Turbocharger wastegate actuator (if equipped)
WARNING: This page is about a different car, the 2013 Ford F-550 Super Duty, 2013 Ford F-450 Super Duty, 2013 Ford F-350 Super Duty, and 2013 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.
when the boost pressure reaches a predetermined value, the turbocharger wastegate control valve opens allowing vacuum to open the turbocharger wastegate actuator.