Yeah, some stuff makes you go through the head unit on some machines. Any replacement head unit would have to implement the same controls somehow.
Wealthy will be the person who makes a generic 2 DIN head unit, where you have physical buttons which you can map to various CANBus messages.
Does the factory display/controls use the canbus to do their work? How much stuff can you reasonably do through that? Do you know if it varies between manufacturers?
Of course this isn't a problem per se, it's good design -- but it has the side effect of making it harder to hack your own car through a single point of entry other than the main OBD2 port, which is connected to the top-level gateway.
Thanks! Do you know by chance if the OBD2 port can talk to/control everything? Would that be a good entrypoint?
I have a only half-joking business idea to build high-quality physical controls for all of the crap touchscreen shit being forced upon us. High-end ovens for example rarely now include physical controls so (I'm looking at you Miele) so I would like an aftermarket thing that sticks on to the outside of it. Maybe even directly over the touch screen. Actually, hmm, that's a good idea. Maybe we need a device that is the size of various standard touch screens that can read the contents of the screen, interpret them, and then have some sort of way to do capacitance touch on the screen. All of this of course hidden from the user who just wants a damned analog knob.
This is one of those rare 'holy shit do this right now' kind of things.