The lights on my 12ft aluminum boat trailer won't work when I hook them up to my jeep liberty. They work when hooked up to my dad's ford ranger. The lights on our other 2 boat trailers work fine as well when hooked up to both vehicles. I have a uhaul hitch and wiring.  Has anyone else had this kind of problem? I think it might be the ground wire but I'm not sure.

You might be onto something with the ground.  If none of the lights, regular tail, brake, or signal lights are working, chances are it is the ground.

For whatever reason, the ground on that one trailer hitch is probably not making sufficient contact between tow vehicle and trailer.

Apparently the plugs on the other two do, for whatever reason.

No ground = no lights.

I feel your pain man... I just hooked up the other day and all my lights work until I hit the brakes then.. nothing..  its gettin pretty annoying to figure out, haha

If you are testing wires from the trailer to the vehicle....take a jumper cable or or wire with alligator clips. hook on trailer frame where it will get a good connection, then hook on truck frame where it will get a good connection. this will insure a good ground connection between the two while you're testing wires.  not much more aggravating then to test all the wires, unhook a bunch of stuff to find out your ground wasn't adequate.

Thanks for the replies guys. I'm sure it's the ground. All of the other trailers have separate ground wires coming from the tail lights. The little trailer doesn't. Looks like I'll have to pick some up.

Sounds too simple but make sure your connectors are clean and corrosion free.

I hade a jeep cherokee and it took a special trailer light hook up I had to buy from a NAPA store.  After that it worked great.  Maybe a chrysler thing.