Diagnosis of base brake conditions, which are mechanical in nature, should be performed first. This includes brake noise, lack of power assist, parking brake, or vehicle vibration during normal braking.
The RWAL brake system performs several self-tests every time the ignition switch is turned on and the vehicle is driven. The CAB monitors the system inputs and outputs circuits to verify the system is operating properly. If the CAB senses a malfunction in the system it will set a DTC into memory and trigger the warning lamp.