GMC 2002 Envoy Owner's Manual page 247

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) 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). 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). 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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