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  1. #1

    Default aux 12v power to factory trailer plug

    Hi, New to this forumand i have a question to start. I have a 2008 Chevy 3500HD crew cab long bed single rear wheel Duramax with Allison with factory brake box and towing package. I tow an 18ft gooseneck horse trailer with living quarters that has a coach battery that is used for the breakaway source as well. I realized when my wife used the trailer for a long weekend that the truck was not charging the coach battery that I do not have 12v at the rear plug of the truck. Upon further investigation I read in the owners manual that there is a wire that needs to be connected in the engine compartment. There are two studs at the front of the fuse box in the engine compartment. One (closest to the engine) has a wire connected to it. the second stud(closest to the fender) is empty. Is there a wire hidden somewhere along the fender well that needs to be connected to that stud? Does anyone know what I'm talking about?
    Any reply would be greatly appreciated, thanks ,Neal

  2. #2

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    Yes It should be in a wire bundle coming from the rear of the truck. Check under the brake booster, and around the fuse box.

    1996 Chevy Tahoe LT 5.7L V8 4X4 205,000+ miles. Built proudly at Janesville Assembly in Janesville, Wisconsin
    Basic mods: Lights all over, bunch of electrical work, and a couple cooling mods.

    Check out my other mods in My Garage: http://www.gmtruckclub.com/forum/sho...t-Tahoe-4-Door

  3. #3
    Jr. Engineer Jaele's Avatar
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    Quote Originally Posted by Conlan Rose View Post
    Yes It should be in a wire bundle coming from the rear of the truck. Check under the brake booster, and around the fuse box.
    hes Correct its a red cable, you will connect to the stud that is towards the outside of the fuse box, you will need a fuse and a nut.
    2011 Silverado 1500 Z71 4x4 Crew Cab
    LED Dome light
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  4. #4

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    Thanks for the quick response. The truck isnt here at the moment. Aren't the two studs already fused from inside the fuse box? I'm assuming the stud closest to the engine is powering the "in dash" break controller. Will be able to dig into this when I have the truck here. Thanks, Neal

  5. #5

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    Welcome to the forum!

    I just sent you a Personal Message. Reply with your email address and I will send you something to help.

    - - - Updated - - -

    Got your PM, email sent. Sorry for the delay...
    Finally a signature and Avatar! I also posted some pics in the Gallery.
    2011 2500HD Crew Cab 4X4 Z71 6Liter.
    2011 Outback Travel Trailer 260FL
    So Happy to not be on the edge of GVWR Over Load!!

  6. #6

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    I don't know why Jake is being so secretive, but there should be two wires and two studs. The studs are different sizes and the hole in the wire connectors are different sizes (match the sizes and you won't scew up).

    One wire is for a 3rd party trailer brake controller and the other wire is for the charging system of the on-board battery.

    As @Jaele suggests, you will need fuses and nuts.
    Ray

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  7. #7

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    Quote Originally Posted by RayVoy View Post
    I don't know why Jake is being so secretive, but there should be two wires and two studs. The studs are different sizes and the hole in the wire connectors are different sizes (match the sizes and you won't scew up).

    One wire is for a 3rd party trailer brake controller and the other wire is for the charging system of the on-board battery.

    As @Jaele suggests, you will need fuses and nuts.
    No secrets here Ray... Sometimes pictures help, with me anyway...when I had my first 2007 NBS it went back to the factory for noisy back seats and wen my neighbour ( he was quality control for NBS here in Oshawa) asked if there was anything else I mentioned the trailer wiring hook ups. They put together a PowerPoint with pictures and some instructions and gave it to me. I've asked a few times on how to post it here... but there always was some issue. I've sent it to a few folks here and would posted as everyone I send it to seems appreciative... So if you know how I can send it to you or I can see if I can do it now...
    Nope... to big ...
    Last edited by jake's silverado; 04-27-2013 at 06:35 PM.

  8. #8
    Jr. Engineer Jaele's Avatar
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    Quote Originally Posted by jake's silverado View Post
    No secrets here Ray... Sometimes pictures help, with me anyway...when I had my first 2007 NBS it went back to the factory for noisy back seats and wen my neighbour ( he was quality control for NBS here in Oshawa) asked if there was anything else I mentioned the trailer wiring hook ups. They put together a PowerPoint with pictures and some instructions and gave it to me. I've asked a few times on how to post it here... but there always was some issue. I've sent it to a few folks here and would posted as everyone I send it to seems appreciative... So if you know how I can send it to you or I can see if I can do it now...
    Nope... to big ...
    Ill send you my email and give it a shot.

    - - - Updated - - -

    Here is the walk-through
    If you are only looking at hooking up the 12v aux, skip to the last two photos.

    Thanks to @jake's silverado for supplying this guide. I only uploaded and posted it
    Attached Thumbnails Attached Thumbnails Trailer Hook Up-1_Page_1.jpg   Trailer Hook Up-1_Page_2.jpg   Trailer Hook Up-1_Page_3.jpg   Trailer Hook Up-1_Page_4.jpg   Trailer Hook Up-1_Page_5.jpg  

    Trailer Hook Up-1_Page_6.jpg   Trailer Hook Up-1_Page_7.jpg  

  9. #9

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    Nice info Jake, @jake's silverado, and @Jaele, thanks

  10. #10

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    I found the two wires, but the one between the fuse block and fender was marked 12v aux. when I hooked it to the stud I couldn't figure out where the wire went. I'm thinking that wire goes under the dash for an aftermarket brake box. I found the one under the master cylinder and hooked it up and Hooray! Power to the trailer plug. The only thing I don't like is that it's always hot. On my old truck I wired this line thru a continuous duty solonoid that was wired to a ign hot. That way my trailer, if being used, won't run the truck batteries dead when parked. Thanks for all of the great info, Neal

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