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The vehicle has a shift stabilization 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 is
able to maintain vehicle speed by analyzing things such
as vehicle speed, throttle position, and vehicle load.
If the shift stabilization feature determines that a current
vehicle speed cannot be maintained, the transmission
does not upshift and instead holds the current gear. In
some cases, this could appear to be a delayed shift,
however the transmission is operating normally.
The transmission uses adaptive shift controls. Adaptive
shift controls continually compares key shift parameters
to pre-programmed ideal shifts stored in the
transmissions computer. The transmission constantly
makes adjustments to improve vehicle performance
according to how the vehicle is being used, such as
with a heavy load or when temperature changes. During
this adaptive shift control process, shifting might feel
different as the transmission determines the best
settings.
When temperatures are very cold, the Allison
Transmission
®
and Hydra-Matic
®
6-Speed
transmission's gear shifting could be delayed providing
more stable shifts until the engine warms up. Shifts
could be more noticeable with a cold transmission. This
difference in shifting is normal.
M (Manual Mode): This position is available on vehicles
with the Allison Transmission
®
or Hydra-Matic
®
6-Speed
transmission. It lets drivers select the range of gears
appropriate for current driving conditions. If the vehicle
has this feature, see Range Select Mode (Allison
Transmission
®
or Hydra-Matic
®
6-Speed transmission)
later in this section.
3 (Third): This position is also used for normal driving.
It reduces vehicle speed more than D (Drive) without
using the brakes. You might choose 3 (Third) instead of
D (Drive) when driving on hilly, winding roads, when
towing a trailer, so there is less shifting between gears
and when going down a steep hill.
2 (Second): This position reduces vehicle speed even
more than 3 (Third) without using the brakes. You can
use 2 (Second) on hills. It can help control vehicle
speed as you go down steep mountain roads, but then
you would also want to use the brakes off and on.
If you manually select 2 (Second) in an automatic
transmission, the transmission will start in second gear.
You can use this feature for reducing the speed of the
rear wheels when you are trying to start the vehicle
from a stop on slippery road surfaces.
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