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Mg1 motor temperature number one overheating 360° f

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Travis Sanders, Dec 25, 2021.

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  1. Travis Sanders

    Travis Sanders Junior Member

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    ********FIXED!!!! *********

    Yah!!!! I'm super happy it's fixed now. The motor does not get hot any longer and when I hold the brake and the gas to charge the battery the engine no longer revs up and down. The solution was fixing the wheel speed sensor. The solution was not because it was a half court low and the solution was not because the fluid was nasty. Sure those things were bad and they were remedied as well but I double verified that the wheel speed sensor was the cause by disconnecting it and watching the temperatures immediately start shooting up and the surging engine started at that moment. Actually I had shut the car off while I disconnected the sensor and then restarted but you get the point.
    With the speed sensor disconnected It didn't seem to rise quite as fast as it did the first time perhaps do to the quality fluid at the correct fluid level. I shut it down when it got to 217° F. Actually both electric motors were close to 200f when I shut down. However with the wheel speed sensor plugged back in temperature stay relatively super cool like 90° f during the battery charge test.
    This info should be added to some kind of sticky somewhere that a malfunctioning wheel speed sensor can overheat your electric motor and ruin your transmission and ruin your transmission fluid.
     

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    #21 Travis Sanders, Jan 13, 2022
    SFO, jerrymildred, ammdb and 1 other person like this.
  2. ChapmanF

    ChapmanF Senior Member

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    Would you have a chance to post a photo of the destroyed wiring, showing the wire colors and location?
     
    #22 ChapmanF, Jan 14, 2022
  3. Travis Sanders

    Travis Sanders Junior Member

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    Ok
     
    #23 Travis Sanders, Jan 18, 2022
  4. Travis Sanders

    Travis Sanders Junior Member

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    I can tell you On the front left speed sensor the red wire from the car was connected to the white wire on the sensor and they called it connection number 2 in the connector. And on the other side the pink wire went to the white wire.
     

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    #24 Travis Sanders, Jan 18, 2022
  5. ASRDogman

    ASRDogman Senior Member

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    I'm glad you resolved the problem.
    Very strange that a wheel sensor would cause that though.
    I imagine it would read all the sensors and then know how fast/long to charge???
    And with one sensor not registering it's getting the wrong information???

     
    #25 ASRDogman, Jan 18, 2022
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  6. ChapmanF

    ChapmanF Senior Member

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    And the damage you saw, I take it, was to the black/white wires of the old sensor?

    Like ASR, I find this dubious, though I am not questioning what you have seen.

    In my own work, I never quite consider something solved until I have both done something that made the issue go away, and produced a sensible, testable explanation for why that worked.

    I'm not seeing that kind of an explanation here yet. I am definitely not saying I have any better one to offer at this point. If the car were mine, this would just still be on my "continue figuring this out" list.
     
    #26 ChapmanF, Jan 18, 2022
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  7. Travis Sanders

    Travis Sanders Junior Member

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    Unplugging a wheelspeed sensor is quite easy. I welcome you to try it. As soon as I pulled that wheel speed sensor code I had a tiny suspicion and was in disbelieved that that could cause it. Many people would have simply said the motors shorted out throw the car away. But if you think about the way this transmission works with 2 opposing electric motors The wheel speed is a very important factor to the management of these motors.
     
    #27 Travis Sanders, Jan 18, 2022
  8. Mdv55

    Mdv55 Active Member

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    What is shocking is that a code wasn't thrown. I had a sensor get a little dirty and it tripped something like 9 different codes while it disabled ABS and traction control systems.
     
    #28 Mdv55, Jan 18, 2022
  9. ChapmanF

    ChapmanF Senior Member

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    Certainly does sound easy enough, and it would be great to have a number of people see if your result is reproduced. I'll put it on my next errands list.

    I do a fair amount of thinking about the way this transmission works, and the way that each motor has a resolver built right into it reporting its position and speed to 1/4096th of a revolution. It's pretty unlikely that the MG ECU either needs or wants the wheel speed signal (which is wired to the skid ECU) for that purpose.
     
    #29 ChapmanF, Jan 18, 2022
  10. Travis Sanders

    Travis Sanders Junior Member

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    It did have a code for the wheel speed sensor which I knew about this code the entire time. I had mentioned to my friend who is the vehicle's owner that maybe it could trip up the system and be the cause but told him it was doubtful. I had him mentally prepared for a shorted motor.
     
    #30 Travis Sanders, Jan 19, 2022
  11. Travis Sanders

    Travis Sanders Junior Member

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    That's good to know. Sounds like it Has the ability to function properly so this overheating issue must be Caused by The way it was programmed.
     
    #31 Travis Sanders, Jan 19, 2022
  12. ChapmanF

    ChapmanF Senior Member

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    Well, it may be caused by something. I don't see that any guess at what it "must be caused by" has been substantiated yet.
     
    #32 ChapmanF, Jan 19, 2022
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