Ford 2006 F150 Owner's Manual page 220

Driving
• 4X4 LOW – Momentarily
illuminates when the engine is
started. Illuminates when 4L is
selected.
Using a manual 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.
N (Neutral) – No power to either front or rear wheels.
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 above 3 mph (5 km/h); 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 transfer case lever between 2H (2WD High) and 4H (4WD
High) at a stop or 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.
220
2H
4H
N
4L
4x4
LOW