Question:
I need to know where the 3rd brake light wire is on my 2009 f-150 and how to wire it to a topper that I put on my truck. If you could help that would be awesome!
asked by: Josh H
Expert Reply:
To wire a brake light only on a truck bed topper you will need a dedicated brake light only circuit. Tow package wiring would not work because the brake light circuit and turn signal circuits are together.
So you would either need to find a wire under the truck that is dedicated brake light only or you would need to tap into the center high mount stop lamp circuit. Check the owners manual to see if the "CHMSL" is fused by itself or if the fuse handles other functions as well. If the CHMSL has its own dedicated fuse you could use a fuse tap and run a wire such as # 16-1-1 sold by the foot from that fuse tap, under the truck, and to the wiring for the light.
If the CHMSL shares a fuse then you can't use it. The rumor for Ford's is that there is a 3rd brake light wire behind a cover on the drivers side frame. It is most likely a green wire. To confirm function of the wires, I recommend using a circuit tester like # PTW2993.
