Ford Windstar Owner's Manual page 206

Insert the belt into the proper buckle for that seating position
4.
until you hear and feel the latch engage. See Figure 3. Make
sure the tongue is latched securely to buckle by pulling on
the tongue.
Buckling the belt
Grasp the shoulder portion of the belt and pull downward
5.
until all of the belt is extracted and a click is heard. At this
time, the retractor is in the automatic locking mode (child
restraint mode). See Figure 4.
NOTE: The dual-locking mode retractor must be in the
automatic locking mode to properly restrain a child
seat.
Seating and Safety Restraints
205