GF91.60-P-2001LE Deploy Supplemental Restraint System, Function

GF91.60-P-2001LE Deploy Supplemental Restraint System, Function

General function requirements
^ Circuit 15R On

Triggering supplemental restraint system (SRS), general
The SRS is continuously monitoring the occupation status of the front passenger seat, the status of the front seat belts (buckled or not buckled) and adjusts its deployment behavior with the help of this information.

The triggering of the supplemental restraint system is made up of the following partial functions:
^ System monitoring function sequence
^ Function sequence, evaluation of front passenger seat occupancy state
^ Function sequence for evaluation of front seat belts status
^ Function sequence, evaluation of relative speed in relation to opposing object (model 221 with code (233) DISTRONIC PLUS as of 1.6.09)
^ Impact detection function sequence
^ Frontal impact function sequence
^ Side impact function sequence
^ Rear end collision function sequence
^ Rollover function sequence
^ Function sequence for belt lock system (model 221)
^ Power reserve function sequence
^ Function sequence of additional functions in the event of a crash

System monitoring function sequence
The supplemental restraint system continuously monitors itself and signals faults to the driver via the airbag indicator and warning lamp (A1e15) in the instrument cluster (A1). In addition, the automatic child seat recognition airbag OFF indicator lamp (S6/2e1) in the cockpit switch group (S6/2) is switched on. All faults are stored in the nonvolatile memory of the restraint systems control unit (N2/7). The airbag indicator and warning lamp, automatic child seat recognition airbag OFF indicator lamp are switched off after t = 4 s following a successful self-test.

Function sequence, evaluation of front passenger seat occupancy state
The restraint systems control unit 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 (494) USA version)
- Front passenger seat occupied recognition and automatic child seat recognition (B48) (with code (U18) Automatic child seat recognition (ACSR [AKSE])
- WSS control unit (Weight sensing system) (N2/13) (model 221 with code (494) USA version up to 31.8.08)
- Weight sensing system control unit (WSS) (N110) (model 216 with code (494) USA version, model 221 with code (494) USA version as of 1.9.08)

Without code (U18) Automatic child seat recognition (ACSR) and without code (494) USA version, the status of the passenger side seat occupied recognition has no effect on the actuation characteristics of the SRS. This information is only used to produce the seat belt reminder warning. In this case, the deployment behavior of the supplemental restraint system is dependent on the seat fore/aft position of the front passenger seat. The longitudinal seat position is sent to the central gateway control unit (N93) by the right front seat control unit (N32/2) (on vehicles with left-hand steering) or left front seat control unit (N32/1) (on vehicles with right-hand steering) via the interior CAN (CAN B). The signal is read in by the restraint system control unit via the chassis CAN (CAN E).

Function sequence for evaluation of front seat belts status
The driver seat belt buckle and seat belt reminder warning switch (S68/1) or the front passenger seat belt buckle and seat belt reminder warning switch (S68/2) is actuated by the belt latch which is inserted into the seat belt buckle. This is read in directly by the restraint systems control unit.

The status of the rear seat belts does not have any influence on the deployment behavior of the SRS.

Function sequence, evaluation of relative speed in relation to opposing object
The relative speed in relation to the opposing object is evaluated for actuation of the SRS. The radar sensors control unit (SGR) (N62/1) continuously senses the area in front of the vehicle using radar. The radar sensors control unit (SGR) sends the relative speed sensed and the time to impact via the vehicle dynamics CAN (CAN H) to the ESP control unit (N47-5) (without model 221.095/195) or the regenerative braking system control unit (N30/6) (model 221.095/195).

The ESP control unit or regenerative braking system control unit sends the data to the restraint system control unit via the chassis CAN. The restraint system control unit evaluates the data and calculates the anticipated impact severity. The data recognized by the sensors in the impact recognition function sequence is evaluated as previously for final actuation of the SRS.

The radar sensors control unit (SGR) senses the area in front of the vehicle even when the DISTRONIC PLUS is deactivated and the vehicle is standing still.

Impact detection function sequence
The restraint systems control unit determines the acceleration acting on the vehicle with the aid of its integrated sensor and the following sensors:
- Driver-side frontal acceleration sensor (B48/1)
- Passenger-side frontal acceleration sensor (B48/2)
- Airbag system driver assist (B48/5)
- Airbag system front passenger assist (B48/6)
- Driver door pressure sensor (B48/7)
- Front passenger door pressure sensor (B48/8)
- Rear door pressure sensor, driver-side (B48/9) (model 221)
- Rear door pressure sensor, passenger-side (B48/10) (model 221)

With the aid of this sensor system, the SRS is able to distinguish between the following types of impacts:
- Head-on collision
- Side-on collision
- Rear end collision
- Roll-over

Frontal impact function sequence
A frontal impact is detected by the restraint systems control unit via the signals from the following components:
- Integrated sensor in the restraint systems control unit
- Driver-side frontal acceleration sensor
- Passenger-side 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):
- Passenger airbag squib 1 (R12/4)
- Passenger airbag squib 2 (R12/5)
- Left rear ETR squib (R12/6)
- Right rear ETR squib (R12/7)
- Driver airbag squib 1 (R12/13)
- Driver airbag squib 2 (R12/14)
- Driver kneebag squib (R12/25) (with code (294) Kneebag)
- Drive buckle ETR squib (R46)
- Front passenger ETR squib (R46/1)

The following situations are taken into account:
- Relative speed in relation to opposing object
- Occupied state of the front passenger seat:
The restraint systems 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.

- Driver seat belt buckle status:
If the driver seat belt buckle and seat belt reminder warning 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 buckle emergency tensioning retractor unit.

- Front passenger seat belt buckle status:
If the front passenger seat belt buckle and set belt reminder warning 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 buckle emergency tensioning retractor unit.

The status of the buckle emergency tensioning retractors is evaluated only when the front passenger seat is occupied. If the seat is not occupied, neither the buckle emergency tensioning retractors nor the front passenger airbag unit are deployed.

Side impact function sequence
A side impact is detected by the restraint systems control unit via the signals from the following components:
- Integrated sensor in the restraint systems control unit
- Airbag system driver assist
- Airbag system front passenger assist
- Driver door pressure sensor
- Front passenger door pressure sensor
- Rear door pressure sensor, driver side (model 221)
- Rear door pressure sensor, passenger side (model 221)

Actuation of the restraint equipment is accomplished depending on the severity of the impact and whether the front passenger seat is occupied.

The following squibs can be ignited (at most):
- Left rear sidebag squib (R12/11)
- Right rear sidebag squib (R12/12)
- Front left sidebag squib (R12/20)
- Front right side air bag squib (R12/21)
- Left rear windowbag squib (R12/22)
- Right rear windowbag squib (R12/23)

The following state is taken into consideration:
- The restraint systems control unit makes its decision regarding triggering the front passenger sidebag unit based on the current occupancy of the front passenger seat.

Rear end collision function sequence
A rear end collision is detected by the restraint systems control unit via the signals from the following components:
- Integrated sensor in the restraint systems control unit
- Driver-side frontal acceleration sensor
- Passenger-side frontal acceleration sensor
- Airbag system driver assist
- Airbag system front passenger assist

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 buckle ETR squib
- Front passenger buckle ETR squib
- Left rear ETR squib
- Right rear ETR squib

Actuation of:
- Driver NECK-PRO head restraint solenoid (Y24/12)
- Front passenger 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 and seat belt reminder warning 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 and seat belt reminder warning switch detects that a belt latch is not inserted into the seat belt buckle, the front passenger buckle emergency tensioning retractor unit is not triggered.

Rollover function sequence
A roll over is detected by the restraint systems control unit using the signals from the following components:
- Integrated sensor in the restraint systems control unit
- Driver-side frontal acceleration sensor
- Passenger-side frontal acceleration sensor
- Airbag system driver assist
- Airbag system front passenger assist

The following squibs can be ignited (at most):
- Driver buckle ETR squib
- Front passenger buckle ETR squib
- Left rear ETR squib
- Right rear ETR squib

The following situations are taken into account:
- Driver seat belt buckle status:
If the driver seat belt buckle and seat belt reminder warning 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 and seat belt reminder warning switch detects that a belt latch is not inserted into the seat belt buckle, the front passenger emergency tensioning retractor unit is not triggered.

Belt lock system function sequence
Irrespective of the restraint systems control unit, the belt is mechanically prevented from extending in certain situations.

Power reserve function sequence
The restraint systems control unit provides power reserves for at least t = 300 ms if the battery has been disconnected.

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 tilting/sliding roof (with code (414) Power glass tilting/sliding roof) or the panoramic sliding sunroof (with code (413) Panoramic glass sunroof with top sliding sunroof)
^ 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 activation of hazard warning function
The hazard warning function is activated automatically after a crash event has occurred. The crash signal is transmitted by the restraint systems control unit via the chassis CAN to the central gateway control unit. This routes the signal on the interior CAN to the rear SAM control unit with fuse and relay module (N10/2), which functions as a flash master

The rear SAM control unit sends the request for hazard warning flashing via the interior CAN. The following lamps are then actuated as follows:
- by the front SAM control unit with fuse and relay module (N10/1): the left turn signal light (E1e5) and the right turn signal light (E2e5)
- by the left door control unit (N69/1) (model 216) or by the left front door control unit (N69/1) (model 221): the left outside mirror turn signal lamp (E6/5)
- by the right door control unit (N69/2) (model 216) or by the right front door control unit (N69/2) (model 221): the right outside mirror turn signal lamp (E6/6)
- by the rear SAM control unit: the left turn signal light (E3e1) and right turn signal light (E4e1)

The hazard warning function can be deactivated at any time by pressing the hazard warning system button (A40/9s3).

Function sequence for opening the central locking (CL [ZV])
The central locking is unlocked automatically after a crash event has occurred. The crash signal is transmitted by the restraint systems control unit via the chassis CAN to the central gateway control unit. It routes the signal to the interior CAN. The following central locking motors are then actuated as follows:
- by the left door control unit of the left CL motor (A85m1) (model 216) or by the left front door control unit of the left front CL motor (A85m1) (model 221)
- by the right door control unit of the right CL motor (A85/1m1) (model 216) or by the right front door control unit of the right front CL motor (A85/1m1) (model 221)
- by the left rear door control unit (N69/3): the left rear central locking motor (A85/3m1) (model 221)
- by the right rear door control unit (N69/4): the right rear central locking motor (A85/4m1) (model 221)

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

Function sequence for opening the side windows
After a crash event has occurred, the side windows are automatically opened by approx. s = 50 mm. The purpose of opening the side windows is to speed up the extraction of the smoke particles generated by the pyrotechnical restraint equipment.

The crash signal is transmitted by the restraint systems control unit via the chassis CAN to the central gateway control unit. It routes the signal to the interior CAN. The following power window motors are then actuated as follows:
- by the left door control unit (model 216) or left front door control unit (model 221): of the left front power window motor (M10/3)
- by the right door control unit (model 216) or right front door control unit (model 221): of the right front power window motor (M10/4)
- by left rear door control unit (model 221) of left rear power window motor (M10/5)
- by right rear door control unit (model 221) of right rear power window motor (M10/6)

On model 216 the rear power window motors are actuated by the rear control unit (N22/6).

Function sequence for opening the tilting/sliding roof or panoramic sliding sunroof
After a crash event has occurred, the tilting/sliding roof or panoramic sliding sunroof is automatically opened by approx. s = 50 mm. The tilting/sliding roof or panoramic sliding sunroof open to accelerate extraction of the smoke particles resulting from the pyrotechnical restraint equipment.
The crash signal is transmitted by the restraint systems control unit via the chassis CAN to the central gateway control unit. This transmits the signal to the overhead control panel control unit (N70) via the interior CAN. The overhead control panel control unit then actuates the roof system drive unit (M12) to open the tilting/sliding roof or panoramic sliding sunroof.

Function sequence for shutting off the engine
The engine is shut off automatically after a crash event has occurred. The crash signal is transmitted by the restraint systems control unit via the chassis CAN to the CDI control unit (N3/9) (on model 221 with diesel engine) or to the ME control unit (N3/10) (with gasoline engine). This then causes the engine to be shut off.

Function sequence for shutting off the stationary heater (STH)
The STH is shut off automatically after a crash event has occurred. The crash signal is transmitted by the restraint systems control unit via the chassis CAN to the central gateway control unit. This routes the signal via the interior CAN to the stationary heater control unit (A6n1) (model 216) or to the stationary heater or heater booster control unit (A6n1) (model 221), which triggers the shutoff of the stationary heater.

Function sequence for automatic emergency call
An emergency call is made automatically after a crash event has occurred. The crash signal is transmitted by the restraint systems control unit via the chassis CAN to the central gateway control unit. This then sends the 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 transmitted via a discrete line from the restraint systems control unit to the emergency call system control unit.