trailer brakes not working

[Larry Garrett]

Hello guys, 2017 silverado with trailer towing package. I've used the factory pigtail to hook up my controller off my old truck. But it's not getting power to it, I checked the fuse and it's ok. I was told that another wire is to be connected to the fuse box. That wire is suppose to be there just needs connecting. Which wire is it is my question and is that true.

Thanks

Larry