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Diagnostic port under hood wires , hot while in "run"?

Interior and Electrical

  1. shadango

    shadango Well-Known Member

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    Our tach and the voltmeter is what we are hooking up......just hoping it is easier to find a "hot when in run" wire than under the dash.

    Looking around under the hood, there is a "diagnostic port" under the hood, mounted to the left fender well about halfway back from the battery.

    I am looking for an underhood power source that is ONLY hot when in the RUN position....wondering if anyone knows if any of these diagnostic wires are hot when in run (only)? Easy to get to and in a good spot.....there is a FAT red one going to it.....I assume that is straight from the battery (unswitched).

    We dont have the engine in the car so we cant hook up the electrical system to find out easily.......
     
  2. 80mirada

    80mirada Well-Known Member

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    I believe there is one in that connector. I don't know which one but I will look for it later, as I put my auto books away
     
  3. Aspen500

    Aspen500 Well-Known Member

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    The dark blue wire at the diag connector is switched power. Hot in start and run only.
     
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  4. shadango

    shadango Well-Known Member

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    Thanks very much!

    Yeah our "dark blue" wire is more like medium blue...I guess the years has caused it to fade....but I probed it and confirmed.

    Now, just gotta find the right dimmer wire.......our Chilton manual doesn't have under dash wiring diagrams except at a very high level.
     
  5. Aspen500

    Aspen500 Well-Known Member

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    My suggestion, toss the Chilton in the trash and get a service manual on CD. Yeah they're like $55 but worth every penny. They might have them on DVD-ROM now, not sure.

    My dream is to have an actual paper manual you can page through and have right at the car vs printing out what you need and then going out to the car, come back in, print what you forgot, go back out..................

    1979 Plymouth Chrysler / Dodge Factory OEM Shop Manuals on CD | Detroit Iron
     
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  6. BudW

    BudW Moderator Staff Member

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    Chilton’s (and Motors) do offer quality publications – BUT it is one size fits all, when it comes to the "per car line" books (the books designed for people like us). There, the books are hit and miss (more on the miss side).

    Unless there is absolutely nothing else I can use, then I may consider using a Chilton’s (or Motors) guide, at home.


    That said, I have two bookshelves in my garage full of nothing but factory service manuals. I might sell (or total) the vehicle - but have always kept the books. Don’t know why – but they do come in handy every once in a while.

    Use the Chilton’s guide for starting a fire, or as an “added bonus” if you sell the car. You can’t go wrong with a factory service manual (except for cost).

    BudW
     
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