GMC 1999 Sierra 1500 Pickup Owner's Manual page 232

Your Driving and the Road
If You're Caught in a Blizzard
AM48002
If you are stopped by heavy snow, you could be in a serious situation. You
should probably stay with your vehicle unless you know for sure that you are
near help and you can hike through the snow. Here are some things
to do to
summon help and keep yourself and your passengers safe: Turn on your
hazard flashers. Tie a red cloth to your vehicle to alert police that you've
been stopped by the snow. Put on extra clothing or wrap a blanket around
you. If you have no blankets or extra clothing, make body insulators from
newspapers, burlap bags, rags, floor mats-anything you can wrap around
yourself or tuck under your clothing to keep warm.
You can run the engine to keep warm, but be careful,
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Snow can trap exhaust gases under your vehicle. This can cause
deadly
CO
(carbon monoxide) gas to get inside. CO could overcome
you and kill you. You can't see it or smell it, so you might not know
it
is in your vehicle. Clear away snow from around the base of your
vehicle, especially any that is blocking your exhaust pipe. And check
around again from time to time
to
be sure snow doesn't collect there.
Open a window just a little on the side of the vehicle that's away
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from the wind. This will help keep CO out.
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