Brake Fluid Level Switch

WARNING: This page is about a different car, the 1990 Acura Legend. However, it is still accessible from the selected car via links, so may be relevant.

Remove the reservoir cap. Check that the float moves up and down freely. Replace the reservoir cap assembly if the float does not move freely. See Fig 1.
Check for continuity between the terminals with the float up and down. There should be continuity with the float down and no continuity with the float up. Replace the reservoir cap assembly if necessary.

Fig 1: Identifying Brake Fluid Level Switch

Courtesy of AMERICAN HONDA MOTOR CO., INC.