Testing Trailer Wiring to Determine Function before Installing New Lighting

Question:

My harness on my trail star trailer has Red, Black and a white wire on them for the left/driver side but, the replacement lights have brown, yellow and white wires. I know that the white wires will connect together but, what color will my red and black connect to on the replacement light? Thanks!

asked by: Joey B

Expert Reply:

Since your trailer uses non-standard wire colors you are going to have to use a circuit tester like part # PTW2993 to wires to verify what they are first. Turn on the running lights first and then test the wires. Which ever has voltage is the running light circuit and would run to the brown wire of your lights. Next turn on the blinkers and test. The one that flashes is the stop/turn circuit and should run to the yellow. The remaining wire which will most likely be the white one is going to be the ground.

expert reply by: Jameson C