GMC Sierra Denali Classic 2007, Owner'S Manual, Page: 111 / 502

Leaving Your Vehicle With the Engine
Running
{
CAUTION:
It can be dangerous to leave your vehicle
with the engine running. Your vehicle
could move suddenly if the shift lever is
not fully in PARK (P) 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 your
vehicle with the engine running.
If you have to leave your vehicle with the engine
running, be sure your vehicle is in PARK (P)
and the parking brake is firmly set before
you leave it. After you move the shift lever into
PARK (P), hold the regular brake pedal down.
Then, see if you can move the shift lever away
from PARK (P) without first pulling it toward you.
If you can, it means that the shift lever was
not fully locked into PARK (P).
Torque Lock
If you are parking on a hill and you do not shift
your vehicle into PARK (P) 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 PARK (P).
This is called torque lock. To prevent torque lock,
set the parking brake and then shift into
PARK (P) properly before you leave the driver’s
seat. To find out how, see
Shifting Into Park (P)
on page 110 .
When you are ready to drive, move the shift
lever out of PARK (P) 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 PARK (P).
111