Chevrolet 2003 Impala Owner's Manual page 93

There is also a display, like the graphic above, located
on the instrument panel cluSter that will indicate the
gear the vehicle is in.
Maximum engine speed is limited on automatic transaxle
vehicles when you're in PARK (P) or NEUTRAL (N) to
protect driveline components from improper operation.
There are several different positions for your shift lever
PARK (P): This position locks your front wheels. It's the
best position to use when you start your engine
because your vehicle can't move easily.
It can be dangerous to get out of your vehicle
if the shift lever is not fully in PARK (P) with
the parking brake firmly set. Your vehicle can
roll. If you have left the engine running, the
vehicle can move suddenly. You or others
could be injured. To be sure your vehicle won't
move, even when you're on fairly level ground,
use the steps that follow. If you're pulling a
trailer, see "Towing a Trailer" in the Index.
Make sure the shift lever is fully in PARK (P) before
starting the engine. Your vehicle has an automatic
transaxle shift lock control system. You must fully apply
your regular brakes before you can shift from PARK (P)
when the ignition is in ON. If you cannot shift out of
PARK (P), ease pressure on the shift lever by pushing it
all the way into PARK (P) while keeping the brake
pedal pushed down. Release the shift lever button if you
have a console shift. Then move the shift lever out of
PARK (P). See Shifting Out of Park (f) on page
2-30.
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