Pinpoint Test A : Vibration When Brakes Are Applied
- Normal Operation and Fault Conditions
Diagnostics in this article assume a certain skill level and knowledge of Ford-specific diagnostic practices. REFER to: Diagnostic Methods .
During moderate to heavy braking, noise from the 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. Pedal pulsation or steering wheel nibble when the brakes are applied (frequency is proportioned to the vehicle speed) indicates a concern with a brake or suspension component.
Possible Sources
- Front suspension concern.
- Rear suspension concern.
- Front brake discs.
- Rear brake discs.
- A1 ROAD TEST THE VEHICLE -LIGHT BRAKING
- 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 A4 No GO to A2 - A2 ROAD TEST THE VEHICLE -MODERATE TO HEAVY BRAKING
- 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 A3 No The concern is not present at this time. - A3 CHECK ABS (ANTI-LOCK BRAKE SYSTEM) OPERATIONNOTE: 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 operation of the ABS. Pedal pulsation or steering wheel nibble with the frequency proportional to vehicle speed indicates a concern with a brake or suspension component.
- Road test the vehicle and apply the brakes on a dry, firm surface, then apply the brakes on a wet, snowy or loose surface (such as gravel).
Is the vibration/shudder only present on a wet, snowy or loose surface?
Yes This is a normal operating condition of the ABS. No GO to A5 - A4 ISOLATE BRAKE VIBRATIONNOTE: This test step is not applicable to vehicles with drum-in-hat type or electronic parking brakes. For vehicles with drum-in-hat or electronic 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.
- 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 A7 No GO to A5 - A5 CHECK THE FRONT SUSPENSION
- Check the front suspension.
Are all the suspension components in satisfactory condition?
Yes GO to A6 No REPAIR or INSTALL new components as necessary. TEST the system for normal operation. - A6 CHECK THE FRONT BRAKE DISCS
- Inspect the front brake discs. MACHINE or INSTALL new brake discs as necessary. REFER to: Brake Disc Machining . REFER to: Brake Disc .
- Road test the vehicle.
Is the vibration/shudder present?
Yes GO to A7 No The concern has been repaired. - A7 CHECK THE REAR SUSPENSION
- Check the rear suspension.
Are all the suspension components in satisfactory condition?
Yes INSPECT the rear brake discs. MACHINE or INSTALL new brake discs as necessary. REFER to: Brake Disc Machining . REFER to: Brake Disc . No REPAIR or INSTALL new components as necessary. TEST the system for normal operation.