FORD 2013 F-550 v.3 - Manual (Page 210)

USING FOUR-WHEEL DRIVE (4WD) (IF EQUIPPED )
WARNING: For important information regarding safe operation
of this type of vehicle, see General Information in the Wheels
and Tires chapter.
Note: Do not use 4X4 mode on dry, hard surfaced roads. Doing so will
produce excessive noise, increase tire wear and may damage drive
components. 4X4 mode is only intended for consistently slippery or loose
surfaces.
Note: If 4X4 low is selected while the vehicle is moving above 3 mph
(5 km/h), the 4WD system will not perform a shift. This is normal and
should be no reason for concern. Refer to Shifting to/from 4L (4X4 Low)
for proper operation.
Manual Shift On Stop (MSOS) 4WD system (if equipped)
Note: Some vehicles may be equipped with wheel ornaments that cover
the 4x4 manual hub lock. These ornaments must be removed to access
the manual hub locks.
Note: The vehicle should not be driven in 4X4 High or 4X4 Low modes
with the hub locks set to FREE as this condition may damage driveline
system components.
The 4WD system is engaged or
disengaged by rotating the control
for both front wheel hub locks from
the FREE or LOCK position, then
manually engaging or disengaging
the transfer case with the
floor-mounted shifter. For increased
fuel economy in 2WD, rotate both
hub locks to the FREE position.
Electronic Shift-On-the-Fly (ESOF) 4WD system (if equipped)
Note: If 4X4 Low is selected while the vehicle is moving above 3 mph
(5 km/h), the 4WD system will not perform a shift. This is normal and
should be no reason for concern. Refer to Shifting to/from 4L (4X4 Low)
for proper system operation.
Four-Wheel Drive (If Equipped) 209
2013 F-250/350/450/550 (f23)
Owners Guide gf, 3rd Printing, December 2012
USA (fus)