heres the reason why a bad ignition module will cause the coil not to fire. as the engine rotates so does the distributor, which has your ignition pickup module inside that gets its signal from the slots/ gaps in the reluctor wheel which your rotor sits on. when the pick up mod. gets its signal, its sends that electical pulse to the injectors and the ignition control module. the module then sends its signal to the coil, telling it when to send current to the distibutor cap. without the signal coming from the ign. mod. the coil will never produce spark, and because it is mounted on the distributor it is subjected to more heat which causes them to have a higher failure rate than if it were remotely mounted (on my 94 3.0l its mounted behind the headlight assembly to keep it cool). i hope this helps you make more sense of whats going on if you didnt already know this.