Pls help- engine light on - low horse power - p0a7a diagnostic code

Discussion in 'Prius v Main Forum' started by wstt, Nov 20, 2019.

  1. wstt

    wstt Member

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    Anyone know what could be the problem with engine light on, brake system light on and slip / skid light on, car won’t go into ev mode only gas and car seems to have about only 20% power? Diagnostic code was p0a7a, which I looked up and it said generator inverter performance.

    I went to pass someone, (1 week after getting car serviced), I floor the gas to get some power and it accelerates for a second before losing almost all power and lights on dash come on. I pull over, turn car on and off again, warning lights still on. The notice car won’t go into EV mode but the gas engine comes right on after starting. It drives and can get up to speed, but with very little power.

    I had to go out of town and can’t get the car to the dealer for 2 weeks so I thought I’d see if anyone knows anything about this jere.

    Thanks in advance for any help on this.
     
  2. bisco

    bisco cookie crumbler

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    inverter pump or icm module? have you had the inverter recall update performed?
     
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  3. Mendel Leisk

    Mendel Leisk Senior Member

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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    I should have mentioned: regardless of the title, it was inverter failure.
     
  5. wstt

    wstt Member

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    Thanks for the responses.
    As far as I know I’ve done all the recalls on the car though I don’t remember an inverter recall update.
    I checked my VIN and it shows no open recalls.
    I’ll go through the other guy’s inverter problem thread now.
    Thanks.
     
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  6. wstt

    wstt Member

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    Grumpy’s incident seems a little different. He had complete loss of power and only EV power (engine wouldn’t come on). I had a loss of about 70% of its power, with no EV power, only engine power and engine would come on immediately when power/start button pressed, no delay like normal.

    I hope I get a good outcome like he did though.
     
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  7. Mendel Leisk

    Mendel Leisk Senior Member

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    What struck me as similar was that the failure happened under hard acceleration.

    That's what the recall was about: Toyota found some soldered connections in the inverter were fracturing with the sudden surge of electrons under hard accel, so they revised the programming, to make the surge more gradual.

    Maybe yours, being 2012 had the patch already, from the factory. Regardless, I guess it can still fail: changing the software is a balancing act.

    Definitely step one is a dealership visit.

    Where in the world are you btw?
     
  8. wstt

    wstt Member

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    I’m in the USA.
     
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  9. wstt

    wstt Member

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  10. bisco

    bisco cookie crumbler

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    i forgot about that article. seems to be pretty rare, but definitely something to be aware of.
     
  11. Tim Jones

    Tim Jones Active Member

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    Inverter................... I know first hand.......

    Had the update at 169,000 blew at 196,000
    They replaced a circuit board
    Was going 35 and barely stepped on the gas and then the christmas tree..... and 1100 miles from home
     
    #11 Tim Jones, Dec 6, 2019
    Last edited: Dec 6, 2019
  12. ChapmanF

    ChapmanF Senior Member

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    One part of that story that I don't think we mention enough is that, per the defect information report (third page, last paragraph), it really appears to be overfast cooling of the solder joints leading to the development of voids.

    There's an amphibolous phrase in there (probably thanks to Japanese ⇒ English translation), "if the vehicle is not operated for a long period of time after the IGBT ... reaches its maximum temperature." One reading could be "if the vehicle sits unused for a long time after", but it could also mean "operation of the vehicle isn't continued long enough after", and my money is on the second reading. That would suggest some hard acceleration (or deceleration with regen) that isn't followed by a long enough interval at moderate power for the solder to cool down gradually and anneal nicely; it cools down too suddenly, and gets like refrozen ice cream.

    That has implications for what Toyota's software patch really did. We don't really know, and everybody seems to want to assume it had to be a cap on hard acceleration to limit the heating. I'm pretty sure if I had been a Toyota engineer working on that issue, I would have been much more interested in tackling it from the too-sudden-cooling end. I don't think it would be very hard to stretch out the cooling period after a peak power event, just by temporarily keeping the current a bit elevated and phase shifting to reduce the power factor. Seems like that would aim more directly at the crux of the issue, and could do it without requiring a cap on the peak power.

    I guess it's conceivable I could have thought of that and a roomful of Toyota engineers didn't, but I bet that's so not the case.
     
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  13. wstt

    wstt Member

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  14. Tim Jones

    Tim Jones Active Member

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    I didn't get charged for anything.....
     
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