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Car wont start ! The MCU is off but the Instrument cluster is on

thevaibhav

Member
Dec 10, 2016
171
58
West palm beach
My 2017 MX would not start up this morning.. in the past few weeks the power on would take a little longer than normal and i attributed that to the cold weather or the energy saving that i turned on.. But this morning i get in, the driver side auto present worked. the instrument cluster was on (Temp and Odo showed ---)

Tried reset, the air came on but not the MCU and was not able to put the car in drive.. Had to leave for work so the tow truck will pick it up later.. All doors (Including Falcon door worked) never got any warnings on battery and the car should have over 75% charge)

As i read from forums, that if the MCU dies both MCU and Instrument cluster go dead, which is different here.. so just checking if others have had any experience with this ?
 

arcus

Active Member
Aug 11, 2017
1,301
958
Denton, TX
Mine just did that this morning - The car shows "please wait while the vehicle is powering on" or something similar. Wait a bit and see if you can put it into drive. MCU will remain blank but the IC is working.

One other "side effect" - if it is humid outside, your fan will work based on your preset cabin temp, but you don't have access to other advanced controls such as venting the sunroof or allowing the airflow around the windshield to prevent it from fogging up. Ask me how I know ;)
 

thevaibhav

Member
Dec 10, 2016
171
58
West palm beach
Mine had not warning ons this time around.. i did wait and also tried the rest to no avail..

I have seen the "please wait while the vehicle is powering on" in the past and in a minute or 2 the car was drivable
 

thevaibhav

Member
Dec 10, 2016
171
58
West palm beach
I did not have anything in the USB.. the car was towed to a service center and they said they used a different 12V to start the car up.. funny but they say my 12V has no issues and the voltage etc is correct !!

My app however still can not connect to the car though !!
 

Krash

Data Technician
Apr 18, 2017
1,921
2,095
Intermountain US
...As i read from forums, that if the MCU dies both MCU and Instrument cluster go dead, which is different here.. so just checking if others have had any experience with this ?
If a mid 2018 or later MCU (MCU2) dies the ICU goes blank as that ICU is just a display. If an earlier MCU (MCU1 or 1.1 considering LTE) dies the ICU continues to function as it is a separate computer.

Best practice is to pull any USB drives and then press the brake petal while holding both steering controls down for the most complete reset.
 

EV-Fixme

Vendor
Oct 24, 2019
616
700
Orange County, CA
I did not have anything in the USB.. the car was towed to a service center and they said they used a different 12V to start the car up.. funny but they say my 12V has no issues and the voltage etc is correct !!

My app however still can not connect to the car though !!

Krash is correct, I should have mentioned that IC will continue to be on with MCU1. If your screen is active and app cant connect, then likely you dont have cell/wifi service on your phone or car. Can you see how many cars at the superchargers around you? You still may have some files lost during the crash. Hopefully your under warranty. However if your out, we can probably help.
 
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thevaibhav

Member
Dec 10, 2016
171
58
West palm beach
Krash is correct, I should have mentioned that IC will continue to be on with MCU1. If your screen is active and app cant connect, then likely you dont have cell/wifi service on your phone or car. Can you see how many cars at the superchargers around you? You still may have some files lost during the crash. Hopefully your under warranty. However if your out, we can probably help.

Thank you :)

Luckily I still have warranty :) they SC called and said they have replaced the 12v and are testing the car to make sure all other systems are ok, they said it was funny that there were no alerts.

But for now they say changing the 12v has helped !
 
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thevaibhav

Member
Dec 10, 2016
171
58
West palm beach
True, a weak 12V would also show this, but generally 12V going bad gives lot of notice. Keep an eye, hopefully this gets replaced at some point under warranty.

Got the car back this morning and it shows up on the app again.. Yes, i will keep an eye on the LTE.. I am open to upgrading the MCU to MCU2 as well.. When ever that become available
 

jboy210

Supporting Member
Dec 2, 2016
5,193
3,232
Northern California
I did not have anything in the USB.. the car was towed to a service center and they said they used a different 12V to start the car up.. funny but they say my 12V has no issues and the voltage etc is correct !!

My app however still can not connect to the car though !!

Pretty sure they disable your access when the SC is working on your car. The last think they want is you opening doors, honking the horn, etc.
 

thevaibhav

Member
Dec 10, 2016
171
58
West palm beach
Pretty sure they disable your access when the SC is working on your car. The last think they want is you opening doors, honking the horn, etc.

:) I get that but this was different..

When car is in service the App shows that car is in service, sometimes also gives me an ETA of return.. ..

however this time it was a different error.. picture attached..
 

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EV-Fixme

Vendor
Oct 24, 2019
616
700
Orange County, CA
:) I get that but this was different..

When car is in service the App shows that car is in service, sometimes also gives me an ETA of return.. ..

however this time it was a different error.. picture attached..

Generally that is result of car not on the internet, or it failing to validate with Tesla's servers (failing eMMC)
 

thevaibhav

Member
Dec 10, 2016
171
58
West palm beach
Generally that is result of car not on the internet, or it failing to validate with Tesla's servers (failing eMMC)

I actually was hoping that it was and they gave me the option to upgrade to MCU2.. but with the 12v replace for now, it seems to work.. Ill closely monitor this and update the group if i see any other strange behaviour..
 

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