I too have curious of this. My car did not have power windows. I just recently pulled the complete power window wireing harness from a 240 DL. I note that there are only two wires that connect to the fuse box.

There are a Brown Wire and a Yellow-Blue wire with the plugs to go to the fuse box... I know that fuse #10 is the power window as listed in the sticker supplied on the car. But I did not pay attention to whether both of these wires connected to the 10 fuse, or if just one is supposed to. (also I note that the harness itself does have a black wire that has an o-ring that I presume to be ground and so screw to the body over around the passenger side of the car.)

I don't know but when I hook up the brown on fuse #10 on the left from sitting in seat point of view, and the yellow-blue to the right of #10 the window is then operable. Is this the correct wiring?? I don't want to fry anything??

It looks like on the back of the fuse box there are three possible tabs for each fuse...

THANKS!!!