Ford 2009 F-150 Owner's Manual page 265

WARNING: 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.
After reaching the destination, you must place your vehicle's 4x4
gearshift lever in gear (2H, 4H or 4L).
In case of a roadside emergency with a disabled vehicle, see Wrecker
towing in the Roadside Emergencies chapter.
4WD vehicles equipped with an electronic-shift transfer case: Do
not tow your vehicle with any wheels on the ground, as vehicle or
transmission damage may occur. It is recommended to tow your vehicle
with all four (4) wheels off the ground such as when using a car-hauling
trailer. Otherwise, no recreational towing is permitted.
In case of a roadside emergency with a disabled vehicle, see Wrecker
towing in the Roadside Emergencies chapter.
2009 F-150 (f12)
Owners Guide, 2nd Printing
USA (fus)
Tires, Wheels and Loading
265