2009 GMC Savana Van Owner's Manual - Page 110

While activated, the indicator light on the instrument panel will be on. Parking Brake Tow/haul mode will turn off automatically when the ignition is turned off. See Tow/Haul Mode Light on page 3-40. 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. To set the parking brake, hold the regular brake pedal, then push down the parking brake pedal. If the ignition is on, the brake system warning light will come on. 2-26