'94 Wiring question.

[ice745]

I was in the midst of rewiring my speakers when I noticed a disconnected harness. From the front right door, there are the two harnesses that come out, a blue one and a grey one, both of these were in. Then there was another grey one (not coming from the door, but in that area) that connects to a white fuse block type thing that has a relay in it also. This grey one was never connected. I followed it to see where it went to, and it ends just by the roller for the rear right seat belt, and just has an another open harness. I don't see any wire to plug into this anywhere, and nothing is not working that I know of. Does anyone know what this wire is here for? My guess is an option that I didn't get with my car. If it is any help, there are three wires in the harness, a brown, a yellow, and a black. They look really small, so I doubt its anything high power.