Ford F-150 2005 Owner's Manual page 207

Do not leave the vehicle unattended with the transfer case in the
N (Neutral) position. Always set the parking brake fully and turn
off the ignition when leaving the vehicle.
Using the electronic shift 4WD system (if equipped)
2H (2WD High) - Power to the rear wheels only; used for street and
highway driving. Provides optimal smoothness and fuel economy at high
speeds.
4H (4WD High) - Used for extra traction such as in snow or icy roads
or in off-road situations. Not intended for use on dry pavement.
4L (4WD Low) - Uses extra gearing to provide maximum power to all
four wheels at reduced speeds. Intended only for off-road applications
such as deep sand, steep grades or pulling heavy objects. 4L (4WD Low)
will not engage while the vehicle is moving; this is normal and should be
no reason for concern. Refer to Shifting to/from 4L (4WD Low) for
proper operation.
Shifting between 2H (2WD High) and 4H (4WD High)
• Move the 4WD control between 2H and 4H at any forward speed up to
55 mph (88 km/h).
Note: Do not perform this operation at speeds above 45 mph (72 km/h)
if the outside temperature is below 32°F (0°C).
Note: Do not perform this operation if the rear wheels are slipping.
Note: Some noise may be heard as the system shifts or engages; this is
normal.
Shifting to/from 4L (4WD Low)
1. Bring the vehicle to a complete stop
2. Depress the brake
2005 F-150 (f12)
Owners Guide (post-2002-fmt)
USA (fus)
Driving
207