This 2002 Eldorado ETC started experiencing issues with its anti theft system, as many GM products made during the 90's and early 2000's did. When the doors are opened after disarming the system with the fob, the security light is supposed to flash. Most of the time it does not flash, making it impossible to start the car. Sometimes it begins to flash after a couple of minutes delay, sometimes up to 10 minutes, and the car will start. I began NOT arming the system, but the problem persists. I have noticed when the ambient temperature is under 75 degrees, the security light typically begins to flash immediately. If the temperature is higher, it takes along time before the light will begin to flash. This is really weird since I do not know what the correlation of temperature to the problem is. Sometimes I have to disconnect the battery, wait 10 minutes and upon re-connection, the light will begin the flash. A scan revealed two very generic trouble codes (ie communication errors). I have replaced the ignition switch and the key with the embedded chip and the body control module. Several mechanics have looked at it and they wind up shaking their heads. I love the car, but it is driving me crazy! I do not want to dump the car, but I may wind up having to do just that. Has anybody had the same problem or have insights into what is causing this problem? Any information would be greatly appreciated!