Brake Controller wires on F53

Thanks usersmanual. I did manage to locate the correct blue wire in a rear bundled harness. I now have power and connectivity between the controller and the tow dolly. I haven't been able to take the rig out yet, but I still wonder if I need separate 12V power to the 7-pin plug? The plug came with a short black power wire and I'm trying to figure out where to connect it. The new 7-pin plugged into the old 4-pine, so like I said, everything looks powered up, but I'm fearful that the electric brakes won't actually work. And I doubt that the battery on the dolly will re-charge without the power.
What am I missing? Thanks.