Right Turn Signal Does Not Work on Trailer

Question:

Everything else on the trailer is working- side markers, brake, lights on. When the 4-way is initiated the right side on the trailer doesnt work. When the right turn signal is on, the flashing timing is very fast on the truck but the trailer doesnt work. Left is normal 2022 truck, new 4 pin adaptor, trailer wiring harness never changed- original flat 4 -pin, aluminum trailer. Is this a ground problem or possibly a bad wire? Thanks for helping

asked by: Dave Z

Expert Reply:

There's a few options here, either a ground or bad wire, like you said, or the 4-way on your trailer has corroded. So start easy and check your trailer connector for corrosion, which can be green or white in color. A build-up of corrosion can interfere with the signals getting through the connectors so if it is present you are going to need to replace the trailer connector with a new 4-way, either # HM48133 or # HM38134.

Then you can check and see if you have a damaged wire (though I doubt this is the issue, you do want to check), but pay close attention to the ground. Start with the main ground, and make sure it is attached to the frame and not an aluminum section of the body. Then go to the light and make sure its ground is free of any paint or dirt, and the light is not grounded to an aluminum surface. If it is, connect a wire to the light stud and ground it to the trailer frame.

I have added a link below to a help article on trailer wiring for you to take a look at. Additionally, to help prevent any type of corrosion in your connector, and increase its durability and lifespan I highly recommend using Dielectric Grease for Electrical Connectors # 11755.

expert reply by: Kyle S