GF91.60-P-0002SK Supplemental Restraint System (SRS), Function

GF91.60-P-0002SK Supplemental Restraint System (SRS), Function

Function requirements
^ The supplemental restraint system (SRS) must be programmed to match the vehicle (left-hand drive vehicle or right-hand drive vehicle, equipment programming and configuration parameters)
^ Circuit 15 ON
^ C. 15R On

Function
The SRS is serves as passive interior protection. The following events can be recorded and distinguished:
^ Head-on collision
^ Rear end collision
^ Side collision
^ Rolling along the longitudinal vehicle axis

Impact detection
The restraint systems control unit (N2/7) monitors the acceleration values and controls, depending on the threshold value, actuation of the restraint system equipment.

The following sensors are read in for evaluation purposes:
^ Drive sidebag sensor (A53)
^ Front passenger sidebag sensor (A54)
^ Driver-side frontal acceleration sensor (B48/1)
^ Passenger-side frontal acceleration sensor (B48/2)

In addition, the following data are evaluated for analysis of the situation in the vehicle interior:
^ Status of driver-side seat belt buckle
^ Status of passenger-side seat belt buckle
^ Front passenger seat occupation status

Activation of the restraint systems equipment in the event of a crash takes place dependent on the type of accident. Depending on the severity of an accident as detected by the restraint systems control unit (N2/7), the following restraint system equipment can be triggered:
^ Driver-side airbag unit, 2-stage
^ Passenger-side airbag unit, 2-stage
^ Driver/front passenger sidebag unit
^ Driver/front passenger kneebag unit (only (United States Of America) as from 1.6.06)
^ Driver/front passenger buckle emergency tensioning retractor
^ Driver/front passenger belt force limiter unit

Capacitor
The SRS is equipped with a capacitor in the restraint systems control unit (N2/7). If the battery is disconnected, then the voltage supply is assured for at least 150 ms.

Sensors (A53, A54, B48/1 and B48/2) are supplied for at least 150 ms.

System monitoring
The SRS continually monitors itself and displays any faults over the airbag indicator and warning lamp (A1e15) in the instrument cluster (A1).

Faults are stored in the non-volatile memory of the restraint systems control unit (N2/7).

The following indications are possible:
^ The airbag indicator and warning lamp (A1e15) lights as of circuit 15R On for approx. 4 s and then goes out again. The system did not detect a fault during the self-test.
^ The airbag indicator and warning lamp (A1e15) lights up permanently as of circuit 15R On. The system detected a fault during its cyclic self-test.

Passenger-side seat occupied recognition

Vehicles without code (494) USA version or vehicles with code (494) USA version up to 31.5.06:
The front passenger seat occupied and child seat recognition sensor (B48) detects the seat occupation status of the front passenger seat and forwards this information to the restraint systems control unit (N2/7).

Vehicles with code (494) USA version as from 1.6.06:
The weight applied to the front passenger seat is measured to determine the weight class; this information is then sent from the Weight Sensing System (WSS) control unit (N110) to the restraint systems control unit (N2/7).

Based on this information, the restraint systems control unit (N2/7) locks or enables the corresponding restraint system equipment.

Automatic emergency opening of the central locking (CL)
A crash sensor is integrated into the rear SAM control unit with fuse and relay module (N10/2).

The emergency opening signal is triggered as from a specific value. After a waiting time of 8 to 11 s, this signal is forwarded from the rear SAM control unit with fuse and relay module (N10/2) to the left door control unit (N69/1) and the right door control unit (N69/2), whereupon the respective door is unlocked.

Seat belt reminder warning
The driver seat belt buckle restraint systems switch (S68/3) and the front passenger seat belt buckle restraint systems switch (S68/4) are read in and monitored by the rear SAM control unit with fuse and relay module (N10/2). The seat belt reminder warning is displayed on the instrument cluster (A1) when a seat belt is not fastened at the driver or front passenger seat.

Hazard warning flashers
In the event of a crash, the hazard warning system is switched on automatically. The restraint systems control unit (N2/7) transmits the crash signal to the rear SAM control unit with fuse and relay module (N10/2).

The hazard warning system can be switched off at any time using the hazard warning system switch (N72/1s5).

Automatic alarm call (only (United States Of America) with code (359) TELE AID emergency call system)
If, during a collision or rollover, the relevant triggering threshold is exceeded, an automatic emergency call is additionally sent by the emergency call system control unit (N123/4).