[Joe Johnson]

In most automotive applications of window are not supposed to fall down as the car drives down the road. To that end, there are specs for "wind noise" which spell out how much residual torque the motors retain after the power is released as well as for "forced entry" which define how much the motors can move under various backdrive conditions.

In almost every case, automotive window motors are not intended to be backdriven. In actual fact, the motor manufacturers are walking a fine line -- there is a strong correspondence between backdrive and effeciency. If they make the motors too non-backdriveable, they make the motors less effecient, which means that they need a bigger motor and more current to lift the window -- neither of which their OEM customers like. On the other hand, if they make the motors too efficient, the windows creep down as the cars drive over rough roads, which drives the end users nuts with high pitched wind noise sounds.

The bottom line is that most automotive window motors CAN be backdriven if you torque them hard enough, but they don't like it and you will probably get into trouble eventually.

Joe J.