2008 GMC Acadia Owner's Manual - Page 340

If No Steam Is Coming From Your Engine If you get an engine overheat warning but see or hear no steam, the problem may not be too serious. Sometimes the engine can get a little too hot when you: If there is still no sign of steam, idle the engine for three minutes while you are parked. If you still have the warning, turn off the engine and get everyone out of the vehicle until it cools down. Also, see "Overheated Engine Protection Operating Mode" later in this section. You may decide not to lift the hood but to get service help right away. Climb a long hill on a hot day. Stop after high-speed driving. Idle for long periods in traffic. Tow a trailer. Overheated Engine Protection Operating Mode This emergency operating mode lets your vehicle be driven to a safe place in an emergency situation. If an overheated engine condition exists, an overheat protection mode which alternates firing groups of cylinders helps prevent engine damage. In this mode, there is a significant loss in power and engine performance. The temperature gage indicates an overheat condition exists. Driving extended distances and/or towing a trailer in the overheat protection mode should be avoided. 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 on page 5-15. If you get the overheat warning with no sign of steam, try this for a minute or so: 1. If your air conditioner is on, turn it off. 2. Turn on your heater to full hot at the highest fan speed and open the windows as necessary. 3. If you are in a traffic jam, shift to NEUTRAL (N); otherwise, shift to the highest gear while driving - DRIVE (D) or LOW (L). If you no longer have the overheat warning, you can drive. Just to be safe, drive slower for about 10 minutes. If the warning does not come back on, you can drive normally. If the warning continues, pull over, stop, and park your vehicle right away. 5-26