GMC 2010 T-Series Owner's Manual page 178

If Steam Is Coming From Your Engine
WARNING:
Steam from an overheated engine can burn you
badly, even if you just open the hood. Stay away
from the engine if you see or hear steam coming
from it. Just turn it off and get everyone away from
the vehicle until it cools down. Wait until there is
no sign of steam or coolant before you open
the hood.
If you keep driving when your engine is
overheated, the liquids in it can catch fire. You or
others could be badly burned. Stop your engine if
it overheats, and get out of the vehicle until the
engine is cool.
Notice: If the engine catches fire because of being
driven with no coolant, your vehicle can be badly
damaged. The costly repairs would not be covered
by the vehicle warranty.
5-30
If No Steam Is Coming From Your
Engine
An overheat warning, along with a low coolant light, can
indicate a serious problem. See Low Coolant Warning
Light on page 3 30 for more information.
If you get an engine overheat warning with no low
coolant light, but see or hear no steam, the problem
may not be too serious. Sometimes the engine can get
a little too hot when you:
Climb a long hill on a hot day.
Stop after high-speed driving.
Idle for long periods in traffic.