FORD 2003 F-550 v.2 - Manual (Page 118)

Loaded vehicles, with a higher center of gravity, may handle
differently than unloaded vehicles. Extra precautions, such as
slower speeds and increased stopping distance, should be taken when
driving a heavily loaded vehicle.
AUTOMATIC TRANSMISSION OPERATION (IF EQUIPPED)
Brake-shift interlock
This vehicle is equipped with a brake-shift interlock feature that prevents
the gearshift lever from being moved from P (Park) when the ignition is
in the ON position unless brake pedal is depressed.
If you cannot move the gearshift lever out of P (Park) with ignition in
the ON position and the brake pedal depressed:
1. Apply the parking brake, turn ignition key to LOCK, then remove the
key.
2. Insert the key and turn it to OFF. Apply the brake pedal and shift
to N (Neutral).
When the key is in the ignition OFF position, the automatic
transmission shift lever can be moved from the P (Park) position
without the brake pedal depressed. To avoid unwanted vehicle
movement, always set the parking brake.
3. Start the vehicle.
If it is necessary to use the above procedure to move the gearshift lever,
it is possible that a fuse has blown or the vehicle’s brakelamps are not
operating properly. Refer to Fuses and relays in the Roadside
emergencies chapter.
Do not drive your vehicle until you verify that the brakelamps
are working.
Always set the parking brake fully and make sure the gearshift is
latched in P (Park). Turn the ignition to the LOCK position and
remove the key whenever you leave your vehicle.
Driving
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