Hey Chris now you don't say if the trailer is at the same height when it's off the ball or not, what happens is the connector or plug in sometimes make a good connection or not depending on the angle it is when plugged in, also you don't say how big a trailer you have, I would replace the wiring in it to be on the safe side,cut the plug at the front first tape the new wires to the old ones then pull the wires through with the old ones, make sure you connect the colors to the right ones through the trailer rails, since the trailer has 2 sides, use marine grade connectors ONLY and heat shrink tubing (seal out the water), then change the plug in the vehicle, again stagger cut the wires that way when you put the connectors on it you wont have a BIG bulge of connectors in a bunch, put some split loom to cover the repair, and that will cure your problem, and no tickets for improper lighting on the trailer, hope this helps :-)