Diagnostic Procedure
WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
Disable air bag system. See DISABLING SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM. Reconnect negative battery cable. Perform SYSTEM OPERATION CHECK . If AIR BAG warning light does not illuminate, replace air bag sensor assembly. If AIR BAG warning light is still illuminated, repair AIR BAG warning light circuit Black/Yellow wire or circuit AB (Black/Yellow wire) leading to the DLC3. See WIRING DIAGRAMS .