Fig. 1.57. Security system of the Megane car: 1 – seat belt pretensioners (driver and front passenger); 2 – pyrotechnic seat belt reels on the rear outboard seats; 3 - lap belt pretensioners for driver and front passenger on 5-door "hatchback" models; 4 - driver and front passenger anti-slip airbags on 3-door "hatchbacks"; 5 – front airbags with two gas generators (two-volume); 6 – side chest airbags in the backrests of the front seats; 7 – side curtain airbags; 8 – Side chest airbags for rear seats (if the car is equipped with them)
The safety system of the Megane car is shown in Fig. 1.57.
General information
In the event of a severe frontal impact, seat belts help keep the driver and passengers in place.
The front shoulder belt pretensioners and the rear pyrotechnic retractors tighten the seat belts so that they fit snugly against the body.
The programmable restraint system limits the force with which the belt is pressed against the body.
Front airbags deploy:
- from the center of the steering wheel to protect the driver's head;
- from the dashboard for the front passenger.
Front lumbar pretensioners (5-door modification) or anti-slip airbags (3-door modification) tighten seat belts to protect the lower body.
Note: The inflation level of the driver's airbag can be adjusted by the ECU depending on:
- - seat positions;
- - the force of impact.
In the event of a sufficiently severe side impact, the front side chest airbag, located in the front seat (from the side of the blow), when deployed, protects the chest of the front seat occupant on the door side. Rear side airbag, if the vehicle is equipped with one, located in the side of the body on the corresponding side (from the side of the blow), protects the chest of the person sitting in the back seat from the door side. Curtain airbag (from the side of the blow) protects the head of the person sitting in the front or back seat from the door side.
Depending on the force and location of the impact, pretensioners, seat belt retractors, anti-skid airbags, frontal and side airbags may deploy in various combinations.
When the pyrotechnic gas generator is triggered, a pop is heard and light smoke comes out.
Note: Power to the ECU and igniters is supplied from the vehicle battery under normal operating conditions. However, the airbag ECU has a built-in backup power source in case of battery failure during the initial stage of an impact.
Note: When the seat belt pretensioners or airbags are triggered, the ECU is completely blocked and a warning light comes on on the instrument panel. In this case, the ECU must be replaced (under the influence of ignition energy, some elements lose their nominal characteristics).
Note: After installing all components, perform a system check using a diagnostic tool.
After the hit:
- if the pretensioners are triggered, replace the seat belts if they were fastened, as well as the seat frame (power is supplied to the shoulder belt pretensioners in series);
- if the rear pyrotechnic safety reels are triggered, replace the seat belt together with the pyrotechnic reel (power is supplied to the pyrotechnic coils in series);
- if the driver's front airbag is deployed, the steering wheel and its mounting bolt must be replaced;
- after the front passenger airbag has deployed, replace the instrument panel;
- if the side airbag deploys, replace the seat frame;
- if the anti-slip airbag is deployed, also replace the seat frame;
- if the curtain airbag is deployed, install the plate and replace the deflector.