Testing Procedures
WARNING: This page is about a different car, the 2003 Toyota Prius, 2002 Toyota Prius, and 2001 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
For wiring diagram, see Fig 1. For testing procedures, start by checking brake fluid level. If fluid is low, refill or repair. If fluid level is okay, check brake fluid level warning switch. If switch proves faulty, repair. If switch is fine, check for open circuit in all the wiring harness and components connected to brake fluid level warning light. If any wiring harness are found to be faulty, repair or replace wiring harness and connectors. If wiring harness and connectors seem fine, check and replace brake ECU.