Apply and hold constant foot pressure on the brake pedal with the engine in the IDLE position. Ensure that the transmission is in the NEUTRAL position. The brake hydraulic system may have the following conditions if the brake pedal gradually loses foot pressure:

Perform a visual inspection of the hydraulic system.

Inspect the master cylinder fluid level. A slightly low brake fluid level in either reservoir can result from normal lining wear. An abnormally low fluid level indicates a leak in the system. A full master cylinder does not always indicate that there is no leakage. Slight leakage can occur and not appear as a fluid level condition.

Internal leakage may be the cause if no external leaks are found. Internal leakage is related to an internal master cylinder condition. The master cylinder requires disassembly in order to accurately diagnose internal leakage. Refer to the instructions included with the service repair kit. Contact Allied Signal Truck Brake Systems at 1-800-AIR-BRAK (1-800-247-2725) for additional unit repair information on the Bendix® master cylinder.

Inspect the brake hoses and the pipes at least twice a year for the following conditions:

Inspect the brake hoses and the pipe connections for fluid leaks and damage. Replace the brake hoses and the pipe connections if you detect fluid leaks or damage. Ensure that all of the mounting hardware is in place and secure. Repair the hardware as needed.