I won't bore you with all the details.. but the DSM (Distinguished Stupid Mechanic) put the o ring on the wrong side of the shims. What *was* he thinkin?? That adds .060" to the normal .030" gap, and the magnet loses it's ju ju as the missing tooth on the phonic wheel goes faster and faster. ECU says, "What did you say?" Better play it safe and shut down.
It wasn't all for nought, though. I learned how to check everything at the ECU using KR's excellent pdf, and how to make sure the relays were working normally, courtesy of KR, too. Thank you, sir. Doing all that got it to the point where it *had* to be the timing sensor. I also have a much better understanding of how all this stuff works.. always a good thing.