Welcome to The RV Forum, John!
Bill's right, that's the OBD2 diagnostic port and has nothing to do with a brake controller. You're looking for a grey 4 pin connector to attach an adapter cable for an external brake controller.
I'd take the motorhome down to a Ford dealer and let them look at it. Ford has a superior built-in brake controller as part of their optional trailer towing package. If you have it you'll have a small control panel on the dashboard.
You can buy the panel on Ebay, but I don't know if it will work on a vehicle without the Towing Package. That's where the dealer comes in, he can tell you if it will work or not.