2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 166

To control the fast idle: . Adjustable Throttle and Brake Pedal On vehicles with this feature, you can change the position of the throttle and brake pedals. No adjustment to the pedals can be made when the vehicle is in R (Reverse) or while using the cruise control. The switch used to adjust the pedals is located on the instrument panel below the climate control system. To Enable the Fast idle, press and release the Cruise Control On/Off button and ensure that the LED is lit. For the preset Fast Idle, press and release the cruise set switch. This will set the preset fast idle speed. For the variable fast idle, press and hold the accelerator at the desired RPM, then press and release the cruise control cruise set switch to set the desired idle speed. . . When the fast idle is active the Driver Information Center (DIC) will display "FAST IDLE ON." One of the following actions will turn off the fast idle: ... Pressing the brake. Selecting the Cancel button. Releasing the Parking Brake. The transmission shifter is moved out of P (Park) or N (Neutral). Selecting the cruise control on/off button when it was previously on. Press the arrow at the bottom of the switch to move the pedals closer to your body. Press the arrow at the top of the switch to move the pedals away from your body. Before you start driving, fully press the brake pedal to confirm the adjustment is right for you. While driving, make only small adjustments. . 3-28