Hydraulic Brake Assist System Noise Inspection

Install the Brake Pedal Effort Gage (J-28662) to the brake pedal.
Start the engine and allow it to idle. Ensure that the wheels are directed straight ahead.
Apply and maintain the brakes with 25 Lbs. (111 N) of force to the brake pedal, as indicated on the brake pedal effort gage. Observe for noises.
Quickly release the brakes. Observe for noises.
If chatter and/or a vibration of the brake pedal was apparent during the brake system apply of 25 Lbs. (111 N) of force, the power steering drive belt is probably slipping and would require replacement.
If any significant noise was apparent during the quick release of the brakes following the brake system apply of 25 Lbs. (111 N) of force, there is likely a restriction in the hydraulic brake booster power steering return hose and it would require replacement.
CAUTION: DO NOT apply 100 Lbs. (445 N) of force or more to the brake system pedal for more than 5 seconds at a time.
Apply the brakes with 40 Lbs. (178 N) of force to the brake pedal, as indicated on the brake pedal effort gage, then gradually increase pedal effort up to 100 Lbs. (445 N) of force for not more than 5 seconds at a time. Observe for noises.
Quickly release the brakes. Observe for noises.
If a hiss noise was apparent and increased during the brake system increasing apply of 40-100 Lbs. (178-445 N) of force, the hydraulic brake booster assist system is operating normally from an audible standpoint.
If a clunk, chatter, and/or clicking noise was apparent during the quick release of the brakes following the brake system increasing apply of 40-100 Lbs. (178-445 N) of force, the hydraulic brake booster assist system is operating normally from an audible standpoint.