Troubleshooting Trailer Light Issue with 2016 Ram Big Horn 2500

Question:

When i plug in my trailer plug and turn on the lights the trailer lights will come and go out, then my left tail light goes out on the truck. So I unplug the trailer and start the truck and the tail light comes back on on the truck. I always have brake and turn sigs on the trailer and truck. Had it checked at the dealer and they tested all working good they found no problem. IM stuck the trailer works fine hooked to my 2009 ram.

asked by: David M

Expert Reply:

Since your trailer works fine when connected to your 2009 Ram, the issue is most likely with the truck, however, I recommend checking your trailer ground connections at the main frame ground normally near the trailer battery and then at your tail lights as they often ground through the mounting hardware. Make sure those connections are bare metal to metal. The reason to check these is the trailer could have a slight ground issue that the power from your 2009 is able to overcome so it doesn't show up until you connect a weaker electrical system like your 2016 Ram.

The newer Rams have a more sophisticated lighting system that doesn't draw the same amount of power, so even a very slight amperage change could be the difference between on and off. The next thing I recommend checking is your trailer connector pins. Clean them with a little sand paper and then put some dielectric grease # 11755 on them to keep moisture and debris out. Use a little of this on the connection behind your vehicle trailer connector as well where the factory wiring plugs into the connector. A slight connection issue could cause what you are describing so I would also clean and use this on that left tail light connection on your truck.

Let me know if this doesn't solve the issue and we can continue to troubleshoot. I've attached an article to assist so you can pay special attention to the running light pin connections.

expert reply by: Jason S