Seat Belt System
Technical Description:
All seats in the vehicle are equipped with three-point seat belts with pretensioners.
The pretensioner ensures that the belt keeps the passenger in an optimum position. When a pretensioner system is deployed, the belt webbing is by tightened up to 150 mm. Pretensioners work pyrotechnically with explosive charges.
A gas generator (similar concept to airbag deployment), is activated by an electrical signal from the ACU (airbag control unit) immediately after deployment.
Gas expansion causes balls to travel along the tube and rotate a pinion attached to the belt spool, which is activated in about 2 ms.
- Once they have been deployed, pretensioner systems are no longer effective, and have to be exchanged.
- No repairs may be made to the individual components.
- Electrical testing of the systems may only be carried out when they are installed, and there must be nobody inside the vehicle. Resistance measurements and measurements with the test lamp are forbidden.
Block Diagram Airbag Control Module (ACM)
The ACM controls the deployment of the airbags and seat belt pretensioners, and is connected to the crash sensors fitted to the body frame.
BCM: Body control module
Gateway: The gateway controls data interaction between the vehicle networks. It routes between CAN, LIN and other networks.
VCU: Vehicle control unit
IPC: Instrument panel cluster
MHU: Multimedia head unit
BMS: Battery management system
Seat belt load limiters
The force exerted by the pretensioner can cause injuries to the chest and shoulder area. For this reason, seat belt load limiters are installed. When a certain force is applied to the belt, e.g. in the automatic retractor, a torsion bar is twisted, and this limits the belt force to a maximum value.
- Activate after the pretensioners have been deployed and the seat belt is locked.
- Reduce the load/force on the person's shoulder and chest caused by the seatbelt during a frontal accident.
- Comes into affect after the pretensioner has been activated and before the occupant comes into contact with the airbag.
Operation:
Seat belt warning indicator
Driver seatbelt status:
The seat warning sign will illuminate if the driver starts driving the vehicle without fastening the seat belt and vehicle's speed is greater than 15 km/h (miles). Along with a warning indicator, a warning card pops up and the seat occupancy detection indicator will turn red on the IPC area on the infotainment touch screen. If the driver fastens the seat belt after receiving the warning, the warning sign disappears and the seat occupancy detection indicator turns green. After 4 seconds, the seat occupancy detection indicator turns gray, and after 30 seconds the indicator disappears. If the warning is ignored, the vehicle will sound a chime for 30 seconds.
Driver seatbelt status:
- Tap on the warning card or the seat belt warning icon
- "Vehicle Status" window opens with "Alerts" tab active.
- The alerts tab shows occupied seats with their respective seat belt status.
To check seat belt status (no warning present):