Well, I have had my car for about 18 hours and already I am ready to install my brake controller. I use a Prodigy and ordered a GM interface cable that is supposed to be plug and play. I also received the pigtail harness with the Acadia but haven't been able to determine exactly what is for. I did a search and found that someone said it plugged into the fuse box and was a brake cable; others thought it might be a trailer wire harness. I called GMC customer care and they couldn't tell me either but they are to call me back Monday, dealer didn't have a clue. Has anyone installed a brake controller in the Acadia yet? My previous Jeep had no factory provision and I had to trace and tap into the brake light circuit, don't want to do this if I don't have to Thanks all, up to 54 miles on my new car...it's a world apart from my Jeep!