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Thread: Vacuum pump wiring.

  1. #1
    Join Date
    Jul 2010
    Location
    Leland, NC
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    828
    My Cars
    85 €735i 08 550i/6

    Vacuum pump wiring.

    Am I only supposed to have two wires going to the vacuum pump? I have power going to the pump but can't get it to cut on. I have a different pump that won't cut on when plugged in.

  2. #2
    Join Date
    Mar 2007
    Location
    Quadratechtown, PA
    Posts
    741
    My Cars
    5, 7, 4x4
    The round plug should have voltage on car start up and other times, too, but will turn off if the vacuum demand of the HVAC system is met by the engine vacuum. It is a part time vacuum at best if it even works. The pumps can die and then they don't cut at all. Check the resistance of the vacuum motor to see if it is burned up vs. stuck and not moving. Both do not allow the motor to cut on.

  3. #3
    Join Date
    Jun 2010
    Location
    TX
    Posts
    4,487
    My Cars
    1983/84/85 745i

    Thumbs up

    Yep two wires, brown and a green one. Brown grounds at that main bolt at the base of fuse box, green is that small square plug by paint code.

    Chances are, the bearing is seized due to 100% duty cycle... this is not how it is designed. It runs always due to major system leaks.
    I make E23 parts.
    09/1983 745i (stolen spring '13 around Houston, TX Achatgruen on nutria buffalo. 8481080)
    10/1984 745i
    11/1984 745i
    11/1984 735i (10:1-265/6)
    Ford, MB, and GM round out the pack.



  4. #4
    Join Date
    Jul 2010
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    Leland, NC
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    828
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    85 €735i 08 550i/6
    That's what I figured happened. I bought a used one on eBay that is probably bunk as well.

  5. #5
    Join Date
    Apr 2004
    Location
    Hamburg, NY USA
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    e23, e32, e34, e39
    There's supposed to be a Ford truck that uses the same pump, I'll have to see if I can find the post.

    - - - Updated - - -

    There's supposed to be a Ford truck that uses the same pump, I'll have to see if I can find the post.

    http://bimmerboard.com/forums/posts/1085678

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