The MSD needs to be hooked to both the 12 volt run and 12 volt start circuits (ign 1 & ign 2) and the easiest way to do it is just hook your old coil + wire to the MSD run circuit and then jump the ballast together. Then you have 12 volts in run and 12 volts when cranking. The 12 volt bypass while cranking is still there but its just not bypassing the ballast as you dont need the ballast with the MSD so the 12 volt crank circuit lets it start while cranking. Ron