Ok, we tested all the lights/plug on my truck, that is all fine. My adapter plug seems to work good. So I have narrowed down my issue to the trailer. I have brake lights, turn signals, but no clearance lights. They are on ever so dim that you can hardly tell. When you plug trl into truck, it makes my taillights dim on truck. I am supposing there is a short somewhere. Where do I even start to figure it out?Could a bad trailer light plud do this?

All lights worked when we hooked it to our other truck last week, but we had no brakes...

I'll start off by saying trouble shooting an electrical problem is not my favorite thing- probably because I know just enough to be dangerous, but not enough to know really what I'm doing. That being said, take my advice with a grain of salt! I'd probably start by looking for a bad ground on the trailer, the plug, the lights themselves.  Good luck! 

A few years back, we had the same issues with our trailer lights when using an adapter. To fix it, we had to change the smaller  older plug on the trailer to the more modern large round that matched what all the newer trucks were coming out with from the factory. Those adapters are only meant to be a temporary fix. We found that the ones from the big box stores like Walmart were the worst. If you are unwilling or unable to loose the adapter, then order one of the best made ones available from the trailer dealer.

Most LQ trailers should never have the smaller light plug.  And, a horse trailer should never have a flat boat plug.