Now you are asking about the other side of the system, but haven't described your ECU module. If you have a points distributor, yes you would connect the yellow wire to its single wire. But, I don't think points would last long trying to drive an e-core coil w/ no ballast. If you have an electronic pickup distributor (only thing that makes sense here), as TrailBeast said, its sensing wire pair goes to the ECU and the ECU output drives the yellow wire (shorts to gnd to charge up the coil, get spark when transistor turns off the gnd).
