I have an '02 f-350 that started a mysterious problem. When I shut off the truck and open the door the door chime starts chirpping as if the lights were still on. It remains chirpping for approx 5 seconds then goes off. During this time the running lights come on and go off for the same duration. I can shut the doors, open another door and goes through the same pattern??? My head light switch is in the off position and key is out of the ignition. Any thoughts or ideas would be greatly appreciated.