Four wire Alternator

Discussion in 'Subaru Legacy' started by JCullen, Jun 6, 2021.

  1. JCullen

    JCullen

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    I am using a four wire alternator from a 2010 Legacy GT 2.5 turbo on a project car. Can anyone tell me or show me on a diagram which of the four wires are which and what they connect to?
     
    JCullen, Jun 6, 2021
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  2. JCullen

    remy6908

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    I dont see a four wire alternator connection in the wiring diagrams. Are you sure its for a 2010 Legacy GT?
     
    remy6908, Jun 12, 2021
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  3. JCullen

    JCullen

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    That is what I ordered. I am building a car using a Subaru Legacy GT 2.5 turbo and need to wire up the alternator before I try to start up the project.
    The alternator I received has a three wire plug (pretty standard 3 wire plug) plus the is a larger stud with nut near the 3 wire connector. That stud is insulated from the case as if a wire is to connect to it. I am assuming that goes to the battery positive but I am not familiar with all of the newer charging systems that use an internal regulator.
    My engine management is an expensive ECU and Dash so I am concerned about sending a surge voltage to my electronics.
    So it appears there are four alternator connections. I will try to attach a photo.
     

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    JCullen, Jun 13, 2021
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  4. JCullen

    JCullen

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    My project car using a 2.5 turbo from a 2010 Subaru Legacy GT
     

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    JCullen, Jun 13, 2021
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  5. JCullen

    remy6908

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    That makes a little more sense. So it is a 3 wire plug with the stud being standalone. The stud is for the battery. The 3 wire plug is for starter, ignition trigger and ground. That thing is awesome by the way. What is it going to be used for?
     
    remy6908, Jun 14, 2021
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  6. JCullen

    JCullen

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    I am 75 yr old and have been a car guy since I can remember. It has only been in the last 15 years that I have able to build my dream car. At 16 I commented many times I wanted a car that I could put on like a pair of pants and it would go like a rocket. Muscle cars never wound my watch. I will autocross with it some and make it street legal.
    I started with Mazda RX8 subframes, built my own chassis and body. New short block and rebuilt everything else.
    I have built, and or restored many VW bugs through the years but two cars I had not done. This pants rocket and a Model A Ford pickup hot rod. I built the Ford in 2017-18 The Ford has Miata subframes, 4 whl disc, rack & pinion etc. Did have a Miata power train but no aero so put in a 2.3 turbo from an 85 T-bird. Fast now. Handles great.
    The 71 bug is the last one I did. I gave it to my wife for her 70 th and our 50th.
    Thanks for the info. I was thinking the stud was the battery feed but I have about 3K in the electronics and don’t want to fry that.
    I never dealt with these alternators that have the internal regulators so I appreciate the help there.
    JCullen DD416EBB-6ABF-429A-8FCF-B67A9AE5C983.jpeg B0DDF008-EA82-4A6A-9646-1F90360780B8.jpeg CCEE0E85-88F7-479E-9851-307AACA06005.jpeg
     
    Last edited: Jun 14, 2021
    JCullen, Jun 14, 2021
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  7. JCullen

    JCullen

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    4780F984-CEA8-443C-AB30-B24C03548251.jpeg C2859983-8799-407B-A779-3356DCE2C3B7.jpeg Here it is with body panels.
     
    JCullen, Jun 14, 2021
    #7
  8. JCullen

    remy6908

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    That is awesome. You sir have lived the life most of us dream to live. I have been building a 944 for over 10yrs and hopefully will complete soon. Good luck with your build, I hope its just as much fun to drive as it looks.
     
    remy6908, Jun 14, 2021
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  9. JCullen

    JCullen

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    I love your quote of Samuel Johnson.
    There is wisdom in age and in words.
     
    JCullen, Jun 14, 2021
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