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Starts but won't drive, mechanic says failed "transmission coil"

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by cows, Apr 15, 2020.

  1. cows

    cows New Member

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    2006 Prius I've had for 4 years, has 160k.

    So after sitting on the street for four days, I took my car for a drive around town. On my way home, the red triangle and yellow exclamation point turn on. I foolishly pull off to the side of the street, turn off my engine, and turn it back on again, but the car won't shift into Drive and I get the red hybrid car light on the screen. I had AAA test the 12v battery and they said that that battery is dead. I thought maybe there's a deeper problem than that and I then had AAA tow it to a mechanic I know who works on hybrids, including replacing the hybrid battery in this one a couple years ago.

    After a couple days, this mechanic said that a "coil" in the transmission failed and he said rather than replace the coil it'd be less expensive to replace the whole transmission with a used one. I'd never heard of a transmission coil before and I don't see much on google. So, what would you do? Tow it to another mechanic for another opinion?
     
    #1 cows, Apr 15, 2020
  2. edthefox5

    edthefox5 Senior Member

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    Never heard of a transmission coil either. Dont let that bullshit artist touch your car.

    Your hybrid battery died would be my guess. You have been getting crappy mileage and poor power for quite a while? When the hybrid battery is on its last legs letting it sit for days will push it over the edge. Battery spends alot of time in purple bars?

    If you had a dead 12 volt battery nothing would work. No lights no nothing. Next time you think a car battery is dead turn on the headlights and go look at them. if there on its ok. If there not the 12 volt battery is dead. That works for every car ever made.
     
    #2 edthefox5, Apr 15, 2020
    Aaron Vitolins, M in KC and bisco like this.
  3. bisco

    bisco cookie crumbler

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    did the mech read the trouble codes?
     
    #3 bisco, Apr 15, 2020
  4. royrose

    royrose Senior Member

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    When the hybrid battery was replaced, did you have a Toyota new battery put in or a "refurbished" one? "refurbished" batteries are made with old but still (sometimes barely) working cells taken from failed batteries and therefore often don't last long.
     
    #4 royrose, Apr 15, 2020
  5. ChapmanF

    ChapmanF Senior Member

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    Sometimes we call it a 'stator' or a 'winding'. It's a bunch of wire coiled up.

    Here's the Carolyn Coquillette replacing one on a Gen 1 Prius:



    Of course you would still want the actual trouble codes retrieved from the car before deciding the diagnosis was right.

    There are other coils in there; the one for MG1 is similar but smaller. And there's a tiny resolver coil for each MG, but those aren't things that burn out and nobody talks about them. Generally if one goes it tends to be MG2.
     
    #5 ChapmanF, Apr 15, 2020
    Last edited: Apr 15, 2020
  6. cows

    cows New Member

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    Yes I think that's what he was describing, was a winding. English is not his first language

    The code they read is P0aa6
     
    #6 cows, Apr 16, 2020
  7. cows

    cows New Member

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    Seems that I got to wait for posts to be approved by a mod...
     
    #7 cows, Apr 16, 2020
  8. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    The P0AA6 refers to a High Voltage leak. It's the only fault that produces a unique pattern of problems.
    1. Car runs fine..
    2. Red triangle of death comes on.
    3. Car still runs fine.
    4. Turn the car off.
    5. Car will not go ready and only shifts into neutral.

    If you clear the codes with a code reader or by disconnecting the 12 volt battery the car will start and run normally until the fault is recorded again.

    It's likely the source of the leak is the HV battery. Gen 2 transmissions rarely cause this problem. Toyota Techstream software will provide sub codes to pinpoint the source of the leak. There are also simple and dangerous tests that can be performed to check the HV battery for leaks.
     
    #8 strawbrad, Apr 17, 2020
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