My truck has a round 7 pin blade plug outlet and a 4 pin plug outlet underneath that is not wired. I thought it was for a 4 pin flat utility trailer plug when I bought the truck, but it is for something else. Camera? Yaw Control? Useless for me and I have a 7/4 adapter for 4 pin flat. Thanks. Pro Trailer Backup Assist works perfectly with grid sticker.