Ford Super Duty Owner's Manual page 201

200
D (Overdrive) with Tow/Haul Off
D (Overdrive) with tow/haul off is the normal driving position for the
best fuel economy. The overdrive function allows automatic upshifts and
downshifts through gears one through five.
D (Overdrive) with Tow/Haul On
The tow/haul feature improves transmission operation when towing a
trailer or a heavy load. All transmission gear ranges are available when
using tow/haul.
The TOW HAUL indicator light will illuminate in the instrument
cluster.
Tow/haul delays upshifts to reduce frequency of transmission shifting.
Tow/haul also provides engine braking in all forward gears when the
transmission is in the D (Overdrive) position; this engine braking will
slow the vehicle and assist the driver in controlling the vehicle when
descending a grade. Depending on driving conditions and load conditions,
the transmission may downshift, slow the vehicle and control the vehicle
speed when descending a hill, without the pedals being pressed.
The amount of downshift braking provided will vary based upon the
amount the pedal is depressed.
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.
When you shut-off and restart the engine, the transmission will
automatically return to normal D (Overdrive) mode (Tow/Haul OFF).
3 (Third)
Transmission starts and operates in third gear only.
Used for improved traction on slippery roads. Selecting 3 (Third)
provides engine braking.
2013 F-250/350/450/550 (f23)
Owners Guide gf, 2nd Printing, December 2012
USA (fus)
Transmission
To activate tow/haul, press the
button on the end of the gearshift
lever.