Seatbelt Tension Reducer
WARNING: This page is about a different car, the 2018 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.
Seatbelt Retractor and Pretensioner
The seatbelt tension reducer solenoid switches the seatbelt retractor from its primary spring to the secondary spring, lowering the tension of the seatbelt webbing on the occupant. When the seatbelt tension reducer solenoid switches back, the seatbelt retractor switches back to the primary spring to retract the seatbelt webbing to the stowed position.