Answer to: car is not starting- auto theft light is on- not original radio.Radio has nothing to do with car not starting. In the ignition there is an rfid chip that sends a signal to the computer when it is turned. It is common for the contacts to wear out and cause the issue you are having. It can be fixed by, putting in a new ignition, bypassing the system like you would if you were installing a remote start, or taking it apart and sanding/soldering the contacts so they carry a strong current again. I can't remember where I found the information, it may have been on an enthusiast site like j-body or something similar. Try asking around on the Saturn Ion formus, I'm sure they can give more detail than I ever could.