FORD 2002 F-550 v.3 - Manual (Page 146)

continuous or intermittent tone. This also applies if items being hauled in
the box do not fit entirely inside and protrude rearward.
Always keep the sensors (located on the rear bumper/fascia) free
from dirt, snow and ice (do not clean the sensors with sharp
objects). These elements may cause the system to operate
inaccurately.
If the vehicle sustains damage to the rear bumper/fascia, leaving
it misaligned or bent, the sensing zone may be altered causing
inaccurate measurement of obstacles or false alarms.
FOUR-WHEEL DRIVE (4WD) OPERATION (IF EQUIPPED)
For important information regarding safe operation of this type
of vehicle, see Preparing to drive your vehicle in this chapter.
When four–wheel drive (4WD) is engaged, power is supplied to all four
wheels through a transfer case. 4WD can be selected when additional
driving power is desired.
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 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 the arrow and the
indicator dot on the hub are
aligned, and that both hub
locks are set to the same
position (both set to LOCK or both set to FREE).
Electronic shift on the fly (ESOF) 4x4 system (if equipped)
If equipped with the Electronic Shift 4WD System, and 4WD Low
is selected while the vehicle is moving, the 4WD system will not
Driving
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