GMC Sierra 2008 Owner's Manual page 322

•
Sound the horn as you approach the top of the
hill to let opposing traffic know you are there.
•
Use your headlamps even during the day. They
make your vehicle more visible to oncoming traffic.
CAUTION:
{
Driving to the top (crest) of a hill at full speed
can cause an accident. There could be a
drop-off, embankment, cliff, or even another
vehicle. You could be seriously injured or
killed. As you near the top of a hill, slow
down and stay alert.
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.
4-20
•
If the engine is still running, shift the transmission
to REVERSE (R), release the parking brake, and
slowly back down the hill in REVERSE (R).
•
If the 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) 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.