gauge connected
but not operating.3. Check gauge. Refer (Refer to 8
- ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND
TESTING)
4. Coolant level low. 4. Fill cooling system. (Refer to 7 -
COOLING - STANDARD PROCE-
DURE)
TEMPERATURE GAUGE READS
HIGH. COOLANT MAY OR MAY
NOT BE LEAKING FROM SYS-
TEM1. Vehicle overloaded, high ambi-
ent (outside) temperatures with
A/C turned on, stop and go driving
or prolonged operation at idle
speeds.1. Temporary condition, repair not
required. Notify customer of vehicle
operation instructions located in
Owners Manual.
2. Temperature gauge not function-
ing correctly.2. Check gauge. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING)
3. Air traped in cooling 3. Drain cooling system (Refer to 7
- COOLING - STANDARD PROCE-
DURE) and refill (Refer to 7 -
COOLING - STANDARD PROCE-
DURE)
4. Radiator cap faulty. 4. Replace radiator cap.
5. Plugged A/C or radiator cooling
fins.5. Clean all debre away from A/C
and radiator cooling fins.
6. Coolant mixture incorrect. 6. Drain cooling system (Refer to 7
- COOLING - STANDARD PROCE-
DURE) refill with correct mixture
(Refer to 7 - COOLING - STAN-
DARD PROCEDURE).
7. Thermostat stuck shut. 7. Replace thermostat.
8. Bug screen or winter front being
used.8. Remove bug screen or winter
front.
9. Viscous fan drive not operating
properly.9. Check viscous fan (Refer to 7 -
COOLING/ENGINE/FAN DRIVE
VISCOUS CLUTCH - DIAGNOSIS
AND TESTING)
10. Cylinder head gasket leaking. 10. Check for leaking head gaskets
(Refer to 7 - COOLING - DIAGNO-
SIS AND TESTING).
11. Heater core leaking. 11. Replace heater core.
12. cooling system hoses leaking. 12. Tighten clamps or Replace
hoses.
7 - 2 COOLINGVA
CONDITION POSSIBLE CAUSES CORRECTION
13. Brakes dragging. 13. Check brakes. (Refer to 5 -
BRAKES/HYDRAULIC/MECHANI-
CAL - DIAGNOSIS AND TESTING)
TEMPERATURE GAUGE READ-
ING INCONSISTENT ( ERRATIC,
CYCLES OR FLUCTUATES)1. Heavy duty cooling system, ex-
tream cold ambient (outside) tem-
perature or heater blower motor in
high position.1. None. System operating norma-
ly.
2. Temperature gauge or gauge
sensor defective.2. Check gauge. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING)
3. Temporary heavy usage or load. 3. None. Normal condition.
4. Air traped in cooling system. 4. Fill cooling system (Refer to 7 -
COOLING - STANDARD PROCE-
DURE).
5. Water pump 5. Replace water pump.
6. Air leak on suction side of water
pump.6. Check for leak. (Refer to 7 -
COOLING - DIAGNOSIS AND
TESTING)
RADIATOR CAP LEAKING STEAM
AND /OR COOLANT INTO RES-
ERVOIR BOTTLE. (TEMPERA-
TURE GAUGE MAY READ HIGH)1. Radiator cap defective. 1. Replace radiator cap.
2. Radiator neck surface damaged. 2. Replace radiator.
HOSE OR HOSES COLLAPSE
WHEN ENGINE IS COOLING.1. Vacuum created in cooling sys-
tem on engine cool-down is not
being relieved through coolant re-
servior/overflow system.1. Replace radiator cap, check vent
hose between radiator and reser-
voir bottle for blockage also check
reservoir bottle vent for blockage.
NOISY FAN 1. Fan blade(s) loose, damaged. 1. Replace fan blade assembly.
2. Thermal viscous fan drive. 2. None. Normal condition.
3. Fan blades striking surrounding
objects.3. Locate contact point and repair
as necessary.
4. Thermal viscous fan drive bear-
ing.4. Replace viscous fan drive as-
sembly.
5. Obstructed air flow through radi-
ator.5. Remove obstruction.
INADEQUATE AIR CONDITIONER
PERFORMANCE (COOLING SYS-
TEM SUSPECTED)1. Radiator and/or A/C condenser
air flow obstructed.1. Remove obstruction and/or
clean.
2. Thermal viscous fan drive not
working.2. Check fan drive. (Refer to 7 -
COOLING/ENGINE/FAN DRIVE
VISCOUS CLUTCH - DIAGNOSIS
AND TESTING)
3. Air seals around radiator dam-
aged or missing.3. Inspect air seals, repair or re-
place as necessary.
VACOOLING 7 - 3
CONDITION POSSIBLE CAUSES CORRECTION
INADEQUATE HEATER PERFOR-
MANCE. GUAGE MAY OR MAY
NOT READ LOW.1. Heavy duty cooling system, and
cooler ambient temperatures.1. None. Normal condition.
2. Obstruction in heater hoses. 2. Remove hoses, remove obstruc-
tion.
3. Water pump damaged. 3. Replace water pump.
HEAT ODOR 1. Damaged or missing drive line
heat shields.1. Repair or replace damaged or
missing heat shields.
2. Thermal viscous fan drive dam-
aged.2. Check thermal viscous fan drive.
(Refer to 7 - COOLING/ENGINE/
FAN DRIVE VISCOUS CLUTCH -
DIAGNOSIS AND TESTING)
7 - 4 COOLINGVA