Hydraulic Brake Assist System Noise Inspection

Hydraulic Brake Assist System Noise Inspection

Tools Required

J 28662 Brake Pedal Effort Gauge

1. Install the J 28662 to the brake pedal.
2. Start the engine and allow it to idle. Ensure that the wheels are directed straight ahead.
3. Apply and maintain the brakes with 111 Nm (25 lb) of force to the brake pedal, as indicated on the J 28662. Observe for noises.
4. Quickly release the brakes. Observe for noises.
5. Check the pump and motor are running. If the noise is excessive/abnormal, check the following:

* Damaged high pressure pipe
* Defective pump and motor mounts
* Defective pump and motor assembly

Important: Do NOT apply 445 Nm (100 lb) of force or more to the brake system pedal for more than 5 seconds at a time.


6. Apply the brakes with 178 Nm (40 lb) of force to the brake pedal, as indicated on the J 28662, then gradually increase pedal effort up to 445 Nm (100 lb) of force for not more than 5 seconds at a time. Observe for noises.
7. Quickly release the brakes. Observe for noises.
8. If a hiss noise was apparent and increased during the brake system increasing apply of 178-445 Nm (40-100 lb) of force, the hydraulic brake booster assist system is operating normally from an audible standpoint.
9. If a clunk, chatter, and/or clicking noise was apparent during the quick release of the brakes following the brake system increasing apply of 178-445 Nm (40-100 lb) of force, the hydraulic brake booster assist system is operating normally from an audible standpoint.