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Likely MCU Failure (MCU1 eMMC)

Jkaufm32

Member
Feb 12, 2019
93
149
New York
Hey everyone!

Well it looks like the honeymoon is over. On March 22nd I picked up one of the best cars I've ever owned. A November 2015 Model S 85D. I love every minute of driving it until 2 days ago.

After work on Monday (May 13th) I was driving home and went into settings to look at something. Once I clicked the settings menu the center screen froze and went black. I assumed it would restart on its own since I've read that a lot on the forums. It didn't come back on. I tried to reset it by pressing the 2 scroll wheels on the steering wheel for 15 seconds and nothing happened. I live in New York and lately all it does is rain. So the entire car fogged up.

Car1.jpg


Car2.jpg


I couldn't find a customer service number so I chatted with Tesla customer service while I was pulled over. They couldn't connect to the car remotely and after I attempted more resets they pretty much said there was nothing they could do so I should either drive to a service center or call roadside assistance.

I had to pick up my daughter from my wife's aunts house (I was already late since I sat on the side of the road for 30 minutes chatting with Tesla). When I picked her up I apologized and told her what happened. The uncle laughed and said "you should have bought American" which I thought was funny since it's built in California. I told him that, but he didn't seem to really care.

On my way home I called roadside assistance and they asked me to perform different resets, but those didn't work. It was nice they pulled up the notes from my chat so I didn't have to go over everything again. They said they could have the car towed and an Uber for me, but I said I would drive to a service center since one is about 10 minutes from my house.

I dropped my car off after hours and went back yesterday to pick up a loaner (pre-AP P85+). The service center staff was very nice and helpful. I was worried I was going to get some Enterprise rental, but they told me they rarely ever do that anymore. They even made sure the loaner was a similar battery size since I have the 85, and not a 60 or 75.

Car3.jpg

(never seen the green in person, but I definitely liked it a lot)

I still love my car. Nothing is perfect and cars break all the time. The car is under warranty so I am assuming I should walk away from this with a $0 bill. There were also recalls on the car so they said they would take care of that while the car is there.

The one problem I had was the car was basically useless other than moving. I couldn't see out of any window since I couldn't turn on the defroster. I had to open most of the windows in the pouring rain which I was not a fan of doing.

I think Tesla handled the situation the best they could. They couldn't connect to the car so they offered to have the car towed for no cost and get me home at no cost. I was given a comparable car as a loaner so I was happy (I wish it had AP, but I'll live).

I'm assuming the module that logs data finally went out. Any ideas of how long it normally takes to have this replaced?
 

Scott1620

Member
Nov 21, 2018
23
7
Delaware
How many miles are on your car? I have an OCT build 2015 90D. Driving it to florida from DE this week and this would not be good if it happened on a road trip... Guessing they will just replace the MCU...
 
  • Helpful
Reactions: rchrzanowski

darxsys

Member
Dec 12, 2018
497
482
Seattle
I also just opened my Tesla app and it says "In service Estimated completion: May 23rd". Is this usually pretty accurate?

Not accurate in my experience. It’s some random date they hope to have it done by, but no guarantees.

I have a 11/15 85D with 43k miles. Good to know what might happen soon...
 

Jkaufm32

Member
Feb 12, 2019
93
149
New York
I did notice on the loaner that the screen seems to be a higher resolution than the one in my car. When the MCU is replaced do they upgrade the screen as well?
 

demundus

Active Member
Jul 5, 2015
1,317
852
Oceanside, CA
I did notice on the loaner that the screen seems to be a higher resolution than the one in my car. When the MCU is replaced do they upgrade the screen as well?

I'm not sure. I cant remember the hardware revisions on the MCU specifically. its highly likely you'll get a remanuf. MCU, so hard to know.
 

maximizese

Member
Jan 16, 2018
473
453
California
MCU will be replaced. its a flash memory failure, sadly they chose to solder this piece to the board for whatever reason, so when it goes bad (storage goes bad????!) the whole computer is done.

Such a shame. I hope they engineer better components in the future; it seems like these failures (especially for MCU1) are creeping up. Not sure if it's a bad job of soldering or maybe the units are overheating. I know from my 2001 VW Golf that certain relays would trip when the soldering points overheated (the dread Relay 109 that feeds electricity to the ECU had a high rate of failure). Hopefully the OP gets a revised MCU that will not repeat this problem. It seems like Tesla also revised the master charger also to have a much lower failure rate than the first gen.
 

Jkaufm32

Member
Feb 12, 2019
93
149
New York
Such a shame. I hope they engineer better components in the future; it seems like these failures (especially for MCU1) are creeping up. Not sure if it's a bad job of soldering or maybe the units are overheating. I know from my 2001 VW Golf that certain relays would trip when the soldering points overheated (the dread Relay 109 that feeds electricity to the ECU had a high rate of failure). Hopefully the OP gets a revised MCU that will not repeat this problem. It seems like Tesla also revised the master charger also to have a much lower failure rate than the first gen.

The car is about 3.5 years old. I'm hoping whatever the issue is will be resolved. If it pops up in another 4 years I will likely be out of warranty and the cost will be very high at that point.
 

Kant.Ing

Member
Apr 21, 2016
699
443
Pacific Coast, US
When they started with Intel Atom for MCU2 a couple years ago, they should have moved the storage to SATA or PCI interfaces. Now SATA and M.2 SSD are cheap with bigger capacity for added endurance. Automobile, as a mission critical machine, shouldn't be limited by nVidia's Tegra 3 handheld architecture or low cost--Elon was probably overly influenced by Jensen of nVidia at the time.

I predict MCU3 on the horizon. It's harder and harder nowadays to source that $50 component of good quality.
 

P100D_Me

Active Member
Nov 12, 2018
1,009
945
Australia
As mentioned in the video, when he clicks anything on the screen the write rate jumps up by a lot. My screen froze and went black when I clicked the menu on the main screen.
Sadly most big (arrogant) corporations like Telsa, Apple etc will ignore 'expert' advice from hackers and just continue on as they were. The guy in the video clearly knows his stuff, probably knows more about Linux than some of the Tesla engineers.
So he presents a factual finding showing the cause of the failure that happens to render the MCU dead when it occurs, the fix is 'easy' with some code changes but I bet they won't even bother investigating it.
 

WolfHowl

Member
Aug 28, 2017
32
24
Suffolk, NY
Wow, I can't believe it but the SAME THING happened to me on Sunday, was driving from Nassau to Suffolk (NY), the bluetooth stopped working, I reset the screen and it never came back. Kids in the car, can't see anything out of the front window, wife on windshield wipe duty - not great.

First appointment via the app - June 19th. Called the service center on Monday in Syosset, they asked me to come by to try a reset but told me there are no loaners. Drove there on Tuesday, reset did not work, but luckily a loaner showed up. They took the car in, told me the MCU will likely be replaced. Called on Thursday, the car was ready, asked about what was done, got a confirmation that the MCU was indeed replaced (ok, great!). Drove down to Syosset, sat in the car with the rep, immediately noticed that the old screen protector on my MCU is still on - told them that it did not appear that the MCU was replaced. It was interesting to see the rep trying to check the car only to see that the MCU wouldn't turn on while I'm sitting next to him.

At this point I had mixed feelings as I am sure many of us do when getting our beloved MS serviced at a SC - on the one hand I am glad they took me in and tried to do something, on the other I was very surprised by the poor communication internally and with me. Additionally, I had a mobile appointment to request that the rear left door handle be looked at cause it was getting jammed (common when the hot weather strikes). Saw on the invoice that they replaced the harness IN THE DRIVERS DOOR (again, great, I do not mind but did not ask for that as the issue was with the rear left door, not the driver's door). All said, still love the SC in Syosset and the great people that work there (don't think it's the staff necessarily, perhaps improvements in the overall system are required or just additional SC to reduce the crazy influx of cars adding to the chaos).

Was told that they did a factory reset on the MCU which worked for a while but then stopped working, I guess, right before I arrived and thus the screen was still pitch black.

Was leaving the service center and asked if they are really going to replace the MCU this time (like for real, real :)) and was told that they would and would tend to the other issues I had for my planned mobile appointment.

Still under warranty until August.
 

Prachatice

Member
Jul 3, 2016
88
20
Boulder, Colorado
Similar story. Purchased a pre owned P90DL from Tesla in Fremont. Flew to San Jose to pick up. Received an email in flight that the screen had gone out and the car would not be ready. Could not be repaired that day so Tesla stepped up and paid for a rental (did not have a Tesla available) and my flight back. They are now paying for a rental until they ship the car to me in Colorado next week (plus paying for shipping the car). Although a very frustrating experience, they are owning up and, I think, doing the right thing. The screen was replaced the next day (with what I don't know).
 

tpedwards

Member
Apr 12, 2016
350
304
Fishers, IN
I had a similar experience except I WAS on a road trip to visit family in Indianapolis. I was actually charging. MCU became unresponsive. It was not driveable - Tesla Roadside assistance sent a tow truck and arranged an Uber. Luckily my wife and twin boys were not with me. Worst possible time - late Friday night. I swung by the Indy SvC and although officially closed, they took me AND got me into a loaner. They had an MCU on the shelf and were able to swap it in, but they could not generate new firmware since that comes from Palo Alto - on the Saturday Easter weekend. I had to wait until Monday, but they sent me back to Nashville with the loaner - I can’t say enough about the Indy SvC. They were willing to bring my car to Nashville on a flat bed. I agreed to meet them nearly half way.

I do think Tesla has a problem with the cheapass Hynix 8GB eMMC chip. Heavy volume of writes due to logging is making these chips fail and they die.

Preventive eMMC replacement on MCU1

MCU CPU PCB

I hope they are putting higher quality (more resilient and higher capacity) chips in the MCU as they refurb them. It would seem to make sense to refurb a crap load of the daughter cards that host this eMMC chip. I’m sure that we’ll be hearing more about the long-term effects of this poor part sourcing choice.
 
  • Informative
Reactions: maximizese

stakker

Member
Feb 4, 2019
43
39
TX
This is good information as I have an 2015 S85. So when the MCU fails, you can't turn on the AC by pressing the steering wheel scroll button on the right? Or any scroll button options are gone?
 

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