The passive safety system is designed to preserve the lives and health of people in the car at the time of a collision.
For this purpose, seat belts and special devices - inflatable airbags - are used.
The essence of the airbags' operation is the instantaneous filling of the airbags with non-flammable and non-toxic gas, which occurs at a precisely defined moment. Airbags absorb the inertial forces that act on the most vulnerable parts of the body.
Please note: The airbag system is a supplementary system to the seat belts. If seat belts are not worn during an accident, the injuries sustained by the vehicle occupants when the airbags deploy may be no less severe than those sustained without the airbags.
It is important to remember the peculiarity of airbags.
In order to save a person's life, an instant, almost explosive filling of the pillow shells is used. This action, designed for a specific body position and occurring only in an emergency situation, can cause serious or even fatal injuries to a person if not activated in a timely manner.
Therefore, the authors recommend that car owners do not attempt to repair the passive safety system themselves.
The information provided in this section is intended to provide an understanding of the structure and operation of the system, as well as to enable safe maintenance work on the components and systems associated with the system being described.
We recommend that you do not make any independent interventions into the operation of a complex and precisely tuned system. We recommend that all diagnostic and repair work be carried out in the network of branded service stations by specially trained personnel.
Depending on the configuration option, the vehicle may be equipped with the following devices.
- Safety belt pre-tensioning device (hereinafter referred to as UPN) driver, activated by a pyropatron (R12/1).
- Front passenger seat belt tensioner (R12/2).
- Front passenger airbag, activated by a squib (R12/4).
- Driver's airbag, activated by means of a pyropatron (A45/1r1).
- Left and right airbags that protect the driver's and front passenger's heads from injury in a side impact (R12/16) and (R12/17), respectively (for vehicles with equipment code (SH9).
- Left and right airbags protecting the driver and front passenger chest (R12/32) and (R12/33), respectively (for vehicles with equipment code (SH7). These airbags are located in the seatbacks.
All airbags are equipped with the inscription SRS AIRBAG, applied either directly to the device or at the place where it is installed.
Passive safety devices include control switches that inform you that the seat belt has been fastened. These switches are located in the belt buckles (S68/1) and (S68/2), respectively. There is also a passenger presence sensor (B48) on the front passenger seat (the airbags are automatically turned on and ready to activate) or the presence of a child seat (airbags are automatically turned off).
This sensor is not available when a front double seat is installed (equipment codes S23 or SH4).
If the airbag is deactivated, the Airbag OFF indicator light (N72/1e1) comes on.
By the front acceleration sensor built into the SRS (N₂ /1O) control unit. In this case, the control unit generates a signal to activate the airbags and the seat belt warning light.
In the event of a rear impact or a not very strong frontal impact, only the braking system is activated.
Activation of all side airbags (for the head and for the chest) produced based on the signal from the side impact sensors (A53 - left) and (A54 - right).
When the airbags and the UPN are activated, the SRS control unit (N₂ /10) sends a signal about the accident to the following devices.
- Via the multiplex network (CAN-B) to the electronic ignition switch control unit EIS (EZS) (N73), and from there the signal is transmitted via the multiplex network (CAN-C) to the CDI control unit (N3/9) to switch off the engine.
- Via the multiplex network (CAN-B) to the front door electronic control units (N69/1) and (N69/2) to ensure emergency opening of the doors.
- To the SAM control unit (N10) to activate the hazard warning system. The hazard warning lights can be switched off using the hazard warning light switch (N72/1s6).
Article was borrowed from the website MercedesMAN.ru