SECURITY Indicator Illuminates when Engine is Running
WARNING: This page is about a different car, the 2003 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.
If the theft deterrent control module is unable to measure the ignition key transponder value while the engine is running, the indicator will be illuminated. If the key is turned to OFF, the vehicle will be fail enabled and will start if the condition still exists at the next attempt to start the vehicle.