2003 GMC Yukon Owner's Manual - Page 387

Coolant Surge Tank Pressure Cap See Engine Compartment Overview on page 5-12 for more information on location. Engine Overheating You will find a coolant temperature gage on your vehicle's instrument panel. See Engine Coolant Temperature Gage on page 3-46. In addition, you will find an ENGINE OVERHEATED, and a REDUCED ENGINE POWER message in the DIC on the instrument panel. See Driver Information Center (DIC) on page 3-53. Overheated Engine Protection Operating Mode (V8 Engines Only) The coolant surge tank pressure cap must be fully installed on the coolant surge tank. If an overheated engine condition exists and the REDUCED ENGINE POWER message is displayed, an overheat protection mode which alternates firing groups of cylinders helps prevent engine damage. In this mode, you will notice a loss in power and engine performance. This operating mode allows your vehicle to be driven to a safe place in an emergency. Driving extended miles (km) and/or towing a trailer in the overheat protection mode should be avoided. Notice: If the pressure cap is not tightly installed, coolant loss and possible engine damage may occur. Be sure the cap is properly and tightly secured. Notice: After driving in the overheated engine protection operating mode, to avoid engine damage, allow the engine to cool before attempting any repair. The engine oil will be severely degraded. Repair the cause of coolant loss, change the oil and reset the oil life system. See "Engine Oil" in the Index. 5-29