GMC Chevrolet Tahoe 2003 Manual page 416

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CAUTION:
You can be burned if you spill coolant on hot
engine parts. Coolant contains ethylene glycol
and it will burn if the engine parts are hot
enough. Do not spill coolant on a hot engine.
5-40
1. Park the vehicle on a
level surface. You can
remove the coolant
surge tank pressure
cap when the cooling
system, including
the coolant surge tank
pressure cap and
upper radiator hose, is
no longer hot.
2. Turn the pressure cap slowly counterclockwise
(left) about one full turn. If you hear a hiss,
wait for that to stop. A hiss means there is still
some pressure left.
3. Then keep turning the pressure cap slowly, and
remove it.