I had the same issue with my 07 6-speed. "No bus", the connection between the cab and the engine compartment gave up the ghost. Took a long time to find, had to replace wiring and the main connectors. My 04 automatic truck was a Laramie and had a bus issue also. I would get a message on the dash that said "no bus", but it would always come out of it after a while. May have something to do with the junk TIPM too.