First, Elon Musk promised MCUv1 would be easily upgradable to MCUv2. That was on March 27, 2018. Recently, Musk dismissed the upgrade saying it would bring “limited entertainment improvements,” even though he knows this is not the main reason for such a retrofit. The fact is that people are not willing to wait anymore and have grabbed the bull by the horns. Such as Mr. Green, who now runs his 2017 Model X with MCUv2 and prefers not to reveal his real name.

Gallery: Tesla Cars Have A Memory Problem That May Cost You Much To Repair

He is currently sharing at Twitter his experience with the car on the newer version of MCU. Mr. Green even managed to get OTA updates with it, as you will see in the tweets embedded in this article. Over 5,000 people are currently asking Tesla for the upgrade, but we suspect many more would get it if that were an official offer from the company.

What bugs us is why Tesla has not started to do that already. There are many reasons why it should: MCUv1 has screen-leaking problems, it is laggy compared to MCUv2 and it has a chronic problem related to eMMC that will demand you replace the unit anyway. Why do that with another MCU that will eventually fail? This is what Tesla owners ask themselves, such as Jim Alger and Rick.


We asked Mr. Green his opinion on Tesla’s reasons.

“I've no way to know why Tesla is not doing this. There are likely multiple reasons including their desire for people to buy new cars which obviously brings in a lot better money than these retrofits. It's similar to other retrofits: they could easily offer upgraded batteries to S/X owners and don't. But also loads at the Service Centers – this procedure will take some not insignificant time.”

Robert Cotran, from Cotran Consulting, also thinks the tremendous amount of work Tesla Service Centers currently have can be a reason for the company to avoid the upgrade.

“The reason Tesla doesn't offer the upgrade is likely because they are overwhelmed, yes. I think there will be a huge demand for this once people realize how much faster MCU2 is.”

Do you have any idea of the difference? This video below seems to compare an old Model S and a newer one, already with MCUv2, which all Model S and in the Model X made from March 1st, 2018 on started to have.

Back then, this video already discussed the retrofit. Mr. Green tweeted the procedure he followed to make the upgrade himself:


As you can see, it would almost be a plug-and-play procedure if it was not for the software. What Mr. Green told us about this makes perfect sense if you believe Tesla wants to make long-lasting, upgradable vehicles.

“It's a repeating pattern with Tesla PR where they state things as not supported when in fact you can see they were designed from the get-go to be widely compatible with past cars on both hardware and software levels.”

The issue with the software part is that you either know how to do it or you have to hire someone that does, such as Cotran Consulting or HSR Motors, from Jason Hughes. He is the man taking the MCU out and putting it back in the video above. No one will tell you how for “safety reasons”, as Mr. Green explains.

“Specific details about software parts mostly need to remain private because Tesla often views these as ‘security breaches’ and tries to break these methods to thwart unapproved repairs as much as they could.”


Cotran describes a slightly different process.

“I've been chatting with Green all week while he does the MCU1-MCU2 retrofit. I actually have all the parts here with me and am looking to do the retrofit myself. It's a rather complicated procedure when you don't have the authorized Tesla tools and have to desolder and resolder chips in order to move essential files from the old MCU to the new MCU, etc.  Definitely not for the inexperienced Tesla tinkerer. 

The harnesses are plug and play for cars that have the MCU 1.5 (refresh Model S and all Model X). I'm looking at the new instrument cluster right now and it's basically a second screen to the MCU2 as opposed to a computer on its own (as in MCU1). It has a speaker on the back. I'm looking at wiring diagrams to see how to wire it. Likely from the main instrument cluster harness. But that's not a big deal.”


While there is a demand for the upgrade, Mr. Green has also seen people take the opposite way with this.

“I am also aware of several more cars with MCUv2 to MCUv1 downgrade too. The downside is because MCUv1 is a lot easier to root and security on MCU2, in general, is a lot higher.”

Coincidentally, that was confirmed by a random tweet from the Tesla Motors Club Croatia.


Apart from preventing rooting, could Tesla also stop servicing vehicles with the MCUv2 upgrade? Mr. Green told us what he thinks about this.

“They will likely try to refuse service on some BS grounds to at least some parts of the car. But since it's a replacement of genuine Tesla parts with other genuine Tesla parts, they could be compelled by the courts to still service the cars. I know of some cases where this happened – not with MCUs but other kinds of components – where they, in the end, settled out of court and allowed the repairs. This needs to happen more. 

Overall, Tesla happens to take a very dim view of ‘unapproved replacements/repairs.’ They also don't sell components like MCUs to the general public because these are 'restricted parts,' which is a bummer, and people must resort to parts from crashed cars and also batches of apparently new parts on eBay that nobody knows where they come from.” 


That is something Cotran also stresses: for the MCUv2 upgrades to happen, you will either need the company to change its policy or wish for more recent Teslas to get totaled with recoverable MCUv2 units.

“In terms of offering upgrades, the problem is Tesla doesn't sell the MCUv2 to anyone outside of authorized channels. They are marked as ‘Tesla Only’ in their parts catalog. So upgrades could be offered with units found on eBay, etc., but that's not a stable supply channel.

I'm just getting started on the MCUv1 to MCUv2 journey, but it seems like it shouldn't be too hard. Anyway, I don't think there will be a large aftermarket offering of this upgrade service because of the availability (or lack thereof) of MCUv2 hardware.”

Considering companies are specializing precisely on that, such as, we are not sure if Tesla wants to make it harder for people to get parts or to create business opportunities. Perhaps it could explore them itself: either by selling MCUv2 to customers or by offering the upgrade, as Elon Musk promised almost two years ago.

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