Running The Vehicle While Parked; Automatic Transmission - GMC CHEVROLET Silverado 1500 2021 Owner's Manual

238 Driving and Operating
Warning (Continued)
There are holes or openings in the
vehicle body from damage or
aftermarket modifications that are not
completely sealed.
If unusual fumes are detected or if it is
suspected that exhaust is coming into the
vehicle:
Drive it only with the windows
completely down.
Have the vehicle repaired immediately.
Never park the vehicle with the engine
running in an enclosed area such as a
garage or a building that has no fresh air
ventilation.

Running the Vehicle While Parked

It is better not to park with the engine
running.
If the vehicle is left with the engine running,
follow the proper steps to be sure the
vehicle will not move. See Shifting Into Park
0 235 and
Engine Exhaust 0 237.
If parking on a hill and pulling a trailer, see
Driving Characteristics and Towing Tips
0 288.

Automatic Transmission

If equipped, there is an electronic shift lever
position indicator within the instrument
cluster. This display comes on when the
ignition is in ACC/ACCESSORY, on or
service mode.
There are several different positions for the
shift lever.
See Driver Mode Control 0 250 and Range
Selection Mode under Manual Mode 0 240.
P : This position locks the rear wheels. Use
P (Park) when starting the engine because
the 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
P (Park). See Torque Lock under Shifting
Into Park 0 235.
Warning
It is dangerous to get out of the vehicle
if the shift lever is not fully in P (Park)
with the parking brake firmly set. The
vehicle can roll.
Do not leave the vehicle when the engine
is running. If you have left the engine
running, the vehicle can move suddenly.
You or others could be injured. To be
sure the vehicle will not move, even
when you are on fairly level ground,
always set the parking brake and move
the shift lever to P (Park). See Shifting
Into Park 0 235 and
Driving Characteristics and Towing Tips
0 288.