All power windows in the R56 are operated from the bank of switches in the centre console. The Car Access System (CAS) assumes the central controlling function.
The following components are described for the power windows:
The power window switches are located in the bank of switches on the centre console. The power-window switches have two switch levels in either operating direction.
The IHKA evaluates the button signals from the bank of switches. The IHKA sends information across the K-CAN to the footwell module (FRM). The IHKA is connected across the K-CAN with the junction box electronics (JBE) and the Car Access System (CAS).
There is a DC motor in each door which drives the power windows. 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 the motor operation. The window lifter motor runs at different speeds depending on the window position and operation.
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.
The FRM processes the requests from the IHKA and CAS. The FRM electrically activates the power windows. The FRM is connected to the JBE via the K-CAN.
The JBE receives all signals via K-CAN. The JBE provides the power supply for the power windows.
Block diagram for R56
Index |
Explanation |
Index |
Explanation |
|---|---|---|---|
1 |
Car Access System (CAS) |
2 |
Footwell module (FRM) |
3 |
Power-window switches, driver's side |
4 |
Integrated automatic heating and air conditioning system (IHKA) |
5 |
Power-window switches, passenger's side |
6 |
Junction box electronics (JBE) |
7 |
Fuses in the junction box electronics (JBE) |
8 |
Power window on passenger's side |
9 |
Door lock on the driver's side |
10 |
Power window, driver's door |
The following functions are described for the power windows:
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:
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:
Convenience opening is activated using the same controls as convenience closing. Convenience opening is performed in the following order:
If the activation is interrupted, the convenience function is halted.
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.
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.
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.
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.
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