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Trailer hook up

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Dski1991, Apr 7, 2021.

  1. Dski1991

    Dski1991 Registered User

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    Hi guys,

    I was wondering if any of y’all have insight on the wiring diagram on this.

    the previous owner did a nice job on this and would like to clean it up.

    030851DD-F8C1-41B6-BE61-45DDEC666D73.jpeg 8C9CF7A8-5B28-4527-BB58-7705F48D7834.jpeg
     
  2. Cubey

    Cubey Full timer RVer

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    Best I can suggest is using a test light to see which wires are positive when various things are powered on, such as tail lights, turn signs, and brake lights.
     
  3. cozinsky

    cozinsky Full Access Member

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    There's no real way of knowing how someone else wired it without testing but its usually:
    Yellow-left turn
    Green-right turn
    Brown-tail/marker
    White- ground

    Blue is usually trailer brakes, but if there's no blue wire I use red when I hook them up.
     
  4. Old Goat

    Old Goat Full Access Member

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    The_Josh_Bear and Cubey like this.
  5. Farmer Rock

    Farmer Rock just a fella' without a 10mm socket

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    If you don't mind the extra wiring, it's much better to just run new wires. The previous owner of my 87' had used old brittle wires they had, and them hooked up through 5 T-taps. I was trying to make heads or tails of the mess, but it just wasn't worth it to use junk wires. I ended up tearing all the old wires out, wired in a new 7 way plug, ran all new 10ga wires, up to breakers under the hood. I can get more details if you want them.




    Rock
     
  6. Clb

    Clb Another old truck Supporting Member

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    +1 on etrailer
    I stripped a large paper grocery bag of wiring outta the 88.
    P.o's. Should be banned from scotch locks and crush connectors!
    Check the data base for color codes and see if its factory loomed (later models)

    And fill in the trucks stats in yer sig line so we know what ya gotz....
    Helps diagnosis
     
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  7. ih8minimumwage

    ih8minimumwage Full Access Member

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    You should be able to cut it back to where it isn't a mess and install a flat 4, then replace that trailer plug with one that has a trailer side flat 4 as an inlet. That way you can unplug and use the flat for smaller trailers or Uhaul rentals, or install something like a seven pin for larger trailers with brakes (which takes wiring in a cheap controller and a couple more wires for the brakes).

    I bought the parts and put off doing mine for a long time, then easily did the whole job in a weekend.
     
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  8. mblaney

    mblaney Full Access Member

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    Looks legit to me! :rotflmao

    +1 on banning those crush connectors...
     
  9. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    +2 here!
     
  10. chillman88

    chillman88 Supporting Member Supporting Member

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  11. Farmer Rock

    Farmer Rock just a fella' without a 10mm socket

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    That's a nice setup. And the price is not bad at all compared to a regular plug.
    The 7 way I put in my 87', has one of those "T" adapters in the tail light harness that plugs in with a 4 flat, so if I had to replace the plug, I can just plug it in, but the trailer brake, and trailer hot wires would have to have new connectors crimped on. If I had to do it again, I would go with kind that you linked, and I probably will on my F super duty when I get to that.


    Rock
     
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  12. chillman88

    chillman88 Supporting Member Supporting Member

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    Yeah the wiring was semi hacked in my Dually and I found that and it was perfect. I'll splice another one in the bed at some point for hauling 5th wheels or gooseneck trailers.
     
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  13. TNBrett

    TNBrett Full Access Member

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    I did something similar on mine. It was all stuff I had lying around. I spliced the connector I had from another harness. Most receptacles use the same connector. I’m pretty sure it’s a Pollak design. The receptacle itself is a GM part, but that’s just because most of my trucks at work are Chevy’s. They’re about $30 at the dealer iirc. [​IMG]
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    [​IMG]


    Sent from my iPhone using Tapatalk
     
  14. chillman88

    chillman88 Supporting Member Supporting Member

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    I definitely like that plug better, having a separate but integrated 4 pin connector is wonderful.

    EDIT: Looks like it should plug directly into the harness I used.....

    https://www.amazon.com/General-Motors-2014-2018-Silverado-Receptacle/dp/B07D4R5Y7K#
     
    Last edited: Apr 8, 2021
  15. Dski1991

    Dski1991 Registered User

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    Thank you all for the replies!! I will be going with something new and will reword it correctly.
     

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