1987 325 back window problem
 

My 4 door Bmw 325 is having problems with the rear right window. It used to roll down when i bought the car but now it doesn't. What could be the problem. The other 3 windows roll down fine. Please help.

Zack

Probably your window switch needs cleaning. To test it you can swap with the window switch that works, if the window rolls down and the problem is the switch you can dis assemble the switch and clean the corrosion from the inside and that should solve your problem. if after the swap still the window doesn't work then probably the window regulator or motor needs to be changed.
Hope that solves the problem.

I don't know if the switch is bad because the other switch in the front that controls all of the windows doesn't roll the window down.

Try unplugging one of the known good switches and plug it into the harness for the window that is not opening. If the window still does not go up, that rules out the switch.