Ford Super Duty Owner's Manual page 202

Tow/haul may be automatically activated (without pressing the tow/haul
button). This provides engine braking to assist the vehicles braking
system when going downhill and repetitive braking is sensed. Once the
tow/haul mode has been automatically activated it will not automatically
deactivate.
To deactivate the tow/haul feature and return to normal driving mode,
press the button on the end of the gearshift lever. The tow/haul light will
no longer be illuminated.
Tow/haul will also deactivate when the vehicle is powered down for a few
minutes.
M (Manual) without Overdrive
With the gearshift lever in M (Manual), the driver can change gears up
or down as desired. This is called SelectShift Automatic™ transmission
(SST) mode. By moving the gearshift lever from drive position D
(Overdrive) to M (Manual) you now have control of selecting the gear
you desire using buttons on the shift lever.
To return to normal D (Overdrive) position, move the shift lever back
from M to D.
• The transmission will operate in gears one through six.
2 (Second)
Use 2 (Second) to start-up on slippery roads or to provide additional
engine braking on downgrades.
1 (First)
• Provides maximum engine braking.
• Allows upshifts by moving gearshift lever.
• The transmission will not downshift into 1 (First) at high speeds; it
will downshift to a lower gear and then shift into 1 (First) when the
vehicle reaches slower speeds.
Forced downshifts
• Allowed in D (Overdrive).
• Press the accelerator to the floor.
• Allows transmission to select an appropriate gear.
2013 F-250/350/450/550 (f23)
Owners Guide gf, 1st Printing
USA (fus)
Transmission 201