Brake Warning Lamp
The brake warning lamp illuminates when the parking brake is engaged or when the brake fluid level is low in the master cylinder reservoir.
The brake warning lamp also illuminates during prove out. When the ignition switch is turned to the ON position, the bulb check relay verifies the operation of the brake warning lamp, which momentarily illuminates.
On analog instrument cluster equipped vehicles, the brake warning lamp also proves out with the charge warning lamp through a circuit from the generator/voltage regulator.