Transponder Key Coil
WARNING: This page is about a different car, the 2003 Lexus IS 300 and 2002 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
Check that continuity exists between terminals 1 and 2 of the transponder key coil connector. See CONNECTOR IDENTIFICATION . If continuity is not as specified, replace the coil. See TRANSPONDER KEY COIL under REMOVAL & INSTALLATION.