Engine fuse? Do you mean that the engine has a ten amp fused ignition feed line?

You should stick your meter (whatever type) on the 50V AC setting and measure the input on the low voltage side, coming from the ECU. If there is a square wave coming in, this will be seen by the meter as AC and you will either get needle sweeps, or averaging of the value on the digital.

One thing to check is that you have not destroyed the interference suppressor Caps on the ignition, which usually go short circuit, killing the ignition. Having said that, I've also had one go open circuit too.....