Component Tests: Horn
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.
Connect positive (+) lead from battery to the terminal on horn and ground horn body to chassis. Check that horn blows. If operation is not as specified, replace horn.