The vehicle must be on a level surface when checking the coolant level.
It is normal to see coolant moving in the upper coolant hose return line when the engine is running.
Check to see if coolant is visible in the coolant surge tank. If the coolant inside the coolant surge tank is boiling, do not do anything else until it cools down.

If coolant is visible but the coolant level is not at or above the mark pointed to, add a 50/50 mixture of clean drinkable water and DEX-COOL coolant.
Be sure the cooling system is cool before this is done.
What to Use
How to Add Coolant to the Coolant Surge TankTire Pressure Light
For vehicles with the Tire Pressure
Monitor System (TPMS), this light comes on briefly when the engine is started. It
provides information about tire pressures and the TPMS.
When the Light Is On Steady
This indicates that one or more of the tires are significantly underinflated.
Stop as soon ...
Information Displays
Driver Information Center (DIC)
The DIC displays information about the vehicle. It also displays warning messages
if a system problem is detected. See Vehicle Messages on page 5-26. All messages
appear in the DIC display in the instrument cluster.
DIC Operation and Displays
The DIC has differ ...
Collision Parts
Genuine GM Collision parts are new parts made with the same materials and construction
methods as the parts with which the vehicle was originally built. Genuine GM Collision
parts are the best choice to ensure that the vehicle's designed appearance, durability,
and safety are preserved. Th ...