How do you get brake lights from semi tractor to 5th wheel RV?

Answer 1

The easiest most inexpensive way to have brake lights and turn signals with an RV is to wire your RV plug at the rear of your tractor OFF your taillights. An RV's turn/stop lights are wired TOGETHER, sharing the same hot wire. Where as a semi trailer is wired with three separate hot wires. One each for L and R turn, and a third and separate wire for brake light(S)2. The only other way to adapt a semi trailer plug to RV is with a converter box. I've never priced one, but understand them to be expensive. I do commercial 'Towaway' w/ semi-tractor as profession and have had and seen multiple tractors wired as I just described to you. The only other advise I would give, would be to run your wires thru a weather sealed junction box ahead of where your female plug is wired on the rear of your tractor. I have seen some setups where they just tapped into tail light wiring w/out junction box and corrosion became a BIG issue after a short period of time ,especially if you run in an area where chemicals and salt are used in winter months.