Recommended Flat-Tow Wiring Harness for 2018 GMC Sierra 2500 and Is Brake Relay Needed

Question:

I have a 2018 GMC 2500 Diesel with an SMI Air Force One brake system that I tow behind a 2018 Thor Tuscany diesel pusher. I would like to wire my GMC to connect to the RV wiring for brake and turn signals using something like the RoadMaster Universal Diode Wiring Kit via the 7 way plug on the RV. I am not sure if I also need a brake light relay like the RoadMaster RM-88400. Can you advise? Thanks

asked by: Dean O

Helpful Expert Reply:

The Roadmaster Diode 7-Wire to 4-Wire Flexo-Coil Wiring Kit part # RM-15247 is an excellent option for a 2018 GMC Sierra 2500 that will work well to illuminate the vehicle's tail lights using the motorhome. In regards to the Roadmaster Brake-Lite Relay Kit for Towed Vehicles part # RM-88400, this is not required for a 2018 GMC Sierra 2500.

expert reply by: Conner L