Whenever I hook up my trailer and turn the running lights on whenever you use a blinker, brakes, or four ways the reverse lights come on. Leave the truck lights off and everything functions as normal. I had a reputable shop wire up the brake controller and a new 7 pin about 2 weeks ago, and I know the trailer is good as it gets used by my dad on an almost weekly basis.

Any ideas? Is something wired wrong, or should I be searching for some sort of short?

 

Hmm! I was gunna suggest checking the trailer grounds.
Does it work fine for your dad?
Mike

 

Works fine for my dad. Should also clarify my stating its the truck reverse lights that come on. Also, I forgot to mention that every light on the trailer blinks when this happens. However, everything works correctly if the trucks running lights are off.

Would this suggest the center pin in the truck was wired into the running lights somehow on accident? Even though the reverse lights aren't always on, just when one of those three combos I mentioned happen. I'm going by there in the morning, but if I could fix it myself tonight I'd be much happier since I'd be able to load up tonight.

 

Maybe check inside the connector assy. for a wire strand touching something it's not supposed to? And check your wiring against a diagram? Don't have one in front of me right now. (I'm @ work)

 

I verified with two different trailers over the weekend it's definitely the truck. I'll be stopping by the place that wired it tomorrow after work. Let them deal with the headache, besides it should be free!