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  • Unable to connect ELM327 interface (previously working)

    First off I'd like to say that this forum has been an excellent resource for my car-related pursuits and this is the first time I can't find an answer here to a problem that has really been getting the better of me.

    Around a year ago I acquired a cheap OBD-II USB interface which worked perfectly on my 2003 Ford Focus. After recently purchasing a couple of similar units, but with the newer 1.4b revision of the ELM 327, I am stumped after receiving: "SEARCHING... UNABLE TO CONNECT" errors or "NO DATA" errors even when performing a simple "0100" command.

    AT style commands work well but the unit defaults to VPW protocol on an AT SP 0 command even though I am sure my car uses PWM. Manually setting the protocol to PWM cause all sorts of trouble.

    Has anyone an idea to whether this is a hardware related problem or I am missing something very basic!

    Many Thanks

  • #2
    What sorts of "trouble"?
    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
      Sorry, I should have been more specific.

      The response varies depending on the state of the ignition. If the car is running the output is "NO DATA" otherwise it is "FB ERROR".

      I know the ELM327 datasheet believes this indicates a problem with the wiring but this is unlikely given that the OBD-II port worked fine before.

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      • #4
        That doesn't make much sense. FB ERROR means the tool cannot see what it is transmitting. NO DATA means it could see what it transmitted, but got no reply.

        Try sending ATMA with the engine running, see if you can catch any messages on the bus.

        A UK Ford may be using ISO and not PWM, so you can try hard-setting the protocol to 3 (ATSP 3).

        Unfortunately, with clones you are never sure whether the hardware is any good.

        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.

        Comment


        • #5
          Focus from 2003 is on PWM (engine unit).
          Tomas

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          • #6
            I am unable to connect when setting the Protocol to ISO 9141 which convinces me that my particular ford is PWM.

            When running the AT MA command I get "FF" which am I unsure how to interpret but assume isn't good news.

            I have eliminated the problem being due to the car's wiring as the results are replicated on my girlfriend's ford. I think my next step is to test the units on a car with a different protocol to confirm the hardware problem.

            Thanks for the help so far!

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