GMC Sierra Owners Manual
: Press to turn the system on or off. The indicator light is on when cruise control is on and turns off when cruise control is off.
: Press briefly to make the vehicle resume to a previously set speed, or press and hold to accelerate.
: Press to set the speed and activate cruise control or make the vehicle decelerate.
: Press to disengage cruise control without erasing the set speed from memory.
See Cruise Control on page 9‑63.