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Re: [solectria_ev] 99 Force, Looking for DC-DC converter, and brake booster pump

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  • Dexion
    I d think it more likely to just be the dc to dc. What is it putting out when it s just sitting there what s it do when you,flick on lights with high beams
    Message 1 of 3 , May 12, 2013
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      I'd think it more likely to just be the dc to dc. What is it putting out when it's just sitting there what's it do when you,flick on lights with high beams (voltage).

      Sent from my iPad

      On May 12, 2013, at 9:58 PM, "geo_homsy2" <geo.homsy@...> wrote:

      > Hi all-
      >
      > My brake booster pump and/or the DC-DC in my 99 Force is/are starting to act up. Does anyone have any extras for sale?
      >
      > in more detail, in case anyone has suggestions for me: DC drops out for maybe 1/4 second under large step changes in load. Specifically, when the vacuum brake booster pump comes on. It is possible my brake booster pump is drawing excessive current at startup. I was thinking, though, perhaps the output caps in the DC-DC have started to go bad after all this time?
      >
      > Any comments, inputs, would be welcome.
      >
      > //Geo
      > 99 Force
      > SF Bay Area
      >
      >


      [Non-text portions of this message have been removed]
    • geo_homsy2
      Mystery solved. Checking with the digital storage scope, it turned out that the voltage at the BMS was dropping from 12 to 6 when the booster pump came on.
      Message 2 of 3 , Sep 29, 2013
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        Mystery solved.  Checking with the digital storage scope, it turned out that the voltage at the BMS was dropping from 12 to 6 when the booster pump came on. Now:  WHY?


        * checked the output of the DC-DC; it had only 0.5 volts of droop when the booster came on

        * checked the brake booster motor.  It had 7 volts of droop.

        * checked the + output of the DC-DC against the ground wire at the booster pump.  About 1 volt of droop

        * checked the - output of the DC-DC against the + wire at the booster pump.  About 7.5 volts of droop


        Conclusion: resistance somewhere in the wiring harness was causing the voltage at the booster pump to droop, and most of the rest of the 12 volt system is AFTER this resistance.


        Some careful staring at the Geo Metro wiring manual failed to turn up what fuse, exactly, the booster pump was on.  For sure, it wasn't a beefy wire they chose to use to feed it.


        SO: Again consulting the Geo Metro wiring diagrams, I found an unused fuse in the under-hood fuse box, and an unused relay.  Tied the relay in to turn on when the ignition switch comes on.  Wired the relay to the unused fuse holder, and wired the booster to the relay.  Put in a 20 A fuse.


        System VERY happy now  :)





        ---In solectria_ev@yahoogroups.com, <dexion111@...> wrote:

        I'd think it more likely to just be the dc to dc. What is it putting out when it's just sitting there what's it do when you,flick on lights with high beams (voltage).

        Sent from my iPad

        On May 12, 2013, at 9:58 PM, "geo_homsy2" <geo.homsy@...> wrote:

        > Hi all-
        >
        > My brake booster pump and/or the DC-DC in my 99 Force is/are starting to act up. Does anyone have any extras for sale?
        >
        > in more detail, in case anyone has suggestions for me: DC drops out for maybe 1/4 second under large step changes in load. Specifically, when the vacuum brake booster pump comes on. It is possible my brake booster pump is drawing excessive current at startup. I was thinking, though, perhaps the output caps in the DC-DC have started to go bad after all this time?
        >
        > Any comments, inputs, would be welcome.
        >
        > //Geo
        > 99 Force
        > SF Bay Area
        >
        >


        [Non-text portions of this message have been removed]
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