FORD 2012 F-550 v.1 - Manual (Page 288)

• 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 19 mph
(30 km/h).
• On 4WD vehicles in 4L (4X4 Low), the ELD can be engaged at any
speed and will not automatically disengage.
Activating the electronic locking differential (ELD)
For vehicles equipped with an
electronic shift 4WD system:
Pull the knob on the 4WD control
toward you. The
indicator light
will display in the instrument
cluster.
For 2WD vehicles and vehicles
equipped with a manual shift
4WD system:
Turn the control to ON. The
indicator light will display in the
instrument cluster.
Once the light is displayed in the instrument cluster, both rear wheel
axle shafts will be locked together providing added traction.
If the indicator light in the instrument cluster turns off, one of the
following has occurred:
• The vehicle speed is too high.
• The left and right rear wheel speed difference is too high during an
engagement attempt.
• The system has malfunctioned and will be accompanied by the
CHECK LOCKING DIFFERENTIAL message in the message center.
See your authorized Ford dealer for assistance.
Note: The ELD may have difficulty disengaging either by operator
command or automatically if the driveline is under torque. If driving
conditions allow, releasing the accelerator pedal or turning the steering
wheel in the opposite direction may assist in disengagement.
Note: The ELD is designed for off-road use only and is not intended for
use on dry pavement.
Driving
288
2012 F-250/350/450/550 (f23)
Owners Guide, 1st Printing
USA (fus)