Chevrolet 2008 Colorado Owner's Manual page 224

There are some things you should do if the vehicle stalls,
or is about to stall, and you cannot make it up the hill:
•
Push the brake pedal to stop the vehicle and keep it
from rolling backwards. Also, apply the parking
brake.
•
If your engine is still running, shift the transmission to
REVERSE (R), release the parking brake, and slowly
back down the hill in REVERSE (R).
•
If your engine has stopped running, you will need to
restart it. With the brake pedal pressed and the
parking brake still applied, shift the transmission to
PARK (P), or shift to NEUTRAL if your vehicle has a
manual transmission, and restart the engine. Then,
shift to REVERSE (R), release the parking brake,
and slowly back down the hill as straight as possible
in REVERSE (R).
•
As you are backing down the hill, put your left hand
on the steering wheel at the 12 o'clock position.
This way, you will be able to tell if the wheels are
straight and maneuver as you back down. It is best
that you back down the hill with the wheels straight
rather than in the left or right direction. Turning the
wheel too far to the left or right will increase the
possibility of a rollover.
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There are also 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 your vehicle
has 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.
If, after stalling, you try to back down the hill and decide
you just cannot do it, set the parking brake, put the
automatic 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.