[aosmith]

See all that time the thief spends near the drivers side headlight? The headlights are on the can bus, if you can tap a couple wires in there the cars is yours.

[arjvik]

Genuine question - why do headlights need to be on the main CAN bus? Could they not be operated from somewhere closer to the ECU by wires that just carry power and maybe some very simple data lines?

[aosmith]

A lot of headlights steer with the car, the can bus is a giant network without any authentication.

[EasyMark]

It cuts way down on the amount and expense of wiring, copper is expensive. It makes it easier to pocket some more profit.

[ndesaulniers]

I suspect fancier headlights can pivot based on incline and steering wheel angle.

[sleepybrett]

It may be something as stupid as a wiring harness layout optimization. You can put the headlights controller at the headlights and only run a single set of CAN bus wires (which are probably in that area anyways), haven't played with CAN I assume they are fairly few and fairly thing gauge, through the firewall of the car.

[ddalex]

I'm very surprised to see that the ignition control is on the slow speed can bus...

[EasyMark]

What part of starting a car is fast compared to the canbus? Speed is relative