GMC 1999 Sierra 1500 Pickup Owner's Manual page 135

PO059
Use the pegs inside the compartment door to make sure the button on the
compartment door will contact the control button on the garage door opener.
Add one peg at a time until the garage door opener operates with the
compartment door closed, when you push the button marked PUSH.
PO223
The center overhead compartment can be used
to
conveniently store your
sunglasses. To open the compartment, press the release button located at the
rear of the compartment door.
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