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Black screen: MCU replaced (lost state, firmware version went backwards)

Discussion in 'Model 3' started by Bet TSLA, Dec 3, 2019.

  1. Bet TSLA

    Bet TSLA Active Member

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    On Friday night my Model 3 LR RWD (December 2017 build) screen went dark and unresponsive. This happened while it was sitting parked. Although I was able to do various things (turn on the headlights, move the seats, etc.) the display was quite dead. Scroll wheel reboot did nothing. After getting no useful help from roadside assistance I decided to let it sit until the next day to see if it might behave better.

    Since roadside assistance offered only to have it towed I didn't bother with them again. When the screen remained unresponsive the next day I drove it to a service center. This was no doubt not legal, since I had no speedometer or turn signals, and probably no brake lights. At the SC they tried to do a quick hard reboot. No luck, so they told me they would have to keep it and they'd get to it in a few days since they were busy. I got a loaner, so that was fine.

    They diagnosed it on Monday and replaced the MCU. I got it back Tuesday.

    My car lost (almost) all state. No name, no user profiles, no navigation favorites, no home address, no trip info, etc. The only things it seemed to have retained are the odometer reading and its key info (both phone and card). Can anybody confirm for me that this is expected behavior?

    One other disturbing thing is that I had 2019.36.2.3 when I went in, and 2019.36.2.1 when I got the car back. I didn't think going backward was even possible. Anybody know if this could cause any problems?
     
  2. mswlogo

    mswlogo Well-Known Member

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    Thats exactly what you get on Factory Reset. You keep odometer and keys. I suspect those might be stored elsewhere or redundantly stored else where for security and robustness.
     
    • Informative x 1
  3. fajitamondays

    fajitamondays Supporting Member

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    I had my MCU replaced like a week after I took delivery of my car, so I can't remember if it cleared convenience settings, etc. It was all so new at the time. All I remember is how annoying those screen freeze/reboots were. At the worst, mine would crash several times on a 10 minute drive. It even crashed while on AP on the freeway; that was a fun one.
     
  4. Bet TSLA

    Bet TSLA Active Member

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    Minor update. Got the invoice. Listed as warranty work.

    Found car computer was unresponsive. Replaced car computer, restored configuration and update firmware to the latest version. Verified vehicle is operating as designed.
    Correction: Replace Car Computer

    Parts Replaced or Added
    Part Quantity
    CAR,COMPUTER,MCU,ADAS,ASSY Provisioned 1.0
    (1098058-S0-M)

    Still wondering about my firmware version going backwards.
     
  5. Occar

    Occar Member

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    Why? The MCU *has* the firmware. The new one is on a slightly older version than the old one. You'll get updated in time. There's nothing to be concerned over.
     
    • Like x 2
  6. Bet TSLA

    Bet TSLA Active Member

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    I am wondering because there is not only one computer in the vehicle, there are many. And updates can affect most of them. So they can potentially get out of synch. I am not in the slightest concerned about having the latest. But if half a dozen are touched in updating from 2019.36.2.1 to 2019.36.2.3, then just putting in a new MCU with 2019.36.2.1 would possibly cause incompatibilities unless those other changes are reverted as well.

    I imagine there is a good reason that Tesla never (rarely?) goes backwards in firmware versions. I'm hoping somebody who actually knows something can enlighten me here. Versioning is one of the great unsolved (unsolvable?) problems in software engineering.
     
  7. 640k

    640k Member

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    MCU - Master Control Unit, right? Your SOFTWARE version has little to do with the firmware versions of the ancillary computers within the vehicle. If you've looked in to any of the diagnostics, CANBUS, internal settings, etc., within the MCU of what you see on your screen, you'll soon realize the entire vehicle is controlled (or fed) through the MCU somehow.

    your fears are unfounded (IMO). there's no need to worry about being out of sync with your other internal systems, as they have "nothing" (or very little) to do with the software version on the MCU. the MCU merely controls their behavior.

    i could be WAYYY off here, but this is how i understand it.

    [​IMG]
     
    • Funny x 1
  8. Zirak

    Zirak Member

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    Also brake lights, and turn signal indicators work even if MCU is not working or rebooting... (you just won't hear the clicking sound)
     
  9. Az_Rael

    Az_Rael Supporting Member

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    That is expected behavior for an MCU replacement based on my experience with MCU replacement on an S. All settings, profiles, saved favorites, nav destinations, homelink, etc are all lost. It is a factory reset.
     
  10. mswlogo

    mswlogo Well-Known Member

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    Right the next update should update all the subsystems. They often need to be compatible with one another.
     

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