1996 Cadillac Seville Check Brake Fluid Switch

The switch is in the master cylinder reservoir. It is a serviceable part. One way to diagnose it, it is normally open and closes with low fluid. If you have a low fluid message, you could disconnect it, and it should go out. You could also check the switch when the message is present, if the switch itself has continuity and the fluid is full, the switch is bad.