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Actuate Supplemental Restraint System, Function - GF91.60-P-2012GN

MODEL 166 as of model year 2016 

MODEL 292 

Function requirements, general 

The electronic ignition lock control unit (N73) sends the status of circuit 15 via chassis CAN 1 (CAN E1) 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 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 supplemental restraint system indicator lamp and the automatic child seat recognition airbag Off indicator lamp (except code U10 (Automatic front passenger airbag shutoff)) are switched off. In vehicles with code U10 (Automatic front passenger airbag shutoff), the relevant occupancy status of the front passenger seat is indicated via the automatic child seat recognition airbag Off indicator lamp or the automatic child seat recognition airbag On indicator lamp.

The request for switching on the supplemental restraint system indicator lamp is sent by the supplemental restraint system control unit via chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 (CAN E2) to the instrument cluster.

The request for switching on the respective automatic child seat recognition indicator lamp is sent by the supplemental restraint system control unit via chassis CAN 1, electronic ignition lock control unit, interior CAN (CAN B), SAM control unit (N10) and battery sensor LIN (LIN B15) to the upper control panel control unit, which directly actuates the corresponding automatic child seat recognition 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 chassis CAN 1, electronic ignition lock 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.

IMPORTANT Model 166 as of model year 2016

with code 494 (US version)

Model 292

with code 494 (US version)

An accident data recorder is integrated in the supplemental restraint system control unit, which 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 deployment behavior of the restraint equipment at the passenger-side is adapted on the basis of the occupancy status of the front passenger seat.

IMPORTANT Model 166

as of model year 2016

with code U10 (Automatic seat occupancy recognition and child seat recognition)

Model 292

with 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 front 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 driver belt buckle restraint system switch (S68/3) or front passenger belt buckle restraint system switch (S68/4). The supplemental restraint system control unit reads in the status of the belt buckle restraint system switch directly.

IMPORTANT The status of the rear seat belts 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:

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

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:

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):

The squibs are actuated directly by the supplemental restraint system control unit.

The following situations are taken into account:

If the belt tab is not inserted, the emergency tensioning retractor and the belt anchor fitting tensioner (with CODE 494 (USA version)) at the driver side are not deployed.

Function sequence in the event of a side impact 

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

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):

The squibs are actuated directly by the supplemental restraint system control unit.

The following situations are taken into account:

If the belt tab is not inserted, the emergency tensioning retractor and the belt anchor fitting tensioner (with CODE 494 (USA version)) at the driver side are 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:

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):

The squibs are actuated directly by the supplemental restraint system control unit.

The following situations are taken into account:

If the belt tab is not inserted, the emergency tensioning retractor and the belt anchor fitting tensioner (with CODE 494 (USA version)) at the front passenger side are not deployed.

Function sequence for rollover 

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

The following squibs can be ignited (at most):

The squibs are actuated directly by the supplemental restraint system control unit.

The following situations are taken into account:

If the belt tab is not inserted, the emergency tensioning retractor and the belt anchor fitting tensioner (with CODE 494 (USA version)) at the driver side are not deployed.

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 supplemental restraint system control unit sends the crash signal over chassis CAN 1, electronic ignition lock control unit and interior CAN to the SAM control unit. The SAM control unit then activates the hazard warning flasher function.

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 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 supplemental restraint system control unit sends the crash signal over chassis CAN 1, electronic ignition lock control unit and interior CAN 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 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 chassis CAN 1, electronic ignition lock control unit and interior CAN to the SAM control unit, which implements this request.

The central locking system is unlocked after a waiting time of 8 to 11 s. In the event of a rear-end collision, the central locking is immediately unlocked.

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 side windows 

Smoke particles are produced in the vehicle interior when the pyrotechnical restraint equipment is triggered. The front side windows are opened a gap in order to allow these smoke particles to quickly disperse. The supplemental restraint system control unit transmits the crash signal via chassis CAN 1, electronic ignition lock control unit and interior CAN 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 supplemental restraint system control unit sends the crash signal via chassis CAN 1 to the CDI control unit (N3/9) (diesel engine) or the ME-SFI [ME] control unit (N3/10) (gasoline engine) (except model 166.063)). On model 166.063, the supplemental restraint system sends the crash signal via chassis CAN 1, powertrain control unit (N127) and engine CAN (CAN C1) to the ME-SFI [ME] control unit. The CDI control unit or the ME-SFI [ME] control unit then shuts down the engine.

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 inerting system (with engine 157, 276, 278 with code 2U8 (Alternative refrigerant)) 

The inerting system prevents any leaking refrigerant from the A/C system igniting on hot parts of the engine.

If the supplemental restraint system control unit detects a frontal impact, it actuates the inerting system squib (R12/69). If the inerting system squib is triggered, argon inert gas flows from the gas reservoir into the engine compartment. This displaces the atmospheric oxygen in areas close to the engine that present a fire hazard. This prevents the risk of a fire being caused by refrigerant flowing out of the A/C system.

Function sequence for triggering the pyrofuse 

In order to avoid a possible risk of fire following an accident, the pyrofuse (F32/3f88) in the engine compartment prefuse box (F32/3) is triggered.

On model 166.063, the pyrotechnical separator (K88) is also triggered.

Inside the housing, the main line is designed as bus bar with predetermined fracture point (3). After the occurrence of a corresponding crash event, the pyrofuse and the pyrotechnical separator (model 166.063) are 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 μs the piston movement is started.

After 450 μs the bus bar disconnection is ended.

IMPORTANT By triggering the pyrofuse, the starter (M1) and the alternator (G2) are disconnected from the on-board electrical system.

IMPORTANT Model 166.063 as of model year 2016

Triggering of the pyrotechnical separator causes the high-voltage components to be de-energized.

G11970657

Function sequence for switching off the A/C 

In order to prevent hazardous gases from entering the vehicle interior after an accident, the automatic air conditioning 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, electronic ignition lock control unit and interior CAN to the automatic air conditioning control and operating unit.

Function sequence for shutting off stationary heater (with CODE 228 (Stationary heater)) 

In order to avoid a possible risk of fire following an accident, the stationary heater is automatically switched off. The supplemental restraint system control unit transmits the crash signal via chassis CAN 1, the electronic ignition lock control unit and the interior CAN to the stationary heater control unit (A6n1), which prompts a shutoff of the stationary heater.

Function sequence for automatic emergency call (with code 359 (TELE AID emergency call system), with code 348 (Emergency call/assist system), with code 350 (eCall Europe emergency call system), with code 360 (HERMES UMTS) or with code 362 (HERMES LTE)) 

An emergency call is made automatically after an accident. The Supplemental Restraint System control unit sends the crash signal via the chassis CAN 1, electronic ignition lock control unit and diagnostic CAN (CAN D) to the emergency call system control unit (N123/4) (with code 348 (Emergency call/assist system)), the telematics services communications module (N112/2) (with code 350 (eCall Europe emergency call system)) or the HERMES control unit (N112/9) (with code 360 (HERMES UMTS) or with code 362 (HERMES LTE)), 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 (with code 348 (Emergency call/assist system)) or to the HERMES control unit (with code 360 (HERMES UMTS) or with code 362 (HERMES LTE)).

Function sequence for activating the crash-active easy exit function (with CODE 275 (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:

The supplemental restraint system control unit transmits the crash signal via chassis CAN 1, electronic ignition lock control unit and 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-2055-97NBA
  Overview of system components for supplemental restraint system   GF91.60-P-9996GN 
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