There is only one dtc available in the pcm for the crankshaft position sensor. Quickly following it they have you inspect the flywheel for damaged teeth. This would lead me to believe that you are right about the ckp reading flywheel teeth. BUT, I cannot see how this can be for crankshaft position, and instead be purely crankshaft speed. The flywheel teeth would need to have some sort of indexing tooth, yet still be able to be run from the starter.