Alternator Wiring

Electrical & Ignition

  1. Landon

    Landon Member

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    I have a 69 coronet with a 440, MSD ready to run distributor, MSD 6A, HVS2 coil, dual electric rad fans, vintage air, and 30A round back alternator with old mechanical style voltage regulator. My battery keeps losing voltage after driving a while. With a meter on the battery posts, the volts go up to 12.5 or so when I rev the engine a little, so this tells me the alternator is working.

    I ordered a squareback alt with dual field terminals, and a newer "flat style" voltage regulator. I plan on running a heavy wire from BAT terminal on alternator to the battery. Do I ground the extra field wire, or do I tie it into the blue/brown wire feeding the voltage regulator? I've heard both answers. My MSD box 12v IGN wire, distributor 12v IGN wire, factory blue "run" wire, and factory brown "start" wire all connect to line side of voltage regulator. Is this correct?

    I also have a violet wire going from BAT terminal on alternator to the horn relay per wiring diagram, is this needed?
     
  2. vance.dykes

    vance.dykes Well-Known Member

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    • Nacho-RT74

      Nacho-RT74 Well-Known Member

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      if you didn't changed the wiring, will need to modify it. Electronic "flat" regulator feeds the ground throught the green wire to one of the alt fields while ign switch feed the other field with positive. This is diff than earliers where the regulator sends positive to the earlier alt field system and the other brush is grounded.

      latealtconversion2b.jpg





      Violet wire is the feed for the horns when you trigger horns from steering wheel... it needs to be there


      about the MSD system, you can splice all ballast wires together and remove ballast or jump ballast with a jumper wire between terminals... or also modify the ballast removing the resistor on back and replacing it a wire into the groove. That will make to keep the stock look in front and remain the harness untouched on that ( pics of this attached )

      343795-724e4074a3c1ee37c758f504ba1a54a6a.jpg 343796-8aeb8f6f7c9edb5084df6004233172f6a.jpg

      if you were to use just the MSD Box, even remove or jump the ballast is adviced, could work with the wire originally running to + lead of coil still with ballast in line, but if you are using the RTR MSD distribuitor along with the box, will need to bypass, jump or modify the ballast to feed the dist anyway.
       
      Last edited: Jul 26, 2020
    • RJRENTON

      RJRENTON FBBO Gold Member FBBO Gold Member

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    • Nacho-RT74

      Nacho-RT74 Well-Known Member

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      I went just for the basics to let him know how wire it to make it work because he sure has missed the full sistem conversion. Sure there is allways more and deeper technical information behind that.

      nobody on last 5 days had posted why it wasn't work, I just told him how to wire it to make it, colored diagram included
       
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      • Landon

        Landon Member

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        can I ground one of the leads on my squareback alt. and connect the other lead to the green or blue lead from the new "flat" voltage reg??
         
      • Nacho-RT74

        Nacho-RT74 Well-Known Member

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        NO... as mentioned, you need to wire it like on diagram

        ground the brush on dual field alt works just if using the old mechanical regulator designed for single field alt ( stock pre 70 setups ) getting just one wire, but "flat" electronic regulator works totally diff, hence the reason why wire both fields on alt are isolated and need to be wired
         
        Last edited: Jul 27, 2020
      • Landon

        Landon Member

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        aaaah I gotcha now! What is the difference in the "flat" regulator and the flat blue regulator that puts out 13.5 V "constant"??
         
      • Nacho-RT74

        Nacho-RT74 Well-Known Member

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        one regulates according to te car needs and the other one it gets a fixed voltage rate, designed for Race purpouse. I guess that's all. But both works on the same way and are wired the same
         
      • Nacho-RT74

        Nacho-RT74 Well-Known Member

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        I guess you meant between these

        dcc-4529794_ml.jpg
        dcc-3690731_ml.jpg


        and not with this:

        yIoQK1HUSG_IZ7A7nTKbWK-CU_GzjCNPF4DP9BBLiNsJXb6rvkS606BhByLYgm603_rhAZM2hUJYPWZS10xxy6Gccj1lVtdi.jpg
         
      • Landon

        Landon Member

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      • RJRENTON

        RJRENTON FBBO Gold Member FBBO Gold Member

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        NO....The BLUE wire provide the electronic voltage regulator the system's reference voltage of the voltage present at the battery AND the switched source from the ignigion switch. The GREEN wire RETURNS the current psth from the alternators field.....blue wire power going in TO the alternators the GREEN wire, via the alternator regulator to GROUND, thru the internal transistors. IT HAS NOTHING TO DO WITH RACE PROPOSES AS STATED.
        NACHO....you need to not to explain or exemplify sonething that is incorrect....if you do not understand the how the system operates.....just ask.
        BOB RENTON
         
      • Nacho-RT74

        Nacho-RT74 Well-Known Member

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        Bob, he is asking about the blue regulator, not the wire
         
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        • Nacho-RT74

          Nacho-RT74 Well-Known Member

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          same purpouse than the middle one but for single field wire on pre 70 cars with factory setup...
           
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          • Landon

            Landon Member

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            So I will run the BAT post on alternator to the ammeter (with a fusible link), run one spade to the green lead on the regulator, and the other spade to the blue lead on the regulator.

            Will it cause issues if I have the following ALL tied into the blue wire lead on the regulator:
            factory blue (run) wire
            factory brown (start) wire
            one of the alt. leads
            MSD small red
            Dist. small red

            Does the regulator have to have the blue run wire, or can i bring 12v ign to it from somewhere else like the wiper motor?
             
          • Nacho-RT74

            Nacho-RT74 Well-Known Member

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            no fuse link between alt and ammeter. Fuse link goes just on batt side ( between starter relay and ammeter ). Rest, yes!

            splice ballast wires all together and on same point, the MSD wires. The alt field lead can be spliced on same reg plug as I explain next ( and shown on diagram )


            regulator plug get green and blue wires. Splice existant blue and green wires on the new regulator plug, and an extra blue wire running to alt.

            mopar-voltage-regulator-repair-plug-pig-tail-connector-chrysler.jpg

            wiper motor blue wire is a very diff source.
             
            Last edited: Jul 27, 2020
          • Landon

            Landon Member

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            so the regulator needs the blue (run) wire, it can't have 12v ignition hot from somewhere else?
             
          • Nacho-RT74

            Nacho-RT74 Well-Known Member

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            why think on a diff source if already have one ?!!!

            you only need to run a new blue wire between the existant one and the alt prong. On same point, splice the new plug too
             
          • Landon

            Landon Member

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            i want to know if i can bring 12v ign source to the regulator from somewhere else, will it still work properly or does it have to be THAT wire?

            i want to tie blue (start) and brown (run) together, & connect to MDSred/distributor red. Then get 12v ign to the regulator from a IGN hot source on the wiper motor, and tie in my 2nd alt. wire to those...?
             
          • Nacho-RT74

            Nacho-RT74 Well-Known Member

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            I already told.
             
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