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Alternator Help

Discussion in 'Jeepster Commando and Commando Tech' started by Lightfall, Mar 22, 2019.

  1. Mar 22, 2019
    Lightfall

    Lightfall New Member

    wisconsin
    Joined:
    Mar 22, 2019
    Messages:
    4
    Hello, I think I did something stupid, please help me figure it out.

    I have a 69' that wouldn't start recently due to a dead 3 month old battery. I replaced the battery and it died again. I had it jumped, guy told me it was probably the alternator since it was reading low 12v. I removed the delco alternator (I think 10si) and got a replacement (12si?). The 10si seemed to test OK but the guy thought the brushes could potentially be equivocal so I bought a new one anyway. Upon closer inspection of the engine bay I noticed some worn wire insulation that could have been shorting out so I taped and sealed all of them and replaced the alternator.

    It fired up and I let it run for a bit but the belt tension was low so I removed the alternator again and adjusted things. I think I may have plugged something in incorrectly absentmindedly somewhere in there because when I went to re-start it I just got a brief click and then nothing. I went back and unplugged everything and plugged it all back in. I was very tired, but I think I may have plugged one wire from the orphan motorola regulator still attached to the fender into the #2 alternator prong (that should have been the battery/starter or ignition wire?) and the green (starter or ignition?) wire into prong 1.

    At this point I don't know what I did, I think I plugged everything in correct again, but I don't get anything from the ignition. I am an idiot for not taking photos of all the connections and double checking what I was doing but I thought I still had some old photos that were apparently deleted or lost.

    Anyway - why nothing from ignition? Did I wire wrong again or did I fry something? Any help is much appreciated.
     
  2. Mar 23, 2019
    Twin2

    Twin2 wasn't me Sponsor 2019 Sponsor

    Virginia Beach, VA
    Joined:
    Apr 28, 2011
    Messages:
    3,759
    welcome
    wiring 10si
    10si wiring.jpg
     
    Focker likes this.
  3. Mar 25, 2019
    Lightfall

    Lightfall New Member

    wisconsin
    Joined:
    Mar 22, 2019
    Messages:
    4
    Thank you so much I will work off of this, I am sure I did something wrong along the way.
     
  4. Apr 5, 2019
    Lightfall

    Lightfall New Member

    wisconsin
    Joined:
    Mar 22, 2019
    Messages:
    4
    Hello - would there happen to be any more detailed wiring diagrams? I spent all day trying to figure out how to wire this but I am not sure which wire is which and a few combos I tried resulted in a click or an attempt to turn over, but it wasn't reproducible. I think the PO may have wired some things differently than stock. They have an amperage gauge, so I think the amp light may be bypassed or something. I think what I may have done is hooked the AMP lite (maybe?) wire (light grey) to the battery screw post on the back of the alternator.

    I am at wits end trying to figure this thing out and google is quite scarce on the subject.
     
  5. Apr 5, 2019
    Sierra Bum

    Sierra Bum Member

    The High Sierra
    Joined:
    Oct 23, 2017
    Messages:
    145
    I think your problem is that your jeep came with an externally regulated alternator and your 10si has been adapted into the original wiring and gauge assembly. Ditch the external regulator if you want to run this. You'll just confuse yourself. Sometimes its better to run new wires and start fresh. You may end up rewiring other stuff too, like your starting circuit. And lastly, if I understand correctly you have an amp gauge? Ditch that too. Get a volt meter. Amp gauges read charge current, are wired in series and defunct with a higher output internally regulated Alternator.


    This explanation may help....
    The 10si and 12si alternators have 3 wires:

    1.The large POST terminal is the charge wire. For simplicity sake you can connect it with the appropriate size wire (depending on Alt amp rating) to the + side of the battery. This is not ideal but it works. Make sure the charge wire is heavy enough. Ask if you're not sure. And you might use a fuse breaker on this wire as well..again amp rating dependent.

    2. The number "1" terminal/wire in the double pigtail at the Alt, is for the dash "charge" light. It is a ground when the engine is off or alternator is not turning. This dash light has one pole connected to this wire and one pole connected to power coming from the "ign" pole on the the ignition switch. The light will turn on when the key is turned "on"...the light then goes out when the engine starts. Basically the light loses its ground because this #1 wire is putting out juice when the alternator is working. My charge light is a little aftermarket LED. You do NOT NEED this #1 wire connected at all for the alternator to work.

    3. The number 2 terminal in the double pigtail at alt, is for the sensor wire. This wire is normally connected to the primary wire at the fuse box. It reads the output demand and tells the alternator how much juice to produce. This wire can also be looped back directly to the output post on the Alt...again this is not ideal but it works.
     
    Last edited: Apr 5, 2019
  6. Apr 5, 2019
    Sierra Bum

    Sierra Bum Member

    The High Sierra
    Joined:
    Oct 23, 2017
    Messages:
    145
  7. Apr 6, 2019
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
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    19,943
    Jeep used the 10SI in several of its models starting in 1976 IIRC. The factory manual has a thorough discussion of the theory, operation and trouble shooting of these alternators. Good stuff ... http://oljeep.com/gw/76_tsm/Section3.pdf Page 3-21 forward.

    For the external wiring, I would look at the Jeep factory diagram for 1976 and trace through the wiring so I understood it. It's also there at the Tom Collins page - http://oljeep.com/gw/76_tsm/Section22.pdf Since your Jeep came with a different alternator, you will need to understand how the circuits for the 10SI work in order to fix whatever is not wired right, now that it's been modified. There will be no "recipe" for your existing wiring.
     
    Last edited: Apr 6, 2019
  8. Apr 11, 2019
    Lightfall

    Lightfall New Member

    wisconsin
    Joined:
    Mar 22, 2019
    Messages:
    4
    Thank you again. I will pour over this material and have another go at it.
     

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