MCU on Mid 2014 MS Replaced

[markn455]

The MCU on my mid 2014 had to be replaced. It all started with the screen going black. The first couple of times a reboot resolved the issue. After about the 3rd time of this, the MCU would no longer reboot. No, AC, or control of anything. The app could not access the car either. The SC said the MCU had to be replaced. I have already had to reboot the screen twice in less than a week with the replacement MCU. These things are not cheap and I am concerned this will happen again. I am worried about taking my MS on a log trip for fear that the MCU is going to fail again.

I am wondering if the MCU's are typically this unreliable? Also, is it normal to have to reboot the MCU very often? Just today we were driving and listening to streaming music. Suddenly the music turned to just digital noise and the AC and other controls became unresponsive. The the navigation screen froze up as well.

I am really worried this will continue to be an issue. I am becoming very insecure about the reliability of the MS when they start getting some age on them. Is the MCU problem an ongoing issue with these cars?

 

[Derek Kessler]

Do you know if your replacement was a new or remanufactured MCU?

 

[markn455]

I test it. While it does seem a little quicker than the fairest one, they replaced it with the old one.

 

[hans]

I have been waiting for over 4 weeks for a globally backordered MCU replacement part for my 2013 Model S. Seem this part is failing across the board and is not in adequate supply by Tesla.

 

[Tozz]

Your issue sounds to me like failing eMMC or 'failed SD card'.

Especially older cars (like yours) did lots of logfile writing to the SD-cards. SD-cards have a limited write cycle count. Because of the extensive logging, some MCUs, especially those that stay on (Always-On, TeslaLog/TeslaFi frequent polling, etc, etc) run through their SD-card write cycles. When that happens, strange things occur, such as random lockups, reboots, failures and what not.

This logging issue has been fixed in later firmware. The MCU now log considerably less data, which in turns means the SD-card will last longer.

Unfortunatly the SD-card (or actually, the memory chip) is soldered on the MCU and cannot be field replaced. Thus you indeed need a new MCU. I don't know if they replace the memory card at Tesla to restore this MCU as a remanufactured unit.

So chances this will happen another time are small. The issue (too much writing to the card) has been fixed some quite some time now.

Ofcourse, all this only holds up if you have indeed a faulty memory chip and its not something else.