2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 221

Do not exceed the maximum vehicle capacity when loading the vehicle. For more information on vehicle capacity and loading, see Loading the Vehicle on page 5‑33. . Rear Seat Armrest Vehicles with a rear seat armrest have two cupholders. Pull the armrest down from the rear seatback to access the cupholders. If small heavy objects are placed on the roof, cut a piece of 3/8 inch plywood to fit inside the crossrails and siderails to spread the load. Tie the plywood to the siderail supports. Tie the load and secure it to the crossrails or the siderail supports. Use the crossrails only to keep the load from sliding. To move a crossrail, lift the release lever up, on both sides of the rail. Then slide the crossrail to the desired position balancing the force side to side. Press the release lever down on both sides of the rail, down to tighten it. Try to slide the crossrail back and forth slightly to make sure it is tight. To carry long items, move the crossrails as far apart as possible. Tie the load to the crossrails and the siderails or siderail supports. Also tie the load to the bumpers, but do not tie the load so tightly that the crossrails or siderails are damaged. After moving a crossrail, be sure it is securely locked into the siderail. Sunroof On vehicles with a power sliding sunroof, the ignition needs to be turned to RUN, or the Retained Accessory Power (RAP) must be activated to open or close the sunroof. When RAP is active, the sunroof will work for 10 minutes after the ignition is turned off, or until the driver's door is opened. See Retained Accessory Power (RAP) on page 3‑25 for more information. Do not leave the sunroof open for long periods of time while the vehicle is not in use. Debris can collect in the tracks and damage the sunroof operation and plug the water draining system. . . . A Center High-Mounted Stoplamp (CHMSL) is located above the rear window glass. Make sure items loaded on the roof of the vehicle do not block or damage the CHMSL. 3-83