FORD 2001 F-550 v.1 - Manual (Page 139)

When Four–wheel drive (4WD) is engaged, power is supplied to all four
wheels through a transfer case. 4WD power can be selected when
additional driving power is desired.
If equipped with the Electronic Shift 4WD System, and the
instrument panel control is moved to 4WD Low while the vehicle
is moving, the system will not engage and no damage will occur to
the 4WD system. Before 4WD Low can be engaged, the vehicle
must be brought to a complete stop with the brake pedal
depressed and the transmission placed in neutral (or the clutch
pedal depressed on manual transmissions).
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.
Electronic shift on the fly (ESOF) 4x4 system (if equipped)
The 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 2WD, 4x4 High or 4x4 Low operation.
• uses hub locks that can be engaged and disengaged automatically by
using a rotary control located on the instrument panel.
• automatic hub locks can be
manually overridden by rotating
the hub lock control from AUTO
to LOCK. Automatic operation of
the hub locks is recommended.
• For proper operation, make
sure that the arrow and the
indicator dot on the hub are
aligned.
Driving
139