GMC 2000 Sierra 1500 Pickup Owner's Manual page 221

Q:
Suppose, after stalling, I try to back down the
hill and decide I just can't do it. What should
I do?
A:
Set the parking brake, put your transmission in
PARK (P) (or the manual transmission in
FIRST (1)) and turn off the engine. Leave the
vehicle and go get some help. Exit on the uphill
side and stay clear of the path the vehicle would
take if it rolled downhill. Do not shift the transfer
case to NEUTRAL (N) when you leave the vehicle.
Leave it in some gear.
CAUTION:
Shifting the transfer case to NEUTRAL (N) can
cause your vehicle to roll even if the transmission
is in PARK (P) (or, if you have the manual
transmission, even if you're in gear). This is
because the NEUTRAL (N) position on the
transfer case overrides the transmission. You or
someone else could be injured. If you are going to
leave your vehicle, set the parking brake and
shift the transmission to PARK (P) (or, put your
manual transmission in FIRST (1)). But do not
shift the transfer case to the NEUTRAL (N)
position. Leave the transfer case in the 2 Wheel
High, 4 High or 4 Low position.
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