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Is there a Neutral Safety switch on a prius?

Discussion in 'Gen 2 Prius Main Forum' started by PriusWolf, Dec 21, 2012.

  1. PriusWolf

    PriusWolf Junior Member

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    Okay so I have a dead prius.
    Its stuck on a trailer right now and there is no electricity at all due to the front end being taken apart.
    So is there ANY way to put the car into neutral without power?
     
  2. nh7o

    nh7o Off grid since 1980

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    The only thing keeping the car from rolling is the parking pawl. Remove that, and the planetary gears are free to spin.
     
  3. PriusWolf

    PriusWolf Junior Member

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    what is the parking pawl?
     
  4. nh7o

    nh7o Off grid since 1980

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    It's a small motor/gear on the side of the transaxle case that pushes a wedge into the output gear of the planetary gear set. It comes on automatically at shut down, so there is no way to have the car not in park when it is off. You either have to power the car up, or take off the parking pawl assembly, or supply power to the parking pawl motor.
     
  5. dorunron

    dorunron Senior Member

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    Drastic Measures! Or do what the tow truck drivers do, put oil/soap whatever on the tires and the surface of the trailer, then drag the Prius off with tires squealing. If you had a dolly like the tow trucks have, you could raise the front end, roll the dolly under it, and then the Prius could roll on the dolly and the rear tires as long as the parking brake is off. Either get the front tires off of the ground, or undue the pawl. If you drag it off, you may cause more problems later on.

    If you do follow the advice I gave, I will not be responsible for any damages that may be caused by this action. Remember that this is what I would consider a drastic or last ditch effort. (dragging with tires locked)

    If I was to give you my honest answer, it would be this. The exact opposite of how the Prius was put on the trailer to begin with. I am guessing it was already disabled when the car was loaded on the trailer.

    Ron
     
  6. Jason dinAlt

    Jason dinAlt Member

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    You might think about these as a simple solution: [​IMG]
     
  7. dorunron

    dorunron Senior Member

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    Better than dragging it off, same principle as the dolly I suggested. Nice looking skid rollers.
     
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    Getting sarcy, just picturing a PIP purchase getting rung up:

    "Ok, you'll be needing your skid rollers, for when you want to move the car around the driveway when it's turned off. Oh, and you'll be needing a temporary (or full size) spare thrown in the hatch area."
     
  9. fuzzy1

    fuzzy1 Senior Member

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    Shorter answer: it is what the Park position of any automatic transmission uses to lock the wheels.
     
  10. dorunron

    dorunron Senior Member

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    Technically speaking, it is a metal wedge that engages into a gear inside the transmission when the gears are not moving. This in turn locks the drive wheels to keep the car stationary. It generally has a spring on it which will allow the pawl to chatter if you (click click click, then sudden stop when the car gets slow enough) put the tranny in park while the car is rolling. The Prius will not engage Park unless the car is standing still or moving very slow. If you were to hit the P button while going down the road, the tranny will shift into N rather than P. Toyota thought that one out just in case some one happened to push the big P when trying to hit a button on the dash. It is not a good idea to try to engage the pawl when the car is moving as it does cause excessive wear on internal parts, and can damage the tranny over time. As stated earlier, it is engaged electronically therefore you must have some sort of power to disengage it (accessory or ready mode), or you need to somehow energize the motor/actuator on the parking pawl to get the pawl disengaged.

    One thought comes to mind, I wonder if the OP can hook up a 12 volt battery to the jump post long enough to get the car in nuetral, then roll it off the trailer? If so, that may be another option. Even a couple of new 6 volt lantern batteries hooked together in series might be enough to energize the computers long enough to get it off the trailer in accessory mode.

    Ron
     
  11. Britprius

    Britprius Senior Member

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    Nh70 I could be wrong but the parking pawl motor is basically a 3phase motor and would require the transmission ecu to be used with all that that implies to disengage it.
     
  12. nh7o

    nh7o Off grid since 1980

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    Yes, it's a three phase motor. Don't know the frequency, but probably somewhere in the range of a 500 Hz to ~2 kHz. It would be a project to figure out what was required to get it to spin, sans ECU.
     
  13. ChapmanF

    ChapmanF Senior Member

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    Reanimating 11-year-old thread just to set straight that the parking pawl motor is a switch-reluctance motor, not a three-phase. It's wound with U, V, and W coils like a three-phase motor, but there are differences in the construction.

    SR.png

    The overall point that you need to do some fancy switching between the U, V, and W windings to make the thing move still holds.

    Drawing credit: Walter Lawrence
     
  14. mr_guy_mann

    mr_guy_mann Senior Member

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    I was wondering why I often had difficulty falling asleep. Now I know. ;)

    Posted via the PriusChat mobile app.
     
  15. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Here is video, as stated it tries to go to park every time you power down. If your 12 volt battery is dead, you will get a p-lock error.
     
  16. Mendel Leisk

    Mendel Leisk Senior Member

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    If you disconnect the 12 volt neg cable while cars fully on and in Drive, then shut it down, would you have an “off Prius in Neutral”? Wouldn’t be doing this, just curious.
     
  17. ChapmanF

    ChapmanF Senior Member

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    Or just pull the P CON MTR fuse in that condition. Don't tell anyone I said so.
     
    Mendel Leisk likes this.
  18. TMR-JWAP

    TMR-JWAP Senior Member

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    If you're not able to connect a jump pack to the front jump point and throw the car into neutral then just drag the dang car off and be done with it. It happens everyday and cars aren't damaged. Throw some sand or dish soap under the front tires and have at it.