Door Courtesy Switch Circuit
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.
For door courtesy switch circuit inspection, see DOOR COURTESY SWITCH CIRCUIT under CIRCUIT TESTS under BODY CONTROL SYSTEM article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.