Electronic tensioner for a short drop window regulator system in a frameless door

A window regulator system including an electronic tensioner for a window coupled to a door of a vehicle and movable between at least a fully open position and a fully closed position and a short drop position in which the window moves a predetermined distance below the fully closed position, comprising:

• a motor for moving at least one cable coupled to the window to move the window;
• an electronic control unit electrically coupled to said motor and configured to:
• identifying a short drop request to move the window between the fully closed position and the short drop position;
• ensure that no freeplay associated with one of slack in the at least one cable and backlash of at least one window regulator lifter plate assembly and at least one rail exists in said window regulator system to provide accurate movement of the window, and
• control said motor at one of a first power level to remove the slack without moving the window and at a second power level greater than the first power level to move the window based on identifying the short drop request to selectively raise the window to the fully closed position in response to the door being shut and temporarily lower the window to the short drop position in response to the door being opened.

A method of operating a window regulator system including an electronic tensioner for a window coupled to a door of a vehicle and movable between at least a fully open position and a fully closed position and a short drop position in which the window moves a predetermined distance below the fully closed position, comprising the steps of:

• identify a short drop request to move the window between the fully closed position and the short drop position, sensing a rotational position of a motor coupled to the window and outputting a motor position signal including a plurality of freeplay pulses using a position sensor coupled to the motor and to an electronic control unit;
• ensuring that no freeplay associated with one of slack in at least one cable and backlash of at least one window regulator lifter plate assembly and at least one rail exists in the window regulator system based on the plurality of freeplay pulses to provide accurate movement of the window;
• and
• controlling the motor to selectively raise the window to the fully closed position in response to the door being shut and temporarily lower the window to the short drop position in response to identifying the short drop request.