GMC C series 2002 Owner's Manual page 189

Specialty Hood
Sloped Hood
5-22
When the engine is cold, the coolant level should be
above the HOT LEVEL mark on the vehicle with the
specialty hood, or at or above the COLD LEVEL mark
on the vehicle with the sloped hood. If it isn't, you may
have a leak at the pressure cap or in the radiator hoses,
heater hoses, radiator, water pump or somewhere else in
the cooling system.
CAUTION:
Heater and radiator hoses, and other engine
parts, can be very hot. Don't touch them.
If you do, you can be burned.
Don't run the engine if there is a leak. If you run
the engine, it could lose all coolant. That could
cause an engine fire, and you could be burned.
Get any leak fixed before you drive the vehicle.
If there seems to be no leak, start the engine again.
The engine cooling fan speed should increase when
idle speed is doubled by pushing the accelerator pedal
down. If it doesn't, your vehicle needs service. Turn
off the engine.