Tow/Haul Mode - GMC 2005 Sierra 1500 Pickup Owner's Manual

If you manually select SECOND (2) in a light duty
automatic transmission, the transmission will drive in
second gear. You may use this feature for reducing the
speed of the rear wheels when you are trying to start
your vehicle from a stop on slippery road surfaces.
FIRST (1): This position gives you even more power
(but lower fuel economy) than SECOND (2). You
can use it on very steep hills, or in deep snow or mud.
If the selector lever is put in FIRST (1) while the
vehicle is moving forward, the transmission will not shift
into first gear until the vehicle is going slowly enough.
Notice: Spinning the tires or holding the vehicle in
one place on a hill using only the accelerator
pedal may damage the transmission. If you are
stuck, do not spin the tires. When stopping on a hill,
use the brakes to hold the vehicle in place.
On cold days, approximately 32°F (0°C) or colder, your
transmission is designed to shift differently. The
transmission uses a warm-up mode shift schedule until
the engine reaches normal operating temperature.
While the transmission is in warm-up mode it is normal
for transmission upshifts to be delayed or held longer.
This feature improves heater performance by giving
quicker vehicle warm-ups.

Tow/Haul Mode

If your vehicle has an automatic transmission, it may be
equipped with a Tow/Haul mode. The selector button
is located on the end of the column shift lever. You can
use this feature to assist when towing or hauling a
heavy load. Turn Tow/Haul on and off by pressing the
button until the Tow/Haul indicator light illuminates
on the instrument panel.
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