FORD 2013 F-550 v.3 - Manual (Page 366)

As an added safety feature, your vehicle has been equipped with a tire
pressure monitoring system (TPMS) that illuminates a low tire pressure
telltale when one or more of your tires is significantly under-inflated.
Accordingly, when the low tire pressure telltale illuminates, you should
stop and check your tires as soon as possible, and inflate them to the
proper pressure. Driving on a significantly under-inflated tire causes the
tire to overheat and can lead to tire failure. Under-inflation also reduces
fuel efficiency and tire tread life, and may affect the vehicle’s handling
and stopping ability.
Please note that the TPMS is not a substitute for proper tire
maintenance, and it is the driver’s responsibility to maintain correct tire
pressure, even if under-inflation has not reached the level to trigger
illumination of the TPMS low tire pressure telltale.
Your vehicle has also been equipped with a TPMS malfunction indicator
to indicate when the system is not operating properly. The TPMS
malfunction indicator is combined with the low tire pressure telltale.
When the system detects a malfunction, the telltale will flash for
approximately one minute and then remain continuously illuminated.
This sequence will continue upon subsequent vehicle start-ups as long as
the malfunction exists.
When the malfunction indicator is illuminated, the system may not be
able to detect or signal low tire pressure as intended. TPMS malfunctions
may occur for a variety of reasons, including the installation of
replacement or alternate tires or wheels on the vehicle that prevent the
TPMS from functioning properly. Always check the TPMS malfunction
telltale after replacing one or more tires or wheels on your vehicle to
ensure that the replacement or alternate tires and wheels allow the
TPMS to continue to function properly.
The tire pressure monitoring system complies with part 15 of the FCC
rules and with RSS-210 of Industry Canada. Operation is subject to
the following two conditions: (1) This device may not cause harmful
interference, and (2) This device must accept any interference received,
including interference that may cause undesired operation.
Wheels and Tires 365
2013 F-250/350/450/550 (f23)
Owners Guide gf, 3rd Printing, December 2012
USA (fus)