Rear power windows

Functional description, see BMW Technology:

TIS -> Documents> SI Technology -> 61 05 03 (025)

Notes on function

The power-window motors for the rear doors are connected to the body base module (KBM). The KBM contains the relays and electronic evaluation unit for the anti-trapping mechanism, anti-repeat circuit and the fault code memory.

The central functions of the power windows (convenience operation and conditions required for switch-off) are controlled by the Car Access System (CAS).

Anti-trapping protection

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 KBM 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'.

Initialisation

So that the anti-trapping protection functions reliably, an initialisation must be run the first time it is used and after all repair work on the power windows! In contrast to the front power windows, a special procedure is required here.

The initialisation is divided into the functions:

• Standardisation
  Recording the mechanical end stops of the power window
  
• Learning the characteristic curve
  Recording the mechanical closing forces of the power window
  

The initialisation must always by run with the power window switch on each door.

The following procedure must be used:

• Press the power-window switch towards 'open'. When the side window has reached the lower limit position, operate the switch for at least 15 seconds but not longer than 25 seconds.
  
• Then let go of the power-window switch and immediately pull the switch beyond the 'close' direction. Do not let go of the switch!
  
• The side window moves to the upper limit position and is then fully opened and closed. During the entire operation, the switch must be pulled beyond the 'Close' direction.
  
• Once the window has fully closed, the initialisation is complete.
  

Important! Anti-trapping protection

During the entire initialisation, the anti-trapping mechanism is not active!

Anti-repeat circuit

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.