2002 GMC Envoy Owner's Manual - Page 294

If you no longer have the overheat warning, you can drive. Just to be safe, drive slower for about 10 minutes. If the warning doesn't come back on, you can drive normally. If the warning continues, pull over, stop, and park your vehicle right away. If there's still no sign of steam, push down the accelerator until the engine speed is about twice as fast as normal idle speed for at least three minutes while you're 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's safe to lift the hood, here's what you'll see: A. Coolant Recovery Tank B. Radiator Pressure Cap C. Engine Fan If the coolant inside the coolant recovery tank is boiling, don't do anything else until it cools down. 5-10