72 duster steering column wiring

Trying to help nephew with his car,steering column has 4 connectors on it,1 is ignition switch,2 is turn signal wiring 3 is for lighted key switch(these i have hooked to proper connectors in wiring harness,but I still have 1 connector(voilet,tan,green-in flat white plastic connetor)where does it go? It is wired in with turn signal switch from what I could see.