Troubleshooting Brake Lights on a Horse Trailer

Updated 04/11/2017 | Published 04/09/2017

Question:

I have a 2002 ford f150 with a flat 4 prong for the trailer i got an old horse trailer which has a 6 prong round i cut the round plug off and wired a 4 wire flat plug to match my truck plug all good but NO BREAK LIGHTS i have 2 wires left over a blue and brown comeing from trailer i just need need breaklights to work

asked by: Ellen

Expert Reply:

Typically on a horse trailer with a 6-Way, the different colored wires should have the following functions:

Yellow - Left Turn & Stop
Green - Right Turn & Stop
Blue - Brake Controller Output
Brown - Tail & Running Lights
White - Ground
Black - 12V Power

Sometimes the Blue and Black functions are swapped, but for your application it looks like you will just need to switch out the Brown wire with the Black wire to the 4-Way on your horse trailer. This will give you full functioning lights for the trailer. If you make this switch and you are still having issues, you can test the 4-Way at the rear of your 2002 Ford F-150 with a Circuit Tester, like part # PTW2992, to make sure that it is all functioning properly.

If you run into any more issues or you would like to use all of the functions on your horse trailer, just let me know and I can recommend the parts that you will need to do so.