Ford F-150 2010 Owner's Manual page 173

2. Be sure the belt is not twisted. If the belt is twisted, remove the twist.
3. Insert the belt tongue into the proper buckle for your seating position
until you hear a snap and feel it latch.
4. Make sure the tongue is securely fastened to the buckle by pulling on
the tongue.
WARNING: The lap belt should fit snugly and as low as possible
around the hips, not across the waist.
WARNING: Front and rear seat occupants, including pregnant
women, should wear safety belts for optimum protection in an
accident.
WARNING: Each seating position in your vehicle has a specific
safety belt assembly which is made up of one buckle and one
tongue that are designed to be used as a pair. 1) Use the shoulder belt
on the outside shoulder only. Never wear the shoulder belt under the
arm. 2) Never swing the safety belt around your neck over the inside
shoulder. 3) Never use a single belt for more than one person.
While you are fastened in the safety belt, the combination lap/shoulder
belt with a cinch tongue adjusts to your movement. However, if you
brake hard, turn hard, or if your vehicle receives an impact of 5 mph
(8 km/h) or more, the safety belt will become locked and help reduce
your forward movement.
Lap belts
Adjusting the lap belt (Front center seat position SuperCab and
SuperCrew only)
WARNING: The lap belt should fit snugly and as low as possible
around the hips, not across the waist.
The front center lap belt tongue is designed to fit only in the correct
buckle. The tongue will not securely latch if you attempt to use it in any
of the outboard seating position buckles. To ensure that you have used
the correct buckle you should hear a snap and feel it latch.
Seating and Safety Restraints
173