GMC 2011 Sierra Owner's Manual page 337

This vehicle is equipped with
an electronic shift lock release
system. The shift lock release is
designed to:
Prevent ignition key removal
unless the shift lever is in
P (Park) with the shift lever
button fully released.
Prevent movement of the shift
lever out of P (Park), unless
the ignition is in ON/RUN or
ACC/ACCESSORY and the
regular brake pedal is applied.
The shift lock release is always
functional except in the case of an
uncharged or low voltage (less than
9 volt) battery.
If the vehicle has an uncharged
battery or a battery with low voltage,
try charging or jump starting the
battery. See
for more information.
To shift out of P (Park) use the
following:
1. Apply the brake pedal.
2. Move the shift lever to the
desired position.
If you still are unable to shift out of
P (Park):
1. Ease the pressure on the shift
lever.
2. While holding down the brake
pedal, press the shift lever all
the way into P (Park).
3. Move the shift lever to the
desired position.
If you are still having a problem
shifting, then have the vehicle
serviced soon.
Things that can burn could touch
hot exhaust parts under the
vehicle and ignite. Do not park
over papers, leaves, dry grass,
or other things that can burn.