Ford 2009 F-250 Owner's Manual page 252

Tires, Wheels and Loading
4. Press and hold the brake pedal
for two (2) seconds, then release.
5. Turn the ignition to off—DO
NOT remove the key.
6. Cycle the ignition from off to on three (3) times ending in on. DO
NOT start the engine.
If the reset mode has been entered successfully, the horn will sound
once, the TPMS indicator will flash and the message center will
display TRAIN LEFT FRONT TIRE.
If after repeated attempts to enter the reset mode, the horn does not
sound, the TPMS indicator does not flash and the message center
does not display TRAIN LEFT FRONT TIRE, seek service from your
authorized dealer.
252
2009 F-250/350/450/550 (f23)
Owners Guide, 2nd Printing
USA (fus)