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Trailer Wiring Harness

Discussion in 'The DIY Room' started by BCB, Feb 25, 2019.

  1. BCB

    BCB

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    Hello Everyone,
    I picked up a 2000 GMC K2500 last week and need to install a hitch.

    I was going to order the hitch and wiring online and do the job myself. E-trailer has some good vids on wiring however when I looked under my bed I noticed that the existing wiring is connected by a 4 way flat and it runs from the driver's side then across the bumper and up into the bed wall on the passenger side. I have no idea what it controls. There isn't an existing trailer plug on the vehicle. It has a step bumper with a bumper ball but no place to plug trailer lights into it. I plan on adding a hitch with a trailer brake controller.

    I've attached a pic of the 2 4-way flat connection.

    Any ideas? I've watched several vids on e-trailer's website and haven't seen anything like this.

    Engine compartment
    2318A80A-A468-43E5-BFFE-5F4D2E8CA24C.jpeg

    Under tailgate. The small plugs are for the license plate lights.
    89B0C774-F926-4360-8253-7FC7DF97FC2C.jpeg
     
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  2. BCB

    BCB

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    Here’s the truck. 2000 GMC K2500 ECSB with only 83k miles

    C453541D-9D04-4F3D-9EC8-5FB66D710EEB.jpeg
     
  3. stuckinthemuck

    stuckinthemuck

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  4. BCB

    BCB

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    Looks like I need a T connector instead of the connector I was originally looking out.
     
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  5. BCB

    BCB

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    Ordered a class 4 hitch and the T connection. Skipping the brake controller for now since none of my existing trailers are equipped w brakes.

    The wiring going across the rear is for the taillights. Derp! Lol
     
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  6. stuckinthemuck

    stuckinthemuck

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    I like the selection on Etrailer. How heavy of a trailer are you planning to get? There is always the option of surge brakes if you don’t want electric brakes.
     
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  7. Winston

    Winston

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    Lol I wasn’t fast enough to tell you, went through that same exercise on my 97 1500 Silverado trying to figure out how to wire it . T connection and good to go like you just figured out.
     
  8. ironpony

    ironpony

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    pull back your front drivers side floor mat the trailer brake wires might be there already, just have to find them the other end. Also if you add brakes you will need a 7 pin connector
     
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  9. BCB

    BCB

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    I checked it out this afternoon and there’s no wires in place for a controller. I’d have to drill and run it through the firewall.
     
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  10. BCB

    BCB

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    Lol it’s good for now. Just need it wired to pull my enclosed and utility trailers.
     
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  11. BCB

    BCB

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    It’s not that heavy. 6x12 enclosed to pull my mowing equipment and a 5x8 1 ton utility.

    If I decide to get a dump trailer in the future I’ll have to add the brake controller. But I’m leaning towards going w a dump bed insert. I don’t have room for another trailer at the house.
     
  12. T.Jeff Veal

    T.Jeff Veal

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    I have an '01 F-150. The brake controller was easy to hook up. The plug for the controller was already made into the wiring harness, plug in was close to steering column under dash.
     
  13. ironpony

    ironpony

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    Do a search on etrailer they say all the wiring is already there in the truck just needs connected. wires thru firewall and the rest are tucked up above the spare.
     
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  14. Creekin

    Creekin

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    Sometimes the 12v charge wire (orange) and trailer brake wire (blue) are already at the back taped back into the harness, might have to pull some tape off to find them, under the hood charge wire should be near fuse box with an eyelet that can be put on one if the two studs on the fuse box
    Under the dash, can't seem to remember where the brake wire is
     
  15. BCB

    BCB

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    Got everything bolted on and connected yesterday morning. Took me about an hour.
     
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  16. billb3

    billb3

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    On my last truck the after market control box for the trailer lights/harness was in/behind the left rear tail light assembly well.
     
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