The 3 prong does tie into the choke as well but is involved in the ignition circuit using the dark blue wire that is split throughout more of the ignition system. The idea is that the light turns on with the key on and once started it stays on until the opposite prong of the two gives a reading to say there is proper oil pressure and thus the light goes out. Since the plug is semi hard to find I am just going to put the gauge sending unit right into the block and bypass the dummy light while I wait for another one to show up.