I had a 2014 3500 dually. I could not get full braking on my 40' 5er with the integrated brake controller, put a Voyager in it, good brakes.
I bought a 2017 3500 dually. The brake controller worked as little as the one in the 14. Back to Dodge They installed a new switch, no help.
I had to make sure it wasn't in my trailer so I installed all new backing plates. No change. I completely rewired the brakes from the front to the brakes, testing voltage at each wheel, 12.8 to 12.4 drop. Hooked up to my new 2017 RAM, same as before. I do have a very little braking, I mean very little. The best I can get from the pickup is 7.6 with no change in the bulb test. The bulb in dim and will not change when the manual override is moved.
Dodge says that's the way it is supposed to be. I am a full time r v er and could not stay where the dealer was to argue with them anymore.
IS ANYONE ELSE HAVING THIS PROBLEM? I'm sure I didn't get the only 2 pickups that dodge made that has this problem. Please respond to this I'm going crazy.

 

I run mine at 4.5 anything higher the trailer brakes lock up. On the highway I go down to 3.5. 4.5 in town and pulling thru the rv park.

 

so your Brake controller that came in the truck does work?

 

Yes. Very well. Check the fuses for trailer under the hood.

 

Something else I thought of. Depending on weight you will need to change from Light braking (default). To heavy.