The system includes two pyrotechnic devices mounted on the side of the front seats and an electronic control unit.
The ECU is installed under the center console and consists of a deceleration sensor and an amplifying unit. If the sensor perceives a deceleration beyond a certain limit, the amplifying block sends a signal to the fuses in the blocks
seat belt tensioners. On most models, the electronic pretensioner control unit is integrated into the airbag control unit.
As soon as the fuse is fired, the small primer instantly releases gas, filling the pretensioner cylinder. The piston in the cylinder, moving along the cylinder, pulls the cable (about 70 mm), by tightening the seat belt accordingly.
After the seat belt pretensioner has deployed, it must be replaced.
Do not overheat pretensioners. If any work on the vehicle requires heavy impact on vehicle parts, remove the fuse for the pretensioner control system by de-energizing it and wait at least 5 minutes for the system to deactivate. Installing any systems with magnets (e.g. loudspeakers), do not place them close to the pretensioner control unit.
Shutdown procedure (deactivation):
- turn off the ignition;
- remove the system fuse (see section «electrical equipment»);
- wait at least 5 minutes before starting work;
- working in turn under each seat, disconnect the system wiring connector.
Connection order (activation):
- connect the system connectors under the seats;
- install a system fuse.
Removal and installation of the pretensioner assembly
Removing
- deactivate the system (see above);
- remove the front seat;
- remove the front seat cover;
Figure 9.120. Disconnecting the connector from the pretensioner assembly
- disconnect the wiring connector on top of the pretensioner assembly (Figure 9.120) and pass the wiring through the overlay (leave the wiring attached under the seat);
Figure 9.121. Removing the pretensioner mounting bolt from the seat frame
- unscrew the bolt securing the pretensioner assembly (Figure 9.121), remove the assembly from the seat frame.
Installation
- pass the pretensioner wiring through the slot in the seat pad and connect the connector to the block;
- install the unit in the seat, screw in and tighten the mounting bolt;
- install the seat cover;
- install the seat;
- activate the system as described above.
Removal and installation of the computer
Removing
- deactivate the pretensioning system;
- remove the center console;
Figure 9.122. Removing the screws securing the air ducts to the computer bracket
- unscrew the fastening screws and move the two air ducts to the side (Figure 9.122);
- remove the mat to gain access to the computer. To facilitate the work, the mat can be cut;
Figure 9.123. Releasing the wiring retainer and disconnecting the ECU connectors
- disconnect the computer connectors (Figure 9.123);
- unscrew the nuts securing the computer;
- lift the computer and remove it from the floor along with the diagnostic connector bracket.
Installation
Figure 9.124. The arrow on the ECU case is directed in the direction of the car
- install the computer in place so that the arrow on its body points in the direction of the car (Figure 9.124);
- Install the ECU mounting nuts and tighten them securely. Do not connect the connectors before tightening the nuts;
- connect the ECU connectors;
- install the air ducts by screwing in the screws of their fastening;
- reinstall the center console;
- activate the pretensioning system.