2003 GMC Yukon Owner's Manual - Page 389

If No Steam Is Coming From Your Engine An overheat warning, along with a low coolant condition, can indicate a serious problem. See Low Coolant under DIC Warnings and Messages on page 3-64. If you get an engine overheat warning with and do not have a low coolant condition, 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 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, you can 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. Also, seeOverheated Engine Protection Operating Mode listed previously 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. See Towing a Trailer on page 4-61. If you get the overheat warning with no sign of steam, try this for a minute or so: 1. In heavy traffic, let the engine idle in neutral while stopped. If it is safe to do so, pull off the road. Shift to park or neutral and let the engine idle. 2. Turn on your heater to full hot at the highest fan speed and open the window as necessary. 5-31