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reverse engineering ECU->Dash communication?

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  • Aaron Turner
    Long story short, I want to remove the dash from a 2003 Suzuki SV650 and just run an idiot light for the EFI system. (why? because it s a race bike, and I
    Message 1 of 31 , Jan 22, 2013
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      Long story short, I want to remove the dash from a 2003 Suzuki SV650
      and just run an "idiot light" for the EFI system. (why? because it's
      a race bike, and I want to use my GPX Pro dash which has a
      GPS/datalogger and having two dashes on a racing motorcycle is a bit
      much. :) The GPX Pro as great it is just a generic dash and doesn't
      know anything about my Suzuki ECU.

      So I've gone through the wiring harness and unfortunately, the dash's
      EFI idiot light isn't on a dedicated wire from the ECU.

      So apparently I need to decode the signal between the ECU to the dash,
      do some basic decoding (figure out what kind of signaling it is,
      figure out the signal for the EFI light (don't care about anything
      else, but there are other signals being sent too- it's got a basic LCD
      display for other things like engine temp, etc).

      I know this bike doesn't have a CAN bus, and there are only *two* data
      wires between the ECU and dash. One of those two wires according to
      the wiring diagram is dedicated for the Tach, so that leaves only one
      data wire- no clock or anything else so it's gotta be pretty low speed
      and simple right?

      Chips on the dash are an: OKI MSM6544 which drives the LCD (60 pins)
      and another chip I can't quite figure out. Markings are:

      12H18
      MV8790
      D

      The D has an underscore, and seems like the manufacturer marking? The
      dash assembly is apparently made by Denso, so maybe it's something by
      them? Dunno, can't find any data on it. All I do know is that it is
      a 80QFP pin package and the some of the traces go to the LCD and
      others go off to other parts of the board to capacitors and stuff like
      that.

      Lastly, There's also a clock showing 4.19 which I assume is in Mhz and
      seems to indicate that the dash is pretty slow which makes sense.

      So, that's the background. My goal is to end up programming something
      like a Teensy board to decode the signal from the ECU and turn on my
      own EFI light without the need for a dash (which is a big PCB + tach
      and LCD). Then I can always just plug in the OEM dash to read the EFI
      error codes when the EFI warning light comes on.

      That said, I'm more of a software guy (I've done some Arduino stuff
      though, driving a LCD, having two boards talk over RF, measuring
      temperature via thermistors, stuff like that) and could use some
      suggestions on how to proceed. The only diagnostic tools I own today
      are a multimeter and a BusPirate, but I keep on thinking about getting
      an oscilloscope so maybe now is the time?

      Anyways, I'm hoping for is some tips/pointers/educated guesses to help
      aid me in reverse engineering this single wire protocol between the
      ECU and dash. I assume (ha!) it's a simple digital protocol, but
      honestly I'm not really familiar with the best tools or where to
      start. I'd love it if someone wrote: "RTFM. Here's the manual:
      <link>"

      That said, if anyone has any idea what that 1-wire signaling protocol
      might look like or the best ways to view it so I can start figuring
      out how to reverse engineer it that would be great.

      Thanks!

      --
      Aaron Turner
      http://synfin.net/ Twitter: @synfinatic
      http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix & Windows
      Those who would give up essential Liberty, to purchase a little temporary
      Safety, deserve neither Liberty nor Safety.
      -- Benjamin Franklin
      "carpe diem quam minimum credula postero"
    • Aaron Turner
      Yep, EcuEditor is pretty awesome. :) Too bad they don t (yet) support the SV650 ECU. Apparently they re almost done and I won t have to run a Power Commander
      Message 31 of 31 , Feb 11, 2013
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        Yep, EcuEditor is pretty awesome. :) Too bad they don't (yet) support
        the SV650 ECU. Apparently they're almost done and I won't have to run
        a Power Commander any more. It didn't occur to me (until just now)
        that it might be able to tell the ECU to ignore the secondary throttle
        position sensor, but that would probably be pretty easy with that
        software.

        FWIW, BRG Racing (who built my motor and is doing the tuning) has used
        the EcuEditor very successfully on other bikes and prefers that to
        other solutions on the market.

        On Mon, Feb 11, 2013 at 9:52 AM, mark hubrich <meistro57@...> wrote:
        > I was just scrolling through and thought i would post this link..
        > http://www.ecueditor.com
        >
        > Probably too late but what the heck anyway ;)
        > On Feb 11, 2013 10:19 AM, "Aaron Turner" <synfinatic@...> wrote:
        >
        >> **
        >>
        >>
        >> So finalized my board design (very first board I've designed btw!) and
        >> just sent it off to OSHPark for fabrication. Unfortunately I ran out
        >> of time for the secondary throttle position emulator and so I ended up
        >> buying a commercial eliminator. Just gives me something to add in
        >> version 2.0 I guess. :)
        >>
        >> Thanks again to everyone who helped answer my questions!
        >>
        >> On Sun, Feb 3, 2013 at 8:54 AM, Aaron Turner synfinatic@...> wrote:
        >> > Just wanted to say thanks to everyone for their advice. Got this
        >> > working perfectly. :) A little challenging trying to talk at 7800
        >> > baud, but was able to hack the software library to add support for it.
        >> > Then everything pretty much fell into place. Thanks again!
        >> >
        >> > --
        >> > Aaron Turner
        >> > http://synfin.net/ Twitter: @synfinatic
        >> > http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix &
        >> Windows
        >> > Those who would give up essential Liberty, to purchase a little temporary
        >> > Safety, deserve neither Liberty nor Safety.
        >> > -- Benjamin Franklin
        >> > "carpe diem quam minimum credula postero"
        >>
        >> --
        >> Aaron Turner
        >> http://synfin.net/ Twitter: @synfinatic
        >> http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix &
        >> Windows
        >> Those who would give up essential Liberty, to purchase a little temporary
        >> Safety, deserve neither Liberty nor Safety.
        >> -- Benjamin Franklin
        >> "carpe diem quam minimum credula postero"
        >>
        >> [Non-text portions of this message have been removed]
        >>
        >>
        >>
        >
        >
        > [Non-text portions of this message have been removed]
        >
        >
        >
        > ------------------------------------
        >
        > Please trim excess when replyingYahoo! Groups Links
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        --
        Aaron Turner
        http://synfin.net/ Twitter: @synfinatic
        http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix & Windows
        Those who would give up essential Liberty, to purchase a little temporary
        Safety, deserve neither Liberty nor Safety.
        -- Benjamin Franklin
        "carpe diem quam minimum credula postero"
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