Actuate Supplemental Restraint System, Function - GF91.60-P-2012LF
Model 217, 222
Function requirements, general
- Circuit 15R ON
The electronic ignition lock control unit (N73) transmits the status of circuit 15 via 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 (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 occupation 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 event of crash
Function sequence system monitoring
When circuit 15R is switched on, the following indicator lamps are actuated:
- Supplemental Restraint System indicator lamp in the instrument cluster (A1)
- Front passenger airbag ON indicator lamp (S6/2e2) (with code U10 (Automatic front passenger airbag shutoff) or model 222 with code U18 (Automatic child seat recognition ACSR)) (up to model year 2018)
- Front passenger airbag OFF indicator lamp (S6/2e3) (up to model year 2018)
- Center instrument panel display field (A40/19) (as of model year 2018)
After a successful self-test (t = 4 s), the Supplemental Restraint System indicator lamp and the front passenger airbag OFF indicator lamp (model 222 Except Code U18 (Automatic child seat recognition ACSR) and Except Code U10 (Automatic front passenger airbag shutoff)) (up to model year 2018) or the center instrument panel display field (A40/19) (as of model year 2018) are switched off. On vehicles with code U10 (Automatic front passenger airbag shutoff) or on model 222 with code U18 (Automatic child seat recognition (ACSR [AKSE]), the relevant occupation status for the front passenger seat is indicated by the front passenger airbag ON indicator lamp or the front passenger airbag OFF indicator lamp.
The supplemental restraint system control unit sends the request to switch on the supplemental restraint system indicator lamp via user interface CAN to the instrument cluster. The request to switch on the respective front passenger airbag indicator lamp is transmitted by the Supplemental Restraint System control unit via the user interface CAN, electronic ignition lock control unit, interior CAN (CAN B), front SAM control unit (N10/6), and instrument panel LIN (LIN 1) to the center instrument panel button group (S6/2) (up to model year 2018), which directly actuates the corresponding front passenger airbag indicator lamp. As of model year 2018, the corresponding front passenger airbag indicator lamp is displayed in the center instrument panel display field, which is also actuated via the instrument panel LIN.
During vehicle operation, the Supplemental Restraint System control unit constantly monitors the Supplemental Restraint System, and reports faults to the driver via the instrument cluster and the Supplemental Restraint System indicator lamp. The supplemental restraint system control unit transmits the request to display a corresponding message via user interface CAN to the instrument cluster. The faults are stored in the nonvolatile memory of the supplemental restraint system control unit.
An accident data recorder is integrated in the Supplemental Restraint System control unit; it 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 occupation status of front passenger seat
The supplemental restraint system control unit uses the occupancy status of the front passenger seat to adapt the deployment behavior of the restraint equipment at the passenger-side.
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 following switches are activated if the belt tab is inserted into the belt buckle:
- 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 belt buckle switch (S68/12)
The supplemental restraint system control unit reads in the status of the driver belt buckle switch and the status of the front passenger belt buckle switch directly.
The rear SAM control unit (N10/8) reads in the status of the rear belt buckle switches directly and sends this information via interior CAN, electronic ignition lock control unit and user interface CAN to the supplemental restraint system control unit.
The status of the center rear belt buckle switch (S68/14) does not have any influence on triggering behavior of the supplemental restraint system.
Function sequence for impact detection
The supplemental restraint system control unit makes a distinction between a:
- Frontal impact
- Side impact
- Rear impact
- 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 222)
- Right rear door pressure sensor (B48/10) (model 222)
The supplemental restraint system control unit directly reads in the sensor signals.
In addition, the supplemental restraint system control unit assesses the lateral acceleration of the vehicle. The Electronic Stability Program control unit (N30/4) transmits the corresponding information to the Supplemental Restraint System control unit via the suspension FlexRay (Flex E), electronic ignition lock control unit, and user interface CAN.
On vehicles with code P20 (Driving Assistance package Plus), the traffic area in front of and behind the vehicle is also monitored using different radar sensors. In the event of impending collisions, an autonomous brake application can be initiated by the driver assistance system. The respective deployment points of the restraint equipment are adapted in accordance with the situation. The radar sensors control unit (N62/1) (up to model year 2018) or the Mercedes-Benz Intelligent Drive control unit (N62/4) (as of model year 2018) transmits the "Autonomous brake application" signal to the Supplemental Restraint System control unit via the suspension FlexRay, electronic ignition lock control unit, and user interface CAN.
Function sequence for frontal impact deployment
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):
- 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)
- Front passenger kneebag squib (R12/24) (model 217 with CODE 494 (USA version) or CODE 460 (Canada version))
- Driver kneebag squib (R12/25) (with CODE 494 (USA version) or CODE 460 (Canada version))
- 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))
- Front passenger airbag bleed valve squib (R12/44)
- Left rear belt airbag squib (R12/51) (model 222 with code 306 (Belt airbag))
- Right rear belt airbag squib (R12/52) (model 222 with code 306 (Belt airbag))
- Left rear cushion airbag squib (R12/57) (model 222 with code 453 (Rear reclining seats))
- Right rear cushion airbag squib (R12/58) (model 222 with code 453 (Rear reclining seats))
- Left roll bar squib (R12/61) (model 217.4)
- Right roll bar squib (R12/62) (model 217.4)
- Inertisation system squib (R12/69) (with code 2U8 (Alternative refrigerant) and gasoline engine)
- Driver PRE-SAFE® pulse squib (R46)
- Front passenger PRE-SAFE® pulse squib (R46/1)
The supplemental restraint system control unit directly actuates the squibs.
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/front passenger seat belt buckle status:
If the seat belt is not fastened, the driver or front passenger airbag is triggered with an advanced ignition timing instead of the emergency tensioning retractor, the PRE-SAFE® pulse unit and the belt force limiter (with code 494 (USA version) or code 460 (Canada version)).
- Status of seat belt buckles in rear:
If the seat belt is not fastened, no restraint equipment is triggered in the left or right rear.
- Inclination of the backrests in the rear (model 222 with code 453 (Rear reclining seats)):
The cushion airbag unit is only triggered if the respective rear seat is in the reclining position. The inclination of the backrest is detected by the left rear backrest inclination switch (S54/5) or the right rear backrest inclination switch (S54/6). The rear SAM control unit directly reads in the status of the rear backrest inclination switches and, as from a certain backrest inclination, it transmits the "Rear backrest in sleep position" signal via the interior CAN, the electronic ignition lock control unit and the user interface CAN to the supplemental restraint system control unit.
Function sequence for side impact deployment
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):
- 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)
- Right rear sidebag squib (R12/12)
- Left windowbag squib (R12/22) (model 222, 217.3)
- Right windowbag squib (R12/23) (model 222, 217.3)
- Left headbag squib (R12/39) (model 217.4)
- Right headbag squib (R12/40) (model 217.4)
- Left roll bar squib (model 217.4)
- Right roll bar squib (model 217.4)
The supplemental restraint system control unit directly actuates the squibs.
The following situations are taken into account:
- Occupancy status of the front passenger seat:
The supplemental restraint system control unit uses the current occupation status of the front passenger seat to reach a decision on whether to deploy the sidebag.
- Driver/front passenger seat belt buckle status:
If the seat belt is not fastened, the relevant emergency tensioning retractor is not triggered.
- Status of seat belt buckles in rear:
If the seat belt is not fastened, the corresponding 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 (maximum):
- Driver ETR [GUS] squib
- Front passenger ETR [GUS] squib
- Left rear emergency tensioning retractor squib
- Right rear emergency tensioning retractor squib
- Left roll bar squib (model 217.4)
- Right roll bar squib (model 217.4)
The supplemental restraint system control unit directly actuates the squibs.
The following situations are taken into account:
- Driver/front passenger seat belt buckle status:
If the seat belt is not fastened, the relevant emergency tensioning retractor is not triggered.
- Status of seat belt buckles in rear:
If the seat belt is not fastened, the corresponding emergency tensioning retractor in the rear is not triggered.
Function sequence for rollover deployment
The deployment of restraint equipment takes place depending on the status of the seat belts.
The following squibs can be ignited (maximum):
- Driver ETR [GUS] squib
- Front passenger ETR [GUS] squib
- Left rear emergency tensioning retractor squib
- Right rear emergency tensioning retractor squib
- Left windowbag squib (model 222, 217.3)
- Right windowbag squib (model 222, 217.3)
- Left headbag squib (model 217.4)
- Right headbag squib (model 217.4)
- Left roll bar squib (model 217.4)
- Right roll bar squib (model 217.4)
The supplemental restraint system control unit directly actuates the squibs.
The following situations are taken into account:
- Driver/front passenger seat belt buckle status:
If the seat belt is not fastened, the relevant emergency tensioning retractor is not triggered.
- Status of seat belt buckles in rear:
If the seat belt is not fastened, the corresponding emergency tensioning retractor in the rear is not triggered.
Function sequence for additional functions in event of crash
The additional functions in a crash event encompass the following subfunctions:
- Function sequence for shutting off the engine
- Function sequence for triggering the pyrofuse
- Function sequence for deactivating the high-voltage components (models 222.004/057/104/157/163/173)
- Function sequence for shutting off stationary heater (With Code 228 (Stationary heater))
- Function sequence for switching off the A/C
- Function sequence for activating the hazard warning function
- Function sequence for opening the side windows
- Function sequence for switching on interior illumination
- Function sequence for opening the central locking system
- Function sequence for activating crash-active steering column adjustment
- Function sequence for activating the active belt buckles in the rear (model 222 With Code 305 (Rear PRE-SAFE))
- 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 shutting off the engine
After an accident, the engine is switched off and the fuel supply stopped to reduce the fire hazard risk. 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 and the fuel supply to be stopped.
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
After an accident the pyrotechnical separator (K88) is triggered to reduce the fire hazard risk.
Pyrofuse shown
Time sequence:
Piston movement starts after t = 300 μs.
The bus bar disconnection is terminated after t = 450 μs.
The main line inside the pyrofuse housing is designed as busbar with predetermined fracture point (3). After a crash event has occurred, 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.
By triggering the pyrofuse, the starter (M1) and the alternator (G2) are quickly and reliably disconnected from the on-board electrical system.
Function sequence for deactivating the high-voltage components (models 222.004/057/104/157/163/173)
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 then switches the high-voltage components off.
The crash signal is also transmitted over a direct line from the supplemental restraint system control unit to the battery management system control unit.
Redundantly to this, the control circuit line (circuit 30c) is interrupted by the high-voltage pyrofuse (F33f51) blowing in the rear pre-fuse box (F33). The high-voltage on-board electrical system is switched off due to this voltage drop at the high-voltage components. The supplemental restraint system control unit directly actuates the high-voltage pyrofuse.
Function sequence for shutting off stationary heater (With Code 228 (Stationary heater))
After an accident, the stationary heater is turned off to reduce the fire hazard risk. The supplemental restraint system control unit sends the crash signal over the user interface CAN, electronic ignition lock control unit and interior CAN to the stationary heater control unit (A6n1), which switches off the stationary heater.
Function sequence for switching off the A/C
After an accident the A/C system is switched off and the air recirculation flap closed. This serves to prevent any hazardous gases entering into the vehicle interior. The supplemental restraint system control unit sends the crash signal over the user interface CAN, electronic ignition lock control unit and the interior CAN to the climate control, control unit (N22/1), which implements this request.
Function sequence for activating the hazard warning function
In the event of an accident, the hazard warning flasher function is activated automatically in order to warn other road users. 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 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.
The front SAM control unit then generates a redundant crash signal on the interior CAN.
Additional function requirements for opening the side windows
- Power windows normalized
Function sequence for opening the side windows
After an accident the front side windows are opened to a gap. This also allows the smoke particles generated by the pyrotechnical restraint equipment to disperse quickly. 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)
The front door control units implement this request, and the side windows are opened.
Function sequence for switching on interior illumination
After an accident the interior illumination is switched on to make orientation easier for the vehicle occupants or persons giving assistance. 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.
The front SAM control unit then generates a redundant crash signal on the interior CAN.
Function sequence for opening the central locking system
After an accident, all doors, the trunk lid and the tank cap are unlocked via the central locking. The unlocking of the doors allows rescuers to gain access to any vehicle occupants who may be injured. The unlocking of the trunk lid enables access to aids such as the hazard warning triangle and first aid kit. The unlocking of the tank cap enables access to the QR code located in the tank cap with which the rescue services can quickly determine the corresponding rescue card for the vehicle.
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:
- Rear SAM control unit
- Left front door control unit
- Right front door control unit
- Left rear door control unit (N69/3) (model 222)
- Right rear door control unit (N69/4) (model 222)
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 rear SAM control unit unlocks the trunk lid and the tank cap. The respective front door control unit and the respective rear door control unit (model 222) unlocks the corresponding door.
The crash signal is also transmitted via a direct line from the supplemental restraint system control unit to the front SAM control unit.
The front SAM control unit then generates a redundant crash signal on the interior CAN.
Function sequence for activating crash-active steering column adjustment
After an accident the steering column is immediately moved upwards when the following actions are carried out to enable the driver to exit the vehicle or to enable first aiders to help the driver out of the vehicle:
- Driver door opened
- Status switch from circuit 15C ON to circuit 15C OFF
The supplemental restraint system control unit sends the crash signal over the user interface CAN, the electronic ignition lock control unit and the interior CAN to the driver seat control unit (N32/1), which actuates the crash-active steering column adjustment function.
Additional function requirements for activating the active belt buckles in the rear (model 222 With Code 305 (Rear PRE-SAFE))
- Respective belt tab inserted into seat belt buckle
- Vehicle speed v = 0 km/h
The status of the rear seat belt buckle switch is read in directly by the rear SAM control unit and transmitted via the interior CAN to the active belt buckle control unit (N2/3).
The instrument cluster transmits the vehicle speed via the user interface CAN, electronic ignition lock control unit and interior CAN to the active belt buckle control unit.
Function sequence for activating the active belt buckles in the rear (model 222 With Code 305 (Rear PRE-SAFE))
To make it easier for the vehicle occupants or first aiders to access the belt buckle after an accident, the corresponding active belt buckle is moved to the convenient position when the respective rear door is opened.
The supplemental restraint system control unit sends the crash signal over the user interface CAN, the electronic ignition lock control unit and the interior CAN to the active belt buckle control unit.
The left rear door control unit or the right rear door control unit sends the door status via the interior CAN to the active belt buckle control unit.
The active belt buckle control unit then actuates adjustment of the active belt buckles to the convenient position. To do this, the left rear seat active belt buckle motor (M64/1) or right rear seat active belt buckle motor (M64/2) is actuated correspondingly by the active belt buckle control unit.
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 automatic emergency call is made after an accident.
Depending on the type of transmission involved the following data, among others, are 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
| Electric function schematic for deployment of supplemental restraint system | Model 217, 222 as of model year 2018 | PE91.60-P-2055-97SEB | |
| Model 217, 222 up to model year 2018 | PE91.60-P-2055-97SEA | ||
| Overview of system components for supplemental restraint system | GF91.60-P-9996LF |