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Relay to cut power to ElmScan?

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  • Relay to cut power to ElmScan?

    Hi folks,

    I searched. Concerns over the 'always-on' LED on the ElmScan interface tend to draw responses that go a little something like this:

    This little light of mine,
    I'm going to let it shine!


    I guess that's fine for some folks, but I'm not really keen on knowingly introducing a constant power drain into my system, no matter how small. Has anyone ever tried to use a relay to cut power to the ElmScan when the car PC is off? I imagine this would involve intercepting the appropriate lead in the supplied cable, but I don't know enough about cable shielding and such to know if this would have any unintended consequences.

    Any insight would be appreciated.
    -
    8^{D>

  • #2
    OBDII communication is done at a ridiculously slow data rate and does not involve any large power signals or anything like that, therefore wire shielding is not very important for it. however, it would probably be easiest to simply modify the board itself, by finding the power trace and cutting it, and soldering wires to each piece and then to the relay.

    or if you really want to be non-invasive, get a male and a female DB-9 connector from radio shack or somewhere, and build yourself a little short pass-through cable that can be plugged in between the elmscan board and the OBD cable, that passes all the wires straight through pin-for-pin except intercepts the power wire.
    But don't take it from me! here's a quote from a real, live newbie:
    Originally posted by Viscouse
    I am learning buttloads just by searching on this forum. I've learned 2 big things so far: 1-it's been done before, and 2-if it hasn't, there is a way to do it.
    eegeek.net

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    • #3
      Say, that's a good idea! Non-invasive is good.

      Thanks for the speedy response!
      -
      8^{D>

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      • #4
        I couldn't see the draw close to what an alarm does. Digimoto wheres the current draw spec.
        Setup:
        Dynaudio 240GT
        PPI PC4100, PPI PC2350
        Zapco DSP6
        ADS DAC
        Testing new board (Albatron KI690-AM2)

        "I dont know if complaints were filed, or mistakes were made, but feelings were hurt." -Krystal Washington

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        • #5
          Does this help you guys?

          http://www.elmelectronics.com/DSheets/ELM320DS.pdf
          Joel Konecny
          Digimoto OBDII Diagnostics

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          • #6
            I have another diagram of the board laying around here somewhere... I'll search for it today.
            Joel Konecny
            Digimoto OBDII Diagnostics

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            • #7
              I'm curious about this too. Are most people just leaving their ELM connected?

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