I hate to start an answer with "it depends." But it does. Many of the newer cars have a chip in the key that doesn't even require the key to be in the ignition switch. There is a decoder in the switch that can read the chip in the key and decide if you have the right chip. The same thing happens in many of the keyless entry doors. Just wave the keys near the door and they unlock.
GM for years used the VATS ignition system. The key had a resister on the metal of the key and the decoder in the switch got a signal from the computer telling it whether the resistance of your key was the same on record in the computer. I spent a good bit of time learning how to defeat that system last summer. But for those that have the key, that's a very vague idea of how it works. I can put everyone to sleep explaining in detail how it works but that's the readers digest version. ----- Original Message ----- From: Brice To: blindhandyman@yahoogroups.com Sent: Friday, July 10, 2009 8:54 AM Subject: [BlindHandyMan] ignition key Does anyone know how an ignition key can open and lock a car? My wife asked me that yesterday and I had know answer for her other than it may have some kind of battery in it that may get charged as it's in the ignition. Ours even has what they call a panic button. __________ Information from ESET Smart Security, version of virus signature database 4231 (20090710) __________ The message was checked by ESET Smart Security. http://www.eset.com [Non-text portions of this message have been removed]