FORD 2012 F-550 v.3 - Manual (Page 302)

4WD operation is not recommended on dry pavement. Doing so could
result in difficult disengagement of the transfer case, increased tire wear
and decreased fuel economy.
Manual Shift On Stop (MSOS) 4x4 system (if equipped)
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.
• For proper operation, make
sure that each hub is fully
engaged and that both hub locks are set to the same position
(both set to LOCK or both set to FREE). To engage LOCK,
turn the hub locks completely clockwise; to disengage the hubs
(FREE), turn the hub locks completely counterclockwise.
• 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.
• 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.
Electronic Shift-On-the-Fly (ESOF) 4x4 system (if equipped)
If equipped with the electronic shift 4WD system, and 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.
The ESOF 4WD system:
• provides 4x4 High engagement and disengagement while the vehicle is
moving.
• is operated by a rotary control located on the instrument panel that
allows you select 4x2, 4x4 High or 4x4 Low operation.
• uses auto-manual hub locks that can be engaged and disengaged
automatically based on the 4x4 mode selected.
Driving
302
2012 F-250/350/450/550 (f23)
Owners Guide, 3rd Printing
USA (fus)