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  1. #1

    Default Truck side trailer wiring problem

    Hello all, I have a 2004 GMC Sierra 1500 Z71 crew cab.

    My truck is used mainly for towing my trailer and not driven much otherwise and my 10 month old Lab puppy chewed the harness a bit for the 7pin trailer wiring plug on my truck.

    I re-connected all the wires by matching the colored wires to one another but have one blue wire left over with no match for it. There was two blue wires, do a couple of them get combined up? The only think on my trailer that isnt working is the electric brakes.

    Anyone have a photo of theirs or a diagram? thanks, Im hoping to use my trailer tomorrow.

    Morgan Trotter

  2. #2


    Try this link:

    The heavy gauge blue wire is for the trailer brake. The blue is paired with an orange that runs along the frame rail to the under-hood fuse block.

    Good luck,

    I'm going to try this, too... @Mtrotter
    technology, huh?
    Last edited by KidHauler; 03-03-2012 at 12:31 PM.

    1999 Chevy K2500 Suburban 350
    K&N, reworked cai, Thrush cat-backs
    Vinyl, cranks, floor shift, and rear air!

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