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Roller Sun Blind, Function - GF68.50-P-0004LF

Model 217 

with code 540 (Electric roller blind for rear window) 

Model 222 

with code 540 (Electric roller blind for rear window) 

G15299552Courtesy of MERCEDES-BENZ USA

Function requirements, general 

IMPORTANT The electronic ignition lock control unit sends the status of circuit 15 over the interior CAN to the rear SAM control unit.

Roller sun blind, general 

The roller sun blind is located in front of the rear window and can be extended and retracted vertically.

The roller sun blind can be operated from the following control points:

Depending on the status of the reverse gear, the roller sun blind is automatically extended or retracted.

The extended roller sun blind offers the following comfort for the passenger in the rear:

The roller sun blind is driven by the rear window roller sun blind motor. Two Hall sensors for position sensing are integrated in the rear window roller sun blind motor.

IMPORTANT The function includes a soft start-up and delaying of the roller sun blind in a defined range in front of the corresponding mechanical stop to reduce wear to the roller sun blind mechanism as well as noise development. This function is called soft stop.

IMPORTANT At temperatures below -20°C, mechanical effects can occur that have an undesired influence. The system becomes sluggish, which is expressed by a high power consumption and a slow travel speed.

Furthermore, it may not be possible to wind the roller sun blind up or down without causing creases. For this reason, the roller sun blind function is switched off at temperatures below -20°C.

The climate control, control unit sends the information about the interior temperature via the interior CAN to the rear SAM control unit. The front SAM control unit sends information about the outside temperature via the interior CAN to the rear SAM control unit.

The roller sun blind function comprises the following partial functions:

Normalizing 

Normalization is the basis for the assignment of the current position to the position of the sun roller blind recorded by the rear SAM control unit. Normalization must be performed at the time the car is put into service and in the denormalized state. When normalizing the roller sun blind, the upper and lower mechanical end stop of the roller sun blind is actuated and the corresponding position of the rear SAM control unit is stored.

IMPORTANT By actuating the rear window roller sun blind button or a rear window roller sun blind switch for longer than 15 s, the roller sun blind is denormalized. This function can be deactivated via the diagnosis tester. If the voltage of the on-board electrical system is too low, the roller sun blind is also denormalized.

Normalization can be started manually by pressing and holding down the rear window roller sun blind button or a rear window roller sun blind switch. The roller sun blind is extended or retracted and switched off at reduced speed until the mechanical stop is reached. The location counter of other limit stop is set to zero. The normalization process is triggered when the function is activated again.

During the subsequent actuation, the rear SAM control unit defines the adjustment range of the roller sun blind by counting the Hall sensor signals. Blockage detection takes place at the mechanical end stop of the target position. The maximum adjustment range is stored in the corresponding location counter in the rear SAM control unit.

Normalization is terminated.

When the rear window roller sun blind button or a rear window roller sun blind switch is pressed, the retraction movement of the roller sun blind is started. The roller sun blind is retracted until the lower mechanical end stop is reached and is then extended (reversed) as far as the lower soft stop. The soft stop defines a certain distance to the mechanical stop by softly decelerating the roller sun blind. The reversing operation releases any mechanical tension present in the roller blind system. Normalization is terminated.

IMPORTANT The roller sun blind is normalized automatically after moving 100 times in normal operation or after lockup.

When opening, the roller sun blind moves past the lower soft top to the mechanical stop at reduced speed. Then the roller sun blind is extended as far as the lower soft stop. The next time the roller sun blind is closed, it moves past the upper soft top at reduced speed until the mechanical stop is reached. Then the roller sun blind is retracted as far as the upper soft stop. Normalization is terminated.

Extending and retracting the roller sun blind 

The roller sun blind can be extended and retracted manually or retracted automatically.

The request to extend or retract the roller sun blind is generated by actuating one of the following control elements.

The rear SAM control unit reads in the corresponding request via the interior CAN and directly actuates the rear window roller sun blind motor. The roller sun blind is then extended and retracted.

IMPORTANT If the child safely lock in the rear power window is activated, the roller sun blind cannot be operated with the corresponding rear window roller sun blind switches. The left front door control unit transmits the status of the child safety lock to the rear SAM control unit via the interior CAN.

When gear range R is engaged, the roller sun blind is retracted automatically.

Gear range R is engaged through the fully integrated transmission control unit. The fully integrated transmission control unit then sends the "Gear range R engaged" status to the electronic ignition lock control unit via the drive train CAN, powertrain control unit and suspension FlexRay. The electronic ignition lock control unit uses the incoming information to generate the "reverse gear engaged" signal and sends it to the SAM control unit via the interior CAN. The rear SAM control unit then actuates the rear window roller sun blind motor accordingly. The roller sun blind is retracted.

In addition the gear range, the rear SAM control unit evaluates the vehicle speed for reverse travel detection. The instrument cluster sends the information on the vehicle speed via user interface CAN, electronic ignition lock control unit and interior CAN to the rear SAM control unit.

Blockage detection 

Blocking of the roller sun blind during extension or retraction is detected either if a rise in the power consumption of the rear window roller sun blind motor is detected or if no Hall sensor signals are received for a certain time.

The rear SAM control unit evaluates the power consumption of the rear window roller sun blind motor and the signals from the Hall sensors in the rear window roller sun blind motor.

Failure of the Hall sensor signals can have the following causes:

If the rear SAM control unit detects a blocking of the roller sun blind, it stops the movement of the roller sun blind and reverses the direction of the movement. The roller sun blind is then normalized automatically.

If blocking is detected again when reversing or before reaching the mechanical stop and no Hall sensor signals are available, the function changes to emergency operation. In emergency operation, the roller sun blind can still be extended and retracted manually. If the Hall sensor signals are available again, the roller sun blind must be normalized manually. If the Hall sensor signals are available again during extension or retraction in emergency operation, manual normalization is performed in the direction of movement.

  Electrical function schematic for roller sun blind   PE68.50-P-2052-97SEA 
  Overview of system components for windows and sightproofing   GF67.00-P-9999LF
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