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Toyota OBD output signal

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  • Toyota OBD output signal

    can anyone tell me whats the output of OBD-II in normal condition, let say i make a cable which is OBD-II to RS232 converter. and i attach this cable to OBD-II socket J1962, what will i be getting on RS232 end on these conditions.
    1. engine off
    2. ignition on engine off
    3. engine on

  • #2
    If you mean a "dumb" converter (like the old VAG-COM optocoupler-based design), you won't see anything.

    If you mean a smart converter (e.g., ELM327-based or similar), then you may see some traffic if there is more than one ECU and the protocol allows it (i.e., it's J1850 or CAN).

    Usually there is no OBD traffic when the engine is off, and everything comes alive once you turn the ignition on (regardless of whether the engine is running or not).

    Vitaliy
    OBDLink MX: world's smallest, fastest, most advanced OBD/Bluetooth adapter with SW and MS CAN support. Read the review to learn more.
    Need to look up a diagnostic trouble code? Try the most up-to-date, free DTCsearch.com!

    You cannot send me a private message using this forum. Use my email instead: vitaliy[@]scantool.net.

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    • #3
      i just want to use a simple cable OBD to RS232 using transistors (only to convert signal level). is there any signal on this cable with ignition ON.
      im talking about Toyota and i guess its ISO 9141-2 there in toyota

      Comment


      • #4
        Originally posted by osqureshi View Post
        i just want to use a simple cable OBD to RS232 using transistors (only to convert signal level). is there any signal on this cable with ignition ON.
        im talking about Toyota and i guess its ISO 9141-2 there in toyota
        Yes there will be a signal, but it will not be compatible with serial data streams. This is sort of like taking your blender, chopping off the power cord, soldering on an HDMI connector, plugging it into your TV and expecting to get HD cable channels through it.

        A connector does not convert the data, it is just a means of connecting.
        Fusion Brain Version 6 Released!
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        • #5
          r u saying that i cannot communicate with OBD-II having protocol ISO 9141 by connecting it with serial port.??
          i think OBD-II output (J1962) must be converted to RS232!!!!

          Comment


          • #6
            Think of it this way...

            Your car speaks Japanese and your computer only speaks Swahili. Yes you can connect them together, but they will have no idea what the other is saying. You need a translator like Vitaliy said (like an ELM chip).

            So: Car <-> Translator <-> Computer
            Fusion Brain Version 6 Released!
            1.9in x 2.9in -- 47mm x 73mm
            30 Digital Outputs -- Directly drive a relay
            15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
            Buy now in the MP3Car.com Store

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            • #7
              ok
              tell me how to communicate with it having ISO 9141???

              Comment


              • #8
                Originally posted by osqureshi View Post
                ok
                tell me how to communicate with it having ISO 9141???
                Buy an OBDII scanner
                Fusion Brain Version 6 Released!
                1.9in x 2.9in -- 47mm x 73mm
                30 Digital Outputs -- Directly drive a relay
                15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
                Buy now in the MP3Car.com Store

                Comment


                • #9
                  hhahahahah....
                  nice solution..
                  actually i dont want a scan tool.
                  i want to communicate with OBD-II only by interfacing with some microcontroller.
                  tell me how to interface microcontroller with OBD-II???? without ELM chips.
                  is it possible?

                  Comment


                  • #10
                    plz check this link.
                    http://hem.passagen.se/tomasf/obd2/

                    can i use this cable to simply connect my microcontroller with OBD-II
                    or i must need some extra arrangements. ??/

                    Comment


                    • #11
                      seriously? you should consider your source of info...



                      no way id let something like that touch my obd port or computer. who ever this guy is does not even bother spending $1 on a board. that picture looks like the equivalent or randomly sticking paper clips in a light socket. IMHO

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