Ford F-150 2000 Introduction Manual page 105

How to use the automatic locking mode
Buckle the combination lap and
shoulder belt.
Grasp the shoulder portion and
pull downward until the entire
belt is extracted.
Allow the belt to retract. As the belt retracts, you will hear a clicking
sound. This indicates the safety belt is now in the automatic locking
mode.
How to disengage the automatic locking mode
Ford recommends that all safety belt assemblies and attaching
hardware should be inspected by a qualified technician after any
collision. Safety belt assemblies not in use during a collision should also
be inspected and replaced if either damage or improper operation is
noted.
Seating and safety restraints
105