I have a 1987 2 door 325is... one window works and the other does not. I can switch the window switches and found I had a bad switch... see repair procedure on another post at this site.
The wiring can be checked very easily.. follow these steps
1) on the window that works, pull out the window switch and snap open the back of the plug and expose the wires.
2) with the ignition in the on position, take a volt meter and test volt of each wire (5 in total). The only wire that should have voltage is the grn/gry wire. You should find this to be true.
3) Now for the window that does not work.
4) do the same and see if you have voltage only at the grn/gry wire. If yes then it's the switch or the motor. If not, then fuse or wire problem.
5) switch the switches and see if the window works with the switch that works. If not the problem is in the motor. IF it works, then repair the switch... see article at www.bmwe30.net
... see below for where to look on the site.
I don't think anyone ever told you about the fuse definition at www.bmwe30.net
See articles & tips > then Electrical > then "fuse..." article.
Old man fix it