1999 Lexus SC 400 Owners Manual - Page 35

KEYS AND DOORS The engine immobiliser system is a theft prevention system. When you insert the key in the ignition switch, the transponder chip in the key's head transmits an electronic code to the vehicle. The engine will start, only when the electronic code in the chip corresponds to the registered ID code for the vehicle. The system is automatically set when the key is removed from the ignition switch. At this time, the security indicator light at the bottom of the instrument cluster flashes. When you insert the key in the ignition switch, the security indicator light goes out and the system is canceled automatically, which enables the engine to start. For your Lexus dealer to make you a new key with built-in transponder chip, your dealer will need your key number and master key. However, there is a limit to the number of additional keys your Lexus dealer can make for you. If you make your own duplicate key, you will not be able to cancel the system or start the engine. 17