I installed a Hopkins today to get ready for my new '69 Airstream I'll be pulling home this week. Well it took a bit longer than I had hoped, however it beat the $300 alternative quoted by my local hitch guy. Went to harbor freight, picked up a proportional unit for $55, got the wiring kit which came with a fuse, 3 rolls of wire, and different connectors and a couple other things. The best thread I could find was here
Brake Controller & 7-pin trailer Install 3rd Gen 4Runner - YotaTech Forums
My issue was he didn't quite explain it like I had hoped. I like details sometimes..
A few pointers in addition to the link above.
1-The black wire he runs to the rear 4runner needs to be a home run (meaning one wire) from the positive side of the battery to where it will connect to the black wire on the trailer receiver.
2- The blue wire will go from the brake controller straight back to the blue of the trailer receiver.
3- The green wire with the white strip I found underneath the dash by laying on my back and following where the brake sends it info. By this I mean look at the brake peddle and you'll see a wire clip with 4 wires. One of them is a green wire with a white stripe. This I used a snap connector to attach to the red brake wire coming off of the brake controller unit.
4- My 2001 4runner has the factory tow package. I did not follow his wiring when he changed colors, i.e. brown to green, red to yellow, but I kept mine the same as the receiver harness. If you look at his photos where it shows the 7 wires connected you may see what I mean.
I hope this helps those who are looking to install in a 3rd generation. It really wasn't too bad. A 4 beer job.