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.
With the ignition on, power is provided to the seatbelt tension reducer solenoids (integral to the seatbelt retractor). When the driver or front passenger seatbelt buckle is buckled, the seatbelt tension reducer solenoid circuit is grounded and enabled. When the seatbelt buckle is unbuckled, ground is removed, disabling the seatbelt tension reducer solenoid.