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Supplemental Restraint System Function - GF91.60-D-0003TSA

Model 907 

G13791942

Function requirements, general 

IMPORTANT The electronic ignition lock (EZS) control unit transmits the status of circuit 15 to the SRS control unit via the user interface CAN.

IMPORTANT After switching off circuit 15R, parts of the Supplemental Restraint + System remain active for a certain run-on time.

IMPORTANT Energy reserve: The supplemental restraint system control unit provides an energy reserve for at least 300 ms after a battery disconnection.

Supplemental restraint system, general information 

The Supplemental Restraint System is used for occupant protection.

IMPORTANT Belt lock:

The belt is prevented from extending in certain situations, irrespective of the status of the Supplemental Restraint System.

The following subfunctions are described in separate documents:

Passenger-side seat occupied recognition, general 

The occupancy of the front passenger seat is recorded by the supplemental restraint system control unit.

The passenger-side seat occupied recognition function includes the following subfunctions:

Function sequence for seat occupied recognition 

The front passenger seat occupancy is recorded by the front passenger seat occupancy recognition. Only the status "seat occupied" or "seat not occupied" can be detected. The supplemental restraint system control unit reads in the relevant signals of the front passenger seat occupancy recognition.

IMPORTANT The occupancy status of the front passenger seat has no influence on the triggering behavior of the supplemental restraint system. The occupancy status is only required by the instrument cluster for the seat belt warning.

Additional function requirement for issuing status and fault messages 

Function sequence for issuing status and fault messages 

The SRS control unit transmits the respective request via the user interface CAN, the electronic ignition lock control (EZS) control unit, the interior CAN, the SAM control unit and the battery sensor LIN to the instrument cluster control unit which directly actuates the corresponding indicator lamp.

Fault messages: 

The following indicator lamps are switched on in the event of a fault (e.g. seat occupancy recognition defective, faulty connection to SRS control unit):

A fault code is also stored in the SRS control unit and an appropriate message is displayed in the multifunction display of the instrument cluster.

The SRS control unit transmits the request for displaying a corresponding message to the instrument cluster.

Actuate Supplemental Restraint System, general 

The supplemental restraint system continuously monitors the occupancy of the front passenger seat and the status of the front seat belts (fastened or not fastened) and adapts its triggering behavior on the basis of this information.

The supplemental restraint system deployment function includes the following subfunctions:

Function sequence system monitoring 

When circuit 15R is switched on, the following indicator lamps are actuated:

Following a successful self-test (4 s), the SRS indicator lamp and the airbag Off indicator lamp are switched off.

The SRS control unit transmits the request for switching on the SRS indicator lamp to the instrument cluster via the user interface CAN, the electronic ignition lock (EZS) control unit and the suspension CAN.

The SRS control unit continues to monitor the SRS while driving and notifies the driver of errors via the multifunction display and the SRS indicator lamp in the instrument cluster. The SRS control unit transmits the request for displaying a corresponding message to the instrument cluster via the user interface CAN, the electronic ignition lock (EZS) control unit and the suspension CAN. The faults are stored in the nonvolatile memory of the supplemental restraint system control unit.

Function sequence for evaluation of occupation status on front passenger seat 

The deployment behavior of the restraint equipment at the passenger-side is matched to the occupancy status of the front passenger seat.

IMPORTANT The status of the seat occupied recognition does not have any influence on the deployment behavior of the supplemental restraint system.

Function sequence for detecting the status of front seat belts 

The triggering behavior of the restraint equipment is adapted on the basis of the status of the seat belts (fastened or not fastened).

The driver seat belt buckle switch or the front passenger seat belt buckle switch is operated by the seat belt tongue inserted into the seat belt buckle. The status of the seat belt buckle switch is read in directly by the supplemental restraint system control unit.

IMPORTANT The status of the rear belt buckles does not have any influence on the triggering behavior of the supplemental restraint system.

Function sequence for impact detection 

The supplemental restraint system control unit makes a distinction between a:

To do so, the signals of the following sensors are evaluated:

The supplemental restraint system control unit directly reads in the sensor signals.

Function sequence for frontal impact 

The deployment of the restraint equipment takes place depending on the severity of the impact, the occupation of the front passenger seat and the status of the seat belts. The following squibs can be ignited (maximum):

The supplemental restraint system control unit directly actuates the squibs.

The following situations are taken into account:

The SRS control unit decides on the corresponding trigger time of the driver airbag according to the status of the driver seat position detection switch. The supplemental restraint system control unit reads in the status of the driver seat position detection switch directly.

The SRS control unit decides on the corresponding trigger time of the front passenger airbag according to the status of the front passenger seat position detection switch. However, this only applies if an occupied front passenger seat has been detected. The supplemental restraint system control unit reads in the status of the front passenger seat position detection switch directly.

The supplemental restraint system control unit uses the current occupancy to decide about suppression or 1 or 2-stage deployment of the front passenger airbag.

If the seat belt is not fastened, the driver airbag is triggered with advanced ignition timing instead of the seat belt tensioner and seat belt force limiter.

If the seat belt is not fastened, the front passenger airbag is triggered with advanced ignition timing instead of the seat belt tensioner and seat belt force limiter. However, this only applies if an occupied front passenger seat has been detected. No restraint equipment is triggered at the passenger side if the seat is unoccupied or the seat belt is not fastened.

Function sequence in the event of a side impact 

The deployment of the restraint equipment takes place depending on the severity of the impact, the occupation of the front passenger seat and the status of the seat belts.

The supplemental restraint system control unit directly actuates the squibs.

The following situations are taken into account:

Function sequence for rear impact 

The deployment of the restraint equipment takes place depending on the severity of the impact and the status of the seat belts.

The supplemental restraint system control unit directly actuates the squibs.

The following state is taken into consideration:

Function sequence for rollover 

The restraint equipment is deployed depending on the occupancy of the front passenger seat and the status of the seat belts.

The supplemental restraint system control unit directly actuates the squibs.

The following situations are taken into account:

Function sequence for additional functions in the event of a crash 

The additional functions in the event of a crash include the following subfunctions:

Function sequence for activating the hazard warning flasher function 

The hazard warning flasher function is activated automatically in order to warn other road users in the event of an accident. The SRS control unit transmits the crash signal to the SAM control unit. The SAM control unit then activates the hazard warning flasher function.

The crash signal is also transmitted via a direct line from the supplemental restraint system control unit to the SAM control unit.

Function sequence for switching on interior illumination 

In order to make it easier for the vehicle occupants or persons giving assistance to find their way around inside the vehicle in the event of an accident, the interior illumination is automatically activated. The SRS control unit transmits the crash signal to the SAM control unit. The SAM control unit then activates the interior illumination.

The crash signal is also sent over a direct line from the supplemental restraint system control unit to the SAM control unit.

Function sequence for opening the central locking system 

In order to make it possible for persons giving assistance to gain access to vehicle occupants who may be injured in the event of an accident, the central locking is automatically unlocked. The SRS control unit transmits the crash signal to the SAM control unit, which implements this request.

The central locking system is unlocked after a waiting time of 8 to 11 s.

Function sequence for opening the side windows 

Smoke particles are produced in the vehicle interior when the pyrotechnical restraint equipment is triggered. The front side windows are opened automatically by approx. 50 mm in order for these smoke particles to quickly disperse. The SRS control unit sends the crash signal to the following control units:

Function sequence for shutting off the engine 

In order to avoid the potential risk of fire after an accident, the engine is turned off automatically. The SRS control unit transmits the crash signal to the CDI control unit.

The CDI control unit then causes the engine to be shut off.

The crash signal is also transferred from the SRS control unit to the CDI control unit via a direct line.

Function sequence for triggering the pyrofuse 

In order to avoid a possible risk of fire following an accident, the pyrofuse is triggered.

Inside the housing, the main line is designed as bus bar with predetermined fracture point (3).

After a crash event has occurred (frontal crash with two-stage airbag deployment), the pyrofuse is directly actuated by the supplemental restraint system control unit. Because of the actuation, pressure builds up in the chamber (1). The piston (2) then moves against the predetermined fracture point, thereby disconnecting the bus bar. Time sequence:

After 300 the piston movement is started. + _ Bus bar disconnection is finished after 450 js.

IMPORTANT By triggering the pyrofuse, the starter and the alternator are disconnected from the onboard electrical system.

IMPORTANT Triggering of the pyrofuse causes the high-voltage components to be de-energized.

G13791943

Function sequence for switching off the A/C 

In order to prevent hazardous gases from entering the vehicle interior after an accident, the air conditioning is shut off and the air recirculation flap closed automatically. The SRS control unit transmits the crash signal to the automatic air conditioning control and operating unit via the user interface CAN, the electronic ignition lock (EZS) control unit and the interior CAN.

Function sequence for automatic emergency call 

An emergency call is made automatically after an accident.

Depending on the type of transmission involved the following data, among others, are sent to the Mercedes-Benz Emergency Call Center

Overview of system components for supplemental restraint system GF91.60-D-9996TSA 
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