GMC 2011 GMG Canyon Owner's Manual page 216

It can be dangerous to leave the
vehicle with the engine running.
The vehicle could move suddenly
if the shift lever is not fully in
P (Park) with the parking brake
firmly set. And, if you leave the
vehicle with the engine running, it
could overheat and even catch
fire. You or others could be
injured. Do not leave the vehicle
with the engine running.
If you have to leave the vehicle with
the engine running, be sure the
vehicle is in P (Park) and the
parking brake is firmly set before
you leave it. After you have moved
the shift lever into P (Park), hold
the regular brake pedal down.
Then, see if you can move the shift
lever away from P (Park) without
first pulling it toward you. If you can,
the shift lever was not fully locked
into P (Park).
If you are parking on a hill and
you do not shift the transmission
into P (Park) properly, the weight
of the vehicle may put too much
force on the parking pawl in the
transmission. You may find it difficult
to pull the shift lever out of P (Park).
This is called torque lock. To
prevent torque lock, set the parking
brake and then shift into P (Park)
properly before you leave the driver
seat. To find out how, see Shifting
Into Park (Automatic Transmission)
in this section.
When you are ready to drive, move
the shift lever out of P (Park) before
you release the parking brake.
If torque lock does occur, you may
need to have another vehicle push
yours a little uphill to take some of
the pressure from the parking pawl
in the transmission, so you can pull
the shift lever out of P (Park).
The vehicle has an automatic
transmission shift lock control
system. You have to fully apply the
brake pedal before you can shift
from P (Park) when the ignition
is ON/RUN. See
The shift lock control system is
designed to do the following:
Prevent the ignition key from
being removed unless the shift
lever is in P (Park).
Prevent movement of the shift
lever out of P (Park), unless the
ignition is in ON/RUN and the
brake pedal is applied.
.