Troubleshooting Trailer Tail Light with Only Running Light Function

Updated 11/27/2017 | Published 11/24/2017

Question:

I brought new lights trying to hook they up got the green and the brown one hook up and the white one on ground hook up to but all that comes on is the running lifght but when I turn the Signal light it don’t come on

asked by: Blake

Expert Reply:

I recommend using a circuit tester like # PTW2993 to test the function of your green wire. That wire color is traditionally a brake and turn signal function wire, so it may not be getting the signal to the light. If you test it and there is function, then you will need to clean up the ground wire connection to make sure it is bare metal to metal versus the slight rust we see in your attached photo. Once you have a good clean connection you can use paint to seal it from future rust.

If you don't have function at the green wire for turn and stop, trace the wire checking every few feet to determine if there is a short where the power gets to a certain point and not farther and replace as needed. You alternatively can choose to run a separate wire for those functions. I've attached a wiring article to assist.

expert reply by: Jason S