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  1. #1
    Sr. Mechanic Ridyn's Avatar
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    Feb 2011
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    Default Trailer running lights question

    I have a 2012 Silverado crew cab with the HD towing package and cooler and the 3.42 gears, I had connected my fathers trailer after re-wiring it for him, and every light worked except for the running lights when the headlamps were on.

    However when I connected the trailer to my sisters truck which is an older model like a 2002 ext cab, it worked just fine.

    Question here is, do I have to have a special type of hitch connected so the truck knows that it's about to tow in order to engage the running lights for the trailer connection in the rear or do I need to take it to the dealer so they can have a look to see if it was even installed correctly from the factory?

    Please respond asap, I haven't pulled a trailer yet and this was supposed to be the first I have never messed with the truck for towing until now.

    "Never ask a man if he's from Texas. If he is, he'll tell you. If he isn't, there is no need to embarrass him."

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  2. #2


    Running light circuit is not getting power. For some reason on your new truck it sounds like the plug has that connection in a different location than what your trailer thinks it is supposed to be. At this point, I take my truck to my auto electric guy. Of course, he may want to take a look at my wiring job on the father's trailer, or suggest trying your truck plug on a different trailer to see if the problem persists.
    1994 Chevy K2500 Silverado, 454 (modified), original owner.
    And other vehicles and toys.

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    And treat those two imposters just the same;'ll be a Man, my son!" Rudyard Kipling

  3. #3


    Have you checked your fuse for the running lights if you have one?

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  4. #4
    Sr. Engineer
    Join Date
    Oct 2010
    Indianapolis, In


    Try looking here, . Before you start changing wiring on a new vehicle I would make sure the trailer wiring complies with the diagrams in this post. I don't know the history of the trailer but if it was normally towed with sisters truck then maybe it was wrong and trailer was wired to work with it. If you have electric brakes then make ABSOLUTELY sure it is wired correctly, last thing you want is turn signals working the brakes.
    Good luck and be safe.
    2000 GMC YUKON SLT, 5.3L tow pkg, G80 rear/w 3.73 gear

  5. #5
    Sr. Engineer
    Join Date
    Oct 2010
    Indianapolis, In


    Hey Mods, can you move the trailer pin out sticky to the trailer towing site?

  6. #6


    Quote Originally Posted by dpeter View Post
    Hey Mods, can you move the trailer pin out sticky to the trailer towing site?
    Very good idea. Done. I also left the link in the Electrical sub-forum for posterity.

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