Troubleshooting LED Trailer Running Lights Randomly Turning Off On 2020 GMC Sierra Denali 2500

Question:

I have a 2020 GMC Duramax Denali. My trailer Brake and turn signal lights work all of the time. However, my running lights will not stay on all of the time. It is not a loose connection. I can sit and not move for 10 minutes plus and then out of the blue the running lights go off. They are Led lights on the trailer. Do i possibly need a converter and where can I get one?

asked by: Michael B

Expert Reply:

There is a connector that some vehicle's require to use LED trailer lights which is # C35FR for 7-way to 5-way/4-way or # 20142 for 7-way to 7-way. The way you would know if you need one of these adapters is your vehicle would display an error code when plug in to the trailer due to LED lights having such a low amp draw compared to incondessiant lights.

Since your running lights are working sometimes and you did not mention an error code in the truck I suspect you have a different issue which is likely a connection that is not completely secured or a ground with a poor connection causing the connection to work some of the times but not consistently.

I recommend double checking that the running light connections on your trailer and the trailer connector are completely secured with no visible corrosion or debris and that all of the grounds are secured to bare clean metal.

If all of the trailer wiring and connections check out I would check that the running light wire going to the trailer connector is secured, you can test this by giving it a light pull.

I included a helpful article on troubleshooting trailer wiring for you to take a look at.

expert reply by: Samuel C