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Sigh; Dead MCU1 right before a trip. Turn signals do *not* work.

cduzz

Member
Jun 6, 2019
432
568
boston ma
Early 2016 90D with 53k miles...

Woke up this morning, checked how hot it is outside by turning on and off the climate control on my car.

Weirdly, it turned it on but then refused to turn it off. Hm. Go out to the car and the app won't unlock the doors either, but will open and close rear trunk/hatch.

Get in and scroll wheel reboot.... nothing. Try the "buttons over the scroll wheel" and it reboots the IC and the main screen. Car drives and works fine. Curious.

Couple hours later need the car for another short trip... and screen is dead again. I can turn on and off AC with the app, though.

I drive the car home and watch in the rear lights using my nest and ... the signal lights are absolutely not working. I'm thinking of going to go get it inspected just to fail the inspection for impartial evidence that a dead MCU indeed kills the signals.

Now AC is going even though I just got out of the car and the app won't turn it off, meaning it'll probably wipe out the battery overnight.

I got the car "NotCPO" from tesla a year ago so it's got 3 more years of the bumper to bummer warranty so I'll be made whole except for the unpleasant drive and possibly being stranded if supercharging doesn't work. I wonder if they'll have a loaner for me or if I'll just wait at the service center. I think I'll bring my 2 kids to just have them fight with each other while we wait in the waiting room at the service center.

Oh, and I'm about to go on a trip tomorrow. Fun times.
 
Last edited:
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Reactions: David29

AustinP

Active Member
Apr 6, 2015
1,341
1,079
Belgium
That’s indeed a bummer.
In 2017, also right before leaving on vacation with the car, the drive unit failed.
We did not know what was the issue, I had a power reduced warming and the car would accelerate as if it had only 1 horse power left.
Fortunately we were close to the SeC. It was on a Saturday and it was open, but only manned with the sales team.
While I was on the phone with the road assistance, who diagnosed I had to leave the car and was arranging a cab, one of the sales guy called the service manager (who was off indeed)
Within 10 minutes, he got approval to give me a loaner (P90DL) and I could just leave my car there. I ended up going to our vacation with the loaner.
Excellent service in the end, hope it turns out all right for you too.
 

cduzz

Member
Jun 6, 2019
432
568
boston ma
I went out and verified that
  1. no turn signals (got honked at a couple times)
  2. supercharging worked
  3. hazard light button flashes hazards
  4. not sure about automatic lights, but high beam flashing didn't seem to work
  5. forgot to check if autopilot works; I imagine it will
  6. forgot to disable easy entry which doesn't work when the MCU is dead
I double-clicked several times and eventually on the way home the center display started working; I turned off the AC so hopefully that keeps it from nuking the battery overnight.

I also set the charge level to 90%.

Sigh. Love the car, and other than the terrible (high) buy in price and the 2 flat tires it's been pretty cheap to drive.
 
May 13, 2019
668
2,668
Raleigh, NC
My car is very similar to yours: Early model 2016 bought a year ago from Tesla and now have 49k miles. Car acted a bit weird last night, charge was at 55% and wanted to up it a bit so i set the limit to 60% via the app and then plugged it in and went to bed. (Kinda planned to be next to a supercharger today and wanted to get more of a 'free charge'). Woke up this morning with the car at 81% charged. Weird.

I bet you get a loaner while you wait, or some Uber Credits since i'd imagine they would have it for a few days. Do you plan to upgrade to MCU2 when it is available for AP1 cars?

I wonder if turn signals not working is considered something that would qualify MCU failure to be part of a nhtsa recall/replacement.
 

cduzz

Member
Jun 6, 2019
432
568
boston ma
Many of the symptoms of a 12v battery dying.

While I have no knowledge of the 12v battery's history -- the one that was in the car when I got it 13 months ago is still in the car, I can say that that doesn't seem likely.

The 12v system is fed by the HV battery while the car is on and operational so the MCU1 should work "normally" while the car is powered on and driving, and that's not the case in my car.

Thankfully the mode of the crashing right now seems to be only if I click on climate control with the app, so I'm just going to avoid doing that for now. I'm sure it'll get worse not better though.

I got this car as a replacement for a 2003 allroad, so I'm used to a car with .... personality.
 

cduzz

Member
Jun 6, 2019
432
568
boston ma
Just to close the loop;
When I had the screen working I opened a new service request. They pushed firmware to it twice and that seems to have "fixed" the issue. I expect that it'll come back at the least convenient time possible, but probably within the 3 remaining years of B2B coverage "notCPO" warranty coverage.

My hope is that the further down the road I kick the problem (within reason) the more likely it is that they'll actually fix the issue instead of just putting people on a MCU1 go-round where they replace a broken MCU with an almost broken MCU...

One can dream, right?
 
May 13, 2019
668
2,668
Raleigh, NC
Just to close the loop;
When I had the screen working I opened a new service request. They pushed firmware to it twice and that seems to have "fixed" the issue. I expect that it'll come back at the least convenient time possible, but probably within the 3 remaining years of B2B coverage "notCPO" warranty coverage.

My hope is that the further down the road I kick the problem (within reason) the more likely it is that they'll actually fix the issue instead of just putting people on a MCU1 go-round where they replace a broken MCU with an almost broken MCU...

One can dream, right?

I *think* there are 2 partitions for your flash memory, 1 for each version of firmware as they progress so it can fall back if the upgrade fails. So lets say Partition A and B. You had failing partition A so they pushed a new update to your car and it wrote to partition B and now you are using that one. Next time you get an update it will probably fail again.

That said, I posted above that mine was acting a little weird and I have a similar car as yours today coming back from a long road trip the screen went blank when i got out of the car for a minute and wouldn't turn on and had to do the brake+2 scroll reboot. Then when i was driving i lost cell service and it wouldn't come back and wouldn't draw the maps and had to do the same reboot I just crossed the 50k mark and still have the 'Tesla used 4 car year warranty' which sounds to me like th esymptoms listed here for the dying emmc. I am hoping to get in on the $1750 discounted upgrade to MCU2, but we'll see what happens.
 

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