jappee

HI all,
I have a '84 nissan truck with a no spark condition and cannot test out the IC ignition unit according to the manual due to an extra wire not appearing in the diagrams or descriptions. The module also appears to have a different orientation/arraignment, "I" <>"E". The "extra" wire is labeled "C" with a circular depression. From Left>Right - "I","B","C","E". Also I read good values when testing as instructed, ergo good unit(?). Anyone who can tell me what this wire does and testing it would be great. I just don't want to get a module(if i can locate the same 4 wire type) and not correct the problem. I think that the module is responsible for this fault because it is being powered and the coils test good, but i find B+ on both sides of the coil(+,-) when ON, and or cranking yet no spark. TIA,
jappee