Window goes down on its own.... ghrrrrr

[MarkX50]

So the past two morning I’ve got in the car to head to work and the rear passenger went down on it own, and when I put up a few mins later it happens again.... sometimes all the way down, sometime part way down.

Any ideas?

[henrym3]

Had a similar problem a few weeks ago on my b3 except all the windows opened. Started as yours is and progressed to them all opening when I unlocked the car. Finally traced to a faulty drivers door lock module.

[MarkX50]

Ah, okay. Did you have to get it plugged into a diagnostics machine?

[henrym3]

Plugged into INPA plus Foxwell 644 and no codes. Was stumped till it progressed to happening when I unlocked the car. At that point I removed the drivers door card and unplugged the door module. The central locking still worked on everything but obviously not the drivers door. The windows stopped opening and I just used the key for the drivers door. Got a used module of the bay, fitted that and no more problems. Not saying that’s your problem but it seems similar.

[MarkX50]

So if I put the rear window child lock on the fault stops.... any ideas?

[henrym3]

Could be a faulty GM3 module, https://www.bmwgm5.com/GM3_Info.htm This site gives info on the GM3 module and tells how it controls the rear windows

[henrym3]

I suspect but don’t know for definite but the child lock probably just disables the window motor hence the window doesn’t come down

[Wayfarer]

By no means an expert on this matter, but if you mean the child window lock on the drivers door, stops the rear window going down on its own, but you can still open and close it from the drivers door controls, then I would look at the window switch and associated wiring on the affected rear door, as from previous cars I have owned, not Bmw’s and the child window lock switch on the drivers door just breaks the circuit on the window switch on the rear door.