2010 prius Check Hybrid system and P lock malfunction

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Onyx Araya, Jan 29, 2020.

  1. Onyx Araya

    Onyx Araya Junior Member

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    Hello and thank you to everyone ahead of time for reading and providing any advice.

    I have a 2010 toyota prius with 192k miles. Over the last couple months I've been running into an odd issue. I've I drive my prius for an extended period of time, 70 80 90 miles or even time wise, maybe 2 or 3 hours, I will randomly get a P Lock malfunction when I stop to park. To remedy the issue I disconnect the 12 v positive side wait a couple minutes and reconnect, the malfunction will go away and car will be in park. This issue will go away for a couple.days or a couple weeks and rare occurrences come back 20 30 mins later.

    Apart from that issue, sometimes if I go for a long drive, 150-200 miles, the check hybrid system light will come on. I can drive as far as I want but car will not use the hybrid system, engine only. If I pull over and disconnect the battery and pull the hybrid fuse on the hybrid battery itself the issue will.go away for another 150-200 miles or longer.

    I'm at a loss for what this issue could be.

    Any help is appreciated.

    Thank you.
     
    #1 Onyx Araya, Jan 29, 2020
  2. ASRDogman

    ASRDogman Senior Member

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    How old is the 12v battery? It could be getting weak. A weak battery will tend to cause all
    kind of weird things to happen. You can search for the thread for checking the battery and voltages.

    You can also check the hybrid fan. The hybrid battery could be over heating.
    The intake is on the passenger side of the rear seat.
    If you have dogs that ride in the car the fan could be clogged with fur.
     
    #2 ASRDogman, Jan 29, 2020
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  3. bisco

    bisco cookie crumbler

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    If not the 12v, perhaps the ecu
     
    #3 bisco, Jan 29, 2020
  4. Rebound

    Rebound Senior Member

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    What happens is that the car detects errors from its sensors, but it waits until it detects errors several times until it displays a message. So you’re resetting the warning but you aren’t fixing the problem.

    If your 12V battery is old, it’s worthwhile and inexpensive to replace it, because a failing battery can cause all sorts of gremlins to appear. But if that doesn’t do it, you need to use a code reader to thoroughly read all of the diagnostic codes.
     
    #4 Rebound, Jan 29, 2020
  5. ChapmanF

    ChapmanF Senior Member

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    The ECU that controls the P lock is one that actually cares about, and measures, the 12 v battery voltage. If you do read the trouble code, you might find it is actually telling you "hey, power supply a little dodgy here..." with a freeze-frame page that will show you what the exact voltage was when it said that. (Which makes it not so much an "all sorts of gremlins" kind of thing, as a "monitor system performing as designed" kind of thing.)

    If that is the code you find, keep in mind that it is measuring the voltage as it reaches the ECU, so while the battery can be implicated, so can the wiring or connections on the way.
     
    #5 ChapmanF, Jan 29, 2020
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