Why does my 2007 Chrysler 300 anti theft not work?

[Benito]

the factory anti-theft system will not arm.

[GTCturboII]

Check your owners manual for info on arming/disarming. On some Chrysler products, it was as simple as locking or unlocking the driver door with a key while running or not running. If all else fails, call the dealer and ask the service manager if he knows. Once in a while, you'll get a helpful one with information, rather then one who insists you come in for a diagnosis of a basic non-problem.