Tried a couple of different trailers and checked power out of both the 4 pin and 7 pin sockts. No power from either. All other lights work. Can't find a fuse. Taking it to dealer in the morning.

 

Check the fuses under the hood on the driver's side.

 

had same prob. after hours of looking at wires, it was just te fuse

 

Check Where Harness Runs Under Drivers Side "a" Pillar For Rub Through. If Not, Bet Ya 10 Bucks Your Gonna Need A Pdc. There Are Relays Interior To It. Ive Replaced Dozens In The Last 3 Years, For Same Complaint.

 

Could be the Trailer light module sensed a spike in voltage and cut the power off. This may have to be reset by the dealer. While it is in there get the TIPM reflashed to the new spec. to avoid these issues.

 

Got the truck back. They found three codes and reflashed the TIPM. The update was 8.021.06. They say it is working now but I don't have a way to check at this point.

 

http://dodgeram.info/tsb/2006/08-021-06.htm

Check this out.