Ford Mustang (1999-2004) Service Manual: Pinpoint Tests

The pinpoint tests are a step-by-step diagnostic process designed to determine the cause of a condition. It may not always be necessary to follow a pinpoint test to its conclusion. Carry out only the steps necessary to correct the condition. Then, test the system for normal operation. Sometimes, it is necessary to remove various vehicle components to gain access to the component requiring testing.

Reinstall all components after verifying system operation is normal.

PINPOINT TEST A: BRAKE VIBRATION/SHUDDER

Test Step Result / Action to Take
A1 ROAD TEST THE VEHICLE-LIGHT BRAKING Yes

GO to A4 .

No

GO to A2 .

  • Check that the wheel and tires are correct for the vehicle.

    Inspect the tires for abnormal wear patterns.

  • Road test the vehicle. Warm the brakes by slowing the vehicle a few times from 80-32 km/h (50 to 20 mph) using light braking applications. At highway speeds of 89-97 km/h (55-60 mph), apply the brake using a light pedal force.
  • Is there a vibration/shudder felt in the steering wheel, seat or brake pedal?
A2 ROAD TEST THE VEHICLE-MODERATE TO HEAVY BRAKING Yes

For vehicles with ABS, GO to A3 . For vehicles with standard brakes, GO to A4 .

No

Vehicle is OK. VERIFY condition with customer.

TEST the vehicle for normal operation.

  • Road test the vehicle. At highway speeds of 89-97 km/h (55-60 mph), apply the brake using a moderate to heavy pedal force.
  • Is there a vibration/shudder?
A3 NORMAL ACTUATION OF THE ABS SYSTEM DIAGNOSIS Yes

GO to A5 .

No

The brake system is operating correctly.

  • During moderate to heavy braking, noise from the hydraulic control unit (HCU) and pulsation in the brake pedal can be observed. Pedal pulsation coupled with noise during heavy braking or on loose gravel, bumps, wet or snowy surfaces is acceptable and indicates correct functioning of the ABS system. Pedal pulsation or steering wheel nibble, (frequency is proportioned to the vehicle speed) indicates a concern with a brake or suspension component.
  • Is the vibration/shudder vehicle speed sensitive?
A4 APPLICATION OF THE PARKING BRAKE Yes

GO to A7 .

No

GO to A5 .

  • NOTE: Begin at the front of the vehicle unless the vibration or shudder has been isolated to the rear.
  • This test is not applicable to vehicles with drum-in-hat type parking brakes. For vehicles with drum-in-hat parking brakes, proceed to the next test. For all other vehicles, apply the parking brake to identify if the problem is in the front or rear brake. At highway speeds of 89-97 km/h (55-60 mph), lightly apply the parking brake until the vehicle slows down. Release the parking brake immediately after the test.
  • Is there a vibration/shudder?
A5 CHECK THE FRONT WHEEL BEARINGS Yes

GO to A6 .

No

INSPECT the wheel bearings. ADJUST or REPAIR as necessary.

TEST the system for normal operation.

  • Check the front wheel bearings. Refer to Wheel Bearing Check in this section.
  • Are the wheel bearings OK?
A6 CHECK THE FRONT SUSPENSION Yes

GO to A7 .

No

REPAIR or INSTALL new components as necessary. TEST the system for normal operation.

  • Check the front suspension for:
  • Broken or loose bolts.
  • Damaged springs.
  • Worn or damaged upper and lower control arm bushings.
  • Loose or rough front bearings.
  • Uneven tire wear.
  • Are all the suspension components in satisfactory condition?
A7 RESURFACE THE FRONT BRAKE DISCS Yes

GO to A8 .

No

Vehicle is OK.

  • CAUTION: Do not use a bench lathe to machine brake discs.
  • NOTE: Follow the manufacturer's instructions to machine the brake discs. After machining, make sure the brake disc meets the thickness specification.
  • Refer to Brake Disc Machining in this section. Resurface the front brake discs. Road test the vehicle.
  • Is the vibration/shudder present?
A8 CHECK THE REAR SUSPENSION Yes

GO to A9 .

No

REPAIR or INSTALL new components as necessary. TEST the system for normal operation.

  • Check the rear suspension for:
  • Broken or loose bolts.
  • Damaged or worn springs or spring bushings.
  • Worn or damaged upper and lower control arm bushings.
  • Worn or damaged trailing arms.
  • Loose or rough rear bearings.
  • Uneven tire wear.
  • Are all the suspension components in satisfactory condition?
A9 RESURFACE THE REAR BRAKE DISC OR DRUM Yes

CHECK the front suspension for wear or damage. RESURFACE the front brake discs.

TEST the system for normal operation.

No

Vehicle is OK.

  • CAUTION: Do not use a bench lathe to machine brake discs.
  • NOTE: Follow the manufacturers instructions to machine the brake discs. After machining, make sure the brake disc meets the thickness specification.
  • Refer to Brake Disc Machining in this section. Resurface the rear brake discs or drums. Road test the vehicle.
  • Is the vibration/shudder present?

PINPOINT TEST B: ENGINE TICKING NOISE

Test Step Result / Action to Take
B1 CHECK FOR TICKING NOISE AT THE FUEL RAIL Yes

CHECK for TSB for applicable vehicle.

REPAIR as necessary. TEST the system for normal operation.

No

GO to B2 .

  • Disconnect the first fuel line clip.
  • Is the ticking noise gone?
B2 CHECK FOR TICKING NOISE AT THE FUEL INJECTOR Yes

INSTALL a new fuel injector.

No

GO to B3 .

  • Using an EngineEAR, listen at the fuel injectors by placing a probe on each injector.

    To isolate the faulty injector, disconnect the injector electrical connector and listen for the noise.

  • Is the fuel injector the source of the ticking noise?
B3 CHECK THE BELT TENSIONER FOR TICKING NOISE Yes

INSTALL a new belt tensioner. TEST the system for normal operation.

No

GO to B4 .

  • Inspect the accessory drive. Check for the belt tensioner bottoming at end of travel or not at end of stroke.
  • Using an EngineEAR, listen at the belt tensioner.
  • Is the belt tensioner the source of the noise?
B4 CHECK THE WATER PUMP FOR TICKING NOISE Yes

INSTALL a new water pump. TEST the system for normal operation.

No

GO to B5 .

  • Using an EngineEAR, listen at the water pump for ticking noise.
  • Is the water pump the source of the noise?
B5 CHECK FOR AN OBSTRUCTION OF THE COOLING FAN Yes

REPAIR or INSTALL a new cooling fan.

TEST the system for normal operation.

No

GO to B6 .

  • Inspect the cooling fan for obstructions.
  • Check the cooling fan and shroud for wear or damage.
  • Was there an obstruction or does the cooling fan show signs of damage?
B6 CHECK THE OIL PUMP FOR TICKING NOISE Yes

INSTALL a new oil pump. TEST the system for normal operation.

No

GO to B7 .

  • Check the oil pump using EngineEARs and probe at the oil filter adapter to verify the oil pump as a source.
  • Is the oil pump the source of the noise?
B7 CHECK VALVE LIFTERS OR LASH ADJUSTERS FOR CORRECT OPERATION Yes

VERIFY customer concern. CONDUCT a diagnosis of other suspect components.

No

INSTALL a new valve lifter/lash adjuster (s). TEST the system for normal operation.

  • Check valve lifter/lash adjuster for correct operation, using EngineEARs.
  • Are the valve lifters/lash adjusters operating correctly?

PINPOINT TEST C: ACCESSORY DRIVE BEARING HOOT

Test Step Result / Action to Take
C1 CHECK THE IDLER AND TENSIONER PULLEY BEARINGS Yes

INSTALL a new pulley/idler. CARRY OUT the Vehicle Cold Soak Procedure and TEST the system for normal operation.

No

CONDUCT a diagnosis on other suspect accessory drive components.

  • Carry out the Vehicle Cold Soak Procedure in this section.
  • Key in START position.
  • Place an EngineEAR probe directly on the pulley center post or bolt to verify which bearing is making the noise.
  • Key in OFF position.
  • Is either bearing making the noise?

PINPOINT TEST D: POWER STEERING MOAN

Test Step Result / Action to Take
D1 CHECK THE POWER STEERING SYSTEM Yes

GO to D2 .

No

CONDUCT a diagnosis on other suspect accessory drive components.

  • Carry out the Vehicle Cold Soak Procedure in this section.
  • Key in START position.
  • Turn the steering wheel while the noise is occurring and listen for changes in sound pitch or loudness.
  • Key in OFF position.
  • Does the sound pitch or loudness change while turning the steering wheel?
D2 VERIFY THE SOURCE Yes

VERIFY that the supply tube to the pump is unobstructed. CHECK the fluid condition and level. DRAIN the fluid and REFILL. CARRY OUT the Vehicle Cold Soak Procedure and TEST the system for normal operation.

No

Normal system operation.

  • Key in START position.
  • Place an EngineEAR probe near the power steering pump/reservoir while the noise is occurring. While an assistant turns the steering wheel, listen for changes in sound pitch or loudness.
  • Key in OFF position.
  • Does the sound pitch or loudness change while turning the steering wheel?

PINPOINT TEST E: ENGINE DRIVEN COOLING FAN MOAN

Test Step Result / Action to Take
E1 CHECK THE ENGINE DRIVEN COOLING FAN AFTER A COLD SOAK Yes

TEST the fan for normal operation. If the fan tests normal, GO to E2 . Otherwise, REPAIR as necessary.

No

Normal system operation.

  • Carry out the Vehicle Cold Soak Procedure in this section.
  • Key in START position.
  • Assess the airflow.
  • Raise the engine speed to 1500 rpm while listening for the moan to increase in proportion to the airflow.
  • Key in OFF position.
  • Does the moan increase in proportion to the airflow?
E2 CHECK THE ENGINE DRIVEN COOLING FAN AT NORMAL OPERATING TEMPERATURE Yes

Normal clutch operation.

No

INSTALL a new fan clutch. TEST the system for normal operation.

  • Key in START position.
  • Run the engine to normal operating temperature while listening for the moan to stop.
  • Key in OFF position.
  • Does the moan stop?

PINPOINT TEST F: DRUMMING NOISE

Test Step Result / Action to Take
F1 CHECK THE EXHAUST SYSTEM Yes

CARRY OUT Exhaust System Neutralizing in this section. TEST the system for normal operation.

No

GO to F2 .

  • Key in START position.
  • Increase the engine rpm until the noise is the loudest. Note the engine rpm.
  • Key in OFF position.
  • Add approximately 9 kg (20 lb) of weight to the exhaust system. First place the weight at the tail pipe and test, then at the front pipe.

  • Key in START position.
  • Increase the engine rpm and listen for the drumming noise.

    Note the engine rpm if the noise occurs.

  • Key in OFF position.
  • Using a vibration analyzer (VA), determine the amount of vibration that occurs with the drumming noise.
  • Is the noise/vibration reduced or eliminated, or does the noise/vibration occur at a different rpm?
F2 POWERTRAIN/DRIVETRAIN MOUNT NEUTRALIZING Yes

Vehicle OK. TEST the system for normal operation.

No

CONDUCT diagnosis of other suspect components.

  • Carry out Powertrain/Drivetrain Mount Neutralizing in this section. Test the system for normal operation.
  • Is the noise reduced or eliminated?

PINPOINT TEST G: ENGINE TICKING, KNOCKING OR CONTINUOUS RATTLE

Test Step Result / Action to Take
G1 CHECK FOR NOISE AT THE VALVE COVERS AND THE FRONT COVERS (OHC ENGINES) Yes

REMOVE the appropriate cover and INSPECT for loose, worn/broken components. REPAIR as necessary.

TEST the system for normal operation.

No

GO to G2 .

  • Carry out the Vehicle Cold Soak Procedure in this section.
  • Key in START position.
  • NOTE: For a short-duration ticking noise, multiple engine starts may be necessary.
  • Using an EngineEAR, listen closely at the valve covers and the front covers (OHC engines) by placing the probe near the surface of the valve cover and then on the surface front cover.
  • Key in OFF position.
  • Is the noise source apparent?
G2 CHECK FOR NOISE AT THE CYLINDER BLOCK Yes

REPAIR or INSTALL new components as necessary.

No

GO to G3 .

  • Key in START position.
  • Using an EngineEAR, listen closely at the cylinder block by placing a probe on or near each freeze plug.
  • Key in OFF position.
  • Is the noise source apparent?
G3 CHECK FOR NOISE WHILE DISCONNECTING EACH FUEL INJECTOR ELECTRICAL CONNECTOR, ONE AT A TIME Yes

INSTALL a new fuel injector. TEST the system for normal operation.

No

INSPECT accessory drive system or the transmission as a possible source.

  • Key in START position.
  • Disconnect each fuel injector electrical connector, one at a time, to decrease piston force and listen for the noise.
  • Key in OFF position.
  • Is the noise reduced or eliminated?

PINPOINT TEST H: FRONT SUSPENSION NOISE

Test Step Result / Action to Take
H1 ROAD TEST THE VEHICLE Yes

GO to H2 .

No

The suspension system is OK. CONDUCT a diagnosis on other suspect systems.

  • Test drive the vehicle.
  • NOTE: An assistant will be needed for this road test.
  • During the road test, drive the vehicle over a rough road.

    Using ChassisEARs, determine from which area/component the noise is originating.

  • Is there a squeak, creak or rattle noise?
H2 INSPECT THE STEERING SYSTEM Yes

REPAIR the steering system. INSTALL new components as necessary.

TEST the system for normal operation.

No

GO to H3 .

  • WARNING: The electrical power to the air suspension system must be shut off prior to hoisting, jacking or towing an air suspension vehicle. This can be accomplished by turning off the air suspension switch. Failure to do so can result in unexpected inflation or deflation of the air springs, which can result in shifting of the vehicle during these operations.
  • Raise and support the vehicle.
  • Check the steering system for wear or damage. Carry out a steering linkage test.
  • Inspect the tire wear pattern. Refer to Tire Wear Patterns chart in this section.
  • Are the steering components worn or damaged?
H3 FRONT SHOCK ABSORBER/STRUT CHECK Yes

TIGHTEN to specifications if loose. INSTALL new front shock absorbers/struts if damaged. TEST the system for normal operation.

No

GO to H4 .

  • Check the front shock absorbers/strut mounts for loose bolts or nuts.
  • Check the front shock absorbers/struts for wear or damage.

    Carry out a "bounce test".

  • Are the front shock absorbers/struts loose or damaged?
H4 CHECK THE FRONT SPRINGS Yes

REPAIR or INSTALL new components as necessary.

TEST the system for normal operation.

No

GO to H5 .

  • Check the front spring and front spring mounts/brackets for wear or damage.
  • Are the front springs or spring mounts/brackets worn or damaged?
H5 CHECK THE CONTROL ARMS/RADIUS ARMS Yes

REPAIR or INSTALL new components as necessary.

TEST the system for normal operation.

No

GO to H6 .

  • Inspect the control arm bushings for wear or damage.
  • Inspect for twisted or bent control/radius arm.
  • Are the control/radius arms damaged or worn?
H6 CHECK THE STABILIZER BAR/TRACK BAR Yes

REPAIR or INSTALL new components as necessary.

TEST the system for normal operation.

No

Suspension system OK.

CONDUCT diagnosis on other suspect systems.

  • Check the stabilizer bar/track bar bushings and links for damage or wear.
  • Check the stabilizer bar/track bar for damage.
  • Check for loose or damaged stabilizer bar isolators or brackets.
  • Are the stabilizer bar/track bar components loose, worn or damaged?

PINPOINT TEST I: REAR SUSPENSION NOISE

Test Step Result / Action to Take
I1 ROAD TEST THE VEHICLE Yes

GO to I2 .

No

The suspension system is OK. Conduct a diagnosis on other suspect systems

  • Test drive the vehicle.
  • NOTE: An assistant will be needed for this road test.
  • During the road test, drive the vehicle over a rough road.

    Using ChassisEARs, determine from which area/component the noise is originating.

  • Is there a squeak, creak or rattle noise?
I2 REAR SHOCK ABSORBER/STRUT CHECK Yes

TIGHTEN to specifications if loose. INSTALL new rear shock absorbers/struts if damaged. TEST the system for normal operation.

No

GO to I3 .

  • WARNING: The electrical power to the air suspension system must be shut off prior to hoisting, jacking or towing an air suspension vehicle. This can be accomplished by turning off the air suspension switch. Failure to do so can result in unexpected inflation or deflation of the air springs, which can result in shifting of the vehicle during these operations.
  • Raise and support the vehicle.
  • Check the rear shock absorber/strut mounts for loose bolts or nuts.
  • Check the rear shock absorbers/struts for damage. Carry out a shock absorber check.
  • Are the rear shock absorbers/struts loose or damaged?
I3 CHECK THE REAR SPRINGS Yes

REPAIR or INSTALL new components as necessary.

TEST the system for normal operation.

No

GO to I4 .

  • Check the rear springs and rear spring mounts/brackets for wear or damage.
  • Are the rear springs or spring mounts/brackets worn or damaged?
I4 CHECK THE CONTROL ARMS/TRAILING ARMS Yes

REPAIR or INSTALL new components as necessary.

TEST the system for normal operation.

No

GO to I5 .

  • Inspect the control arm/trailing arm bushings for wear or damage. Check for loose control arm/trailing arm bolts.
  • Inspect for twisted or bent control arm/trailing arms.
  • Are the control arm/trailing arms loose, damaged or worn?
I5 CHECK THE STABILIZER BAR/TRACK BAR Yes

REPAIR or INSTALL new components as necessary.

TEST the system for normal operation.

No

Suspension system OK.

CONDUCT diagnosis on other suspect systems.

  • Check the stabilizer bar/track bar bushings and links for damage or wear.
  • Check the stabilizer bar/track bar for damage.
  • Check for loose or damaged stabilizer bar isolators or brackets.
  • Are the stabilizer bar/track bar components loose, worn or damaged?

PINPOINT TEST J: WHEEL AND TIRE

Test Step Result / Action to Take
J1 ROAD TEST THE VEHICLE Yes

GO to J2 .

No

The wheel and tires are OK. CONDUCT a diagnosis on other suspect systems.

  • NOTE: Wheel or tire vibrations felt in the steering wheel are most likely related to the front wheel or tire. Vibration felt through the seat are most likely related to the rear wheel or tire. This may not always be true, but it can help to isolate the problem to the front or rear of the vehicle.
  • Test drive the vehicle at different speed ranges.
  • During the road test, if the vibration can be eliminated by placing the vehicle in neutral or is affected by the speed of the engine, the cause is not the wheels or tires.
  • Is there a vibration and noise?
J2 CHECK THE FRONT WHEEL BEARINGS Yes

GO to J3 .

No

INSPECT the wheel bearings. ADJUST or REPAIR as necessary.

TEST the system for normal operation.

  • Check the front wheel bearings. Refer to Wheel Bearing Check in this section.
  • Are the wheel bearings OK?
J3 INSPECT THE TIRES Yes

CORRECT the condition that caused the abnormal wear.

INSTALL new tire(s).

TEST the system for normal operation.

No

GO to J4 .

  • Check the tires for missing weights.
  • Check the wheels for damage.
  • Inspect the tire wear pattern. Refer to the Tire Wear Patterns chart in this section.
  • Do the tires have an abnormal wear pattern?
J4 TIRE ROTATION Yes

GO to J5 .

No

CHECK the wheel and tire balance.

CORRECT as necessary. TEST the system for normal operation.

  • Spin the tires slowly and watch for signs of lateral runout.

  • Spin the tires slowly and watch for signs of radial runout.

  • Are there signs of visual runout?
J5 RADIAL RUNOUT CHECK ON THE TIRE Yes

GO to J8 .

No

GO to J6

  • Measure the radial runout of the wheel and tire assembly. A typical specification for total radial runout is 0.045 inch.

  • Is the radial runout within specifications?
J6 RADIAL RUNOUT CHECK ON THE WHEEL Yes

INSTALL a new tire.

TEST the system for normal operation.

No

GO to J7 .

  • Measure the radial runout of the wheel. A typical specification for total radial runout is 0.045 inch.
  • Is the radial runout within specifications?
J7 CHECK THE HUB/BRAKE DISC OR DRUM PILOT RUNOUT OR BOLT CIRCLE RUNOUT Yes

INSTALL a new wheel.

TEST the system for normal operation.

No

REPAIR or INSTALL new components as necessary.

  • Measure the pilot or bolt circle runout. A typical specification for radial runout is:
  • Pilot runout- less than 0.15 mm (0.006 inch).
  • Bolt circle runout- less than 0.38 mm (0.015 inch).
  • Is the radial runout within specifications?
J8 LATERAL RUNOUT CHECK ON THE TIRE Yes

Wheel and tires OK.

CONDUCT diagnosis on other suspect systems.

No

GO to J9 .

  • Measure the lateral runout of the wheel and tire assembly. A typical specification for total lateral runout is 1.14 mm (0.045 inch).

  • Is the lateral runout within specifications?
J9 LATERAL RUNOUT CHECK ON THE WHEEL Yes

INSTALL a new tire.

TEST the system for normal operation.

No

GO to J10 .

  • Measure the lateral runout of the wheel. A typical specification for total radial runout is 1.14mm (0.045 inch.
  • Is the lateral runout within specifications?
J10 CHECK THE FLANGE FACE LATERAL RUNOUT Yes

INSTALL a new wheel.

TEST the system for normal operation.

No

REPAIR or INSTALL new components as necessary.

  • Measure the flange face lateral runout. A typical specification for lateral runout is:
  • Hub/brake disc- less than 0.13 mm (0.005 inch).
  • Axle shaft- less than 0.25 mm (0.010 inch).
  • Is the lateral runout within specifications?

PINPOINT TEST K: HIGH SPEED SHAKE OR SHIMMY

Test Step Result / Action to Take
K1 CHECK FOR FRONT WHEEL BEARING ROUGHNESS Yes

INSPECT the wheel bearings. REPAIR as necessary. TEST the system for normal operation.

No

GO to K2 .

  • Chock the rear wheels.
  • Raise and support the front end of the vehicle so that the front wheel and tire assemblies can spin.
  • Spin the front tires by hand. Refer to Wheel Bearing Check in this section.
  • Do the wheel bearings feel rough?
K2 CHECK THE END PLAY OF THE FRONT WHEEL BEARINGS Yes

GO to K3 .

No

ADJUST or REPAIR as necessary. TEST the system for normal operation.

  • Check the end play of the front wheel bearings.
  • Is the end play OK?
K3 MEASURE THE LATERAL RUNOUT AND THE RADIAL RUNOUT OF THE FRONT WHEELS ON THE VEHICLE Yes

GO to K4 .

No

INSTALL new wheels as necessary and BALANCE the assembly. TEST the system for normal operation.

  • Measure the lateral runout and the radial runout of the front wheels on the vehicle. Refer to Go To Pinpoint Test J .
  • Are the measurements within specifications?
K4 MEASURE THE LATERAL RUNOUT OF THE FRONT TIRES ON THE VEHICLE Yes

GO to K5 .

No

INSTALL new tires as necessary and BALANCE the assembly. TEST the system for normal operation.

  • Measure the lateral runout of the front tires on the vehicle. Go To Pinpoint Test J .
  • Is the runout within specifications?
K5 MEASURE THE RADIAL RUNOUT OF THE FRONT TIRES ON THE VEHICLE Yes

BALANCE the front wheel and tire assemblies. If any tire cannot be balanced, INSTALL a new tire.

TEST the system for normal operation.

No

GO to K6 .

  • Measure the radial runout of the front tires on the vehicle. Go To Pinpoint Test J .
  • Is the runout within specifications?
K6 MATCH MOUNT THE TIRE AND WHEEL ASSEMBLY Yes

BALANCE the assembly.

TEST the system for normal operation.

No

If the high spot is not within 101.6 mm (4 inches) of the first high spot on the tire, GO to K7 .

  • Mark the high runout location on the tire and also on the wheel. Break the assembly down and rotate the tire 180 degrees (halfway around) on the wheel. Inflate the tire and measure the radial runout.
  • Is the runout within specifications?
K7 MEASURE THE WHEEL FLANGE RUNOUT Yes

LOCATE and MARK the low spot on the wheel.

INSTALL the tire, matching the high spot on the tire with the low spot on the wheel. BALANCE the assembly. TEST the system for normal operation. If the condition persists,GO to K8 .

No

INSTALL a new wheel.

CHECK the runout on the new wheel. If the new wheel is within limits, LOCATE and MARK the low spot. INSTALL the tire, matching the high spot on the tire with the low spot on the wheel.

BALANCE the assembly.

TEST the system for normal operation. If the condition persists, GO to K8 .

  • Dismount the tire and mount the wheel on a wheel balancer.

    Measure the runout on both wheel flanges. Go To Pinpoint Test J .

  • Is the runout within specifications?
K8 CHECK FOR VIBRATION FROM THE FRONT OF THE VEHICLE Yes

SUBSTITUTE known good wheel and tire assemblies as necessary.

TEST the system for normal operation.

No

GO to K9 .

  • WARNING: If only one drive wheel is allowed to rotate, speed must be limited to 55 km/h (34 mph) using the speedometer reading, since actual wheel speed will be twice that indicated on the speedometer. Exceeding a speed of 55 km/h (34 mph) or allowing the drive wheel to hang unsupported can result in tire disintegration or differential failure, which can cause serious personal injury and extensive vehicle damage.
  • Spin the front wheel and tire assemblies with a wheel balancer while the vehicle is raised on a hoist. Feel for vibration in the front fender or while seated in the vehicle.
  • Is the vibration present?
K9 CHECK FOR VIBRATION FROM THE REAR OF THE VEHICLE Yes

GO to K10 .

No

TEST the system for normal operation.

  • WARNING: If only one drive wheel is allowed to rotate, speed must be limited to 55 km/h (34 mph) using the speedometer reading, since actual wheel speed will be twice that indicated on the speedometer. Exceeding a speed of 55 km/h (34 mph) or allowing the drive wheel to hang unsupported can result in tire disintegration or differential failure, which can cause serious personal injury and extensive vehicle damage.
  • Chock the front wheels.
  • Raise and support the rear end of the vehicle so that the rear wheel and tire assemblies can spin.
  • Engage the drivetrain and carefully accelerate the drive wheels while checking for vibration.
  • Is the vibration present?
K10 CHECK THE DRIVETRAIN Yes

CHECK/TEST the drivetrain and driveline components. TEST the system for normal operation.

No

SUBSTITUTE known good wheel and tire assemblies as necessary.

TEST the system for normal operation.

  • WARNING: If only one drive wheel is allowed to rotate, speed must be limited to 55 km/h (34 mph) using the speedometer reading, since actual wheel speed will be twice that indicated on the speedometer. Exceeding a speed of 55 km/h (34 mph) or allowing the drive wheel to hang unsupported can result in tire disintegration or differential failure, which can cause serious personal injury and extensive vehicle damage.
  • Remove the rear wheel and tire assemblies. Refer to theappropriate workshop manual for the service procedures.
  • Secure the brake drums (if so equipped), by installing wheel hub bolt nuts, reversed.
  • Carefully accelerate the drivetrain while checking for vibration.
  • Is the vibration present?

PINPOINT TEST L: CLUTCH VIBRATION

Test Step Result / Action to Take
L1 CHECK ENGINE COMPONENTS FOR GROUNDING Yes

REPAIR as necessary. TEST the system for normal operation.

No

GO to L2 .

  • NOTE: Make sure the clutch is the cause of the vibration concern. The vibration should occur during clutch operation. The clutch can also be difficult to engage or disengage. Eliminate all related systems before checking the clutch components.
  • NOTE: Check the driveline angles and driveshaft runout before disassembling the clutch system.
  • Check the powertrain/drivetrain mounts, exhaust manifolds or other engine components for grounding on the chassis.
  • Are any mounts or engine components grounded?
L2 CHECK THE ACCESSORY DRIVE Yes

DIAGNOSE the accessory drive components.

No

GO to L3 .

  • Remove the accessory drive belt.
  • Does the vibration stop with the accessory drive belt removed?
L3 CHECK FOR LOOSE CLUTCH PRESSURE PLATE BOLTS Yes

TIGHTEN the bolts to specifications or if damaged, INSTALL a new clutch pressure plate.

TEST the system for normal operation.

No

GO to L4 .

  • Check for loose clutch pressure plate bolts. Inspect the clutch pressure plate for damage or for material between the pressure plate and flywheel.
  • Are there any loose bolts or damage?
L4 CHECK THE CLUTCH DISC SPRINGS Yes

INSTALL a new clutch disc.

REFER to Section 308-01 . TEST the system for normal operation.

No

GO to L5 .

  • Check for worn, broken or loose clutch disc springs.
  • Are the clutch springs worn, broken or loose?
L5 CHECK THE CLUTCH DISC SPLINES Yes

INSTALL a new clutch disc.

No

GO to L6

  • Inspect the clutch disc splines for damage or wear.
  • Is there damage or wear?
L6 CHECK THE FLYWHEEL BOLTS Yes

TIGHTEN the bolts to specifications.  TEST the system for normal operation.

No

GO to L7 .

  • Check for loose flywheel bolts.
  • Are the bolts loose?
L7 CHECK THE FLYWHEEL SURFACE Yes

INSTALL a new flywheel. TEST the system for normal operation.

No

Clutch system normal. CONDUCT a diagnosis on other suspect systems.

  • Inspect the flywheel surface for wear or damage.

    Check the flywheel runout.

  • Is there any damage or excessive wear?

PINPOINT TEST M: TRANSFER CASE VIBRATION

Test Step Result / Action to Take
M1 INSPECT THE TRANSFER CASE Yes

TIGHTEN to specifications or INSTALL new bolts as necessary. TEST the system for normal operation.

No

GO to M2 .

  • WARNING: The electrical power to the air suspension system must be shut off prior to hoisting, jacking or towing an air suspension vehicle. This can be accomplished by turning off the air suspension switch. Failure to do so can result in unexpected inflation or deflation of the air springs, which can result in shifting of the vehicle during these operations.
  • Inspect the transfer case for loose or missing mounting bolts.

    Check for fluid seepage between the transfer case and the transmission.

  • Are the mounting bolts missing or loose?
M2 INSPECT THE REAR DRIVESHAFT Yes

REPAIR or INSTALL a new driveshaft as necessary. TEST the system for normal operation.

No

GO to M3 .

  • NOTE: Verify that the driveshaft and pinion flange index marks are aligned.
  • Inspect the driveshaft for missing weights, damage or undercoating.
  • Inspect the U-joints for freedom of movement.
  • Check driveshaft runout and, if necessary, check the pinion flange runout.
  • Is the driveshaft or U-joints worn or damaged or misaligned?
M3 CHECK THE DRIVELINE ANGLES Yes

REPAIR as necessary.

TEST the system for normal operation.

No

GO to M4 .

  • Measure the rear driveshaft and pinion angles.
  • Measure the front driveshaft and pinion angles.
  • Are the driveline angles incorrect?
M4 INSPECT THE FRONT DRIVESHAFT Yes

REPAIR or INSTALL a new driveshaft as necessary. TEST the system for normal operation.

No

GO to M5 .

  • NOTE: Verify that the driveshaft and pinion flange index marks are aligned.
  • Inspect the front driveshaft for missing weights, damage or undercoating.
  • Inspect the U-joints and slip yoke for freedom of movement.
  • Check driveshaft runout and, if necessary, check the pinion flange runout.
  • Is the driveshaft or U-joints worn or damaged?
M5 ROAD TEST WITH THE FRONT DRIVESHAFT ONLY Yes

INSTALL and BALANCE the rear driveshaft.

TEST the system for normal operation.

No

GO to M6 .

  • NOTE: Index mark the driveshaft to the pinion flange and to the output shaft before removal.
  • Remove the rear driveshaft.
  • Plug the transfer case with an output shaft seal plug.
  • NOTE: Shift the transfer case into 4WD high so the vehicle is driven by the front driveshaft only.
  • Test drive the vehicle.
  • Is the vibration gone?
M6 ROAD TEST WITH THE REAR DRIVESHAFT ONLY Yes

INSTALL and BALANCE the front driveshaft.

TEST the system for normal operation.

No

GO to M7 .

  • NOTE: Index mark the front driveshaft to the pinion flange.
  • Remove the front driveshaft.
  • Test drive the vehicle.
  • Is the vibration gone?
M7 TRANSFER CASE TAIL SHAFT INSPECTION Yes

REPAIR or INSTALL new components as necessary. TEST the system for normal operation.

No

The transfer case is OK.

CONDUCT a diagnosis on other suspect systems.

  • Inspect the splines of the output shaft for wear or damage.
  • Inspect the splines of the driveshaft slip yoke for wear or damage.
  • Are the splines worn or damaged?
    Symptom Charts
    Symptom Chart - Air Leak and Wind Noise Condition Possible Sources Action Air leak around door perimeter Loose fit seal. Seal installed incorrectly. ...

    Component Tests
    Idle Air Control (IAC) Valve 1. Open the hood. 2. NOTE: Key symptom is elevated idle speed while noise is occurring. NOTE: "Snapping" the throttle can induce the noise. Verify the condition by oper ...

    Other materials:

    Rear Drive Halfshafts (Description and Operation)
    The rear wheel drive halfshaft system consists of and operates as follows: Halfshafts (4K138) transmit engine torque from the rear axle housing to the rear wheels. Halfshafts rotate at approximately one-third the speed of a driveshaft and do not cont ...

    Switch - Window Regulator Control
    Removal 1. CAUTION: Use a shop towel or similar material between the tool and the door trim panel or damage to the door trim panel may occur. Position the window regulator switch plate aside. 1. Pull at the service notch. 2. Lift to release ...

    Engine (Installation)
    Special Tool(s) Spreader Bar 303-D089 (D93P-6001-A3) Support Bracket, Engine 303-639 Lifting Bracket, Engine 303-D087 (D93P-6001-A1) Lifting Bracket, Engine 303-D088 (D93P-6001-A2) Lifting Brac ...