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2008 Prius "Park Button" Not Working

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Prius Newby, Jul 13, 2024 at 9:07 AM.

  1. Prius Newby

    Prius Newby Junior Member

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    The Park Button won't engage park (and therefore, disengage?), and when I shift into Reverse or Drive, the transmission almost immediately shifts back into Neutral (as indicated on the digital gear indicator).

    About 10,000 miles ago I drained and refilled the transmission twice with Toyota WS trans fluid. No leaks.

    No odd dash lights are illuminated.

    What is the problem?
     
    #1 Prius Newby, Jul 13, 2024 at 9:07 AM
  2. bisco

    bisco cookie crumbler

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    how is the 12v health?
     
    #2 bisco, Jul 13, 2024 at 1:50 PM
  3. ChapmanF

    ChapmanF Senior Member

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    A scan tool will probably show some C23xx trouble codes. Those would be helpful.
     
    #3 ChapmanF, Jul 13, 2024 at 2:05 PM
  4. Prius Newby

    Prius Newby Junior Member

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    Replaced the 12V battery in March, though haven't measured voltage since this Parking Button problem started yesterday.
     
    #4 Prius Newby, Jul 13, 2024 at 2:41 PM
  5. Prius Newby

    Prius Newby Junior Member

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    I have simple OBD2 reader, will this read the "C" codes you mentioned?
     
    #5 Prius Newby, Jul 13, 2024 at 2:42 PM
  6. ChapmanF

    ChapmanF Senior Member

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    Simple way to find out....
     
    #6 ChapmanF, Jul 13, 2024 at 2:51 PM
  7. Prius Newby

    Prius Newby Junior Member

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    True, it's pushing 100 degrees here so I'll check in the am and report back here.
     
    #7 Prius Newby, Jul 13, 2024 at 9:36 PM
  8. mr_guy_mann

    mr_guy_mann Senior Member

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    #8 mr_guy_mann, Jul 13, 2024 at 10:37 PM
    Brian1954 likes this.
  9. Prius Newby

    Prius Newby Junior Member

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    Update:
    My OBD2 reader didn't indicate any codes.

    Today the parking button is functioning 100% correctly, and the transmission is shifting into gear and staying in gear as it should.

    WTH?
     
    #9 Prius Newby, Jul 15, 2024 at 9:18 AM
  10. bisco

    bisco cookie crumbler

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    get a free load test on the 12v at many auto parts stores
     
    #10 bisco, Jul 15, 2024 at 12:42 PM
  11. Prius Newby

    Prius Newby Junior Member

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    I followed a YouTube video and checked the 12V battery...Checked out great.

    I am baffled, and open to more ideas on the cause and how to permanently resolve this "phantom issue".

    My wife is about to drive the Prius 100 miles tonight, so she will give me a report.
     
    #11 Prius Newby, Jul 17, 2024 at 6:38 PM
  12. mr_guy_mann

    mr_guy_mann Senior Member

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    If there was something causing a problem, most of the ecu's will retain "history" codes (for awhile, so long as the 12V battery hasn't been disconnected), even if there are no active problems or warning lights on.

    You would need a capable scantool to check this. Or you can wait until it causes more problems - possibly somewhere inconvenient.

    Posted via the PriusChat mobile app.
     
    #12 mr_guy_mann, Jul 17, 2024 at 7:13 PM
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