The brake system is split diagonally. That means that the right rear and left front brakes are connected to the same reservoir. Both systems are routed through, but separated by, the pressure differential valve, which also contains the warning switch. The function of the valve is to activate the switch in the event of brake system malfunction. The warning light switch is the latching type. It will automatically recenter itself after the repair is made and brake pedal depressed.
The bulb can be checked each time the ignition switch is turned to the ON position or each time the parking brake is set.