Replaced dead batteries on 02 Duramax a couple months ago and Security Light came on immediately. Truck starts fine, runs good, and no codes. Tried 30 re-learn with no luck. Disconnected battery cables and grounded positive, no change. Tried check door alarm method and both doors appear okay. Tried different key, no change. Truck is stock with no modifications such as autostarter, tuner, etc. No other maintenance, just changed batteries. Anybody have any other ideas other then paying dealer for a tech 2 hookup?