Power Windows
Power Windows
All power windows in the R56, R55 and R57 are operated from the bank of switches in the centre console. The Car Access System (CAS) assumes the central controlling function. The front power window drives are activated by the footwell module (FRM) and the rear power window drives (only Convertible) by the junction box electronics (JBE).
Brief description of components
The following components are described for the power windows:
- Power window switch
- Integrated automatic heating and air conditioning system (IHKA)
- Power window motor
- Car Access System (CAS)
- Footwell module (FRM)
- Junction box electronics (JBE)
Power window switch
The power window switches are located in the bank of switches on the centre console. On the Convertible, there is an additional power window switch for operation of all power windows (front and rear) in the bank of switches on the centre console.
The power window switches for the front power windows have two switch positions in both operating directions.
The signals of all power window switches are evaluated by the IHKA control module.
R57: The power window switch for actuating all power windows is pressed downwards and held. The rear windows are lowered simultaneously. If the power window switch is still pressed downwards after the rear windows have lowered, the front windows are lowered simultaneously.
Integrated automatic heating and air conditioning system (IHKA)
The IHKA evaluates the button signals from the bank of switches. The IHKA sends a message via the K-CAN to the footwell module (FRM) and junction box electronics (JBE). The IHKA control module is connected across the K-CAN with the junction box electronics (JBE) and the Car Access System (CAS).
Power window motor
There is a DC motor for the drive of the power windows in each of the two front doors and in both rear sides. There is a measuring resistor in the power-window motor. The power windows are designed as wire lifter drives. A measuring resistor measures the voltage drop and thus the current consumption. The footwell module (FRM) monitors motor operation of the front power window drives and the junction box electronics (JBE) monitors that of the rear windows (only Convertible). The window lifter motor runs at different speeds depending on the window position and operation.
Car Access System (CAS)
The CAS assumes the central controlling function. The CAS is connected across the K-CAN with the footwell module (FRM) and the junction box electronics (JBE). The CAS is responsible for the convenience functions of the power windows. All signals to control the power windows are sent by the CAS on the K-CAN.
Footwell module (FRM)
The FRM processes the requests from the IHKA and CAS. The FRM electrically activates the front power windows. The FRM is connected to the JBE via the K-CAN.
Junction box electronics (JBE)
The JBE receives all signals via K-CAN. The JBE provides the power supply for the power windows. On the Convertible, the JBE activates the rear power windows electrically.
System functions
The following functions are described for the power windows:
- Opening / closing
- Convenience opening and/or convenience closing
- One-touch opening
- Anti-repeat circuit
- Anti-trapping protection
- Load cut-off
- Opening / closing on the Convertible
Opening / closing
The power windows may be operated from terminal R ON. With terminal R Off, the power windows can still be operated for approx. 1 minute. If a door is opened, operation of the power windows is interrupted. To ensure that the side windows are securely closed, the power-window motors are briefly moved to the blocked position (mechanical final stop) end in the upper stop. The side windows can be opened and closed using the following actuating buttons:
- Bank of switches in the centre console
- Remote control
- Door lock on the driver's side
Convenience opening and/or convenience closing
This convenience function is controlled by the Car Access System (CAS). The CAS sends the signal for convenience opening or convenience closing on the K-CAN to the footwell module (FRM). This signal can be triggered using the remote control or the driver's door lock. Convenience closing is activated when:
- the remote control button remains pressed and held after locking/securing,
- the mechanical key is kept in the Lock door lock position.
Convenience opening is activated using the same controls as convenience closing. Convenience opening is performed in the following order:
- both front power windows
- sliding/tilting sunroof after a time delay
If the activation is interrupted, the convenience function is halted.
R57: The convenience function is not available for the rear power windows.
One-touch opening
If the power window switch is operated briefly, the window is opened fully. The activating time must be less than 400 ms. Activation of the power windows can be interrupted by pressing the power window switch again.
Anti-repeat circuit
A repeat lock is provided for each motor to prevent the power-window motors from overheating. The running time for the power-window motor is limited. The footwell module (FRM) monitors the power-window motors. The FRM can switch off each motor individually. The last possible movement is always a closing process.
Anti-trapping protection
The anti-trap function is active during the entire window movement in the closing direction. The indirect anti-trap function does not in principle prevent trapping; instead, it limits the maximum permissible force applied to the trapped object. In the event of a blocking power-window motor, the current rises above a defined value. In response. the footwell module (FRM) stops activation of the power window. The mechanical forces for the closing procedure vary according to the ambient temperature and ageing. Consequently, the closing force is relearnt each time the sunroof closes, so that the anti-trap function can adjust accordingly.
R57: The anti-trap function is not available for the rear power windows.
Load cut-off
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.
No liability can be accepted for printing or other faults. Subject to changes of a technical nature
Opening / closing on the Convertible
The power window switch in the bank of switches on the centre console for actuating all power windows is pressed downwards and held. The rear windows are lowered simultaneously. If the power window switch is still pressed downwards after the rear windows have lowered, the front windows are lowered simultaneously.
No liability can be accepted for printing or other faults. Subject to changes of a technical nature