GMC 2006 Sierra 1500 Pickup Owner's Manual page 123

The Allison Transmission
feature that adjusts the transmission shifting to the
current driving conditions in order to reduce rapid upshifts
and downshifts. This shift stabilization feature is designed
to determine before making an upshift if the engine will be
able to maintain vehicle speed by analyzing things such
as throttle position, vehicle load, and hill grade. If the
shift stabilization feature determines that current vehicle
speed cannot be maintained, the transmission does not
upshift and instead holds the current gear. In some
cases, this may appear to be a delayed shift, however
the transmission is operating normally.
The Allison Transmission
controls. Adaptive shift controls continually compares
key shift parameters to pre-programmed ideal shift
conditions. The Allison Transmission
adjustments to improve vehicle performance according
to the way the vehicle is being used, such as with a
heavy load. During this adaptive shift controls process,
some shifts may feel different as the transmission
determines optimum settings for a particular shift.
MANUAL MODE (M): This position, is available on
vehicles with the Allison Transmission
select the range of gears appropriate for current driving
conditions. If your vehicle has this feature, see Range
Select Mode (Allison Transmission
®
uses a shift stabilization
®
also uses adaptive shift
®
constantly makes
®
. It lets drivers
®
) later in this section.
THIRD (3): This position is also used for normal driving,
however it offers more power and lower fuel economy
than DRIVE (D).
SECOND (2): This position gives you more power
but lower fuel economy. 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.
If you manually select SECOND (2) in an automatic
transmission, the transmission will start 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 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.
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.
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