GMC 2005 Sierra 1500 Pickup Owner's Manual page 323

Here are some things you must not do if you stall, or
are about to stall, when going up a hill.
•
Never attempt to prevent a stall by shifting into
NEUTRAL (N) (or pressing the clutch, if you have a
manual transmission) to rev-up the engine and
regain forward momentum. This will not work. Your
vehicle will roll backwards very quickly and you
could go out of control.
Instead, apply the regular brake to stop the vehicle.
Then apply the parking brake. Shift to
REVERSE (R), release the parking brake, and
slowly back straight down.
•
Never attempt to turn around if you are about to
stall when going up a hill. If the hill is steep
enough to stall your vehicle, it is steep enough to
cause you to roll over if you turn around. If you
cannot make it up the hill, you must back straight
down the hill.
Q:
Suppose, after stalling, I try to back down the hill
and decide I just cannot 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 when you
leave the vehicle. Leave it in some gear.
CAUTION:
{
Shifting the transfer case to NEUTRAL can
cause your vehicle to roll even if the
transmission is in PARK (P) (or, if you have the
manual transmission, even if you are in gear).
This is because the NEUTRAL 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 NEUTRAL. Leave the
transfer case in the 2 Wheel High, 4 High or
4 Low position.
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