Encoded Ignition Key
WARNING: This page is about a different car, the 2002 Lincoln Blackwood and 2002 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
When ignition switch is turned to START or RUN position, instrument cluster initiates encoded ignition key interrogation process. Each encoded ignition key must be programmed into instrument cluster before it can be used to start vehicle. Encoded ignition key is much larger in size to accommodate electronics located inside plastic cover.