2010 GMC Acadia Owner's Manual - Page 305

Driving and Operating . 9-49 During the first 800 km (500 miles) that a trailer is towed, do not drive over 80 km/h (50 mph) and do not make starts at full throttle. This reduces wear on the vehicle. The vehicle can tow in D (Drive). Use a lower gear if the transmission shifts too often. See "Tow/Haul Mode" later in this section. Obey speed limit restrictions when towing a trailer. The vehicle is designed primarily as a passenger and load carrying vehicle. If a trailer is towed, the vehicle will require more frequent maintenance due to the additional load. . Check all trailer hitch parts and attachments, safety chains, electrical connectors, lamps, tires and mirror adjustments. If the trailer has electric brakes, start the vehicle and trailer moving and then apply the trailer brake controller by hand to be sure the brakes are working. During the trip, check regularly to be sure that the load is secure, and the lamps and trailer brakes are working properly. Tow/Haul Mode Tow/Haul assists when pulling a heavy trailer or a large or heavy load. The purpose of the Tow/Haul mode is to: . Reduce the frequency and improve the predictability of transmission shifts. Provide the same solid shift feel as when the vehicle is unloaded. Improve control of vehicle speed while requiring less throttle pedal activity. Increase the charging system voltage to assist in recharging a battery installed in a trailer. . . . . Towing with a Stability Control System When towing, the sound of the stability control system might be heard. The system is reacting to the vehicle movement caused by the trailer, which mainly occurs during cornering. This is normal when towing heavier trailers. . Driving with a Trailer Towing a trailer requires experience. Get familiar with handling and braking with the added trailer weight. The vehicle is now longer and not as responsive as the vehicle is by itself.