2008 Hummer H3 Owner's Manual - Page 289

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. If there is still no sign of steam, idle the engine for three minutes while you are parked. Push down the accelerator until the engine speed is about twice as fast as normal idle speed for at least 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. You may decide not to lift the hood but to get service help right away. Cooling System When you decide it is safe to lift the hood, here is what you will see: 3.7L Engine shown, 5.3L Engine similar A. Coolant Recovery Tank B. Engine Cooling Fan C. Radiator Pressure Cap If the coolant inside the coolant recovery tank is boiling, do not do anything else until it cools down. The vehicle should be parked on a level surface. 5-31