The pretensioners are built into the seat belt buckles and attached to brackets on the inside of the seats. The pretensioner selects 80 mm of the seat belt using a cable system that runs parallel to the seat guides. In the event of a collision, the front seat belts are tensioned to keep the passengers and driver securely in their seats.
Each pretensioner has a propellant cylinder and a piston. The piston is attached to a steel cable, the opposite end of which is attached to the seat belt buckle. A squib at the base of the cylinder ignites the propellant when triggered by a trigger signal from the RCM. When the squib receives a trigger signal from the RCM, the squib ignites the propellant. The propellant releases nitrogen gas, which rapidly expands, driving the piston along the cylinder and pulling the cable and seat belt buckle downward.
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