Just recently my trailer running lights have stopped working. My brake lights and turn signals work fine, but I can not figure out what is wrong with those running lights. I bought a new adapter for the truck and put a new plug on the trailer, still now running lights. Any suggestions?
Trailer light issue
First You have to narrow down your problem to your truck or to the trailer. A test light or Volt meter would also be helpful.
Check for a fuse for your trailer running lights...on your truck. Check light bulbs in the trailer. Check for Broken wires? (the Brown wire handles running lights). Are your lights on "ON" and not Daytime running lights? I assume you have a ground wire because you have other light functions. However it still could be the ground (white wire) is loose corroded or broken.
Good luck trailer wires are simple in operation but still a pain in the Butt!
Many vehicles have two fuses for the lights, one for power at all times and another for breaking and turn signal. I've blown the one several times on two vehicles, a Dodge and a Jeep. Not sure if it's common to the vehicle brand or if other vehicles have the same issue.
I would definitely think it was a fuse on the tow vehicle before a grounding issue as the brake lights are brighter and use more amps, if the grounding can handle that draw something else is wrong
I had a truck that would blow a fuse occasionally and my running lights would go on my trailer. I spent a lot of time looking over that trailer wiring and the power connection before finding out I had a blown fuse on the tow vehicle. Like Ulbian said definitely hook it up to a different tow vehicle.
Have you hooked it up to a different vehicle? You can drive yourself nuts chasing a trailer gremlin when the issue is with the tow vehicle. First thing that needs to be done is to isolate which thing is causing the problem. If it does the exact same thing on two different vehicles then you have isolated it to an issue with the trailer.
Work smarter, not harder.
It is likely the fuse, the bulbs, or the ground.
If the fuse is good, and the bulbs are good, I would look for a grounding issue
If you have a 4 or 7 connector check for power going to the brown wire out of the connector to trailer, if none-go to fuse box.Let us know results.Get a test light everyone should have one.
Similar thing happened to me this past weekend, officer followed me into boat launch and informed me that only the brake lights & turn signals were working and that he had seen me numerous times this summer without any issue, fuse had blown on the truck. Hopefully that's all that needs to be checked. Good luck !!
Test your pig tail or plug for power, fuse may have blown on tow vehicle. Then test for power on lights. Light bulb tester works great for this issue.