I have a 1999 Pontiac Grand Am GT. For the last couple days the Security light has been blinking on and off and it comes on while I'm driving. When it comes on while I'm driving it doesn't cause anything to happen but when it starts blinking, the car will not start. Just a few hours ago I got stuck at a gas station for an hour because it would not start. Someone told me it was the Ignition Lock Cylinder that needed to be replaced but I dont know. Someone please, please, please help me.

Leslie

When the light comes on, the BCM and the PCM store codes to assist with diagnosis.
I would recommend taking your car to the dealer and having it looked at.
Most likely senerio on those models is a problem with the Passlock sensor in the lock cylinder, but I would have the problem diagnosed before I installed any parts.