MCU stuck in boot up loop...

[trungsc156]

I've got a 2015 MS 70D & the touchscreen froze on me yesterday. I did the scroll wheel reset but didn't work. Also tried the reset by pressing firmly on the brake & holding the scroll wheel for 45sec with no luck. MCU is in a constant boot up loop. It'll boot up to the Tesla logo screen then back to a blank screen over & over again.

I had this boot up screen loop once about 2 months ago. It came back on after the brake & scroll wheel reset method but not this time. Currently out of warranty & have a scheduled appointment at the service center in a week.

Software version 2018.34.1 3dd3072

Any suggestions on how to fix this before my service appointment? Don't really want to pay $3K-$4K for a new MCU


Thanks!
Trung

 

[Tam]

...boot up loop...

It could be bad a memory bank but Tesla solders it to MCU so it wants to replace the whole unit instead of the memory chip only.

 

[MP3Mike]

It could be bad a memory bank but Tesla solders it to MCU so it wants to replace the whole unit instead of the memory chip only.

Yep, this is likely the cause. Someone on the forum posted pretty good instructions for replacing the bad eMMC chip if you have someone/somewhere that can do component level replacements on a board. (He suggested cell phone repair shops as an option.)

But getting good data to put on the new eMMC chip is a problem since yours is likely too dead to extract it from at this point.

 

[trungsc156]

There's a member on the Tesla forum who suggest I remove the 12V for a few minutes for a reset. What do you think?

Trung

 

[JoeMartin]

Unfortunately it sounds like they're both on point here.
You could also try pulling the fuse for it in the frunk for 5-30 minutes and see if it helps.

 

[trungsc156]

Unfortunately it sounds like they're both on point here.
You could also try pulling the fuse for it in the frunk for 5-30 minutes and see if it helps.

Do you know which fuse?

Trung

 

[trungsc156]

Never mind, it's fuse F51.

 

[d.c.palmer]

My wife's 2014 P85 had this problem - and we ended up having the MCU replaced under warranty.

In our case, the reboot loop happened - consistently - when the car couldn't get a cellular signal (not uncommon in our part of England). I rather suspected that there might be a software bug: perhaps some Tesla geek couldn't understand why anyone would ever not have cellular? Anyway, it was entirely reproducible.

Tesla first upgraded the car to 4G; this helped a bit (presumably when there's no 3G signal there might just be a 4G transmitter in range) - but didn't entirely fix the problem. They then kept the car for three weeks, with much communication to and from Fremont. Presumably no software updates were forthcoming, because they eventually they just ripped out the old MCU (losing all our settings) and installed a new one. That has fixed things (for now).

 

[joebob73]

I had this exact same problem. Do you happen to have a USB drive plugged in? If so, try removing it and doing a reset to see if the problem remains. In my case, that solved the issue. And just to validate, I plugged the USB drive back in and it caused the boot loop. I guess some times these drives wear out.

 

[trungsc156]

No USB drive plugged in. Just an Apple lightning cable with no phone attached.

 

[slainla]

This happened to an Enterprise 2018 75D loaner I had last Sunday morning. It was continuously rebooting and any manual reboots wouldn't work. Tesla's phone rep was able to communicate but couldn't do anything. It was horrible because it was under 40 degrees at 5am in the morning and I couldn't turn on the heat. The only positive is that my car was ready the next day so I returned it.

 

[trungsc156]

So I tried pulling the fuse and also disconnecting the 12V with no luck. Was told to disconnect the orange HV wire too but had a hard time reaching it. Will try again next week.

Also noticed a wire to the right of the 12V, looks like something chewed on it. Mouse? Anyone know what wire is that for?

 

[MP3Mike]

Also noticed a wire to the right of the 12V, looks like something chewed on it. Mouse? Anyone know what wire is that for?

That looks like an AC pressure sensor to me.

 

[laurynas]

Orange battery disconnect cable should be here:

 

[trungsc156]

Update:

Yesterday, I was on the phone with Tesla service to see if they're able to reset & push a firmware update OTA. Was told that they can't cause a firmware download corrupted something about two months ago. Weird, I don't remember confirming any update & the MCU worked ok until it froze last week. So I was told to keep my service appointment for service center to sort out.

Today, I received a call from Kenneth at Tesla service to follow up on my boot up loop on the MCU. He said he'll try to update the firmware via LTE. Two hours later I get a notification from the Tesla app saying that the firmware has successfully been updated to 2018.50.6. I checked the MCU & everything is working again. Sweet!!!

I've been holding back on updating to V9, but you know what, it's not as bad as a lot of forum members make it out to be. I think I'll get used to it & will like it.

Trung

 

[Raechris]

Glad to hear it sounds fixed. Don't forget the frayed wire and maybe a service plan while all is quiet.

 

[trungsc156]

Glad to hear it sounds fixed. Don't forget the frayed wire and maybe a service plan while all is quiet.

That's still the plan.