dgatwood
Active Member
It may not be the techs at all. It is easy to forget that not all Model S’s and X’s are the same. My P85D is an oddball in that it had to have the battery pack changed, but was assigned a 90kWh pack. It fit physically, but they had to retrofit an awful lot of firmware on subsystems to get it to work - three days in Nashville. When I had my MCU replaced (before recall, but under CPO warranty) it took two extra days to get the software to take (in Indy). When it came time for the MCU upgrade, I was surprised that it was done same day considering the Frankenstein nature of my P85/90D. Configuration management must be really valued at Tesla. It is not easy and with the current chip shortage, their configuration management expertise has allowed them to dance lightly swapping in alternatives like no other manufacturer.
That's what happens when you build your software to be modular. Your car has a configuration file that tells which modules are installed. That data tells it which firmware chunks to grab whenever it downloads a new firmware bundle, and which software modules to load so that it can communicate with that particular module, what UI features to enable/disable, etc. You pretty much have to do that when you have so many possible configurations.
I think that's actually pretty typical for car manufacturers. For example, when I got a replacement rear electronics module for my '99 Windstar, I found that there were dozens of almost identical part numbers, and they were all identical hardware with different firmware. They literally used a single body controller for dozens of different configurations (multiple models of car, multiple body styles with different features, etc.), and they used firmware to configure which light was connected to a given output, which sensor was connected to a given input, etc. So you had to pick one from the right model of car so you got the right firmware (unless you had the tools to re-flash it), but still, it was generic hardware.