Brake Fluid Level Warning Switch
WARNING: This page is about a different car, the 2003 Lexus GS 430, 2003 Lexus GS 300, 2002 Lexus GS 430, and 2002 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
Remove the reservoir tank cap and strainer. Disconnect the connector. See Fig 1. Check that no continuity exists between the terminals with the switch OFF (float up). Use siphon, etc. to take fluid out of the reservoir tank. Check that continuity exists between the terminals with the switch ON (float down). Pour the fluid back in the reservoir tank. If operation is not as specified, replace the switch.