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

MODEL 166 up to model year 2016 

Function requirements, general 

• Circuit 15R ON

The status of circuit 15 is sent by the electronic ignition lock control unit (N73) 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 status of the front passenger seat and the status of the front seat belts (fastened or not fastened) and adapts its triggering behavior on the basis of this information in the event of a crash.

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 the upper control panel control unit (N72/1)
• The automatic child seat recognition airbag ON indicator lamp (N72/1e4) (as of 02.06.2014 with CODE U10 (Front passenger seat with weight recognition) or CODE U18 (Automatic child seat recognition (ACSR [AKSE])))

After a successful self-test (t = 4 s) the supplemental restraint system indicator lamp and the automatic child seat recognition airbag OFF indicator lamp (except CODE U10 (Front passenger seat with weight recognition) and except CODE U18 (Automatic child seat recognition (ACSR [AKSE])) are switched off. In vehicles with CODE U10 (Front passenger seat with weight recognition) or CODE U18 (Automatic child seat recognition (ACSR [AKSE])), the relevant occupancy status of the front passenger seat is indicated through the automatic child seat recognition airbag OFF indicator lamp or the automatic child seat recognition airbag ON indicator lamp (as of 02.06.2014).

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 continues to constantly monitor 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.

MODEL 166 as of 7/1/14

up to model year 2016

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

MODEL 166

up to model year 2016

without CODE U10 (Front passenger seat with weight sensor)

without CODE U18 (Automatic Child Seat Recognition)

The status of the seat occupied recognition does not have any influence on the deployment 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 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 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 makes a distinction between:

• 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 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)
• Right rear door pressure sensor (B48/10)
• Left B-pillar body acceleration sensor (B48/15)
• Right B-pillar body acceleration sensor (B48/16)

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 2nd seat row emergency tensioning retractor squib (R12/6)
• Right 2nd seat row emergency tensioning retractor squib (R12/7)
• Driver airbag squib 1 (R12/13)
• Driver airbag squib 2 (R12/14)
• Driver kneebag squib (R12/25)
• Emergency tensioning retractor squib, 3rd seat row at left (R12/35) (model 166.0 with CODE 847 (3rd seat row) or model 166.8)
• Emergency tensioning retractor squib, 3rd seat row at right (R12/36) (model 166.0 with CODE 847 (3rd seat row) or model 166.8)
• Driver anchor fitting tensioner squib (R12/37) (with CODE 494 (USA version))
• Front passenger anchor fitting tensioner squib (R12/38) (with CODE 494 (USA version))

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

The following situations are taken into account:

• Position of the front passenger seat (with CODE (494) USA 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. The status of the front passenger seat position detection switch is read in directly by the Supplemental Restraint System control unit.

• Occupancy status of the front passenger seat:

  The supplemental restraint system control unit uses the current occupancy to decide whether to suppress actuation of the front passenger airbag or deploy it in 1 or 2 stages.

• Driver belt buckle status:

  If the belt tab is not inserted, the driver airbag is deployed with advanced ignition timing instead of the emergency tensioning retractor and the belt anchor fitting tensioner (with CODE 494 (USA version)).

• Front passenger belt buckle status:

  If the belt tab is not inserted, the front passenger airbag is deployed with advanced ignition timing instead of the emergency tensioning retractor and the belt anchor fitting tensioner (with CODE 494 (USA version)). 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 front door pressure sensor
• Right front door pressure sensor
• Left rear door pressure sensor
• Right rear door pressure sensor
• Left B-pillar body acceleration sensor
• Right B-pillar body acceleration 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 2nd row ETR [GUS] squib
• Right 2nd row ETR [GUS] squib
• Emergency tensioning retractor squib, 3rd seat row at left (model 166.0 with CODE 847 (3rd seat row) or model 166.8)
• Emergency tensioning retractor squib, 3rd seat row at right (model 166.0 with CODE 847 (3rd seat row) or model 166.8)
• 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 anchor fitting tensioner squib (with CODE 494 (USA version))
• Front passenger anchor fitting tensioner squib (with CODE 494 (USA version))

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 uses the current occupancy of the front passenger seat to decide whether to deploy the sidebag on the passenger side.

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 frontal acceleration sensor
• Right frontal acceleration sensor
• Left B-pillar body acceleration sensor
• Right B-pillar body 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 2nd row ETR [GUS] squib
• Right 2nd row ETR [GUS] squib
• Emergency tensioning retractor squib, 3rd seat row at left (model 166.0 with CODE 847 (3rd seat row) or model 166.8)
• Emergency tensioning retractor squib, 3rd seat row at right (model 166.0 with CODE 847 (3rd seat row) or model 166.8)
• Driver anchor fitting tensioner squib (with CODE 494 (USA version))
• Front passenger anchor fitting tensioner squib (with CODE 494 (USA version))

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 emergency tensioning retractor and the belt anchor fitting tensioner (with CODE 494 (USA version)) on the driver side are not triggered.

• Front passenger belt buckle status:

  If the belt tab is not inserted, the emergency tensioning retractor and the belt anchor fitting tensioner (with CODE 494 (USA version)) on the passenger side are 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 2nd row ETR [GUS] squib
• Right 2nd row ETR [GUS] squib
• Driver sidebag squib
• Front passenger sidebag squib
• Left rear sidebag squib (with CODE 293 (Left and right rear sidebag))
• Right rear sidebag squib (with CODE 293 (Left and right rear sidebag))
• Left windowbag squib
• Right windowbag squib
• Emergency tensioning retractor squib, 3rd seat row at left (model 166.0 with CODE 847 (3rd seat row) or model 166.8)
• Emergency tensioning retractor squib, 3rd seat row at right (model 166.0 with CODE 847 (3rd seat row) or model 166.8)
• Driver anchor fitting tensioner squib (with CODE 494 (USA version))
• Front passenger anchor fitting tensioner squib (with CODE 494 (USA version))

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 emergency tensioning retractor and the belt anchor fitting tensioner (with CODE 494 (USA version)) on the driver side are not triggered.

• Front passenger belt buckle status:

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

Function sequence for additional functions in the event of a crash 

The function of additional functions in the event of a crash includes 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 front side windows 
• Function sequence for shutting off the engine 
• Function sequence for triggering of the pyrofuse (F32/3f88) 
• Function sequence for switching off the air conditioning system (as of 01.07.2013) 
• Function sequence for switching off stationary heater (STH) (with CODE 228 (Stationary heater)) 
• Function sequence for automatic emergency call (with CODE 348 (Emergency call/assist system) or CODE 359 (TELE AID emergency call system)) 
• Function sequence for activating crash-active steering column adjustment (with CODE 275 (Memory package (Driver seat, steering column, mirrors))) 

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 transmits the crash signal via 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.

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 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 transmits the crash signal via 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.

Detailed information on 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 persons giving assistance to gain access to vehicle occupants who may be injured in the event of an accident, the central locking (CL [ZV]) 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 is unlocked after a waiting time of t = 8 to 11 s. In the event of a rear end collision, the CL 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.

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".

Additional function requirements for opening the front side windows 

• Power windows normalized

Function sequence for opening the front 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:

• 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 chassis CAN 1 to the CDI control unit (N3/9) (diesel engine) or the ME-SFI [ME] control unit (N3/10) (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 possible risk of fire following an accident, the pyrofuse in the engine compartment prefuse box (F32/3) is triggered.

The main line inside the pyrofuse housing is designed as busbar with predetermined fracture point (3). After a crash the pyrofuse 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 disconnecting the bus bar.

Time sequence:

Piston movement starts after t = 300 μs.

Busbar disconnection is complete after t = 450 μs.

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 switching off the air conditioning system (as of 01.07.2013) 

In order to prevent hazardous gases from entering the vehicle interior after an accident, the automatic air conditioning control and operating unit (N22/7) switches the air conditioning off 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.

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 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 chassis CAN 1, electronic ignition lock 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 (TELE AID emergency call system)) 

An emergency call is made automatically after an accident. The supplemental restraint system control unit transmits the crash signal via chassis CAN 1, electronic ignition lock 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 "Audio/COMAND, function" in the subfunction "Emergency call system, function".

Function sequence for activating crash-active steering column adjustment (with CODE 275 (Memory package (Driver seat, steering column, mirrors))) 

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
• Switch off circuit 15C

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 steering column adjustment 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		PE91.60-P-2055-97NAA
	Overview of system components for supplemental restraint system		GF91.60-P-9996GR