Lincoln Mark LT 2010-2014 Hub Lock Vacuum Control Actuator Valve - Front This precision vacuum actuator valve controls front hub lock operation on 2010-2014 Lincoln Mark LT models. It regulates vacuum supply to your locking hubs, enabling smooth 4WD activation and maintaining consistent pressure modulation during shifts. When the actuator valve deteriorates, hub engagement becomes sluggish or fails entirely, compromising traction and handling. This direct-fit replacement restores proper vacuum signal delivery, ensuring your locking hubs respond instantly and perform reliably in all driving conditions and terrain types.