2006 GMC Savana Van Owner's Manual - Page 235

Press this button located to the right of the steering wheel on the instrument panel to turn tow/haul mode on and off. Tow/haul is most effective when the vehicle and trailer combined weight is at least 75 percent of the vehicle's Gross Combined Weight Rating (GCWR). See "Weight of the Trailer" later in this section. Driving with tow/haul activated without a heavy load will cause reduced fuel economy and unpleasant engine and transmission driving characteristics, but will not cause damage. Weight of the Trailer How heavy can a trailer safely be? While activated, the indicator light on the instrument panel will be on. It depends on how you plan to use your rig. For example, speed, altitude, road grades, outside temperature and how much your vehicle is used to pull a trailer are all important. It can also depend on any special equipment that you have on your vehicle, and the amount of tongue weight the vehicle can carry. See "Weight of the Trailer Tongue" later in this section for more information. Maximum trailer weight is calculated assuming only the driver is in the tow vehicle and it has all the required trailering equipment. The weight of additional optional equipment, passengers and cargo in the tow vehicle must be subtracted from the maximum trailer weight. Tow/haul mode will turn off automatically when the ignition is turned off. See Tow/Haul Mode Light on page 3-42. 4-39