My car won't start now after mucking with the ignition system while testing my tacho I'm making using a micro controller. When I touch the lead from the dizzy to the coil I get sparks. The lead measures 0v between it and ground and the pole it attaches to measures a constant 12v between it and ground. Could anyone give me any pointers as to what to check for a broken coil or ignition module? I haven't got much experience with this type of ignition system unfortunately. Thanks

What kind of ignition system in what car?

Dizzy and single coil, ke70, 4k-c

This is normal. 0volts from the distributor indicates that the points are closed, and 12volts at the coil is what you should see with the distributor disconnected as it is an open circuit. You see a spark when you connect the two because you are effectively providing the electricity supplied to the coil with a path to ground. This is all normal.

I did some research and I realised that it was all normal. I swapped to my spare dizzy and then it went fine so I'm guessing the ignition module was bust.