[loufish]

Man, I thought you guys had me on the right track with fuses and relays, but nope. I've replaced my towing relay, the Jideco brand brown relay that controls the tow plug. The blue relays indicate they control turn signals which i have as well as brake lights. There are two fuses in the relay box by the battery and they are both good to go. I've done all the test light and ohms meter stuff and can't get power to JUST the running lights AND the pos/neg terminals in the tow plug. It's gotta be simple--just not for me!

Just re-read your post.....Your killing me here!

Now it's just the running lights that don't work?

Problem is the tent trailer only, and just one side. Running lights and other turn signal, brake etc work fine.

Here the running lights work fine.....So you lost ALL the lights on one side of the trailer - No running, turn, or brake?

And you checked for power for each pin at the 7 pin connector?....If you don't know that one of the 7 pins are the ground circuit....step away from the truck & get some help...