Quick hack I learned over the years when I leave my trailer plugged into my trucks 7 blade over extended periods of time when I start it the infotainment screen is sometimes blank also no backup camera. A quick unplug and replug has always remedied the problem for me anyway. Also even on older less equipped hd sierra with factory electric brake controllers an alert will come on the dash if trailer brakes aren't working usually remedied again with unplugging and plugging wiring coupling back in. Always worked for me anyway and it's never done it when I'm actually driving with a trailer attached. Only during initial start up.