FORD 2013 F-550 v.1 - Manual (Page 213)

Shifting to/from 4L (4X4 low)
Note: Some noise may be heard as the system shifts or engages; this is
normal.
Note: 4x4 low mode is not intended for use on dry pavement.
1. Bring the vehicle to a speed of 3 mph (5 km/h) or less.
2. Place the transmission in N (Neutral).
3. Move the 4WD control to the desired position.
The information display will display a message indicating a 4X4 shift is in
progress. The information display will then display the system mode
selected. If any of the above shift conditions are not met, the shift will
not occur and the information display will display information guiding the
driver through the proper shifting procedures.
If SHIFT DELAYED PULL FORWARD is displayed in the information
display, transfer case gear tooth blockage is present. To alleviate this
condition, place the transmission in a forward gear, move the vehicle
forward approximately 5 feet (1.5 m), and shift the transmission back to
neutral to allow the transfer case to complete the range shift.
Electronic Locking Differential (ELD) (If Equipped)
Note: The ELD is designed for off-road use only and is not intended for
use on dry pavement. Using the ELD on dry pavement will result in
increased tire wear, noise and vibration.
The electronic locking differential (ELD) is a device housed in the rear
axle which allows both rear wheels to turn at the same speed. It provides
added traction on slippery and/or off road surfaces, particularly when
one wheel is on a poor traction surface. The ELD may be locked or
unlocked by the vehicle operator and can be engaged or disengaged on
the fly. When the axle is unlocked it will function like a standard rear
axle. When the axle is locked it will not allow the rear wheels to rotate
at different speeds when turning.
The ELD is affected by the following conditions:
• On 2WD vehicles and 4WD vehicles in 2H (4X2) or 4H (4X4 High), the
ELD will not engage if the vehicle speed is above 20 mph (32 km/h).
• On 2WD vehicles and 4WD vehicles in 2H (4X2) or 4H (4X4 High), the
ELD will automatically disengage at speeds above 25 mph (40 km/h) and
will automatically reengage at speeds below 20 mph (32 km/h).
• On 4WD vehicles in 4L (4X4 Low), the ELD can be engaged at any
speed and will not automatically disengage.
212 Four-Wheel Drive (If Equipped)
2013 F-250/350/450/550 (f23)
Owners Guide gf, 1st Printing
USA (fus)