Actuate supplemental restraint system, function - GF91.60-P-2012FL

MODEL 212 

Function requirements, general 

• Circuit 15R ON

The status of circuit 15R is transmitted by the electronic ignition lock control unit (N73) via the chassis CAN (CAN E) (up to 28.2.13) or via chassis CAN 1 (CAN E1) (as of 1.3.13) to the Supplemental Restraint System control unit (N2/10).

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 of the supplemental restraint system on the basis of this information. The Trigger Supplemental Restraint System function includes the following subfunctions:

• Function sequence system monitoring 
• Function sequence for evaluating the occupancy of the front passenger seat 
• Function sequence for detecting the status of the front seat belts 
• Function sequence for impact detection 
• Function sequence for frontal impact 
• Function sequence for side impact 
• Function sequence for rear end collision 
• Function sequence for rollover 
• Function sequence for additional functions in the event of a crash 

Function sequence system monitoring 

The supplemental restraint system control unit continuously monitors the supplemental restraint system and reports faults to the driver via the supplemental restraint system indicator lamp (A1e15) and the multifunction display (A1p13) in the instrument cluster (A1). The request for output of corresponding messages is sent by the supplemental restraint system control unit on vehicles up to 28.2.13 via chassis CAN to the instrument cluster. On vehicles as of 1.3.13, the supplemental restraint system control unit sends the request via chassis CAN 1, front SAM control unit with fuse and relay module (N10/1) and chassis CAN 2 (CAN E2) to the instrument cluster.

The automatic child seat recognition warning lamp (S6/1e1) in the instrument panel switch group (S6/1) (up to 28.2.13) or the automatic child seat recognition warning lamp (N72/1e1) (as of 1.3.13) in the upper control panel control unit (N72/1) is also switched on. The request to switch on the automatic child seat recognition warning lamp is sent by the supplemental restraint system control unit via chassis CAN (up to 28.2.13) or via chassis CAN 1 (as of 1.3.13) to the front SAM control unit, which actuates the automatic child seat recognition warning lamp accordingly via instrument panel LIN (LIN 1). Any faults are stored in the nonvolatile memory of the Supplemental Restraint System control unit. The Supplemental Restraint System indicator lamp and the automatic child seat recognition warning lamp are switched off following a successful self-test after t = 4 s.

Function sequence for evaluating the occupancy of the front passenger seat 

The triggering behavior of the restraint equipment at the passenger side is adapted on the basis of the occupancy status of the front passenger seat.

Without code (U18) Automatic child seat recognition (ACSR [AKSE]) and without code (U10) Front passenger seat with weight sensing, the status of the seat occupied recognition does not have any influence on the triggering behavior of the supplemental restraint system.

Detailed information about the seat occupied recognition can be found in the separate partial function "Passenger-side seat occupied recognition, function".

Function sequence for detecting the status of the front seat belts 

The triggering behavior of the restraint equipment is adapted depending on the status of the seat belts (fastened or not fastened). The driver seat belt buckle restraint system switch (S68/3) or the front passenger seat belt buckle restraint system switch (S68/4) is actuated by the belt latch which is inserted into the belt buckle. The status of the belt buckle restraint system switch is directly read in by the supplemental restraint system control unit.

The status of the rear seat belts 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 determines the acceleration forces acting on the vehicle with the aid of the following sensors:

• Integrated sensors
• Left sidebag sensor (A53)
• Right sidebag sensor (A54)
• Left frontal acceleration sensor (B48/1)
• Right frontal acceleration sensor (B48/2)
• Left front door pressure sensor (B48/7)
• Right front door pressure sensor (B48/8)
• Left rear door pressure sensor (B48/9) (with code (293) Left and right rear sidebag)
• Right rear door pressure sensor (B48/10) (with code (293) Left and right rear sidebag)

The signals of the sensors are read in directly by the Supplemental Restraint System control unit.

A distinction can be made between the following types of impact via the evaluation of the signals from these sensors:

• Head-on collision
• Side-on collision
• Rear end collision
• Roll-over

Function sequence for frontal impact 

The supplemental restraint system control unit detects a frontal impact by evaluating the signals from the following sensors:

• Integrated sensors
• Left frontal acceleration sensor
• Right frontal acceleration sensor

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

The following squibs can be ignited (at most):

• Driver emergency tensioning retractor squib (R12/1)
• Passenger emergency tensioning retractor squib (R12/2)
• Front passenger airbag squib 1 (R12/4)
• Front passenger airbag squib 2 (R12/5)
• Left rear emergency tensioning retractor squib (R12/6)
• Right rear emergency tensioning retractor squib (R12/7)
• Driver airbag squib 1 (R12/13)
• Driver airbag squib 2 (R12/14)
• Driver kneebag squib (R12/25) (with code (294) Kneebag)
• Front passenger airbag vent valve squib (R12/44) (with code (U10)

Front passenger seat with weight recognition as of 1.3.13)

The squibs are actuated directly by the Supplemental Restraint System control unit.

The following situations are taken into account:

• Occupancy status of the front passenger seat:

  The Supplemental Restraint System control unit uses the current occupancy to decide about suppression or 1 or 2-stage actuation of the front passenger airbag unit.

• Driver belt buckle status:

  If the driver seat belt buckle restraint system switch detects that a belt latch is not inserted into the belt buckle, the driver airbag unit with advanced ignition timing is triggered instead of the driver emergency tensioning retractor unit.

• Front passenger belt buckle status:

  If the front passenger seat belt buckle restraint system switch detects that a belt latch is not inserted into the belt buckle, the front passenger airbag unit with advanced ignition timing is triggered instead of the front passenger emergency tensioning retractor unit.

• Position of front passenger seat (with code (U10) Front passenger seat with weight recognition as of 1.3.13):

  The supplemental restraint system control unit uses the status of the front passenger seat position detection switch (S68/20) to decide about the corresponding trigger time of the front passenger airbag unit. This only applies, however, if the front passenger seat is known to be occupied. If not occupied, then neither the emergency tensioning retractor nor the front passenger airbag unit are deployed. The status of the front passenger seat position detection switch is read in directly by the Supplemental Restraint System control unit.

Function sequence for side impact 

The supplemental restraint system control unit detects a side impact by evaluating the signals from the following sensors:

• Integrated sensors
• Left sidebag sensor
• Right sidebag sensor
• Left front door pressure sensor
• Right front door pressure sensor
• Left rear door pressure sensor
• Right rear door pressure sensor

The restraint equipment is deployed depending on the severity of the impact and occupancy of the front passenger seat.

The following squibs can be ignited (at most):

• Driver ETR [GUS] squib
• Front passenger ETR [GUS] squib
• Left rear emergency tensioning retractor squib
• Right rear emergency tensioning retractor squib
• Driver sidebag squib (R12/9)
• Front passenger sidebag squib (R12/10)
• Left rear sidebag squib (R12/11) (with code (293) Left and right rear sidebag)
• Right rear sidebag squib (R12/12) (with code (293) Left and right rear sidebag)
• Left windowbag squib (R12/22)
• Right windowbag squib (R12/23)
• Driver pelvis airbag squib (R12/41) (with code (291) PELVIS AIRBAG (PELVISBAG))
• Front passenger pelvis airbag squib (R12/42) (with code (291) PELVIS AIRBAG (PELVISBAG))

The squibs are actuated directly by the Supplemental Restraint System control unit.

The following situations are taken into account:

• Occupancy status of the front passenger seat:

  The Supplemental Restraint System control unit makes a decision about triggering the front passenger sidebag unit based on the current occupancy of the front passenger seat.

• Driver belt buckle status:

  If the driver restraint system seat belt buckle switch detects that a belt latch has not been inserted into the seat belt buckle, the driver-side seat belt buckle emergency tensioning retractor unit is not deployed.

• Front passenger belt buckle status:

  If the front passenger restraint system seat belt buckle switch detects that a belt latch has not been inserted into the seat belt buckle, the front passenger-side seat belt buckle emergency tensioning retractor unit is not deployed.

Function sequence for rear end collision 

The supplemental restraint system control unit detects a rear-end collision by evaluating the signals from the following sensors:

• Integrated sensors
• Left sidebag sensor
• Right sidebag sensor
• Left frontal acceleration sensor
• Right frontal acceleration sensor

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

The following squibs can be ignited (at most):

• Driver ETR [GUS] squib
• Front passenger ETR [GUS] squib
• Left rear emergency tensioning retractor squib
• Right rear emergency tensioning retractor squib

The squibs are actuated directly by the Supplemental Restraint System control unit.

In addition, the following components are actuated by the Supplemental Restraint System control unit:

• Driver seat NECK-PRO head restraint solenoid (Y24/12)
• Front passenger seat NECK-PRO head restraint solenoid (Y24/13)

The triggering of the NECK-PRO head restraint is also described in the separate function description "Driving assistance systems, function" in the "Rear PRE-SAFE, function" subfunction.

The following situations are taken into account:

• Driver belt buckle status:

  If the driver restraint system seat belt buckle switch detects that a belt latch has not been inserted into the seat belt buckle, the driver-side seat belt buckle emergency tensioning retractor unit is not deployed.

• Front passenger belt buckle status:

  If the front passenger restraint system seat belt buckle switch detects that a belt latch has not been inserted into the seat belt buckle, the front passenger-side seat belt buckle emergency tensioning retractor unit is not deployed.

• Right rear emergency tensioning retractor squib

The squibs are actuated directly by the Supplemental Restraint System control unit.

The following situations are taken into account:

• Driver belt buckle status:

  If the driver restraint system seat belt buckle switch detects that a belt latch has not been inserted into the seat belt buckle, the driver-side seat belt buckle emergency tensioning retractor unit is not deployed.

• Front passenger belt buckle status:

  If the front passenger restraint system seat belt buckle switch detects that a belt latch has not been inserted into the seat belt buckle, the front passenger-side seat belt buckle emergency tensioning retractor unit is not deployed.

Function sequence for rollover 

The supplemental restraint system control unit detects a rollover by evaluating the signals from the integrated sensors: Only one roll-over around the longitudinal vehicle axis can be detected.

The following squibs can be ignited (at most):

• Driver ETR [GUS] squib 
• Front passenger ETR [GUS] squib 
• Left rear emergency tensioning retractor squib 

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 function 
• Function sequence for switching on the interior illumination 
• Function sequence for opening the central locking 
• Function sequence for opening the side windows 
• Function sequence for shutting off the engine 
• Function sequence for switching off the air conditioning system (as of 1.3.13) 
• Function sequence for shutting off the stationary heater (STH) (with code (228) Stationary heater) 
• Function sequence for automatic emergency call (with code (359) TELEAID emergency call system or code (348) Emergency call/Assist system) 
• Function sequence for activating the crash-active easy exit function (with code (275) Electrically adjustable front seats memory package) 
• Function sequence for switching off the high-voltage components (model 212.095/098/298) 

Function sequence for activating the hazard warning function 

The hazard warning flasher function is activated automatically in order to warn other road users in the event of an accident. The Supplemental Restraint System control unit sends the crash signal over the chassis CAN (up to 28.2.13) or chassis CAN 1 (as of 1.3.13) to the front SAM control unit. The front SAM control unit initiates the hazard warning flasher function by issuing the flasher frequency via interior CAN.

Detailed information about the hazard warning flasher function can be found in the separate function description "Exterior lights, function" in subfunction "Turn signal light actuation, function".

Function sequence for switching on the 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 when it is dark, the interior illumination is automatically switched on. The Supplemental Restraint System control unit sends the crash signal over the chassis CAN (up to 28.2.13) or chassis CAN 1 (as of 1.3.13) to the front SAM control unit. The front SAM control unit then activates the interior illumination.

Detailed information about the interior illumination can be found in the separate function description "Interior illumination function".

Function sequence for opening the central locking (CL [ZV]) 

In order to make it possible for helpers gain access to vehicle occupants who may be injured in the event of an accident, the central locking is automatically unlocked. The supplemental restraint system control unit sends the crash signal to the following control units via chassis CAN (up to 28.2.13) or chassis CAN 1 (as of 1.3.13), front SAM control unit and interior CAN:

• Left front door control unit (N69/1)
• Right front door control unit (N69/2)
• Left rear door control unit (N69/3)
• Right rear door control unit (N69/4)
• Rear SAM control unit with fuse and relay module (N10/2)

The central locking is unlocked after a waiting time of t = 8 to 11 s. In the event of rear end collision, the CL is unlocked without waiting time.

Detailed information about the CL [ZV] can be found in the "Central locking (CL [ZV]), function" subfunction of the separate function description "Theft protection and locking function description".

Function sequence for opening the side windows 

Smoke particles are produced in the vehicle interior when the pyrotechnical restraint equipment is triggered. The side windows are opened automatically leaving a gap in order to allow these smoke particles to quickly disperse. The supplemental restraint system control unit sends the crash signal to the following control units via chassis CAN (up to 28.2.13) or chassis CAN 1 (as of 1.3.13), front SAM control unit and interior CAN:

• Left front door control unit
• Right front door control unit
• Left rear door control unit
• Right rear door control unit

Detailed information on opening the side windows can be found in the separate function description "Window and sightproofing function description" in the "Power windows (EFH), function" subfunction.

Function sequence for shutting off the engine 

After an accident, the engine is automatically turned off to reduce the risk of fire. The supplemental restraint system control unit sends the crash signal via chassis CAN (up to 28.2.13) or via chassis CAN 1 (as of 1.3.13) to the CDI control unit (N3/9) (with diesel engine) or to the ME-SFI [ME] control unit (N3/10) (with gasoline engine). This then causes the engine to be shut off.

The crash signal is also sent over a direct line by the Supplemental Restraint System control unit to the CDI control unit or the ME-SFI [ME] control unit.

Function sequence for switching off the air conditioning system (as of 1.3.13) 

In order to prevent hazardous gases from entering the vehicle interior after an accident, the automatic climate control control and operating unit (N22/7) shuts off the air conditioning and closes the air recirculation flap. The supplemental restraint system control unit transmits the crash signal via the chassis CAN 1, the front SAM control unit and the interior CAN to the automatic air conditioning control and operating unit.

Detailed information about switching off the air conditioning can be found in the separate function description "Automatic climate control, function" in subfunction "Automatic climate control regulation, function".

Function sequence for switching off the STH (with code (228) Stationary heater) 

After an accident, the stationary heater is automatically turned off to reduce the risk of fire. The supplemental restraint system control unit sends the crash signal via chassis CAN (up to 28.2.13) or via chassis CAN 1 (as of 1.3.13), front SAM control unit and interior CAN to the stationary heater control unit (A6n1), which prompts a shutoff of the stationary heater.

Detailed information about the stationary heater can be found in the separate function description "Stationary heater (STH), function".

Function sequence for automatic emergency call (with code (359) TELEAID emergency call system or code (348) Emergency call/Assist system) 

An emergency call is made automatically after an accident. The supplemental restraint system control unit sends the crash signal via chassis CAN (up to 28.2.13) or via chassis CAN 1 (as of 1.3.13), front SAM control unit and diagnostic CAN (CAN D) to the emergency call system control unit (N123/4), which makes the automatic emergency call.

The crash signal is also sent over a direct line from the Supplemental Restraint System control unit to the emergency call system control unit.

Detailed information on the automatic emergency call can be found in the separate function description "Telematics function description" in the "Emergency call system, function" subfunction.

Function sequence for activating the crash-active easy exit function (with code (275) Electrically adjustable front seats memory package) 

In order to make it easier for the driver to get out of the vehicle and for first aiders to recover the driver from the vehicle after an accident, the steering column is automatically moved upwards in the event of the following actions:

• Driver door opened
• Change of status from circuit 15C ON to circuit 15C OFF

The supplemental restraint system control unit sends the crash signal via chassis CAN (up to 28.2.13) or via chassis CAN 1 (as of 1.3.13), front SAM control unit and interior CAN to the driver seat control unit (N32/1). The driver seat control unit initiates upward adjustment of the steering column.

Detailed information on crash-active easy exit function can be found in the separate "Electrical seats, function" function description in the "Electrically adjustable steering column (ESC [EVL]), function" subfunction.

Function sequence for switching off the high-voltage components (model 212.095/098/298) 

The high-voltage components are switched off after an accident to reduce the risk of fire. The supplemental restraint system control unit sends the crash signal via chassis CAN (up to 28.2.13) or via chassis CAN 1 (as of 1.3.13), CDI control unit or ME-SFI [ME] control unit and Hybrid CAN (CAN L) to the battery management system control unit (N82/2), which then de-energizes the high-voltage components. The pyrofuse (F63) is also actuated by the Supplemental Restraint System control unit.

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