2003 Chevy Malibu. Car sounds like it want to start but will not stay on. I have noticed my theft system light comes on periodically. But my car would still start with no problem. I suppose those were warning signs. Any suggestions on how to fix.
Answer: The problem is most likely the ignition key cylinder. This is also know as the Passlock Sensor. It it what sends the security information to the computer to allow it to start. It would need to be replaced and then programmed. A temporary fix is to do a re-learn procedure. Try to start the car, then release the key to the ON position. Watch the security / theft light. It should go out after about 10 minutes. Turn the ignition off for 1o seconds. Then start the car. This is just a temporary re-learn that may get it to start again, but it will fail again and not start, so don't think it is fixed like many people do. It may not start tomorrow, or 2 weeks from now. The system will need to be repaired for a permanent fix.