GMC TopKick 2007 Owner's Manual page 284

Checking Coolant
The coolant surge tank is located in the engine
compartment on the driver's side of the vehicle.
284
CAUTION:
{
Turning the surge tank pressure cap when
the engine and radiator are hot can allow
steam and scalding liquids to blow out
and burn you badly. Never turn the surge
tank pressure cap — even a little — when
the engine and radiator are hot.
The vehicle must be parked on a level surface.
When your engine is cold, the coolant level should
be at the FULL COLD mark or higher.
See Low Coolant Warning Light on page 171 for
further information.
If the low coolant
warning light comes
on in the instrument
panel cluster and stays
on, it means you are
low on engine coolant.