I will try to answer this question what l remember was Yale used a four wire key switch plug in connecter the key switch was marked one to four the first was battery the second terminal was ignition to coil the third terminal was start for cranking and the fourth terminal was its own circuit that only got current in the crank position so it would apply battery voltage to the coil before the ballast resistor and then the run position would control the ballast resistor. /hope this answered your question