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Thread: Doing more with OBD

  1. #11
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  2. #12
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    This is fantastic. Exactly what I was looking to do in my Vaxhaul Astra (also GM I think)

    So what presses are you using to get say the steering wheel controls? Do you simple run hyperterminal and press the buttons and see what command is generated?

  3. #13
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    Hi Rickersten2 (I apologize if this gets to you twice, but I also sent it through a PM)

    I have a 2004 CTS-V with Onstar. I'm in the process of trying to install a Bluetooth setup that I would like to incorporate into the radio. On my car, though, unlike many of GM's other cars, there is no 'Mute' line into the radio to switch it into 'Onstar' mode. Instead, Onstar uses the serial bus to switch the radio and amplifier into Onstar mode and then the mono Onstar audio is fed through the amp.

    I plan to create a circuit that will replicate these messages and allow me to relay the bluetooth audio through the amp using the Onstar features, but it means I need to snoop the bus line and determine the Onstar message data so I can reproduce it. I'm very interested to learn how you are using the Elmscan 5 to snoop the bus and decipher one message over all the other traffic that I assume is going through the bus. It would be relatively easy for me to sit in the car with the engine off and just hit the onstar button a few times to find the repeating code - but is that how you go about it?

    I'd love to hear about what you've learned and how you've snooped the codes out.

    Thanks!!!!!
    -Chris Bruno
    [email protected]

  4. #14
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    Quote Originally Posted by srracer View Post
    I plan to create a circuit that will replicate these messages and allow me to relay the bluetooth audio through the amp using the Onstar features, but it means I need to snoop the bus line and determine the Onstar message data so I can reproduce it.
    This could help:

    http://www.i-hacked.com/content/view/15/45/
    :: Mark

  5. #15
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    Just came across this... it looks to do more than the Elmwood unit, but I can't be sure...

    http://www.obdpros.com/

    There's even some documentation to control the windows and such over the OBD port and it's a bit cheaper....
    2005 Saturn Ion Redline - Yes it's a Saturn, yes it's fast, yes it's on a race track in the pic.

    Moderator RedlineForums.com - eager CarPC Noob.

  6. #16
    Variable Bitrate xs10x's Avatar
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    Quote Originally Posted by Sp00ner View Post
    Just came across this... it looks to do more than the Elmwood unit, but I can't be sure...

    http://www.obdpros.com/

    There's even some documentation to control the windows and such over the OBD port and it's a bit cheaper....

    Awesome unit. I have it intergrated in my truck running different OBD programs.
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  7. #17
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    Quote Originally Posted by Sp00ner View Post
    Just came across this... it looks to do more than the Elmwood unit, but I can't be sure...

    http://www.obdpros.com/

    There's even some documentation to control the windows and such over the OBD port and it's a bit cheaper....
    pssssst... The dude was here a bit ago looking for beta testers:

    New OBDII scantool - Beta testers?

    Looks like a nice box.

    Keep in mind though, that you shouldn't _expect_ to be able to control your windows via OBDII. That's a manufacturer/implementation specific extension.
    :: Mark

  8. #18
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    Sweet! I'm ordering one now. The process on finding the window down message was exactly what I was looking for. Now, once you know the message, has anybody figured out a cheap way to hard code that into a BASIC stamp or some low buck microcontroller?

    Thanks!!!
    -Chris

  9. #19
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    Quote Originally Posted by srracer View Post
    Sweet! I'm ordering one now. The process on finding the window down message was exactly what I was looking for. Now, once you know the message, has anybody figured out a cheap way to hard code that into a BASIC stamp or some low buck microcontroller?
    Are you talking about sitting directly on the data lines and _not_ using something like an ELM327 chp to do the decode for you? You might wanna take a look at the ELM327 datasheet and get an idea of what's in that chip. There's a reason that not too many folks are trying to sit on the datalines themselves.

    Now, if you're talking about dropping a PIC or a STAMP in front of an ELM, then that's "easy". All you need to do is to mock up whatever the "AT" commands work out to be. I haven't looked real close at the command set (it's in the data sheet above) so I'm not sure what kind of "free" access you'll get to the wire.
    :: Mark

  10. #20
    VENDOR - OBDPros
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    Quote Originally Posted by srracer View Post
    Sweet! I'm ordering one now. The process on finding the window down message was exactly what I was looking for. Now, once you know the message, has anybody figured out a cheap way to hard code that into a BASIC stamp or some low buck microcontroller?

    Thanks!!!
    -Chris
    Chris,

    As midiwall mentioned, the window down message that I decoded was specifically for a 2006 GM trailblazer, now most of the time looks like GM tries to reuse the same message set's in their vehicles, but there is no guarantee that you would find a similar message on another GM vehicle - you would need to monitor the bus like I was doing and figure it out.

    I have been able to trace a bunch of other J1850 VPW messages on the class II bus on GM vehicles and will post the info on www.obdpros.com/yabb in the next couple of weeks.

    Also the fact that it works on GM does not mean that Ford would do something similar, I think ford hardwires the window controls so there are no software commands for the windows, I did try monitoring a 2004 Ford explorer but no joy.

    As far as a cheap way to hook up a micro, for the J1850 VPW there is a bunch of code out there that you could use if you wanted to directly connect to the class II lines (of course as midiwall mentioned if you wanted to hook in front of the OBDPro that is extremely easy)

    For direct access to class II take a look at these projects

    http://www.mictronics.de/?page=j1850_vpw

    There are also other similar projects I think circuit cellar had someone do j1850vpw as a contest project.


    Paul
    www.obdpros.com

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