Are Trailer Wiring Connections Universal

Question:

I hooked up my trailer lights to the harness using this video guide: https://www.etrailer.com/Wiring/Optronics/A35W42B.html starting around 2:40 and confirmation from this QandA along with the FAQ https://www.etrailer.com/question-37489.html https://www.etrailer.com/faq-wiring.aspx So basically, I have black from the light wired to brown and red from the light wired to the respective side. When running the blinkers with the cars headlights OFF, blinkers and brakes work fine. When I turn on the cars headlights, the blinkers and brake lights are very dim both sides. When I reversed the wiring, i.e. red from the light wired to brown and black from the light wired to the respective side, the trailer lights appear to work as expected...the blinkers and brake lights work properly, regardless if the cars headlights are on. Am I doing something wrong, but the correct results are happening? Is this an issue with something else? I did hook up my car to a different trailer and there were no issues with the lighting. Very confused...

asked by: Kayton S

Expert Reply:

Thank you very much for all of the info.

The best answer I can give you is that the color of wires for trailer lights can vary and so what may work for one trailer may not work for another trailer. The correct way to wire your trailer is by connecting your wiring per function instead of color. Typically 12V power (like a battery) and a circuit tester # PTW2992 are used to help determine functions.

If your trailer lights work correctly when you have them wired a specific way (even if the colors seem wrong according to other sources) then odds are your wiring colors are different and you need to keep everything installed based on how your lighting works.

I have attached a link to some other helpful articles that you can check out.

expert reply by: Jon G