Deploy supplemental restraint system, function - GF91.60-P-2001CE

MODEL 204.0 /2 as of model year 2009 /YoM 08 

MODEL 204.3 

MODEL 204.9 

Function requirements, general 

• Circuit 5R On

The electronic ignition lock control unit (N73) provides the status of circuit 15 on the chassis CAN (CAN E).

Deploying supplemental restraint system, general 

The supplemental restraint system constantly monitors the occupation status of the front passenger seat, the status of the front seat belts (buckled or not buckled) and uses this information to adjust its deployment.

The deploy supplemental restraint system function is made up of the following subfunctions:

• Function sequence for detecting occupied status of front passenger seat 
• Function sequence for detecting status of front seat belts 
• Function sequence for impact detection 
• Function sequence for actuating supplemental restraint system in the event of frontal impact 
• Function sequence for actuating supplemental restraint system in the event of side impact 
• Function sequence for actuating supplemental restraint system in the event of rear-end collision 
• Function sequence for actuating supplemental restraint system in the event of rollover (with model 204.9 with code (494) USA version) 
• Function sequence for additional functions in the event of a crash 

Function sequence for detecting occupied status of front passenger seat 

The supplemental restraint system control unit (N2/10) receives the corresponding information from the following components:

• Front passenger seat occupied recognition (B41/1) (without code (U18) Automatic child seat recognition (ACSR [AKSE]) and without code (U10) Front passenger seat with weight detection)
• Front passenger seat occupied recognition and (ACSR [AKSE] (B48)

  (with code (U18) Automatic child seat recognition (ACSR [AKSE]) and without code (U10) Front passenger seat with weight detection)

• WSS control unit (Weight Sensing System) (N2/13) (model 204.0 as of 1.3.11, model 204.9 as of 1.6.11 with code (U10) Front passenger seat with weight detection)
• Weight Sensing System (WSS) control unit (N110) (model 204.0 up to 28.2.11, model 204.9 up to 31.5.11, model 204.3 with code (U10) Front passenger seat with weight detection)

Function sequence for detecting status of front seat belts 

The driver seat belt buckle restraint system switch (S68/3) or the front passenger seat belt buckle restraint system switch (S68/4) is actuated by the belt latch which is inserted into the seat belt buckle. This is read in directly by the supplemental restraint system control unit.

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 determines the acceleration acting on the vehicle with the aid of the integrated sensors and the following 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 front door pressure sensor (B48/9) (model 204.0/2/9 with code (293) Left and rear sidebag)
• Right front door pressure sensor (B48/10) (model 204.0/2/9 with code (293) Left and rear sidebag)

This sensor system enables the supplemental restraint system to distinguish between the following types of impacts:

• Head-on collision
• Side-on collision
• Rear end collision

Function sequence for actuating supplemental restraint system in the event of frontal impact 

A frontal impact is detected by the supplemental restraint system control unit via the signals from the following components:

• Integrated sensors in supplemental restraint system control unit
• Left frontal acceleration sensor
• Right frontal acceleration sensor

The restraint equipment is deployed depending on the severity of the impact, the occupation of the front passenger seat, and the status of the front seat belts.

The following squibs can be ignited (at most):

• Driver ETR squib (R12/1)
• Passenger ETR 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 following situations are taken into account:

• Driver seat belt buckle status:

  If the driver seat belt buckle restraint system switch detects that a belt latch is not inserted into the seat belt buckle, the driver airbag unit with advanced ignition timing is triggered instead of the driver emergency tensioning retractor unit.

• Front passenger seat belt buckle status:

  If the front passenger seat belt buckle restraint system switch detects that a belt latch is not inserted into the seat belt buckle, the front passenger airbag unit with advanced ignition timing is triggered instead of the front passenger emergency tensioning retractor unit.

• Occupied state of the front passenger seat:

  The supplemental restraint system control unit uses the current occupancy to decide whether to suppress the front passenger airbag unit or to use 1-stage or 2-stage deployment.

  This only applies, however, if the front passenger seat is known to be occupied. If not occupied then neither the emergency tensioning retractor nor the front passenger airbag unit are triggered.

Function sequence for actuating supplemental restraint system in the event of side impact 

A side impact is detected by the supplemental restraint system control unit via the signals from the following components:

• Integrated sensors in supplemental restraint system control unit
• Left sidebag sensor
• Right sidebag sensor
• Left front door pressure sensor
• Right front door pressure sensor
• Left rear door pressure sensor (model 204.0/2/9)
• Right rear door pressure sensor (model 204.0/2/9)

The activation of the restraint equipment takes place depending on the severity of the impact and occupation 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 windowbag squib (R12/22)
• Right windowbag squib (R12/23)
• Driver pelvis airbag squib (R12/41) (with code (291) PELVIS AIRBAG (PELVISBAG))
• Front passenger pelvis airbag squib (R12/42) (with code (291) PELVIS AIRBAG (PELVISBAG))

The supplemental restraint system control unit bases its decision with regard to triggering the front passenger sidebag unit on whether the front passenger seat is occupied or not.

Function sequence for actuating supplemental restraint system in the event of rear-end collision 

A rear-end collision is detected by the supplemental restraint system control unit via the signals from the following components:

• Integrated sensors in supplemental restraint system control unit
• Left sidebag sensor
• Right sidebag sensor
• Left frontal acceleration sensor
• Right frontal acceleration sensor

The activation of the restraint equipment takes place depending on the severity of the impact and the status of the front 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 following components are also actuated:

• 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 seat belt buckle status:

  If the driver seat belt buckle restraint systems switch detects that a belt latch is not inserted into the seat belt buckle, the driver emergency tensioning retractor unit is not triggered.

• Front passenger seat belt buckle status:

  If the front passenger seat belt buckle restraint systems switch detects that a belt latch is not inserted into the seat belt buckle, the front passenger emergency tensioning retractor unit is not triggered.

Function sequence for actuating supplemental restraint system in the event of rollover (with model 204.9 with code (494) USA version) 

A rollover is detected by the supplemental restraint system control unit via the integrated sensor.

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 following situations are taken into account:

• Driver seat belt buckle status:

  If the driver seat belt buckle restraint systems switch detects that a belt latch is not inserted into the seat belt buckle, the driver emergency tensioning retractor unit is not triggered.

• Front passenger seat belt buckle status:

  If the front passenger seat belt buckle restraint systems switch detects that a belt latch is not inserted into the seat belt buckle, the front passenger emergency tensioning retractor unit is not triggered.

Function sequence of additional functions in the event of a crash 

The additional functions in the event of a crash comprise the following subfunctions:

• Function sequence for activation of hazard warning function 
• Function sequence for opening the central locking (CL [ZV]) 
• Function sequence for opening the side windows 
• Function sequence for opening the side windows 
• Function sequence for shutting off the engine 
• Function sequence for shutting off the stationary heater (STH) (with code (228) Stationary heater) 
• Function sequence for automatic emergency call (with code (359) TELE AID emergency call system) 
• Function sequence for crash-active exit aid (with code (275) Memory package (driver seat, steering column, mirror) 

Function sequence for activation of hazard warning function 

The supplemental restraint system requests the hazard warning function in order to warn traffic coming from behind in the event of an accident.

The supplemental restraint system control unit transmits this request via the chassis CAN to the front SAM control unit with fuse and relay module (N10/1), which triggers the hazard warning function by outputting the flasher frequency on the interior CAN (CAN B).

The following control units receive the flasher frequency:

• Instrument cluster (A1)
• Rear SAM control unit with fuse and relay module (N10/2)
• Left front door control unit (N69/1)
• Right front door control unit (N69/2)

Information regarding the signal flow of the hazard warning function is described in detail in the separate function description of the exterior lights.

Function sequence for opening the central locking (CL [ZV]) 

The central locking is unlocked automatically after a crash event has occurred. This enables rescuers to gain access to any vehicle occupants who may be injured.

The crash signal is sent by the supplemental restraint system control unit over the chassis CAN to the front SAM control unit. It sends the crash signal over the interior CAN to the following control units:

• Left front door control unit
• Right front door control unit
• Left rear door control unit (N69/3) (model 204.0/2/9)
• Right rear door control unit (N69/4) (model 204.0/2/9)

The central locking is unlocked after a waiting time of t = 8 to 11 s.

Information regarding the signal flow of the central locking opening function is described in detail in the separate function description of central locking.

In the event of rear end collision, the CL is unlocked without waiting time.

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 are opened automatically in order to allow these smoke particles to quickly disperse. The crash signal is sent by the supplemental restraint system control unit over the chassis CAN to the front SAM control unit, which then forwards the crash signal over the interior CAN to the door control units.

Information regarding the signal flow of the side window opening function is described in detail in the separate function description of the power windows.

Function sequence for shutting off the engine 

The engine is shut off automatically after a crash event has occurred. The crash signal is sent by the supplemental restraint system control unit over the chassis CAN to the CDI control unit (N3/9) (for diesel engine) or to the ME-SFI [ME] control unit (N3/10) (for gasoline engine). This then causes the engine to be shut off.

Function sequence for shutting off the stationary heater (STH) (with code (228) Stationary heater) 

The STH is shut off automatically after a crash event has occurred. The crash signal is sent by the supplemental restraint system control unit over the chassis CAN to the front SAM control unit. This sends the crash signal via interior CAN to the stationary heater control unit (A6n1) which initiates shutoff of the STH.

Information regarding the signal flow of the stationary heater shutoff function is described in detail in the separate function description of the stationary heater.

Function sequence for automatic emergency call (with code (359) TELE AID emergency call system) 

An emergency call is made automatically after a crash event has occurred. The crash signal is sent by the supplemental restraint system control unit over the chassis CAN to the front SAM control unit. This then sends the crash signal over the diagnostic CAN (CAN D) to the emergency call system control unit (N123/4), which triggers an 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.

Information regarding the signal flow of the automatic emergency call function is described in detail in the separate function description of the emergency call system.

Function sequence for activating crash-active exit aid With code (275) Memory package (driver seat, steering column, mirrors) 

The steering column is automatically moved upward when the driver door is opened after a crash event has occurred. The crash signal is sent by the supplemental restraint system control unit over the chassis CAN to the front SAM control unit.

The front SAM control unit forwards the crash signal via the interior CAN to the driver seat control unit (N32/1).

Information regarding the signal flow of the function for activating the crash-active easy exit function is described in detail in the separate function description of the electrically adjustable steering column (ESC [ELV]).

	Electrical function schematic, supplemental restraint system (SRS)	PE91.60-P-2052-97FAB
	Overview of supplemental restraint system (SRS) system components	GF91.60-P-9998CE