Function
Function
Sun roof drive mechanism
1. Drain channel support
2. Carriage
3. Guide link
4. Main arm
5. Front arm
6. Return rod
7. Mounting rail
8. Connecting rod
The three main positions of the glass panel (tilted, closed and completely open) are depicted below. When completely open, the glass panel lies under the vehicle roof.
Tilted position
Closed
Completely open
Comfort position
The fourth position (known as the Comfort position) is regulated by the Sun Roof Module (SRM). This position is 80 mm in front of the completely open position. Wind noise is reduced in this position.
When the mechanism slides from the open to the closed position, the it is locked by the notches in the guide rails. The front part of the mechanism stops moving while the rear part slides the rear of the glass panel to the normal closed or tilted position. These positions are electronically regulated. The mechanical stop in the fully tilted position is only used for calibration. The electronically regulated tilted position is slightly lower. The drain rail is part of the mechanism and moves along with it.
Electrical function
The sun roof receives its main input signal from the sun roof switch. The switch has a two-way function and an automatic function. There are two ways to operate the sun roof. If the switch is held, the glass will move to the desired position. A brief press with the switch rearward opens the sun roof to the comfort position. A brief press with the switch forward closes the sun roof completely. Note that the automatic function can be used to move the glass panel from the tilted position to the comfort position. The automatic function cannot be used to close the glass panel from the tilted position.
When the sun roof is tilted, only continual operation is possible (except for automatic opening from the tilted to the completely open position).
Sun roof motor
1. Battery voltage
2. Sun roof switch, forward
3. Sun roof switch, tilt
4. C cable
5. Body connection
6. Battery voltage
7. Sun roof switch, automatic function
8. Sun roof switch, rearward
9. Sun roof switch, switch feed
10. Body connection
The sun roof switch is connected to the Sun Roof Module (SRM) and the Sun Roof Module (SRM) is connected to the motor.
Input signals to the Sun Roof Module (SRM) are the vehicle communication cable (C cable (4)), battery voltage and the sun roof switch. Numbers 1 and 10 are for the motor's power supply, which goes through the Sun Roof Module (SRM). Sun roof feed (9) is the switch's signal voltage.
Calibration function
During calibration, the software of the Sun Roof Module (SRM) detects the sun roof's zero position. The zero position serves as a reference point for the Sun Roof Module (SRM) when the sun roof is operated. This reference point helps the Sun Roof Module (SRM) determine where the main positions of the glass panel should be.
Once calibration is complete, pinch protection is activated. The Sun Roof Module (SRM) then detects if the closing speed of the glass panel decreases, that is to say if something is in the path of the glass panel. Pinch protection is then triggered.
During calibration, glass panel speed is also detected by two light sensors that measure how many revolutions and at what speed the gear wheels of the sun roof motor rotate. The light sensors (1) are located within the sun roof motor. The sun roof motor can handle a drop in voltage down to 9 Volts during calibration and still maintain precision.
If the sun roof stops in the open position when it should be closed, you can pull on the sun roof while holding the switch depressed.
Caution! If for some reason the sun roof is blocked and the switch is held in when the sun roof is tiled/open, the Sun Roof Module (SRM) will calibrate its zero position as the position at which the sun roof is blocked. This means that the main positions of the glass panel will be incorrectly programmed.
This problem is remedied by recalibrating the sun roof. First hold the switch pressed in for 5 seconds when in the tiled/open position. Then open the sun roof to the end position and recalibrate.
If the sun roof should seize, there will not be a diagnostic trouble code in the control module.
Warning! If the Sun Roof Module (SRM) is not calibrated, the sun roof safety functions (specifically the pinch protection function) and the programmed main positions will not be operational.
Caution! In the event of mechanical blockage, which is normally prevented by the Sun Roof Module (SRM), the motor can produce a maximum torque of 6.8 Nm. This can damage drive wheels and cables. If the sun roof has been blocked, all sun roof components must be checked and, if necessary, replaced before recalibration.