2009 Cadillac DTS Owner's Manual - Page 200

Engine Coolant Temperature Gage This gage shows the engine coolant temperature. Tire Pressure Light For vehicles with a tire pressure monitoring system, this light comes on briefly when the engine is started. It provides information about tire pressures and the Tire Pressure Monitoring System. It indicates when the engine has warmed up and if the cooling system is operating properly. If the gage pointer moves into the shaded area, the engine coolant is too hot and the engine coolant temperature warning light comes on. See Engine Overheating on page 5-28 for more information. 3-60