GMC 2010 GMC Sierra, Owner'S Manual, Page: 221 / 660

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 .
. 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.
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.
Rear Seat Armrest
Vehicles with a rear seat armrest have two cupholders.
Pull the armrest down from the rear seatback to access
the cupholders.
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.
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