Ford F-150 2010 Owner's Manual page 286

Driving
Electronic locking differential (ELD) axle (if equipped)
This axle provides added traction on slippery and/or off-road surfaces,
particularly when one wheel is on a poor traction surface. In normal
driving conditions the rear axle function as a standard axle. The ELD
may be locked or unlocked by the vehicle operator. Refer to Four-wheel
drive (4WD) operation section in this chapter for further detail on ELD
function and usage. 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 axle is not
recommended for use on good traction surfaces such as dry pavement.
Doing so may result in abnormal driving behavior while cornering and
excessive tire wear.
PREPARING TO DRIVE
WARNING: Utility vehicles have a significantly higher rollover
rate than other types of vehicles.
WARNING: In a rollover crash, an unbelted person is
significantly more likely to die than a person wearing a seat belt.
Utility vehicles and trucks have larger tires and increased ground
clearance, giving the vehicle a higher center of gravity than a passenger
car.
WARNING: Vehicles with a higher center of gravity such as
utility vehicles and trucks handle differently than vehicles with a
lower center of gravity. Utility vehicles and trucks are not designed for
cornering at speeds as high as passenger cars any more than low-slung
sports cars are designed to perform satisfactorily under off-road
conditions. Avoid sharp turns, excessive speed or abrupt maneuvers in
these vehicles. Failure to drive cautiously could result in an increased
risk of loss of vehicle control, vehicle rollover, personal injury and
death.
WARNING: Loaded vehicles, with a higher center of gravity,
may handle differently than unloaded vehicles. Do not overload
your vehicle and use extra precautions, such as driving at slower
speeds, avoiding abrupt steering changes and allowing for increased
stopping distance, when driving a heavily loaded vehicle. Over-loading
or loading the vehicle improperly can deteriorate handling capability
and contribute to loss of vehicle control and vehicle rollover.
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