Ford 2009 F-250 Owner's Manual page 248

Tires, Wheels and Loading
Low Tire Possible
Pressure cause
Warning Light
Flashing Spare tire in
Warning Light use
TPMS
malfunction
When inflating your tires
When putting air into your tires (such as at a gas station or in your
garage), the Tire Pressure Monitoring System may not respond
immediately to the air added to your tires.
It may take up to two minutes of driving over 20 mph (32 km/h) for the
light to turn OFF after you have filled your tires to the recommended
inflation pressure.
How temperature affects your tire pressure
The Tire Pressure Monitoring System (TPMS) monitors tire pressure in
each pneumatic tire. While driving in a normal manner, a typical
passenger tire inflation pressure may increase approximately 2 to 4 psi
(14 to 28 kPa) from a cold start situation. If the vehicle is stationary
over night with the outside temperature significantly lower than the
daytime temperature, the tire pressure may decrease approximately 3 psi
(20.7 kPa) for a drop of 30° F (16.6°C) in ambient temperature. This
lower pressure value may be detected by the TPMS as being significantly
lower than the recommended inflation pressure and activate the TPMS
warning for low tire pressure. If the low tire pressure warning light is
ON, visually check each tire to verify that no tire is flat. (If one or more
tires are flat, repair as necessary.) Check air pressure in the road tires. If
any tire is under-inflated, carefully drive the vehicle to the nearest
location where air can be added to the tires. Inflate all the tires to the
recommended inflation pressure.
248
2009 F-250/350/450/550 (f23)
Owners Guide, 2nd Printing
USA (fus)
Customer Action Required
Your temporary spare tire is in use.
Repair the damaged road wheel and
re-mount it on the vehicle to
restore system functionality. For a
description of how the system
functions under these conditions,
refer to When your temporary
spare tire is installed in this
section.
If your tires are properly inflated
and your spare tire is not in use
and the TPMS warning light still
flashes, have the system inspected
by your authorized dealer.