I have a 2003 gmc sierra. For towing I have a 7 wiring plug.?

But there is a single wire that comes from under the truck that is only hot when the brakes are applied. For electric trailer brakes? Maybe. Except isn't trailer brakes included with the seven point connector?

If so, I'm curious why the other brake wire is needed.

2 Answers

  • 7 years ago

    do you have a brake controller in the truck?? the seven wire is mot likely for big trailers with brakes. you need an adapter for a four plug that is sold at most dealers or trailer stores.

    that way no cut and pasting of wires. and you need a brake controller if you haul a big trailer with brakes.

  • Kelley
    Lv 5
    7 years ago

    does that wire come from a brake controler.

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