Ford 2010 F-350 Owner's Manual page 181

Conditions of operation
If...
The driver's safety belt is not
buckled before the ignition switch
is turned to the on position...
The driver's safety belt is buckled
while the indicator light is
illuminated and the warning chime
is sounding...
The driver's safety belt is buckled
before the ignition switch is turned
to the on position...
Belt-Minder
The Belt-Minder feature is a supplemental warning to the safety belt
warning function. This feature provides additional reminders to the
driver that the driver's safety belt is unbuckled by intermittently
sounding a chime and illuminating the safety belt warning lamp in the
instrument cluster.
If...
The driver's safety belt is not
buckled before the vehicle has
reached at least 3 mph (5 km/h)
and 1-2 minutes have elapsed
since the ignition switch has been
turned to the on position...
The driver's safety belt is buckled
while the safety belt indicator light
is illuminated and the safety belt
warning chime is sounding...
The driver's safety belt is buckled
before the ignition switch is turned
to the on position...
2010 F-250/350/450/550 (f23)
Owners Guide, 2nd Printing
USA (fus)
Seating and Safety Restraints
Then...
The safety belt warning light
illuminates 1-2 minutes and the
warning chime sounds
4-8 seconds.
The safety belt warning light and
warning chime turn off.
The safety belt warning light and
indicator chime remain off.
Then...
The Belt-Minder feature is
activated - the safety belt warning
light illuminates and the warning
chime sounds for six seconds
every 30 seconds, repeating for
approximately five minutes or until
safety belt is buckled.
The Belt-Minder feature will not
activate.
The Belt-Minder feature will not
activate.
181