MarineandMedic

I have the upfitter switches and everything completely installed, and have been using them for a while, however I needed to add an aftermarket trailer brake controller, and lo and behold, it uses the exact same grey connector (BCM) as the upfitter switches..... Anyone have any ideas if I can make a Y cable and plug both in at the same time to that grey port, or if i can just splice the wires together and use one plug? (controller only has 4 wires, upfitter uses almost all of them) or is there some other option or place to plug in the brake controller or different connector I need? for a 2021 Silverado 1500