Theft / Security Light

The security system on today's cars and trucks prevents the vehicle from being stolen. There are many variations of the system going back to the early 1990's.


This warning could be on when the engine is running, indicating a fault has been detected in the system. If left unrepaired, there is a good possibility that the car will eventually not start.

There are several different possibilities for the cause of the warning, depending on the make / model / year of the vehicle. Anything from a bad ignition cylinder wire, to a bad cylinder to a bad Body Control Module (BCM).

After market (non-factory) alarm and remote start systems can cause havoc with the factory theft system, causing this warning light, or a no start.

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Comments (8)
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  • Guest - John

    04 Dodge Ram 1500 truck will start but once key is removed will not lock doors all power gone & anti theft will beep once key is put back IN.

  • Guest - John

    My truck was running fine, today I tried to u lock the truck & no lights came on once it was open. When I put the key in& turn it anti theft lights beeps then goes off. I am able to start the truck but ounce key is removed truck is dead.?

  • Guest - Elisha

    On my 04 Malibu an when I turn the car off an take the key out an shut the door the anti theft light flashes don't have any problems with it starting

  • Guest - Donna Mattern

    Light got left on and keys were stuck. Had it jumped and the theft dummy light is now on

  • Guest - Justin

    This is a common problem on GM vehicles. I have been dealing with these systems for years. Through much trial and error i have found that BYPASSING these systems is alot more cost effective than trying to diagnose and fix them. The cost is too high and mechanics tend to replace as many things as they can before fixing it. Here is a link to educate and guide you in the right direction. This IS something you can fix yourself and once bypassed will NEVER be an issue again.

  • Guest - Robert

    In reply to: Guest - Justin

    gimme information

  • Guest - victor

    I have a Chevrolet Malibu 2002. I did turn on the theft sysytem, but now I can't get it off. So my car doesn't start. Looks like the theft system is blocking the ignition. Can you help me please?

  • Guest - Tech

    In reply to: Guest - victor

    Not sure what you mean by "I did turn on the theft system." The factory theft is always on. If you have a non-factory alarm, then you disable it with the remote or a kill switch under the dash on many of these systems. If there is no switch, you need to contact the company that made or installed it, since there are many different models and systems.