If I depress the service brakes, parking brake engaged, and put the bus in either D or R, a "buzzer" in the dashboard sounds... on/off, not constant........ If I depress the service brakes, release p...
Could also be a hydroboost for the coach service brakes. Have someone depress the brake pedal while you look under the coach at the brake master cylinder. If present, it is a safety system so you would have brake boost in the event of engine failure.