A bit of a repost b/c I have another discussion going on that Josh has been helpful with, but still no answer.

Does anyone know what causes the window/window motor to stop when the window is going down? I.e. if you hold the switch down (or use express down), what makes the window stop when it gets to the bottom? It seems like a hard stop (i.e. the window or regulator hits something that makes the whole thing come to a stop). When the window is going up, the door frame stops it, but i can't figure out what stops it from going down. My window is going so far down the regulator gear teeth are passing all the way through the motor sprocket, and then the window can't go back up. I've taken the whole thing apart and tried to figure it out, but it's baffling me. It just started doing this out of the blue on Wednesday. Anyone??

PS, it's not a broken regulator wheel.

 

the window is stopped in both directions when the motor "senses" an "over torque" or "stall" and the BCU shuts of the supply current.. ie when it gets to the bottom or hits the frame when going up.

If its passing the teeth on the regulator, then the motor must have orginally "slipped a tooth", so when you put it back together, you have to make sure the window is roughly in the mid postion, and the motor is attached to the regulator with approx equal teeth either side of the motor gear.

 

Makes sense....but what causes the resistance at the bottom of the stroke that results in the motor stalling? The door frame does it at the top like you mentioned. If I wedge something in the bottom of the door, it stops like it's supposed to.

 

And when I reinstall the motor and regulator, there really isn't a way to improperly align the gears. The location of the window is predetermined by the position of the motor sprocket and regulator gear. You basically install the assembly and then move it down to the bottom of the door so you can access the two bolts that bolt the window to the regulator. I guess I'm not understanding how that could be done wrong.