whats this plug do?

[K_Man]

Hey all, tried using search, no idea exactly what im searching for? Thought id ask the experts.

AU1 fairmont wagon

Took the plastic spear (the one above the radio) that the demister and ariel switch are covered by off today, found a 4th plastic connector attached to the end of it on the drivers side. Its plugged in like its blanked off, only has 3 wires coming out of it, just wondering if anyone knows where it goes and what it does? Maybe some feature for the sedan that the wagon doesnt have?