2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 75

Shoulder Belt Height Adjuster The vehicle has a shoulder belt height adjuster for the driver and right front passenger. Adjust the height so that the shoulder portion of the belt is centered on the shoulder. The belt should be away from the face and neck, but not falling off the shoulder. Improper shoulder belt height adjustment could reduce the effectiveness of the safety belt in a crash. To move the adjuster down for the regular and crew cabs, squeeze the buttons (A) on the sides of the height adjuster and move the height adjuster to the desired position. On the extended cab, push down on the release button (A) and move the height adjuster to the desired position. Extended Cab You can move the adjuster up just by pushing up on the shoulder belt guide. After you move the adjuster to where you want it, try to move it down, without squeezing the buttons for the regular and crew cabs, or without pushing the release button for extended cabs, to make sure it has locked into position. Regular and Crew Cab 2-33