How to Determine Which Wire Carries the Brake Controller Signal on a 2016 Ford Expedition

Question:

I can not find the black power wire on my 2016 Ford expedition, I found a purple with a green stripe that has power, would this work? Trailer ebrakes

asked by: Jerry C

Expert Reply:

PTW2993 and test the wires. Since car manufacturers could very well change the color of their wiring this will be your best, and safest, bet.

To test for the wire that carries the brake controller signal to the 7-Way on your 2016 Ford Expedition you will want to set your brake controller, like the Prodigy P3 # 90195, to the highest power setting and then use the manual override lever to send power. The wire that carries the brake controller signal will have an increase in power once you do this (a constant amount of low voltage signal is normal for a brake controller). If you are simply looking for the Stop Light Switch wire then in our experience that wire has been purple and white.

If you already have a 7-Way on your Expedition then the brake controller pin should be the one in the 5 o'clock position (see attached picture). The wire with a constant 12V of power (pin in the 2 o'clock position) is not want you want to use for your trailer brakes. It is used for sending constant power to a breakaway battery or other accessories that may be on your trailer.

expert reply by: Jon G