A modern digital cluster is pretty much all operated off one little computer. Nobody's used hard wired speedometers in probably 20 years or more. And I can tell you that even back when we did have such things, it wasn't unheard of for the cluster to freak out. Had a ground wire crack on my '95 car and the gauges all started making very random readings. Some even looked plausible at first glance, which meant it took two trips to the dealer before they realized it was an electrical problem and not an actual malfunctioning cooling system.

In the case of the Tesla, BTW, the infotainment is 100% separate from the computer that controls the car. E.g. you loose the turn signal sounds, but the signals themselves work, etc. AP will continue to function, but you can't turn it on without the infotainment screen running. You can reboot the infotainment as you're driving down the street without it affecting your control of the car.