I spent four hours yesterday evening trying to fix my tach on my E36 5.0 swap. I had originally wired the tach to the TFI SPOUT signal (thanks, E36V8.com) before I figured out I needed to run new wire from the PIP sensor in the distributor instead. And I needed to add power wiring for the new Dakota Digital tach converter, which a friend of mine just recently used in the same kind of swap with success.
After I got everything wired in I tried to start the car to calibrate the converter. It just would not turn over. I spent about half an hour evaluating the battery starting voltage and current, which were fine. Then it was time to go out to dinner with the family, so I put it on the battery charger and left it for the next day.
So, this morning it occurred to me what probably happened and when I went to look, I was right. See if you can figure it out:
