I think you do indeed need the brake wire for the wireless brake controller. The wireless feature is for setting up the brake controller and then to engage the brake manually using the fob. I have a Subaru and got the autowbrake on my 2019 Scamp. They told me to wire up the 7 pin. The schematic Scamp provided was yellow center, and starting at 1:00 and going clockwise, looking into the trailer end: green, red, white, blue, brown, black. Green - tail/marker lights
, brown - right turn/brake light
, white- ground, blue - electric brakes
, red - left turn/ brake light
, black- positive (charge/hot line), yellow-auxiliary (back up light)
It works fine.