There is a problem with the transmission 'P' lock mechanism. Park your car your car on a flat surfac

Discussion in 'Gen 2 Prius Main Forum' started by Balta, May 3, 2021.

  1. Balta

    Balta New Member

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    Hey how are you doing guys I’m having a problem with my Prius 2008 I get this message There is a problem with the transmission 'P' lock mechanism. Park your car your car on a flat surface and fully apply the parking brake When I’m driving but I don’t notice any change on this speed nor any other change Keep in mind that this is happening when I’m driving in the message disappears and sometimes comes back for a few seconds
     
  2. jkisf

    jkisf Junior Member

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    Did you leave your door open?
     
  3. ChapmanF

    ChapmanF Senior Member

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    The car isn't able to confirm that the parking pawl in the transmission has been pulled all the way out or that it is reliably moving from in to out.

    Since you are able to move the car, obviously the pawl is pulled mostly out. That might be ok as long as it stays that way while you're driving. If it is somewhere near the tipping point of the detent spring and anything jolts it to drop back into the transmission while you are rolling down the road, that could be ... dramatic.

    The cause could turn out to be just something like oxidation on an electrical connector in the park actuator circuit. Maybe the pawl has actually been retracted all the way and there isn't any mechanical risk, and the computer just isn't getting good signals to confirm it. But if I had a choice between looking at it sooner or looking at it later, I think I'd look at it sooner.
     
  4. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    As folks mention, it could be a 'real' fault, but in my experience it is just a symptom of a weak battery.

    When you power that car down without shifting to P first, after the engine stops, the parking Pawl should be motored into place by a small electrical motor. If the 12 volt battery is dead enough, it can't power that motor unless you are in Ready. (P, then Power down, instead of just Power down)

    If so, you replace the 12v Battery and the whole Parking pawl issue goes away.

    I would test the 12 v battery first. The best way is to measure voltage in a morning before you go to Ready.
     
  5. ChapmanF

    ChapmanF Senior Member

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    Also on that note, if you have access to Techstream, you can ask the transmission control ECU what the issue is, and if it is supply voltage it will say that. There will even be freeze-frame data available showing what the relevant voltage was.

    Because that's measured at the ECU, if it is reported low, there is also a possibility that a wiring or connector problem is involved, rather than battery.

    What makes this case interesting is that the issue is being reported (and apparently withdrawn, and reported again) all while driving. Typically, the car is in READY when being driven and the system voltage is what the DC/DC converter outputs.
     
  6. bisco

    bisco cookie crumbler

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    did you try placing your car on a flat surface and engaging the parking brake?
     
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