Brake Switch
WARNING: This page is about a different car, the 1992 Oldsmobile Toronado, 1992 Cadillac Eldorado, and 1992 Buick Riviera. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect brake switch harness connector. Using an ohmmeter, check continuity between brake switch terminals. Continuity should be present. Depress brake pedal to activate brake switch, continuity should not be present.