Bought a new 2020 GMC Sierra last October. Did not hook up my 2020 Winn. Micro Minnie 2108DS until a month ago when I was preparing trip south. Truck would not light up trailer lights or brake controller. Two trips to GMC dealer followed. First time, dealer said problem must be in my trailer (I had already towed it 3,000 miles with my 2014 GMC with no issues). Took trailer to RV repair. Lighted up fine, but not when connected to my new truck. Second trip to GMC dealer. Could not fix. Told me LEDs in trailer did not pull enough current to make truck recognize it was there. New computer controlled electrical system in this truck. Told me they could not fix truck but I could buy an aftermarket device that would make it work, at my cost. Otherwise, call GMC customer service. Warning. Do not buy a 2020 or 2021 GMC as they are controlled by a computer system. Even though my truck equipped with tow package, I can't tow my trailer anywhere without lights and brakes. Terrible service GMC and poor engineering.