Roller sun blind, function - GF68.50-P-0004CE

MODEL 204.0 with code (540) Roller sun blind as of model year 2009 /YoM 08

Fig 1: Identifying Roller Sun Blind Function Diagram

Courtesy of MERCEDES-BENZ USA

Function requirements general

Circuit 15R ON
No overvoltage or undervoltage

The electronic ignition lock control unit transmits the status of circuit 15 via interior CAN.

Roller sun blind function, general

The roller sun blind consists of a vertical running roller blind without rails which operates according to the scissors principle. The roller sun blind is driven by the rear window roller sun blind motor.

The rear window roller sun blind motor is actuated by the rear SAM control unit with fuse and relay module. The roller sun blind is retracted or extended in the automatic mode without intermediate position.

The roller sun blind function comprises the following subfunctions:

Function sequence for retracting/extending roller sun blind
Function sequence for reversing roller sun blind
Function sequence for automatically switching off roller sun blind

Function sequence for retracting/extending roller sun blind

When the rear window roller sun blind button is actuated, the request to retract or extend the roller sun blind is read in by the upper control panel control unit and relayed to the front SAM control unit with fuse and relay module via the instrument panel LIN.

It transmits a signal via the interior CAN to the rear SAM control unit, which actuates the rear window roller sun blind motor. The roller sun blind is retracted or extended to the end position depending on the direction is last moved.

The last direction of motion is stored in the rear SAM control unit, so that the roller sun blind is moved in the direction expected by the operator when the roller sun blind button is actuated again.

Function sequence for reversing roller sun blind

If the rear window roller sun blind button is actuated a second time while a roller sun blind operation is already in progress, the roller sun blind stops and after t = 200 ms it is moved in the opposite direction.

Function sequence for automatically switching off roller sun blind

The partial function automatically switching off roller sun blind comprises the following subfunctions:

Function sequence for switching off with time control
Function sequence for switching off in event of blockage detection
Function sequence for switching off in event of hardware defect
Function sequence for switching off in event of voltage too high or too low
Function sequence for switching off with thermal protection

Function sequence for switching off with time control

The rear window roller sun blind motor is actuated for t = 15 s by the rear SAM control unit regardless of the running direction of the roller sun blind. Under unfavorable conditions (cold, sluggishness) the actuation time is increased by t = 2 s.

After expiration of this time the request is automatically terminated.

Function sequence for switching off in event of blockage detection

When the roller sun blind reaches its end position from a current request or locks up for other reasons, an increase in power of the rear window roller sun blind motor is recognized and compared with the performance maps stored in the rear SAM control unit. If the stored threshold value is exceeded, the rear window roller sun blind motor is switched off by the rear SAM control unit.

Function sequence for switching off in event of hardware defect

A request to the rear window roller sun blind button for t > 30 s is recognized as a "stuck button" by the front SAM control unit. The front SAM control unit does not output a signal via the interior CAN.

Function sequence for switching off in event of voltage too high or too low

If the on-board power supply voltage drops or increases for t = 1 s below or above a certain value, the roller sun blind function is switched off.

If the on-board power supply voltage again reaches a permissible value for longer than t = 5 s, the roller sun blind function is switched back on.

If the voltage in the on-board electrical system is too low, the current request is accomplished up to the corresponding end stop for the roller sun blind.

Function sequence for switching off with thermal protection

A request from the rear window roller sun blind motor is stored in the rear SAM control unit. If more than one request is present within a specified time, they are listed and compared with the threshold value stored in the rear SAM control unit.

If the threshold value is exceeded, the rear SAM control unit switches off the rear window roller sun blind motor to prevent overheating.

A new request from the rear window roller sun blind motor is only possible after a cooling time stored in the rear SAM control unit.

	Electrical function schematic for roller sun blind	PE68.50-P-2052-97FAB
	Overview of system components for roller sun blind	GF68.50-P-9995CE