Actuate supplemental restraint system, function - GF91.60-P-2012RF
Model 205, 253
Function requirements, general
- Circuit 15R ON
The electronic ignition lock control unit (N73) sends the circuit 15 status over the user interface CAN (CAN HMI) 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 seat belts (worn or not being worn) and adapts its deployment behavior on the basis of this information.
The supplemental restraint system deployment 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 seat belts
- Function sequence for impact detection
- Function sequence for frontal impact deployment
- Function sequence for side impact deployment
- Function sequence for rear end collision deployment
- Function sequence for rollover deployment
- 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)
- Front passenger airbag OFF indicator lamp (N72/1e1) in upper control panel control unit (N72/1)
- Front passenger airbag ON indicator lamp (N72/1e2) (with CODE U10 (Automatic front passenger airbag deactivation))
Following a successful self-test (t = 4 s) the supplemental restraint system indicator lamp and the front passenger airbag OFF indicator lamp (except CODE U10 (Automatic front passenger airbag deactivation)) are switched off. On vehicles with CODE U10 (Automatic front passenger airbag deactivation) the front passenger airbag ON indicator lamp or the front passenger airbag OFF indicator lamp indicates the corresponding occupancy status of the front passenger seat.
The supplemental restraint system control unit sends the request to switch on the supplemental restraint system warning indicator lamp over the user interface CAN to the instrument cluster. The supplemental restraint system control unit sends the request to switch on the respective front passenger airbag indicator lamp via user interface CAN, head unit (A26/17), telematics CAN (CAN A), Audio/COMAND control panel (A40/9) and the LCP [UBF] LIN (LIN A3) to the upper control panel control unit, which actuates the corresponding front passenger airbag indicator lamp directly.
The supplemental restraint system control unit continues to monitor the supplemental restraint system while driving and signals 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 transmitted by the supplemental restraint system control unit via the user interface CAN to the instrument cluster. The faults are stored in the nonvolatile memory of the supplemental restraint system control unit.
Function sequence for evaluation of occupancy status of front passenger seat
The deployment behavior of the restraint equipment at the passenger-side is adapted on the basis of the occupancy status of the front passenger seat.
Model 205, 253
except code U10 (Automatic seat occupancy recognition and child seat recognition)
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 status of seat belts
The deployment behavior of the restraint equipment is adapted on basis of the status of the seat belts (worn or not being worn). The status of the respective seat belt is defined via the corresponding switch:
- Driver seat belt buckle switch (S68/3)
- Front passenger seat belt buckle switch (S68/4)
- Left rear seat belt buckle switch (S68/11)
- Right rear seat belt buckle switch (S68/12)
- Center rear seat belt buckle switch (S68/14) (model 205.0/1/2, 253)
The status of the driver seat belt buckle switch and the front passenger seat belt buckle switch is read in directly by the supplemental restraint system control unit.
The status of the rear seat belt buckle switch is read in directly by the rear SAM control unit (N10/8). The rear SAM control unit sends this over the interior CAN (CAN B), electronic ignition lock control unit and the user interface CAN to the supplemental restraint system control unit.
Model 205.0/1/2, 253
The status of the center rear belt buckle switch does not have any influence on 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
- Rollover (along vehicle's longitudinal axis)
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) (model 205.0/1/2, 253 with CODE 298 (Sidebag in rear incl. belt force limiter))
- Right rear door pressure sensor (B48/10) (model 205.0/1/2, 253 with CODE 298 (Sidebag in rear incl. belt force limiter))
The sensor signals are read in directly by the supplemental restraint system control unit.
The lateral acceleration of the vehicle is also evaluated. It is detected by the acceleration sensor integrated into the supplemental restraint system control unit.
In vehicles with CODE 23P (Driving Assistance package Plus) the traffic area in front of and behind the vehicle is monitored using different radar sensors. This makes it possible to detect an imminent collision at an early stage. The respective deployment points are adapted in accordance with the situation. The radar sensors control unit (N62/1) sends the corresponding information over the chassis FlexRay, electronic ignition lock control unit and user interface CAN to the supplemental restraint system control unit.
Function sequence for frontal impact deployment
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)
- Front 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)
- Front passenger belt force limiter (R12/26) (with CODE 494 (USA version) or CODE 460 (Canada version))
- Driver belt force limiter (R12/27) (with CODE 494 (USA version) or CODE 460 (Canada version))
- Driver anchor fitting tensioner squib (R12/37) (with CODE 494 (USA version) or CODE 460 (Canada version))
- Front passenger anchor fitting tensioner squib (R12/38) (with CODE 494 (USA version) or CODE 460 (Canada version))
- Front passenger airbag ventilation valve squib (R12/44) (with CODE 494 (USA version) or CODE 460 (Canada version))
The squibs are actuated directly by the supplemental restraint system control unit.
The following situations are taken into account:
- Position of the driver seat (with CODE 494 (USA version) or CODE 460 (Canada version)):
The supplemental restraint system control unit uses the status of the driver seat position detection switch (S68/19) to decide about the corresponding trigger time of the driver airbag. The supplemental restraint system control unit reads in the status of the driver seat position detection switch directly.
- Position of the front passenger seat (with CODE 494 (USA version) or CODE 460 (Canada version)):
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. 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.
- Occupancy status of the front passenger seat:
- If the front passenger seat is unoccupied or occupied with a child seat and the belt lock tongue has not been inserted, no restraint equipment is triggered at the passenger side.
- If the front passenger seat is unoccupied or occupied with a child seat and the belt lock tongue has been inserted, the front passenger airbag is not triggered.
- If the front passenger seat is occupied by a person and the belt tab has not been inserted, the emergency tensioning retractor, the anchor fitting tensioner (with CODE 494 (USA version) or CODE 460 (Canada version)) and the belt force limiter (with CODE 494 (USA version) or CODE 460 (Canada version)) are not deployed on the front passenger side.
- Driver seat belt buckle status:
If the belt tab is not inserted, the emergency tensioning retractor, the anchor fitting tensioner (with CODE 494 (USA version) or CODE 460 (Canada version)) and the belt force limiter (with CODE 494 (USA version) or CODE 460 (Canada version) on the driver side are not deployed.
- Status of seat belt buckles in rear:
If the belt lock tongue is not inserted, the relevant emergency tensioning retractor in the rear is not triggered.
Function sequence for side impact deployment
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 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 298 (Rear sidebag including belt force limiter))
- Right rear sidebag squib (R12/12) (with CODE 298 (Rear sidebag including belt force limiter))
- Left windowbag squib (R12/22)
- Right windowbag squib (R12/23)
- Driver anchor fitting tensioner squib (with CODE 494 (USA version) or CODE 460 (Canada version))
- Front passenger anchor fitting tensioner squib (with CODE 494 (USA version) or CODE 460 (Canada version))
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:
- If the front passenger seat is unoccupied and the belt tab has not been inserted, the emergency tensioning retractor, the anchor fitting tensioner (with CODE 494 (USA version) or CODE 460 (Canada version)) and the sidebag are not deployed on the passenger side.
- If the front passenger seat is occupied (person or child seat) and the belt tab has not been inserted, the emergency tensioning retractor and the anchor fitting tensioner (with CODE 494 (USA version) or CODE 460 (Canada version)) are not deployed on the passenger side.
- Driver seat belt buckle status:
If the belt tab is not inserted, the emergency tensioning retractor and anchor fitting tensioner (with CODE 494 (USA version) or CODE 460 (Canada version)) on the driver side are not deployed.
- Status of seat belt buckles in rear:
If the belt lock tongue is not inserted, the relevant emergency tensioning retractor in the rear is not triggered.
Function sequence for rear end collision deployment
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
- Driver anchor fitting tensioner squib (with CODE 494 (USA version) or CODE 460 (Canada version))
- Front passenger anchor fitting tensioner squib (with CODE 494 (USA version) or CODE 460 (Canada version))
The squibs are actuated directly by the supplemental restraint system control unit.
The following situations are taken into account:
- Driver/front passenger seat belt buckle status:
If the belt tab is not inserted, the corresponding emergency tensioning retractor and anchor fitting tensioner (with CODE 494 (USA version) or CODE 460 (Canada version)) are not triggered.
- Status of seat belt buckles in rear:
If the belt lock tongue is not inserted, the relevant emergency tensioning retractor in the rear is not triggered.
Function sequence for rollover deployment
Restraint equipment is deployed depending on 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
- Left windowbag squib
- Right windowbag squib
- Driver anchor fitting tensioner squib (with CODE 494 (USA version) or CODE 460 (Canada version))
- Front passenger anchor fitting tensioner squib (with CODE 494 (USA version) or CODE 460 (Canada version))
The squibs are actuated directly by the supplemental restraint system control unit.
The following situations are taken into account:
- Driver/front passenger seat belt buckle status:
If the belt tab is not inserted, the corresponding emergency tensioning retractor and anchor fitting tensioner (with CODE 494 (USA version) or CODE 460 (Canada version)) are not triggered.
- Status of seat belt buckles in rear:
If the belt lock tongue is not inserted, the relevant emergency tensioning retractor in the rear 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 function
- Function sequence for switching on interior illumination
- Function sequence for opening the central locking system
- Function sequence for opening the side windows
- Function sequence for shutting off the engine
- Function sequence for triggering pyrofuse (model 205.012/047/147/212/247)
- Function sequence for deactivating the high-voltage components (model 205.012/047/147/212/247)
- Function sequence for switching off the A/C
- Function sequence for shutting off stationary heater (with CODE 228 (Stationary heater))
- Function sequence for automatic emergency call (with CODE 347 (Mercedes-Benz emergency call system) or CODE 348 (Emergency call/assist system) or CODE 350 (Ecall Europe emergency call system))
- Function sequence for activating the crash-active easy exit function (with CODE 275 (Memory package))
Function sequence for activating the hazard warning function
In order to warn the other road users in the event of an accident, the hazard warning flasher function is automatically activated by the exterior lights. The supplemental restraint system control unit transmits the crash signal via the user interface CAN, the electronic ignition lock control unit and the interior CAN to the front SAM control unit (N10/6). The front 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 front 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 orientate themselves inside the vehicle in the event of an accident, the interior illumination is automatically activated. The supplemental restraint system control unit transmits the crash signal via the user interface CAN, the electronic ignition lock control unit and the interior CAN to the front SAM control unit. The front SAM control unit then activates the interior illumination.
The crash signal is also transmitted via a direct line from the supplemental restraint system control unit to the front 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 supplemental restraint system control unit transmits the crash signal via the user interface CAN, the electronic ignition lock control unit and the interior CAN to the front SAM control unit, which implements this request.
The central locking is unlocked after a waiting time of t = 8 to 11 s. In the event of a rear-end collision, the central locking is immediately unlocked.
The crash signal is also transmitted via a direct line from the supplemental restraint system control unit to the front SAM control unit.
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 front are automatically opened a gap by the power window lifters in order to achieve quick dispersion of these smoke particles. The supplemental restraint system control unit transmits the crash signal via the user interface CAN, the electronic ignition lock control unit and the interior CAN to the following control units:
- Left front door control unit (N69/1)
- Right front door control unit (N69/2)
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 user interface CAN, electronic ignition lock control unit, chassis FlexRay, powertrain control unit (N127), and engine CAN (CAN C) to the CDI control unit (N3/9) (diesel engine) or to the ME-SFI [ME] control unit (N3/10) (gasoline engine). This then causes the engine to be shut off.
The crash signal is also transmitted 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 (model 205.012/047/147/212/247)
In order to avoid a possible fire hazard following an accident, the pyrofuse (F63) and the pyrotechnical separator (K88) are triggered.
Inside the housing, the main line is designed as bus bar with predetermined fracture point (3). After a crash event has occurred, the pyrofuse and the pyrotechnical separator are actuated directly 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:
Piston movement starts after t = 300 μs.
Bus bar disconnection is complete after t = 450 μs.
Triggering of the pyrofuse causes the high-voltage components to be de-energized.
The starter (M1) and the alternator (G2) are disconnected from the on-board electrical system when the pyrotechnical separator is triggered.
Function sequence for deactivating the high-voltage components (model 205.012/047/147/212/247)
The high-voltage components are switched off after an accident to reduce the risk of fire. The supplemental restraint system control unit transmits the crash signal via the user interface CAN, the electronic ignition lock control unit, the chassis FlexRay, the powertrain CAN and the hybrid CAN (CAN L) to the battery management system control unit (N82/2). It switches the high-voltage components off.
Function sequence for switching off the A/C
In order to prevent hazardous gases from entering the vehicle interior after an accident, the climate control control unit (N22/1) shuts off the A/C and closes the air recirculation flap. The supplemental restraint system control unit transmits the crash signal via the user interface CAN, the electronic ignition lock control unit and the interior CAN to the A/C control unit.
Function sequence for shutting off stationary heater (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 transmits the crash signal via the user interface CAN, the electronic ignition lock control unit and the interior CAN to the A/C control unit. With the stationary heater switched on, the climate control control unit activates a stationary heater emergency shut-off and transmits the heating request (0%) over the climate control LIN 2 (LIN B8-2) to the stationary heater control unit (A6n1). The heater is then permanently switched off.
Function sequence for automatic emergency call (with CODE 347 (Mercedes-Benz emergency call system) or CODE 348 (Emergency call/assist system) or CODE 350 (Ecall Europe emergency call system))
An emergency call is made automatically after an accident.
Depending on the type of transmission involved the following data are also sent to the Mercedes-Benz Emergency Call Center:
- GPS position data for the vehicle
- Last known GPS position data for vehicle route
- Direction of travel
- Vehicle identification number
- Estimated accident severity
- Estimated number of people in vehicle
- Type of drive in vehicle
Function sequence for activating the crash-active easy exit function (with CODE 275 (Memory package))
To make it easier for the driver to exit the vehicle or for first aiders to remove the driver from the vehicle after an accident, following a crash event the steering column is automatically adjusted upward to a predefined position if the following occurs:
- Driver door opened
- Change of circuit status from circuit 15C On to circuit 15C Off
The supplemental restraint system control unit transmits the crash signal via the user interface CAN, the electronic ignition lock control unit and the interior CAN to the driver seat control unit (N32/1), which controls the crash-active easy exit function.
| Electrical function schematic for deployment of supplemental restraint system | PE91.60-P-2055-97FBA | ||
| Overview of system components for supplemental restraint system | GF91.60-P-9996RF |