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Consolidated eMMC Thread (MCU repair) (Black Center Screen)

Discussion in 'Model S' started by Wiki, Jan 8, 2020.

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The first post in this thread is a WikiPost, and can be edited by anyone with the appropriate permissions.
  1. supratachophobia

    supratachophobia Active Member

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    Just a data point for you. I'm at 110k miles, Feb 2016, pre refresh build. Always connected, no power saving (thanks to the USB re-scan issue). 90/10 split between USB audio and streaming, maybe even 95/5. A few long trips where we were updating map tiles frequently, but not a lot of fussing with it regularly and certainly not day to day NAV use.

    I was told from deep inside Tesla that their internal "warning" limit for write cycles is 2800 on the Tegra memory chip (hex number converted to binary). Others on here have said that normally chips like the one in the Tegra are rated for 3-5k write cycles. So those two numbers from different sources aren't in contradiction.

    As of last week, and almost exactly 4yrs, I was at 2500 write cycles.

    Now I've certainly seen the symptoms for about a year; hard crashes, super long reboots, the text all screwed up with missing letters, but there you have it, 90% usage of the chip. I'm certain that heavy streaming could have sped that along because one owner I know had their MCU replaced 3 months ago for the exact same symptoms, half the miles, same car age, all streaming audio.
     
    • Informative x 3
  2. Bigriver

    Bigriver Member

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    And how do you know the number of write cycles you are on? Is that something Tesla service center can check on, either remotely or in person?
     
    • Like x 2
  3. supratachophobia

    supratachophobia Active Member

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    Yes, I had someone on the inside go specifically looking for the hex code. I'm trying to figure out if there is a way for just anyone to get the same info by asking. And the 2800 number is from internal Tesla documentation. I doubt they would volunteer that plus the other info because then you'd get a rush of people trying to get replacements before their warranties were up. And our service center is being VERY tight fisted about proactive MCUv1 replacements.
     
  4. EV-Fixme

    EV-Fixme Vendor

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    Actually the missing and screwed up letters while supercharging generally is not a eMMC issue. I've seen this even with a brand new eMMC on car taken to SuperCharger right after the upgrade.
     
    • Helpful x 1
    • Informative x 1
  5. Spacey73

    Spacey73 Member

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    Getting a bit worried about my old S85 Nov 2014 build, 118k miles.

    Am in UK so not sure what my options are for getting the memory chip sorted. Will have to stop streaming from Spotify and just use usb I guess for the moment.
     
  6. Nosken

    Nosken Member

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    Lincoln, CA
    Please help with some info. Is this eMMC pending failure or some other issue?
    I am on a 3,000 mile road trip and are getting errors, I think are related to a failing eMMC.
    Two errors so far-
    1. Code: i_w172_SW-Drive_iso Car needs service, May not restart
    2.Code: BMS_u008 Acceleration and top speed reduced, performance may be restored on next drive
    I have a late 2016 Model S 90D with MCU 1 and AP2 with FSD. 87,000 miles with original 12V battery.
    I have done Binnacle and MCU reboot a few times, and did Car Off shut down-no change.
    Yes, acceleration is reduced but regen is completely missing-Dotted yellow lines on both acceleration and regen.
    A few weeks ago, a tech reported that my eMMC was at 90%. I cleared 3 years worth of Nav data.
    I am scheduling Mobile service Monday once I reach Big Sky Montana.
    Any input would be greatly appreciated.
    Moderator-If this is the wrong thread, please move and notify me.
     
  7. EV-Fixme

    EV-Fixme Vendor

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    Think you likely have 2 issues. 90% eMMC it is wearing out. However with iso and reduced speeds, sounds like the drive unit issues, along with the regen loss.
     
    • Like x 1
  8. EV-Fixme

    EV-Fixme Vendor

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    @LuckyLuke can help you
     
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  9. supratachophobia

    supratachophobia Active Member

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    I would be. I would be terrified for any 2014 owner right now.
     
  10. supratachophobia

    supratachophobia Active Member

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    Hang on, is he saying his memory is 90% full or his write cycle count is 90%? And is there a correlation between the two; less free space, sooner failure?
     
  11. MikeBur

    MikeBur ManualPilot

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    Less free space increases write cycles on remaining storage cells.

    Could do whacky things using heuristics to move predominantly stable data to areas with higher write cycles to effectively balance, though has inherent risks including data loss unless programmed well and with integrity checks.

    real solution is to proactively call in people when they hit a wear cycle anywhere on eMMC of 2500+, and replace with larger size eMMC (min 32GB) in refurb units.

    Question is though why would they do this now when cars are exiting warranty and they can stretch this to self pay for their early adopters and evangelists? Anyone of this sound familiar... *cough* battery *cough* @wk057 ?
     
    • Like x 1
  12. EV-Fixme

    EV-Fixme Vendor

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    Refurb units are same 8 gig chip... I don't think they plan to make changes....
     
    • Informative x 1
  13. EV-Fixme

    EV-Fixme Vendor

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    I assumed 90% used up. There are a few partitions on the chip. However 90% full is pretty common also.
     
  14. SmartElectric

    SmartElectric Active Member

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    "wacky" , um , it's pretty standard to use "Wear leveling techniques", see below for an example of a recommendation to OEM's:

    Flash Wear Management in Android Automotive
     
    • Helpful x 1
  15. taminatorv

    taminatorv Member

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    I got my eMMC replacement back from TonyT last Saturday. It booted up normally with all of my settings and with connectivity back to Tesla intact, but is quite a bit faster than before. Now, the web browser works again and the fireplace/romance app displays a fire where it was just a black screen before. Music now plays smoothly instead of skipping periodically. I'm very happy with TonyT's service and highly recommend him if you're thinking about doing this.

    Also, taking apart the dash to remove the MCU isn't that difficult. Send me a PM if you need pointers.

    20200201_133414_HDR.jpg
     
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    • Love x 1
  16. supratachophobia

    supratachophobia Active Member

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    How bad was operating the car without the MCU for a week?
     
  17. runvus

    runvus New Member

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    To add my info if it helps. Bought a used 2016 90D with 54k miles last Thursday. I started having issues with music skipping and no connectivity soon after. The service center on Monday and MCU has to be replaced. The total was $1300 for the MCU, $155 labor, $77 diagnostics and rest tax. Ended up being $1630 or so. Great way to start with a new to me car. :(
     
    • Informative x 4
  18. taminatorv

    taminatorv Member

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    I didn't drive it for the week. Not much worked with the MCU in without the Tegra card, so it would have been tough. Nothing like a week in an old minivan to make you appreciate a Tesla.
     
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  19. amiral_sub

    amiral_sub Member

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    do we still have heat in the car without the mcu ?
     
  20. taminatorv

    taminatorv Member

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    Nope, no HVAC controls without the MCU. Even the windows didn't work without the MCU and AC charging is limited to 488W (2A, 244V). I put a battery tender on the posts behind the cone, plugged the MCU back in without the screen, and parked it for a week. Periodically, I would check to see what the SOC was, in case I needed to plug in again. In the week it was parked, I only lost 6% SOC.
     
    • Informative x 1
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