Front Top & Side Running Lights Don't Work, but Back, Brake and Turn Single Light Do?

[Lynde B]

Hi folks!

So I own a 2011 Rockwood Ulta-Lite 5th Wheel! 29ft.

Here is the issue, When Plugged into my tow vehicle 2500 GMC Sierra 2006 my FRONT Top Running Lights & Side Marker Lights won't work, BUT ALL my back lights work fine (Back brake lights, turn signals and back side marker lights).

Now, many have said they should all be on the same circuit on the 7 way pigtail pin so why shouldn't they all work if the back lights are working. I have checked and replaced my Fuses on my Truck when ALL my running light quit on me due to a blown fuse and that brought back my BACK running lights and side marker lights, but NO Front Top lights and Front side markers. They won't come on, but everything else does fine?

I checked my pigtail plugs, cleaned them with cleaner and check the grounds with voltage meter, all good. I still don't know what to do?

Any thoughts? What am I missing here?

thanks!

[TheWolfPaq82]

Simplest explanation is a broken connection between the "main" part of the circuit on the trailer to the non-working lights. Now if ALL your marker lights were not working, then that might be a problem at truck or trailer plug, but as you said your back marker lights are working and the front and side are not. I'd say that's trailer wiring problem. Have you looked under the frame of Trailer where the cord runs to and check all the wiring under there ??