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Home >> Mercedes Benz >> 2004 >> CLK 55 AMG Cabriolet (209.476) V8-5.5L (113.987) >> Repair and Diagnosis >> Restraints and Safety Systems >> Air Bag Systems >> Description and Operation >> GF91.60-P-0002QMC Supplemental Restraint System (SRS), Function

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



GF91.60-P-0002QMC Supplemental Restraint System (SRS), Function
- as of 1.6.04
- with CODE (494a) USA version

Component Identification:






General
The supplemental restraint system (SRS) provides passive interior protection. The following events can be recorded and differentiated:
^ Head-on collision
^ Rear-end collision
^ Side-on collision

If an accident occurs the relevant airbags and emergency tensioning retractors are triggered depending on the severity of the impact. The following safety equipment can be activated in case of an accident, depending on the configuration:
^ Driver airbag
^ Passenger airbag
^ driver side airbag
^ Front passenger sidebag
^ Left and right rear sidebags (with code (293) rear left and right sidebags)
^ Emergency belt tensioner for driver
^ Emergency belt tensioner for front passenger
^ Left rear emergency belt tensioner
^ Right rear emergency belt tensioner
^ Right windowbag
^ Left windowbag

The system monitors itself continuously and immediately notifies the driver of faults via the multifunction display (A1p13) in the instrument cluster (A1). Faults are stored in the non-volatile memory of the restraint systems control unit (N2/7). The system has a backup power supply in the restraint systems control unit (N2/7). If the battery is torn off, the entire system is supplied with voltage for at least 150 ms.

Function requirements:
^ Circuit 15R ON
^ Circuit 15 ON

System monitoring
Following a successful self-test, the system continuously monitors the inputs and outputs of the restraint systems control unit (N2/7). Malfunctions in the system are indicated by the airbag indicator and warning lamp (A1e15) and the multifunction display (A1p13) in th instrument cluster (A1). In order to do this the instrument cluster (A1) receives the relevant message from the restraint systems control unit (N2/7) via the Controller Area Network Bus class B (interior) (CAN-B).

Sensors
^ Passenger seat occupied and child seat recognition sensor (B48)
^ Sidebag and windowbag sensor, left (A53/1)
^ Sidebag and windowbag sensor, right (A54/1)
^ Driver side seat belt buckle restraint systems switch (S68/3)
^ Passenger side seat belt buckle restraint systems switch (S68/4)

Seat occupied recognition sensor
When the front passenger airbag is deployed by the restraint systems control unit (N2/7) the data received by the front passenger seat occupied and child seat recognition sensor (B48) and the status of the driver seat belt buckle restraint systems switch (S68/3) and the front passenger seat belt buckle restraint systems switch (S68/4) are also taken into consideration. Under certain conditions the restraint systems control unit (N2/7) (e.g. certified child seat detected) prevents the airbag and seat belt buckle restraint unit from being deployed at the passenger side. The automatic child seat recognition function and the deactivation of the front passenger airbag by the WSS (Weight Sensing System) control unit (N2/13) are indicated by the automatic child seat recognition airbag OFF indicator lamp (N72/1e1) being on.

The installed airbag units bear the label "SRS AIRBAG".

Diagnosis
Diagnosis takes place via STAR DIAGNOSIS.

Automatic emergency opening of central locking (CL)
A crash sensor is installed in the rear SAM control unit with fuse and relay module (N10/2). If the vehicle acceleration is > 60 m/s 2, after a delay of 8 to 11 seconds the rear SAM control unit with fuse and relay module (N10/2) unlocks the doors by sending an unlock signal to the respective door control unit.
The following control units receive the emergency opening signal:
^ Left door control module (N69/1)
^ Right door control module (N69/2)

Hazard warning flashers
In the event of a crash, the hazard warning system is switched o 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) via CAN-B. The rear SAM control unit with fuse and relay module (N10/2) acts as the master and cyclically transmits the hazard warning signal request on the CAN-B for the duration of the request. The message is received by the front SAM control unit with fuse and relay module (N10/1), the left door control unit (N69/1) and the right door control unit (N69/2) and used to actuate the relevant turn signals flashers. The message is read in by the upper control panel control unit (N72/1) and the instrument cluster (A1) so that the driver can be provided with optical and acoustic feedback. The hazard warning system can be switched off at any time using the hazard warning system switch (N72/1s5).

Emergency call telegram
The restraint systems control unit (N2/7) transmits (with code (359) TELE AID emergency call system) a crash signal to the emergency call system control unit (N123/4) via a discrete line, irrespective of the severity of the accident.

The emergency call system control unit (N123/4) automatically sends an SMS to the responsible control center containing the following emergency information:
^ Vehicle location, direction and history
^ Vehicle data (e.g. circuit status)
^ Crash detection (severity of accident)
^ Customer data (telephone number)





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