Last week I had a 600 mile trip transporting cars to storage for my upcoming move this summer. I was going to haul a heavy 1968 station wagon with a 440. I needed to be able to stop this thing so I installed a Tekonsha Prodigy brake controller.
The first step for me was to convert my four pin wiring to seven pin. I picked up a seven pin receptacle and a four pin extension cable. I cut the four pin extension cable in half and fed the wires to the seven pin outlet.
Then, Starting from the rear, I began to add 12 gauge wire following the factory electrical harness for the trailer lights. This is the red wire you see. it goes into the seven pin with the four light wires above. Simply following the harness gets you all the way to the wheel well:
The harness runs over the gas tank and is tough to get to so I had to go by feel through here:
You can see my wire tie between the bed and the frame rail.
When you get to the fuel filler tube the harness is easier to see:
Here I ran the wire between the cab and the cross member section because there was too much dirt in the space where the harness goes through to feed the wire through.
Then I rejoined the harness on the other side:
I followed the harness along the frame rail all the way to the front.
I brought another length of wire down from the engine compartment through the space between the wheel well liner and the firewall and spliced it to the end of my first wire, which ran out right at the bend you see above. The harness runs through the wheel well liner as well, show below:
For power You hook up to the battery with a self resetting circuit breaker, and run a wire through the firewall into the cab:
Above is the circuit breaker. Below you see a green wire and a red going through the firewall. The green is spliced to the orange wire circuit breaker, and the red is the one i told you I ran down through the wheel well liner. They both go inside to hook into the controller.