GMC SIERRA 2020 Owner's Manual page 52

The sunroof also has a sunshade,
which can be pulled forward to block
sun rays. The sunshade must be
opened and closed manually.
Automatic Reversal System
The sunroof has an automatic
reversal system that is only active
when the sunroof is operated in
express-close mode.
If an object is in the path while
express-closing, the reversal system
will detect an object, stop, and open
the sunroof slightly.
If frost or other conditions prevent
closing, override the feature by
closing the sunroof in manual mode.
To stop movement, release
Dirt and debris may collect on the
sunroof seal or in the track. This
could cause an issue with sunroof
operation or noise. It could also plug
the water drainage system.
Periodically open the sunroof and
remove any obstacles or loose
debris. Wipe the sunroof seal and
roof sealing area using a clean
cloth, mild soap, and water. Do not
remove grease from the sunroof
tracks.
If water is seen dripping into the
water drainage system, this is
normal.
(1).
Keys, Doors, and Windows 51