2004 GMC Envoy Owner's Manual - Page 303

Driving with a Trailer CAUTION: (Continued) {CAUTION: If you have a rear-most window open and you pull a trailer with your vehicle, carbon monoxide (CO) could come into your vehicle. You can not see or smell CO. It can cause unconsciousness or death. See Engine Exhaust on page 2-34. To maximize your safety when towing a trailer: • Have your exhaust system inspected for leaks, and make necessary repairs before starting on your trip. • Keep the rear-most windows closed. CAUTION: (Continued) • If exhaust does come into your vehicle through a window in the rear or another opening, drive with your front, main heating or cooling system on and with the fan on any speed. This will bring fresh, outside air into your vehicle. Do not use the climate control setting for maximum air because it only recirculates the air inside your vehicle. See Dual Climate Control System on page 3-22. Towing a trailer requires a certain amount of experience. Before setting out for the open road, you'll want to get to know your rig. Acquaint yourself with the feel of handling and braking with the added weight of the trailer. And always keep in mind that the vehicle you are driving is now a good deal longer and not nearly as responsive as your vehicle is by itself. 4-61