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P85D Front Motor Died

Discussion in 'Model S' started by Woland, Jul 20, 2015.

  1. Woland

    Woland Member

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    I felt some stuttering yesterday as the car regen braked. Then another stutter and red lights flashed with service warnings about the front motor. I had no power and drifted to the side of the road. I had to get out of the car for it to shut off and then restart, but the front engine came back alive and I drove the last half-mile home. This morning on the way to work, the same stuttering on regen braking and then front motor failure, but this time it was only white (as opposed to red) warning, and it let me drive after it automatically shut off the front, and carried on with just the rear, for the last mile to work.

    Tesla picked it up this morning and just called to say it would likely be several days while they ordered a new front motor. :(

    I only had about 3,800 miles on the car so far.

    Has this happened to anyone else? Should I be worried about any permanent damage to other parts of the car that Tesla might not replace in this case?

    Thanks.
     
  2. sorka

    sorka Active Member

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    Interesting. I thought the P85D would allow you to limp along on one motor?
     
  3. jerjozwik

    jerjozwik Member

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    ^^^ sorka
     
  4. Rule_of_72

    Rule_of_72 Member

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    I have a 70D and my rear motor went out after 2000 miles. Unfortunately my car wouldn't even budge after it went bad. After a tow however and a motor swap (which they had on the shelf) I was back to normal in no time. Other than an unusually long wait for a tow the experience was pretty painless.
     
  5. ecarfan

    ecarfan Well-Known Member

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    #5 ecarfan, Jul 20, 2015
    Last edited: Jul 20, 2015
    I read the OP to say that in both instances he could drive with just one motor.
    However the post by @Rule_of_72 says he could not drive on just the front motor after his rear motor failed.
    Did you ask Tesla why your car was unable to move on the front motor only?
     
  6. gg_got_a_tesla

    gg_got_a_tesla Model S: VIN P65513, Model 3 Res Holder

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    It appears that a rear motor failure is catastrophic but not the front. With a functional rear motor, it'd be no different from the RWD Model S.
     
  7. Krugerrand

    Krugerrand Active Member

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    To answer the OPs question, no, you shouldn't be worried about other permanent damage to other parts of the car that Tesla might not fix.
     
  8. TomL

    TomL Member

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    My front motor went out at <2000 miles, but the only indication of a problem was messages on the display (front motor disabled, power reduced). There was no stutter or other indication that a problem existed. Reduced power down to 470 Hp in the rear wasn't a big problem. :) Service center fixed it in a few days, said it was a failed temp sensor, so the car thought it was overheating.
     
  9. ecarfan

    ecarfan Well-Known Member

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    I had thought that a rear motor failure in a Dual Motor car would not necessarily prevent the car from moving, and that it could move on the front motor alone. While this thread provides evidence against that hypothesis, I would not assume that in every instance of rear motor failure the car will be unable to move, as there are complexities to the system that those of us who are not Tesla engineers are likely unable to fully appreciate.
     
  10. Ingineer

    Ingineer Electrical Engineer

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    Well, the accelerator pedal is hooked to the rear motor only, and apparently it sends the torque commands to the front motor via the CAN bus. So if the rear motor fails such that the inverter logic is offline, the car is dead.
     
    • Informative x 1
  11. wk057

    wk057 Senior Tinkerer

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    I noticed this in the schematics also and found it interesting...
     
  12. Matias

    Matias Active Member

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    Where can you find this information?
     
  13. yobigd20

    yobigd20 Well-Known Member

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    dual motors = double the possibility of 'car shutting down, pull over now'. glad I got my single motor P85.




    (sike, totally wish I had a P85D).

     
    • Like x 1
  14. AmpedRealtor

    AmpedRealtor Active Member

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    So the front motor is really just a slave to the rear motor.
     
  15. MsElectric

    MsElectric Active Member

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    I thought Elon had said that if "one" of the motors failed the "other" could still be used... Could they adjust this with software such that that in the event of a rear motor failure, the car can be driven with just the front motor?
     
  16. Ingineer

    Ingineer Electrical Engineer

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    Well, my take is that a front motor failure is survivable, but not a rear, unless it is a failure that leaves the rear inverter completely intact.
     
  17. ggr

    ggr Roadster R80 537, SigS P85 29

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    What does "hooked to" mean? My understanding (possibly wrong) is that the accelerator pedal is really only connected to a spring-loaded position sensor, which sends the position to the power module via CANbus. The power module then figures out what power is needed in both motors, and sends appropriate commands to the front motor. Since it's integrated with the rear motor, I guess it just controls it directly.
     
  18. Ingineer

    Ingineer Electrical Engineer

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    No, the pedal sends 2 analog voltages to the rear inverter (aka "power module") and that inverter generates the CAN frames that are sent to the front motor, so if the rear inverter is non-functional, then the front motor can't get CAN frames.

    - - - Updated - - -

    Yes if "One" of the motors that fails is the front motor, and the other motor (rear) is still good, then the car can still drive.
     
    • Informative x 1
    • Funny x 1
  19. brianman

    brianman Burrito Founder

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    Point of clarification:
    I can't speak to the rear motor failures, but in the case of front motor "failure" it depends. Some front motor failures are compatible with the car being allowed to "limp" along with just the rear drive unit, some aren't.
     
  20. neroden

    neroden Happy Model S Owner

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    Hmm. Odd design. I'd expect Tesla would change it to allow for more redundancy in the future...
     

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