I'm still thinking the SPEEDO is based on the front wheels, but we KNOW the ABS has to know what the rears are doing as well.

This is where it's hard to say, so much of this stuff is in the electronics and you can't simply LOOK, like in the old days where you could follow a wire and know - now it's all an input or inputs to a microP which then talks to another microP and yadda, yadda, yadda.

I bet Rudy knows...