2002 GMC Sierra computer not shutting down-possible causes beside door locks.

The batteries are being drawn down in my truck. About 1.6 amp draw with everything off. I spoke with the service guy at my GM dealer and he thought the door lock was the problem because the radio does not shut off after the ignition is turned off and the door opened. I removed the lock assy and there is one switch within the lock that shows a short regardless of the position of the locking dog. However, I can plug the lock assy in and the symptoms are the same whether I remove the connector from the lock assy or not. I also removed the connectors from the passenger side lock without any effect. I really don't want to spend over $100 for a new lock without knowing for sure that it is the problem. I do not have a set of schematics yet.