Chevrolet 2008 TrailBlazer Owner's Manual page 99

THIRD (3): This position is also used for normal driving.
It reduces vehicle speed more than DRIVE (D) without
using your brakes. You might choose THIRD (3) instead
of DRIVE (D) when driving on hilly, winding roads,
when towing a trailer, so there is less shifting between
gears and when going down a steep hill.
To shift to the THIRD (3) position, you must first press
the large button on the shift handle. While the button
is pressed, move the shifter in the THIRD (3) position.
SECOND (2): This position reduces vehicle speed even
more than THIRD (3) without using your brakes. You
can use SECOND (2) on hills. It can help control
your speed as you go down steep mountain roads, but
then you would also want to use your brakes off
and on.
To shift to the SECOND (2) position, you must first
press the large button on the shift handle. While
the button is pressed, move the shifter in the
SECOND (2) position.
You can also use SECOND (2) for starting the vehicle
from a stop on slippery road surfaces.
FIRST (1): This position reduces vehicle speed even
more than SECOND (2) without using your brakes. You
can use it on very steep hills, or in deep snow or
mud. If the shift 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.
To shift to the FIRST (1) position, you must first
press the large button on the shift handle. While the
button is pressed, move the shifter in the FIRST (1)
position.
Notice: Spinning the tires or holding the vehicle in
one place on a hill using only the accelerator
pedal may damage the transmission. The repair will
not be covered by your warranty. If you are stuck,
do not spin the tires. When stopping on a hill,
use the brakes to hold the vehicle in place.
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