GMC 2011 Sierra Owner's Manual page 309

When off-roading takes you
downhill, consider:
How steep is the downhill? Will I
be able to maintain vehicle
control?
What is the surface like?
Smooth? Rough? Slippery?
Hard-packed dirt? Gravel?
Are there hidden surface
obstacles? Ruts? Logs?
Boulders?
What is at the bottom of the hill?
Is there a hidden creek bank or
even a river bottom with large
rocks?
If you decide you can go down
a hill safely, try to keep the vehicle
headed straight down. Use a low
gear so engine drag can help the
brakes so they do not have to do all
the work. Descend slowly, keeping
the vehicle under control at all
times.
Heavy braking when going
down a hill can cause your
brakes to overheat and fade.
This could cause loss of control
and a serious accident. Apply the
brakes lightly when descending a
hill and use a low gear to keep
vehicle speed under control.
Things not to do when driving down
a hill:
When driving downhill, avoid
turns that take you across the
incline of the hill. A hill that is
not too steep to drive down
might be too steep to drive
across. The vehicle could
roll over.
Never go downhill with the
transmission in N (Neutral),
called free-wheeling. The brakes
will have to do all the work and
could overheat and fade.
Vehicles are much more likely to
stall when going uphill, but if it
happens when going downhill:
1. Stop the vehicle by applying the
regular brakes and apply the
parking brake.
2. Shift to P (Park) and, while still
braking, restart the engine.
3. Shift back to a low gear, release
the parking brake, and drive
straight down.
4. If the engine will not start, get
out and get help.