Hello and welcome to Just Answer!
I have run into this numerous times and it has always been caused by the Totally integrated power module(Main fuse box). The TIPM controls the trailer lights internally and there are no external fuses or relays to control this. The circuit inside the module fails and the only thing you can do is replace the TIPM. I would have you test this but I am sure it will need the module. Let me know if you want to test the wire coming out of the module, it is a light green wire in connector 3. Thanks, Richard
Thanks for the info it is the kind of problem I sort of figured it would be . It would help if you could tell me how to test to make sure that this is the problem. How much does this module cost and should I just take it to the dealer since it is on an extended warrantty with a $100 deductible.
I just remembered on 2006 ram trucks there is an update that might fix the trailer tow problem inside the TIPM. This update changes the software that controls the trailer tow lights and it may fix this. I would suggest you get this update done to see if it fixes it. It only take 1/2 hour to do. I tried to see if this would be covered under your service contract but I can't because I am in Canada and I can't access the info from the U.S.
I would phone up your dealer and ask them to check to see if the TIPM would be covered if the update does not fix it. the part number is XXXXX and it retails for $957.00 cad so I would definitely ask them about coverage. I hope this helps you, let me know if the update repairs it. Thanks, Richard