Ford F-150 Owner's Manual page 188

Seating and Safety Restraints
When the Safety Canopy System and/or the front airbags are activated,
the safety belt pretensioners for the driver and right front passenger
seating positions will be activated when the respective seatbelt is
properly buckled.
WARNING: The driver and the right front passenger safety belt
system (including retractors, buckles and height adjusters) must
be replaced if the vehicle is involved in a collision that results in
deployment of front airbags or Safety Canopy System and safety belt
pretensioners.
WARNING: Failure to replace the safety belt assembly under
the above conditions could result in severe personal injuries in
the event of a collision.
Refer to the Safety belt maintenance section in this chapter.
Safety belt usage sensors
The driver and front outboard passenger safety belt buckles are
equipped with sensors that detect if the safety belts are fastened. The
sensors provide information to the Personal Safety System which can
then adapt the airbag deployment or safety belt pretensioner activation
based upon safety belt usage.
WARNING: The Personal Safety System provides the most
benefit to belted occupants. The system monitors and tailors the
airbag deployment based upon safety belt usage. Failure to properly
wear your safety belt will increase your risk of injury.
188
2011 F-150 (f12)
Owners Guide, 3rd Printing
USA (fus)