GMC 2001 Yukon XL Owner's Manual page 227

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Ease up on your speed as you approach the top of
the hill.
D
Attach a flag to the vehicle to make you more visible
to approaching traffic on trails or hills.
D
Sound the horn as you approach the top of the hill
to let opposing traffic know you're there.
D
Use your headlamps even during the day. They make
you 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
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.
4-24
Q:
What should I do if my vehicle stalls, or is about
to stall, and I can't make it up the hill?
A:
If this happens, there are some things you should
do, and there are some things you must not do.
First, here's what you should do:
D
Push the brake pedal to stop the vehicle and keep it
from rolling backwards. Also, apply the parking brake.
D
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).
D
If your engine has stopped running, you'll need
to restart it. With the brake pedal pressed and the
parking brake still applied, shift the transmission
-
off,
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).
D
As you are backing down the hill, put your left hand
on the steering wheel at the 12 o'clock position. This
way, you'll be able to tell if your wheels are straight
and maneuver as you back down. It's best that you
back down the hill with your 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.