Tekonsha is a very popular electric brake controller. They have a variety of units.
I bought a used Voyager one to get a used TT I bought home with a borrowed F-150.
The truck had the needed wiring harness in a plastic bag in the door pocket to snap right into the existing vehicle socket under the dash. I only had to use a few crimp-on butt splices to get from the controller wires to the provided factory harness, then up under the dash to plug it in.
I then duct taped the controller to the middle seat and adjusted the inertia based control for the 3h drive home.
Once I bought a TV, I then upgraded to the Prodigy P2 and have been very happy with it.