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Thread: 6.5 Alternator question

  1. #1
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    Default 6.5 Alternator question

    Is this prong on the 6.5 isolated ground or a positive terminal?


  2. #2
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    Positive charge lug off the rectifier. The alternator is grounded through the housing.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  3. #3
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    Quote Originally Posted by DmaxMaverick View Post
    Positive charge lug off the rectifier. The alternator is grounded through the housing.
    Ok thanks! Does the 6.5 tach reading come from the alternator?

  4. #4
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    Yes. It also makes the pulley size (crank and alt.) critical to accuracy.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  5. #5
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    Quote Originally Posted by DmaxMaverick View Post
    Yes. It also makes the pulley size (crank and alt.) critical to accuracy.
    Ok. The 4 wires that are on the connector, what do they do? Color codes?

  6. #6
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    I can't help without a specific application and a diagram, and I have neither. Typically, the alternators are either 2 or 4 wire connectors (4 place, with only 2 used, in the 2-wire). One is the field exciter, the others are for voltage regulation and the tach (if the correct application). I don't know the colors, but I bet google does.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

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