Hi everyone thanks for taking the time to reading about my problem.
I have a 2002 Discovery 2 and I thought my passenger window was totally dead as nothing would move. I bought a new regulator mechanism as the plastic wheel had broken with age.
After taking it all apart and having the motor free of the mechanism, I tried operating it with the switch. This was when I discovered that the motor would only run in one direction.
My first thought was that the switch might have failed so swapped the drivers side and passengers side and it made no difference and the drivers one worked fine.
I saw that motors were quite cheap and bought a new one but it still does the same. I have assumed it its not a fuse but as its still moving.
I was just wondering if anyone could shed some light on this. After a bit of a search I am getting concerned by the possibility of the BCM and wouldnt know where to start if it was that!
Any feedback would be most appreciated.

 

I assume you mean you swapped the switch? While it's no small feat, can you try one of the motors on the opposite side to confirm up and down work on the new (or previous) motor? Pretty sure the plugs are the same. Apart from that the next step would be to trace the wire from the plug in the door panel to the appropriate pin at the plug to the BCU to confirm the wiring is good. Or, if you can get your hands on a Nanocom it may tell you if there's a problem with the BCU.

 

A window motor should be diagnosed alone by feeding with 12V in both polarities to confirm works. If motor works in both directions, the next suspect is the switch. Mechanical binding of gears after travel limit is next.