Anybody happen to know where this red wire goes ? It comes from a 3 pin connector on the passenger side of car. There's a red wire, a red black wire and a green wire. As in pic, the red wire goes to a female bullet connector, then goes to another female bullet connector. Where do the bullet connectors go ? Thank you very much.

It could be from the inhibitor switch and automatic transmission selector light. I think they piggybacked of one wire like your example and had those colors.