Functional description, see BMW Technology:
TIS -> Documents> SI Technology -> 61 05 03 (025)
The power-window motors of the driver and passenger doors are connected to the door module of each door. The door module contains the relay and electronic evaluation unit for anti-trapping protection, anti-repeat circuit and fault memory.
The central functions of the power windows (convenience operation and conditions required for switch-off) are controlled by the Car Access System (CAS).
Two Hall sensors are fitted in the power window mechanism to register the direction of rotation and speed of the power window motor. The signals are transferred to the door module and evaluated there together with the motor voltage. If blocking is detected in the direction of 'close window', the power window motor is stopped and then briefly activated towards 'open window'.
So that the anti-trapping mechanism works reliably, the upper limit position of the window regulator motor must be learned on initial operation of a power-window motor. To do so, the side window must be moved to the upper limit position.
An anti-repeat circuit is provided to protect the power window motor from overheating. After approx. 5 complete window movements, the power window motor is switched off for a few seconds.
The switch block in the driver's door can be used for operation of all the windows of all doors. In addition, the child locks for the rear windows can be activated. The switch block is connected across an LIN bus (LIN = Local Interconnect Network) with the door module of the driver's door.