Hay, I was all through that system on my 03 so I have some for you. On my 2003, the dome light is controlled by the gauge cluster if you can believe it, and the gauge cluster gets the signal that a door is open from the security module.
The gauge cluster has the timer that shuts off the lights after time. The “battery saver” relay. It would be my best guess that it has gone bad perhaps?? I guess it could be the security module too.
Has this friend done any messing with the wiring?
Edit: I went back and looked. With what you described, my best guess is the relay in the cluster. Or fuse number 35. Fuse 41 is for the map lights, and fuse 35 is for the courtesy lights.
I hope your 06 is similar to my 2003 F350 KR.
Last edited by Egmonster; 02-01-2010 at 03:23 AM.