Hi I have a similar problem mine has separate power supply to coil, running 7.5 amp fuse that blew. It's Been ok like thos for several years. The amps are around 5 to start with but after a few seconds it climbs to over 20 where tester maxs out. I've tried new coil and module on distributor. But still it dead shorts. I've tested wires to coil but no problem found. Can't find any diode. Help please