Automatic Transmission Operation - GMC Sierra 2008 Owner's Manual

Automatic Transmission Operation

If your vehicle is has an automatic transmission,
it has an electronic shift position indicator within the
instrument panel cluster. This display comes on when
the ignition key is turned to the ON/RUN position.
There are several different positions for the shift lever.
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Hydra-Matic 4-Speed
Automatic Transmission
2-28
Allison Transmission
Automatic Transmission
See "Range Selection Mode" later in this section.
PARK (P): This position locks your rear wheels.
It is the best position to use when you start the engine
because your vehicle cannot move easily. When
parked on a hill, especially when the vehicle has a heavy
load, you might notice an increase in the effort to shift
out of Park. See Torque Lock (Automatic Transmission)
under Shifting Into Park on page 2-48 for more
information.
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or Hydra-Matic 6-Speed