Low Brake Fluid Warning
WARNING: This page is about a different car, the 1990 Oldsmobile Toronado, 1989 Oldsmobile Toronado, and 1988 Oldsmobile Toronado. However, it is still accessible from the selected car via links, so may be relevant.
A reed switch and float, inside reservoir, activate and deactivate fluid level sensor. The switch is normally closed and opens the circuit between pins "A" and "B" if brake fluid gets low.