2010 Cadillac DTS Owner's Manual - Page 221

Lane Departure Warning (LDW) Light For vehicles with the lane departure warning system, this light briefly comes on green, while starting the vehicle, to indicate that it is working. Engine Coolant Temperature Warning Light The engine coolant temperature warning light comes on when the engine is very hot. This light also comes on briefly when the vehicle is started. If it does not, have the vehicle serviced by your dealer/retailer. If the system is working normally the indicator light will then go off. This light also comes on green if the system detects a left or right lane marking. It flashes, changes to amber and three beeps sound if a detected lane marking is crossed without using a turn signal. For more information, see the Index in the Navigation Manual. If the light does not go out or comes on and stays on while driving, there may be a problem with the cooling system. Driving with engine coolant temperature light on could cause the vehicle to overheat, see Overheated Engine Protection Operating Mode on page 6-29. See Engine Overheating on page 6-27 and DIC Warnings and Messages on page 4-67 for more information. 4-55