Brake Fluid Level Warning Switch
WARNING: This page is about a different car, the 2001 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect brake fluid level warning switch harness connector. Remove filler cap and strainer. Using DVOM, ensure continuity is not present between switch terminals when float is up. Remove fluid. Ensure continuity is present between switch terminals when float is down. If continuity is not as specified, replace switch. Refill fluid reservoir.