How to Determine Function of Yellow/Brown Trailer Wire When Installing New Lights on Trailer

Question:

If I have brown/yellow wire at left trailer light, do I connect this to the single brown wire st rest light? Is so, where does the single yellow and white wires from new light connect?

asked by: Russ H

Expert Reply:

You will need to test the brown/yellow wire on your trailer to determine what its' function actually is, as colors of wires don't necessarily always indicate the function. You'll want to use a circuit tester like the # PTW2993 to determine if it carries the blinker function or the running light function. If it carries the running light power then you'll connect to the brown and if it carries the left blinker function you'll use the yellow wire; the white wire will be the ground wire, which can be connected to any paint and rust free spot on the trailer frame with a self tapping screw and ring terminal.

I've also linked a helpful article we did on 4 way trailer wiring that you might find helpful. If you can tell me what circuit that wire is getting power on, I can give you some more specific directions on the installation.

expert reply by: Erik B