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Odometer stepper motor twitching, not spinning...

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    Odometer stepper motor twitching, not spinning...

    So, I'm attempting to repair a VDO speedometer, but I just can not get it to drive the odometer.

    Here's what a good one (aside from all the missing teeth on the gears) looks like:
    http://youtu.be/d-eSvNBlrSE

    Here's what the other one is doing:
    http://www.youtube.com/watch?v=XZkH8jANnHc&feature=plcp

    Unfortunately, it's not a simple mechanical issue with the gears. It just sits there twitching even if I remove a gear:
    http://www.youtube.com/watch?v=XZkH8jANnHc&feature=plcp

    Any thoughts on what is going on here?
    2006 GMC Sierra 2500HD 4WD LBZ/Allison
    2002 BMW M3 Alpinweiß/Black
    1999 323i GTS2 Alpinweiß
    1995 M3 Dakargelb/Black
    - S50B32/S6S420G/3.91
    1990 325is Brilliantrot/Tan
    1989 M3 Alpinweiß/Black

    Hers: 1996 Porsche 911 Turbo Black/Black
    Hers: 1988 325iX Coupe Diamantschwartz/Black 5spd

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    #2
    Your last two videos seem to be the same. If the odo gear fails to move freely (will all other gears removed, unloaded) then something else is wrong.

    Perhaps you are using the incorrect signal to drive the speed input?
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      #3
      could be a component on the speedo PCB. the quality of the VDO board is pretty crummy - it's got a really awful 16v capacitor that's probably toast by now, and some other equally flaky components. you could try to rebuild the whole thing, would cost probably $5-$10 in components and your time to solder them.

      the UAF 2115 chip that controls the speedo/odo is pretty robust/common, but everything else is crap (especially the PCB). could be a broken solder joint or trace, and even a cracked PCB wouldn't be a surprise.

      this is the janky capacitor I speak of:


      I replaced one with a modern 50v equivalent.
      Build thread

      Bimmerlabs

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        #4
        Originally posted by nando View Post
        could be a component on the speedo PCB. the quality of the VDO board is pretty crummy - it's got a really awful 16v capacitor that's probably toast by now, and some other equally flaky components. you could try to rebuild the whole thing, would cost probably $5-$10 in components and your time to solder them.

        the UAF 2115 chip that controls the speedo/odo is pretty robust/common, but everything else is crap (especially the PCB). could be a broken solder joint or trace, and even a cracked PCB wouldn't be a surprise.

        this is the janky capacitor I speak of:


        I replaced one with a modern 50v equivalent.
        Yeah, I've replaced the capacitor and resoldered the joints. I guess that I need to go over the solder traces.
        2006 GMC Sierra 2500HD 4WD LBZ/Allison
        2002 BMW M3 Alpinweiß/Black
        1999 323i GTS2 Alpinweiß
        1995 M3 Dakargelb/Black
        - S50B32/S6S420G/3.91
        1990 325is Brilliantrot/Tan
        1989 M3 Alpinweiß/Black

        Hers: 1996 Porsche 911 Turbo Black/Black
        Hers: 1988 325iX Coupe Diamantschwartz/Black 5spd

        sigpic

        Comment


          #5
          Originally posted by Gregs///M View Post
          Your last two videos seem to be the same. If the odo gear fails to move freely (will all other gears removed, unloaded) then something else is wrong.

          Perhaps you are using the incorrect signal to drive the speed input?
          The signal is tested good on a Motometer and a VDO cluster, so I presume that it's fine.

          Here is the correct link to the fully unloaded video:
          http://www.youtube.com/watch?v=cUUyS...=ULd-eSvNBlrSE
          2006 GMC Sierra 2500HD 4WD LBZ/Allison
          2002 BMW M3 Alpinweiß/Black
          1999 323i GTS2 Alpinweiß
          1995 M3 Dakargelb/Black
          - S50B32/S6S420G/3.91
          1990 325is Brilliantrot/Tan
          1989 M3 Alpinweiß/Black

          Hers: 1996 Porsche 911 Turbo Black/Black
          Hers: 1988 325iX Coupe Diamantschwartz/Black 5spd

          sigpic

          Comment


            #6
            After swapping circuit boards and getting irritated, I took a brute force approach. As it turns out, swapping the M3 needle and face plate onto a Motometer speedo and then recalibrating it is a hell of a lot easier than worrying about this VDO shit.
            2006 GMC Sierra 2500HD 4WD LBZ/Allison
            2002 BMW M3 Alpinweiß/Black
            1999 323i GTS2 Alpinweiß
            1995 M3 Dakargelb/Black
            - S50B32/S6S420G/3.91
            1990 325is Brilliantrot/Tan
            1989 M3 Alpinweiß/Black

            Hers: 1996 Porsche 911 Turbo Black/Black
            Hers: 1988 325iX Coupe Diamantschwartz/Black 5spd

            sigpic

            Comment

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