Hi and welcome,

Something about your testing of the dizzy out of the car didn't sound right to me. The Hall device is a switch, so you don't see "output" whether you measure in AC or DC mode on a meter. The usual fault is with the internal wiring inside the dizzy from plug to the Hall-effect module itself. It loses its insulation, becomes intermittent, and shorts out. Many have fixed these with a bit of disassembly and application of something like "liquid electrical tape."

Maybe you have gone in that far, but the remarks about 5V and millivolts measured tells me you expect voltage out, but it is just a switch. I'd expect what you saw from a good one.

I used this back when I could pretty surely count on finding one in the junkyard.


--
Art Benstein near Baltimore

Two secrets to keep your marriage brimming 1. Whenever you're wrong, admit it, 2. Whenever you're right, shut up.
-Patrick Murra