Turbocharger Actuator
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.
The turbocharger actuator is a 4-way proportional hydraulic flow control valve with a closed center position. The valve controls the linear actuator position of a closed loop hydraulic servo by charging and venting the flow on both sides of a piston. Linear displacement feedback from the actuator varies a feedback spring force to move the valve spool to the center closed position when the actuator reaches the desired position. The actuator position is dependent only on the control valve current and not on the hydraulic fluid temperature and viscosity.