Ignition Module Question

Thanks for posting the photo. It looks like a very simple circuit. Once 67Dart273 gets it, I bet he will post a circuit schematic, since he is a detailed guy. Us FABO guys might go further and pick a better transistor to upgrade the design, which is outdated. At my last job, I designed a circuit to pulse an EM coil using a Motorola FBGT. I tested it by switching a Mopar ignition coil to jump a 1" gap. A bright spark. Left it going all weekend with no failure.

mcnoople is correct. The 5th pin was for dual ballast resistors, which were probably on the earliest electronic ignition cars. The second ballast was to protect the ignition module itself. They later re-designed it so the module could handle full 12 V, so didn't need the extra ballast or pin. Just because you have a 5th pin doesn't mean it is used. Many were made that way, with the 5th pin unconnected internally.

Anyone installing electronic ignition in a points car might do better by using a GM HEI module. Many FABO posts on that.