Windows and Glass: Description and Operation
Power Windows
Power windows
All power windows can be operated from the switch block in the driver's door. The electric power windows are controlled by different control units. The Car Access System (CAS) performs the central control function.
Brief component description
The following components for power windows are described:
- Driver's door switch block
- Power window switch
- Power window motor
- Car access system (CAS)
- Footwell module (FRM)
- Junction Box Electronics (JBE)
Driver's door switch block
All power window functions can be operated from the switch block in the driver's door. The switch block in the driver's door sends its signals across the LIN bus to the footwell module (FRM).
Power window switch
The passenger's door and the rear doors are equipped with separate power window switches. The power window in the front passenger door and the power windows in the rear doors send their signals directly to the junction box electronics (JBE).
Power window motor
There is a direct current motor in each door which drives the power window regulators. The power windows are designed as wire lifter drives. Each power window motor has a hall effect sensor. The direction of rotation, speed and position can be determined through these. The power window motor runs at varying speeds depending on window position and switch operation.
Car access system (CAS)
The CAS is connected across the K CAN with the footwell module (FRM) and the junction box electronics (JBE).
The CAS performs the convenience functions for the power windows. All signals to control the power windows are sent from the CAS on the K-CAN.
Footwell module (FRM)
The footwell module processes the signals from the driver's door switch block, JBE and CAS. The footwell module (FRM) activates the front power windows electrically. The FRM is connected to the CAS and JBE via the K-CAN.
Junction Box Electronics (JBE)
The JBE processes the signals from the power window switches in the doors. The JBE electrically activates the rear power windows. The JBE sends the requests from the power window on the front passenger side to the FRM via K-CAN.
System functions
The following functions for power windows are described:
- Opening or Closing
- Convenience opening and/or convenience closing
- Unlocking
- One-touch function
- Emergency closing
- Panic mode
- Child safety lock
- Repeat interlock
- Anti-trap mechanism
- Energy-saving deactivation of power consumer
Opening or Closing
The power windows may be operated from Terminal 30B ON. After terminal 30B OFF, the power windows can be operated for another minute. The power windows cannot be operated if one of the front doors is open. The side windows can be opened and closed using the following control units:
- Switch block in driver's door
- Power window switch in the front passenger door or rear doors
- Master key
- Driver's door lock
Convenience opening and/or convenience closing
This convenience function is controlled by the CAS. The CAS sends the signal for convenient opening or convenient closing via K-CAN. This signal can be triggered using the remote control or the driver's door lock cylinder. Convenience closing is activated when:
- the remote control button remains pressed and held after locking/deadlocking
- the mechanical key is kept in the "Lock" door lock position.
Convenience opening is activated analogous with convenience closing using the same operating points.
Convenience opening is performed in the following order:
- both front power windows
- both rear power windows after a time delay
- sliding/tilting sunroof after a time delay
If the activation is interrupted, the convenience function will stop.
One-touch function
The power-window drive runs at higher speed during one-touch opening or closing. One-touch opening or closing is only possible with the anti-trap function activated. To ensure that the side windows are securely closed, the power-window motors are briefly moved to the locked position (mechanical end stop) end in the upper stop.
Emergency closing
Emergency closing is for intentional closing of the side windows with the anti-trap mechanism. To do this, the power window switch must be pressed and held. It might be necessary to use this function in the event of an attack or if the side windows are frozen in place. Emergency closing can be activated at a speed of up to 16 km/h. Releasing the power window switch will interrupt the function.
When the childproof locks are activated, emergency closing for the rear side doors can only be triggered via the switch block in the driver's door. If emergency closing is triggered for any side window via the switch block in the drivers door: The closing operation can be stopped by the other power window switches unless the childproof locks have been activated.
Panic mode
The panic mode can only be triggered after emergency closing has been performed. If the user releases and then presses and holds the power-window switch within four seconds, the side window is closed without the anti-trap mechanism. The side window is then closed with maximum force and speed. In the event of blocking, the power-window motor is supplied with current until the overheating protection is activated. The side windows can be opened at any time, even if the thermal switch has tripped. Releasing the power window switch will interrupt the function.
Child safety catch
The child safety lock inhibits the function of the rear power-window switch. The childproof locks are activated or deactivated through a switch on the switch block in the driver's door. When the childproof locks are activated, the function LED in the button is switched on. The child safety locks are deactivated in crash mode. Observe the following safety functions with engaged child safety catch and operational automatic closing function on the rear power window:
- The closing operation can be stopped by the relevant local power-window switch.
Repeat interlock
A repeat lock is provided for each motor to prevent the power window drive from overheating. The running time for the power-window motor is limited. The drive is switched off for a defined time. The repeat interlock permits at least five complete window movements (opening/closing). The last possible movement is always a closing process. If something becomes trapped, the anti-repeat circuit will not prevent opening. The anti-trap circuit always reverses the movement of the side window.
Anti-trap mechanism
The anti-trap function is active during the entire window movement in the closing direction. The indirect antitrapping mechanism does not prevent trapping as a general principle, rather it limits the maximum permitted trapping power. The anti-trap function is only enabled once the power windows have been successfully initialized and automatic closing is possible. The mechanical forces for the closing procedure vary according to the ambient temperature and ageing. Consequently, the closing force is relearned each time the sunroof closes, so that the antitrap function can adjust accordingly.
Load cutoff
To protect the battery, the power windows will not operate while the engine is being started. Every ongoing function of the power windows is halted. If the battery voltage falls below 9 volts, the power-window motors are switched off.
Notes for Service department
Notes on encoding/programming
IMPORTANT: Initialize power window regulators
When programming and encoding of the footwell module is complete, the front power window regulators must be reinstalled. When programming and encoding of the junction box electronics is complete, the rear power window regulators must be reinstalled.
Initialize power window regulators
On initialization of the power window regulators, two parameters are learned by the control unit:
- Upper end stop (normalization of the power window regulators).
- Power characteristic curve for opening and closing (learning the characteristic curve).
Preconditions
The following prerequisites must be met to ensure initialization can be carried out correctly:
- Vehicle stationary.
- Adequate battery voltage present, connect charger if necessary.
- Terminal "15" switched on.
- All doors closed.
The initialization can be carried out using the control switch in each door or the power-window switch block in the driver's door.
Erasure of initialization
Deleting an initialization and subsequent re-initialization can remedy sporadic incorrect shut-downs in the power window automatic mode (toll mode).
Execution
Open the window of each door completely. Press and hold in the operating switch completely (switch position: automatic mode) for longer than 15 seconds and less than 20 seconds.
The deletion of the initialization was successful when the automatic mode (toll function) is no longer possible for the "Close window" function.
Performing the initialization
The re-initialization is carried out as follows:
- Fully close the window by pulling the switch so that the top end stop is reached.
- The switch must remain pulled during the procedure.
- The power window is initialized when the top end stop is reached.
The initialization was successful if the window can be opened and closed without errors in the automatic mode (toll mode).