Troubleshooting Trailer Lights Not Working on Old Boat Trailer With New Wiring and Lights

Question:

I have a old boat trailor I bought to make a nice 4 wheeler trailor.I bought a brand new wiring kit.I went by the book an wired.after making sure I had a clean metal to metal ground surface I put a connector on the ground wire an took a self tapping medal screw an grounded.the tail lights with ground wires so I did same process.i have a Yukon I bought a plug to adapt with a 4 an 5 prong hook.My wiring called for 4 prong.Still nothing

asked by: Joe B

Helpful Expert Reply:

To troubleshoot, let's start with the vehicle. Without the trailer connected, you will want to use a circuit tester like # PTW2993 and go through each of the functions individually to make sure they work properly with the incandescent light in the tester. I've attached a video to assist.

Once you have confirmed the vehicle side trailer wiring is working properly, then you will test the trailer. You can use a 12V battery connecting a jump wire from the positive terminal to each function and the negative terminal to the trailer frame. If the trailer lights work, then you can connect the vehicle to the trailer to check for connection issues between the two.

If lights still don't work clean the connections on the trailer and vehicle side with a little sandpaper. If still no lights, then you will want to run all your ground connection to a common ground location using # 16-1-1. This will mean running a jump wire from the tail light frame ground connection on your lights to the main trailer frame ground near the coupler. It is rare to need this common ground, but every trailer is different and especially aluminum trailer frames like some boat trailers are a little more difficult for a solid ground connection.

I've attached some articles to further assist.

expert reply by: Jason S