Pinpoint Test B: Vibration When The Brakes Are Applied

• Check the On-Line Automotive Service Information System (OASIS) and Technical Service Bulletins (TSBs) for applicable brake concerns.
• Is there applicable information available on OASIS or in a TSB? 

Yes  : REFER to . CARRY OUT any necessary repairs that are indicated by OASIS or the TSB. If the concern is still present, GO to B2.

No  : GO to B2.

• Inspect the wheels and tires. Refer to SUSPENSION SYSTEM-GENERAL INFORMATION .
• Road test the vehicle. Warm the brakes by slowing the vehicle from 80 to 32 km/h (50 to 20 mph) using light brake force. At highway speeds of 89-97 km/h (55-60 mph), apply the brake using light pedal force.
• Is there a vibration/shudder felt in the steering wheel, seat or brake pedal? 

Yes  : GO to  B5.

No  : GO to B3.

• 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? 

Yes  : GO to B4.

No  : The concern is not present at this time.

• 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 alone or steering wheel nibble (frequency is proportional to the vehicle speed) indicates a concern with a brake or suspension component.
• Is the vibration/shudder vehicle speed sensitive? 

Yes  : GO to  B6.

No  : The concern is not present at this time.

• 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 step. 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? 

Yes  : GO to  B8.

No  : GO to B6.

• Check the front suspension. Refer to SUSPENSION SYSTEM-GENERAL INFORMATION .
• Are all the suspension components in satisfactory condition? 

Yes  : GO to B7.

No  : REPAIR or INSTALL new components as necessary. TEST the system for normal operation.

CAUTION: Do not use a bench lathe to machine the brake discs.
NOTE: Follow the manufacturer's instructions to machine the brake discs. After machining, make sure the brake disc meets the thickness specification.
• Resurface the front brake discs. Refer to BRAKE DISC MACHINING  in this section.
• Road test the vehicle.
• Is the vibration/shudder present? 

Yes  : GO to B8.

No  : The concern is not present at this time.

• Check the rear suspension. Refer to SUSPENSION SYSTEM-GENERAL INFORMATION .
• Are all the suspension components in satisfactory condition? 

Yes  : GO to B9.

No  : REPAIR or INSTALL new components as necessary. TEST the system for normal operation.

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.
• Resurface the rear brake discs. Refer to BRAKE DISC MACHINING  in this section.
• Road test the vehicle.
• Is the vibration/shudder present? 

Yes  : REFER to NOISE, VIBRATION & HARSHNESS to continue diagnosis of the vibration.

No  : The concern is not present at this time.