Actuate supplemental restraint system, function - GF91.60-P-2012FQ
MODEL 218
Function requirements, general
- Circuit 15R ON
The status of circuit 15 is sent to the supplemental restraint system control unit (N2/10) by the electronic ignition lock control unit (N73) via chassis CAN (CAN E) (up to 28.02.2013) or chassis CAN 1 (CAN E1) (as of 01.03.2013).
Actuate supplemental restraint system, general
The supplemental restraint system continuously monitors the occupancy of the front passenger seat and the status of the seat belts (fastened or not fastened) and adapts its triggering behavior on the basis of this information.
The Trigger supplemental restraint system function includes the following subfunctions:
- Function sequence system monitoring
- Function sequence for evaluation of occupancy status of front passenger seat
- Function sequence for detecting status of 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
When circuit 15R is switched on, the following indicator lamps are actuated:
- Supplemental restraint system indicator lamp (A1e15) in the instrument cluster (A1)
- Automatic child seat recognition airbag OFF indicator lamp (N72/1e1) in upper control panel control unit (N72/1)
The Supplemental Restraint System indicator lamp and the automatic child seat recognition airbag OFF indicator lamp are switched off after a successful self-test (t = 4 s). Then, on vehicles with code (U18) Automatic child seat recognition (ACSR) [AKSE] or code (U10) Front passenger seat with weight recognition, the occupancy status of the front passenger seat is displayed by way of the automatic child seat recognition airbag OFF indicator lamp.
The request to switch the Supplemental Restraint System indicator lamp on is sent by the Supplemental Restraint System control unit via the chassis CAN to the instrument cluster on vehicles up to 28.02.2013. On vehicles as of 01.03.2013, 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 request to switch the automatic child seat recognition airbag OFF indicator lamp on is sent by the Supplemental Restraint System control unit via the chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013), front SAM control unit, and instrument panel LIN (LIN 1) to the upper control panel control unit, which directly actuates the automatic child seat recognition airbag OFF indicator lamp.
The supplemental restraint system control unit constantly monitors the supplemental restraint system when driving and reports faults to the driver via the multifunction display (A1p13) and the supplemental restraint system indicator lamp in the instrument cluster. The request to display a corresponding message is sent by the Supplemental Restraint System control unit via the chassis CAN to the instrument cluster on vehicles up to 28.02.2013. On vehicles as of 01.03.2013, the Supplemental Restraint System control unit sends the request via the chassis CAN 1, front SAM control unit, and chassis CAN 2 to the instrument cluster. The faults are stored in the nonvolatile memory of the supplemental restraint system control unit.
On vehicles with code (494) USA version, as of 01.09.2014 an accident data recorder is integrated in the supplemental restraint system control unit that records relevant data before, during and after an accident. The data stored can be used to trace back the course of the accident.
Function sequence for evaluation of occupancy status of 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 recognition, 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 subfunction "Passenger-side seat occupied recognition, function".
Function sequence for detecting status of front seat belts
The triggering behavior of the restraint equipment is adapted on the basis of the seat belts (worn or not being worn). The driver belt buckle restraint system switch (S68/3) or the front passenger belt buckle restraint system switch (S68/4) is actuated when the belt lock tongue 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 belt buckles does not have any influence on the deployment behavior of the Supplemental Restraint System.
Function sequence for impact detection
The supplemental restraint system control unit makes a distinction between a:
- Head-on collision
- Side-on collision
- Rear end collision
- Roll-over
To do so, the signals of the following sensors are evaluated:
- 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 sensor signals are read in directly by the supplemental restraint system control unit.
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)
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 deployment of the front passenger airbag.
- Driver belt buckle status:
If the belt tab is not inserted, the driver airbag with advanced ignition timing is triggered instead of the emergency tensioning retractor for the driver.
- Front passenger belt buckle status:
If the belt tab is not inserted, the front passenger airbag with advanced ignition timing is triggered instead of the emergency tensioning retractor for the front passenger. This only applies, however, if the front passenger seat is known to be occupied. Neither the emergency tensioning retractor nor the front passenger airbag is deployed if the seat is unoccupied.
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 window bag squib (R12/22)
- Right window bag squib (R12/23)
- Driver pelvisbag squib (R12/41) (with code (291) PELVIS AIRBAG (PELVISBAG))
- Front passenger pelvisbag squib (R12/42) (with code (291) PELVIS AIRBAG (PELVISBAG))
The squibs are actuated directly by the supplemental restraint system control unit.
The following state is taken into consideration:
- 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.
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 following situations are taken into account:
- Driver belt buckle status:
If the belt tab is not inserted, the driver emergency tensioning retractor is not triggered.
- Front passenger belt buckle status:
If the belt tab is not inserted, the front passenger emergency tensioning retractor is not triggered.
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
- 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 belt tab is not inserted, the driver emergency tensioning retractor is not triggered.
- Front passenger belt buckle status:
If the belt tab is not inserted, the front passenger emergency tensioning retractor is not triggered.
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
- Function sequence for switching on interior illumination
- Function sequence for opening the central locking (CL [ZV])
- Function sequence for opening the side windows
- Function sequence for shutting off the engine
- Function sequence for triggering the pyrofuse
- Function sequence for switching off the air conditioning system (as of 01.03.2013)
- Function sequence for shutting off the stationary heater (STH) (with code (228) Stationary heater)
- Function sequence for automatic emergency call (with code (348) Emergency call/assist system or code (359) TELEAID emergency call system)
- Function sequence for activating the crash-active easy exit function (with code (275) Electrically adjustable front seats memory package)
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 Supplemental Restraint System control unit sends the crash signal via the chassis CAN (up to 28.02.2013) or via the chassis CAN 1 (as of 01.03.2013) to the front SAM control unit. The front SAM control unit then activates the hazard warning flasher function.
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 interior illumination
In order to make it easier for the vehicle occupants or persons giving assistance to orientate themselves inside the vehicle in the event of an accident, the interior illumination is automatically activated. The Supplemental Restraint System control unit sends the crash signal via the chassis CAN (up to 28.02.2013) or via the chassis CAN 1 (as of 01.03.2013) to the front SAM control unit. The front SAM control unit then activates the interior illumination.
Detailed information about interior illumination can be found in the separate function description "Interior illumination (IBL), function" in the subfunction "Automatic interior lights control, function".
Function sequence for opening the central locking
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 via the chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013) to the front SAM control unit, which implements this request.
The central locking (CL [ZV]) 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 central locking (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 at the front 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 via the chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013), front SAM control unit, and interior CAN to the following control units:
- Left front door control unit (N69/1)
- Right front door control unit (N69/2)
Detailed information on opening the side windows can be found in the separate function description "Power windows (EFH), function".
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 the chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013) to the CDI control unit (N3/9) (with diesel engine) or 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 via a direct line by the supplemental restraint system control unit to the CDI control unit or to the ME-SFI [ME] control unit.
Function sequence for triggering the pyrofuse
In order to avoid a risk of fire after an accident, on vehicles without code (B03) ECO start/stop function, the pyrofuse 150 (F32f150) in the front prefuse box (F32) is triggered, and on vehicles with code (B03) ECO start/stop function, the pyrofuse (F63) is triggered.
Inside the pyrofuse housing, the main line is designed as busbar with predetermined fracture point (3). After a crash event has occurred, the pyrofuse 150 (without code (B03) ECO start/stop function) or the pyrofuse (with code (B03) ECO start/stop function) is actuated directly by the Supplemental Restraint System control unit. When the pyrofuse is actuated, pressure builds up in the chamber (1). The piston (2) then moves against the predetermined fracture point, thereby disconnecting the bus bar.
Time sequence:
Piston movement starts after t = 300 μs.
Bus bar disconnection is complete after t = 450 μs.
By triggering the respective pyrofuse, the starter (M1) and the alternator (G2) are quickly and reliably disconnected from the on-board electrical system.
Function sequence for switching off the air conditioning system (as of 01.03.2013)
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 sends the crash signal via chassis CAN 1, front SAM control unit and 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 the "Automatic climate control regulation, function" subfunction.
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 the chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013), front SAM control unit, and interior CAN to the stationary heater control unit (A6n1), which prompts a shutoff of the stationary heater.
Detailed information on switching off the STH can be found in the separate function description "Stationary heater (STH), function".
Function sequence for automatic emergency call (with code (348) Emergency call/assist system or code (359) TELEAID emergency call system)
An emergency call is made automatically after an accident. The Supplemental Restraint System control unit sends the crash signal via the chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013), 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 about the automatic emergency call can be found in the separate "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 circuit status from circuit 15C On to circuit 15C Off
The Supplemental Restraint System control unit sends the crash signal via the chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013), front SAM control unit, and interior CAN to the driver seat control unit (N32/1), which controls the crash-active easy exit function.
Detailed information about the electric steering column adjustment can be found in the separate function description "Electrical seats, function" in the subfunction "Electrically adjustable steering column (ESC [EVL]), function".
| Actuate supplemental restraint system, electrical function schematic | MODEL 218 up to model year 2014 | PE91.60-P-2055-97XAA | |
| MODEL 218 as of model year 2014 | PE91.60-P-2055-97XAB | ||
| Overview of system components for supplemental restraint system | GF91.60-P-9996FQ |