2015 Prius shutting down mid-drive, new transaxle needed?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by ChrisChrisPrius, Apr 18, 2021.

  1. ChrisChrisPrius

    ChrisChrisPrius New Member

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    After working with multiples dealerships and a specialist sent out by Toyota Corporate, I'm hoping you all have more answers than they do!

    Car: 2015 Prius 4, purchased at a Lexus dealership (my first mistake) Sept 2020, 69k. Had it inspected before purchase and it checked out. No extended warranty.

    Problem:
    Oct 2020: 6 days after purchase, Check hybrid system + check engine + red triangle on, took to local Toyota dealership 1, was told there was water in the engine from when the selling dealership detailed it. They cleaned out whatever was affected, gave it back.

    Nov 2020: Check hybrid system + check engine + red triangle on again, drove to a different toyota dealership #2 (was traveling), and it all shut off just before I got there. They found code P0A4B, couldn't replicate the problem, and gave it back.

    Dec 2020: Check hybrid system + check engine + red triangle on, car shut down while driving, had it towed to local Toyota dealership 1, they found code P0A4B and told me invertor needed replacing. Replaced under warranty.

    Dec 2020: Car wouldn't power on, jumped it, and replaced the 12V battery, which had been replaced in 4/2020 by previous owner (only noticed this in maintenance log after paying for it....), at recommendation of Toyota Dealership 1.

    March 2021: Check hybrid system + check engine + red triangle on, drove straight to local Toyota dealership 1 (made it before car shut down!). They found code P0A4B again, said it was a fluke, looked me in the eye and said nothing was wrong, it was safe to drive.

    April 2021: Check hybrid system + check engine + red triangle on, car shut down while driving. Was in another state and had towed to a nearby dealership, Toyota dealership #3. The next day the car ran fine for them, but they found code P0A4B. They were shocked it hadn't been escalated to corporate by dealership #1 after happening repeatedly and fixes not resolving it. Told me to trade it in ASAP. They clear the code, I drive off towards home.

    April 2021 (last weekend): Check hybrid system + check engine + red triangle on, car shut down while driving back (~4 hours of driving since last occurrence). Had it towed to my local dealership #1. Same code, P0A4B, and now they want me to replace the transaxle. I opened a tech case with corporate, and am waiting to hear back, but the dealership says the specialist corporate sent has only ever seen this happen in one other Prius ever. Waiting to talk to the case managers again tomorrow.

    At this point I'm hoping to trade it in (no chance I'm trusting them to "fix" the problem after 4 rather traumatizing shutdowns while driving and many "fixes"), and they will, but I'm losing a lottttt of money. I'll be sad to leave the Prius family, but they don't have any CPOs on the lot and I can't spring for new at this point.

    It seems I am down the creek without a paddle on this one, and would appreciate any advice. Am I missing some other possible diagnosis? Other solutions? Do dealerships trade cars (e.g. if I find a CPO Prius elsewhere)?

    Thanks in advance!
     
  2. JC91006

    JC91006 Senior Member

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    My friend has a 2015 with a similar repeat problem. The hybrid warning will come on while he's driving, goes off in about a day. When he takes it to the dealer, the problem can not be duplicated. They only told him that rats may be causing these issues for him, chewing on the car's wires.
     
  3. ChapmanF

    ChapmanF Senior Member

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    Somebody should ask the dealer if they've heard of this thing called the Repair Manual, or if they have anybody there who looks in it, ever. They can pull it up online, using a subscription they probably already have.

    Considering you had a P0A4B in November, and in December, and in March, and in April (twice) ... I think the code here is going to turn out to be P0A4B. That indicates an electrical short between two phases of the MG1 resolver circuit. If it comes and goes, it's an intermittent electrical short.

    The resolver is a little position-indicating device that reports back the rotor position of MG1 in real time to 1/4096th of a revolution. The hybrid system needs this information to shape the waveforms to and from MG1. If it doesn't have the information, it can't control MG1, and without control of MG1, it hasn't got much use for the engine. So things don't work well when the resolver signal is flaky.

    It's possible the resolver itself is bad, but there's not much to it to go bad. Some kind of wiring damage is more likely. The resolver itself is inside the transaxle, so if the resolver itself is the problem, that would be a transaxle replacement. Same if it's a wiring problem in the portion of its wiring that's inside the transaxle. But again, how likely is that?

    I would be looking really hard at the connectors on the outside of the transaxle and the outside of the inverter and the wiring between them. Find a problem there, fix it, and the P0A4B goes away.

    Those are literally the first three numbered steps in my repair manual for what to inspect for a P0A4B. (Mine's a 2010; I don't know if they rewrote any of that for 2015.) They refer to some more detailed procedures that appear elsewhere in the manual, for the code P0A1A, but that shouldn't slow down a dealer mechanic who's viewing the manual online; the cross-references are hyperlinks.

    Did it ever occur to any of them to grab a meter and test a few wires and connectors, before they start throwing replacement inverters and transaxles around?
     
  4. ChrisChrisPrius

    ChrisChrisPrius New Member

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    Sorry your friend is having a similar problem! Although I am glad to know I'm not the only one out there with an issue that can't be replicated at the dealership. Will ask my dealership about potential wire damage.
     
  5. ChrisChrisPrius

    ChrisChrisPrius New Member

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    Thanks - this is super helpful. Reading this I'm not sure they've cracked open the repair manual at all! I'll ask about checking wires.
     
  6. ChrisChrisPrius

    ChrisChrisPrius New Member

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    Dealership says they checked all the wiring and nothing was wrong with it, and that at this point it's process of elimination. The field specialist corporate sent recommends the transaxle replacement.

    Looks like I'll be trading it in this afternoon for a non-hybrid that's hopefully more reliable!
     
  7. AW82

    AW82 Member

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    I'm sure if the car was under warranty they'd go to the trouble.

    I don't blame you...but this sort of situation just sucks. Your easiest (and perhaps best) option is to trade it in when the light is off, but that means someone else is going to end up with this problem.
     
  8. ChapmanF

    ChapmanF Senior Member

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    Well, now they've said they "checked all the wiring and nothing was wrong with it", so maybe they did.

    If it were my car I know what I'd be out in the driveway doing, all the same.
     
  9. ChrisChrisPrius

    ChrisChrisPrius New Member

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    It's off my hands now, traded it for a Corolla last night, but will hopefully be back to the Prius family at some point :)

    I traded at the dealership that diagnosed it, so it's on their conscience to fix it before they auction it off, and I sure hope they do. That said, if anyone sees a navy blue 2015 Prius with 75k miles up for sale in the coming weeks, take a good hard look at the CarFax and stay away!

    Thanks again for your help!
     
  10. Grit

    Grit Senior Member

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    doubt it. New members always join here after they find the issues and get the carfax post purchase.
     
  11. JC91006

    JC91006 Senior Member

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    if the car starts, it's good enough to go to auction. It's a different story if they sell it on their lot and have to stand behind it. Dealership with conscience?
     
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