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OBD2 Power

Discussion in 'Prius v Technical Discussion' started by Air_Boss, May 29, 2023.

  1. Air_Boss

    Air_Boss Senior Member

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    Quick question: Is the OBD2 port powered (live) when the car is off (prior to pressing START button, after shutting down with START button, systems not at READY)?

    Situation: On the 2012 v Five, I have a sensor attached to the OBD2 port whose LCD display of engine and systems parameters has recently decided to stay on, powered after the car has been shut down.
     
    #1 Air_Boss, May 29, 2023
  2. rjparker

    rjparker Tu Humilde Sirviente

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    Powered up all the time. Some smart devices monitor the voltage level and sleep below 13v. That is not always reliable, so my P10 monitor also watches for rpm and will sleep after a period of minutes without rpm.
     
    #2 rjparker, May 29, 2023
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  3. Mendel Leisk

    Mendel Leisk Patron saint of newly poured sidewalks

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    Memory saver cables (for maintaining 12 volt when swapping batteries) take advantage of the constant-on 12 volt in the OBD port, have just the 12 volt pins.
     
    #3 Mendel Leisk, May 29, 2023
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  4. jzchen

    jzchen Newbie!

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    Googling it says pin 16 is 12 V always on.
     
    #4 jzchen, May 29, 2023
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  5. ChapmanF

    ChapmanF Senior Member

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    If I remember right, the ScanGauge II had a "hybrid mode" I could select during setup, so it would not go to sleep every time the engine stopped.

    But I set it up a long time ago, so I might not remember right.
     
    #5 ChapmanF, May 29, 2023
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  6. Air_Boss

    Air_Boss Senior Member

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    It’s a P10 that is staying on. Just changed the 12V battery, whose resting voltage is below 13v. (Didn’t happen with the six year old end of life battery.)
     
    #6 Air_Boss, May 30, 2023
  7. rjparker

    rjparker Tu Humilde Sirviente

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    There are several adjustments. I believe I set the off timer to 180 seconds, verified it did not have a speed offset and set it for one of the protocols as listed in step 10 in pdf.

    IMG_0276.jpeg IMG_0277.jpeg
     

    Attached Files:

    #7 rjparker, May 30, 2023
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  8. Air_Boss

    Air_Boss Senior Member

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    Thanks. Good thoughts. Perhaps it reset itself when the original 12V aux battery went dead-dead.
     
    #8 Air_Boss, May 30, 2023
  9. CR94

    CR94 Senior Member

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    I believe you had it right; it functions while the engine is stopped. However, my ScanGauge II shows phantom fuel consumption when the car is coasting with injectors and ignition off, so the fuel consumption-related data it shows is not credible. For the same reason, the fuel calibration procedure shown in the manual never settles on any one value as it should.
     
    #9 CR94, May 30, 2023
  10. Air_Boss

    Air_Boss Senior Member

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    It is a P12, which somehow reset itself to factory. Once customized, works fine again.
     
    #10 Air_Boss, Jun 1, 2023
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