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Alternator Issue

Discussion in 'Early CJ5 and CJ6 Tech' started by Steve's 70-5, Oct 21, 2021.

  1. Oct 25, 2021
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Tantallon, Nova...
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    It doesn't matter which way they rotate.

    You say it tested good, yet it's not working for you.

    Just to verify it's the "Batt" stud on the alternator you have connected to the starter stud with the wire going to the battery?
     
    timgr likes this.
  2. Oct 25, 2021
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    MAD electrical site might be helpful...it also has application info for different clocking etc and wiring diagrams...It seems you want a single wire, but i am confused as your initial post describes a 3-wire or something. Some pics would help...
     
  3. Oct 25, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Apparently some "one wire" alternators can use the normally unused excite wire for an alternator light. Unlike the three-wire alternators, they do not require this connection. This was my understanding of the situation. The OP wanted to use the excite wire for his voltmeter, which kinda sorta works, but not really what he wants. See my post above.
     
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  4. Oct 25, 2021
    Steve's 70-5

    Steve's 70-5 Active Member

    Louisville, Ky
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    My alternator has a stud for the battery cable and a spot for a 2 spade plug. There is a ground location on the back of the case too.

    What is a part number or vehicle application for a single wire alternator. Since I have changed my gauges/cluster, I will get a new alternator.
     
  5. Oct 25, 2021
    boopiejones

    boopiejones I can’t drive 55

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    Have you tried running a separate ground wire to the alternator? It should be grounded through the mounting bolt but if there is paint, grease or dirt that might cause issues.
     
  6. Oct 25, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    They are all aftermarket, AFAIK. It's a 3-wire alternator with a replacement regulator that eliminates the need for the two plug-in wires. Only the regulator internal to the alternator changes.

    https://www.amazon.com/1-WIRE-VOLTAGE-REGULATOR-ALTERNATOR-EXCITING/dp/B01FWHPSG6
     
  7. Oct 25, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    If you actually have a 3-wire alternator and you do not connect the two plug-in wires correctly, it will not charge. It will also test good on an alternator test jig, assuming the tester properly connects the three wires.
     
  8. Oct 25, 2021
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

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    this would be an option...its a 100amp 12si, can be run as either a single or 3-wire set-up...it has the 2spade plug on the side, but that would only be used if wiring as a 3wire set-up, and no idea if this clocking would be right for you - just a way to show you don't have to have specific applicaition info - sites such speedway and summit can search for 12si single wire...
    Powermaster 7294 GM 12SI 100 Amp Alternator, Natural

    also from the instruction sheet: for single wire set-up, there is no jumper from the internal regulator to the BATT post on the back
    I probably am beyond what I can safely give advice, but as you describe a wire going from your blade terminal to the BATT post, it sounds like your wiring is still a bit mixed up between 3-wire and single wire. Tim and other know this subject much better than I...I'll step aside.
     
  9. Oct 25, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Maybe the OP could give the back story about where this alternator was obtained, and how the seller represented it.
     
  10. Oct 25, 2021
    Steve's 70-5

    Steve's 70-5 Active Member

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    I got it from O’Reilly’s I gave them the car I wanted it for and they sold it to me.
     
  11. Oct 25, 2021
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    I see in your original post that you installed a diode in the exciter wire (post #1 on alternator). If you installed it backwards it will not allow power to the terminal to excite the alternator and it won't charge (depending on internal regulator).
     
  12. Oct 25, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    What exactly was said by you and the salesperson? Did you or the salesperson ask for or say "one wire" at any time while you were at the counter? Which car did you tell them you wanted it for? Do you still have the box? Were there any papers with the alternator?

    Do you understand the issue? A 3-wire alternator will not work as a one-wire without aftermarket modification. A 10SI or 12SI is not a one-wire alternator.
     
  13. Oct 25, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    The wire does not go to the starter. It goes to the battery, so it's connected to the battery all the time.

    This is the excite wire, that is typically not connected on a one-wire alternator.

    This is the sense wire, which is typically not connected on a one-wire alternator.

    As Walt points out, the diode must be facing the right direction, with the line on the diode on the alternator side, not the switch side.
     
  14. Oct 25, 2021
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

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    I think he means it goes to the battery terminal on the solenoid Tim, at least that's the way I've been reading it.


    Steve- we're throwing a lot at you about something you're not an expert on, I'm sure your frustration level is through the roof. A couple of photos would be a big help for us to help you, maybe a closeup of the connections at the starter & a pic of the p/n on the alternator if there is one.
     
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  15. Oct 25, 2021
    Steve's 70-5

    Steve's 70-5 Active Member

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    Yes, I am learning

    Thinking back I may have got a 3 wire alternator because I had the original Jeep cluster. I hooked the alternator to the amp light to the Jeep cluster but do not know if it ever worked right.

    I have only driven the Jeep about 30 miles since all this was done. Was working more on the EFI

    To be honest, if I could get the part number of a one wire I would buy and be done with this. If it is not to expensive.

    Will look at the part to change 3 wire to one wire.
     
  16. Oct 25, 2021
    Sierra Bum

    Sierra Bum Member

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    I read through all this...sounds like you've got a three wire Delco. And yes it can be confusing.

    The simplest way to get this working, assuming its a 3 wire and the Alt is indeed good as tested:

    1. Connect the "heavy gauge wire" (the charge wire) from the stud to the + side of the battery (Do you know the alternator amp rating? Make sure you have the correct size wire).

    2. Loop the red wire on the pig tail connector back to the charge wire stud.

    3. Cap off white wire on the pigtail if you don't want an idiot light in the dash.

    Done

    Make sure it reads 14 volts with the engine running.
     
  17. Oct 25, 2021
    Steve's 70-5

    Steve's 70-5 Active Member

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    Just did this, no change
     
  18. Oct 25, 2021
    Steve's 70-5

    Steve's 70-5 Active Member

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  19. Oct 25, 2021
    Sierra Bum

    Sierra Bum Member

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    Check out the PowerMaster stuff. They have 12si options then.

    Also, if you want to learn about this, then Fino's suggestion to read through the MAD electric tech section was a good one.
     
  20. Oct 25, 2021
    Sierra Bum

    Sierra Bum Member

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    See that two-prong plug in your pic? There is a pig tail connector for that. Your FLAPS will have it. It will have a red wire and a white wire on it. Cap off the white wire. Put a ring terminal on the red one and connect it to the charge stud. Try that.
     
    FinoCJ likes this.
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