Ford 2009 F-250 Owner's Manual page 209

Seating and Safety Restraints
5. To put the retractor in the
automatic locking mode, grasp the
shoulder portion of the belt and pull
downward until all of the belt is
pulled out.
6. Allow the belt to retract to remove slack. The belt will click as it
retracts to indicate it is in the automatic locking mode.
7. Try to pull the belt out of the retractor to make sure the retractor is
in the automatic locking mode (you should not be able to pull more belt
out). If the retractor is not locked, unbuckle the belt and repeat Steps 5
and 6.
8. Remove remaining slack from the
belt. Force the seat down with extra
weight, e.g., by pressing down or
kneeling on the child restraint while
pulling up on the shoulder belt in
order to force slack from the belt.
This is necessary to remove the
remaining slack that will exist once
the additional weight of the child is
added to the child restraint. It also
helps to achieve the proper
snugness of the child seat to the
vehicle. Sometimes, a slight lean
towards the buckle will additionally
help to remove remaining slack from the belt.
209
2009 F-250/350/450/550 (f23)
Owners Guide, 2nd Printing
USA (fus)