Belt Extender, Function - GF91.45-P-0001RF
Model 205.3 with code U02 (Belt extender, electric)
Model 205.4
Function requirements, general
- No overvoltage or undervoltage
- Seat belt not fastened
- Backrest locked
- Door closed
- Front passenger seat occupied (not for initial run)
The supplemental restraint system control unit sends the status of the belt buckles and the front passenger seat occupancy via user interface CAN, electronic ignition lock control unit and interior CAN to the rear control unit.
The rear SAM control unit reads in the status of the backrest release microswitch directly, and transmits this via the interior CAN to the rear control unit.
The front door control units transmit the status of the doors (open or closed) via the interior CAN to the rear control unit.
Belt extender, general
The belt extender makes it easier to reach the front seat belts. For this purpose, the belt extender is extended to the convenient position automatically or by pressing the belt extender button.
Extend/retract belt extender
After entering the vehicle (opening and closing the door) and then switching on circuit 15R, the seat belt extender is extended to the convenient position. Alternatively, the belt extender can be manually extended to the convenient position with circuit 15R ON by pressing the belt extender button.
The seat occupied recognition is also taken into account at the passenger side. The signal for the seat occupancy recognition is only available after approx. 5 s after switching on circuit 15R. Only the status of the front passenger door is therefore evaluated for the initial operation.
In vehicles with fully electric seat adjustment (driver's seat with code 221 (Electrically adjustable left driver seat) or code 275 (Memory package), front passenger seat with code 222 (Electrically adjustable right front seat) or code 242 (Electrically adjustable front passenger seat with memory function)), the convenient position is moved to depending on the seat position.
The electronic ignition lock control unit sends the circuit 15 status over the interior CAN to the rear control unit.
Vehicles up to model year 2019 or vehicles as of model year 2019 except code 446 (Touchpad only):
The audio/COMAND control panel reads in the status of the belt extended button via the lower control panel LIN and transmits this via the telematics CAN, the head unit, the user interface CAN, the electronic ignition lock control unit and the interior CAN to the rear control unit.
Vehicles as of model year 2019 with code 446 (Touchpad only):
The touchpad reads in the status of the seat belt extender button via the LCP-LIN and transmits this via the telematics CAN, the head unit, the user interface CAN, the electronic ignition lock control unit and the interior CAN to the rear control unit.
In vehicles with transmission 716, the belt extender button is located at the left lower control panel.
In vehicles with transmission 722, 725 the belt extender button is located at the right lower control panel.
In vehicles with fully electric seat adjustment, the driver seat control unit and the front passenger seat control unit transmit information about the position of the driver seat and the front passenger seat via the interior CAN to the rear control unit. The rear control unit directly actuates the respective belt extender electric motor to extend or retract the belt extender. Belt extender Hall sensors are integrated in the belt extender electric motors. The provide information about the position of the belt extenders. The rear control unit directly reads in the signals of the belt extended Hall sensors.
The belt extender is automatically retracted again under the following conditions:
- A door is opened.
- The seat belt is fastened.
- Circuit 15R is switched off.
- The backrest is unlocked.
- The front passenger seat is recognized as unoccupied.
- Convenience time has elapsed.
- Overload detected.
- Faults were detected.
The actuation voltage of the seat belt extender electric motor is reduced by 30 % 20 Hall pulses before the respective end position is reached. As a result, the seat belt extender is braked as it moves into the end position.
Initialization drive
If the position of the seat belt extender is lost (e. g. due to a hardware fault or external operation), an initialization run is performed. The belt extender is moved to the rear end position (recognized by the belt extender Hall sensor signals not being present) and the location counter is set to the value "0".
Overload recognition
If a counterforce of approx. 100 N is recognized when extending the belt extender, the belt extender reverses into the rear end position. After a dwell time of 1 s the belt extender is extended again. This process repeats itself three times.
| Electrical function schematic for belt extender | PE91.45-P-2050-97FBA | ||
| Overview of system components for supplemental restraint system | GF91.60-P-9996RF |