Troubleshooting Trailer Lights Not Functioning Properly, Only Right Side Light Comes On

Question:

Brand new plug and play tow hitch and wiring kit, I plug in trailer and only the right hand side light comes on.... No other features work.... The light stays on even with hazards blinking turn signals nothing else works Any ideas????? Bought a tester... It says LT comes on... Thats it!!!!

asked by: Albert

Expert Reply:

It sounds like your issues are the results of a grounding or incorrect wiring issue on your trailer, but we can run through a few tests to be sure this is the cause of the problem.

Let's start by testing the new 4-Way wiring connector, like # 18004 that you referenced, on your vehicle. You can use a circuit tester like # PTW2993 to test for correct function at the connector. The green wire should carry the right turn and stop signal, the yellow wire carries the left turn and stop signal, the brown wire is for the taillights, and the white wire is ground. If the connector doesn't test for proper functions, double check the installation of the connector.

If the connector tests for the correct functions, we know the issue is on the trailer. The trailer wire ground should be attached to the trailer's frame, somewhere clean and free of corrosion or rust. If the existing ground location is not clean so the ground has bare metal contact, I recommend relocating the ground to see if that provides a solution to your lighting issues.

You can also check the trailer's wiring to ensure it is properly wired. The typical color code is the same as the color code on the # 18004 4-Way connector. I've attached a photo showing how the wiring should be connected.

expert reply by: Victoria B