Auto Lock Function
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.
When the ignition key is not inserted into the ignition key cylinder and all the doors completely closed, if the door is not actually opened within 30 seconds after the door has been unlocked by pressing the unlock SW on the transmitter, all the doors are automatically locked.