GMC SIERRA 2020 Owner's Manual page 32

Caution
To avoid damage to the tailgate,
make sure the area behind the
tailgate is clear before opening it.
If equipped with this feature, the
vehicle must be in P (Park).
Switches in the inner tailgate
prevent the primary tailgate from
being opened when the inner
tailgate is not fully closed.
To open the primary tailgate:
Press twice quickly on the
RKE transmitter until the tailgate
moves. See Remote Keyless
Entry (RKE) System Operation
(Key Access) 0 13 or
Remote Keyless Entry (RKE)
System Operation (Keyless
Access) 0 16. If equipped with
Keyless Access, the tailgate can
be opened if the RKE transmitter
is within 1 m (3 ft).
Keys, Doors, and Windows
Press on the center stack.
Press the lower touch pad on
the tailgate handle after
unlocking all doors. Use the top
of the tailgate to pull against if
assistance is required.
To close the primary tailgate, firmly
push it upward until it latches. Pull it
back to be sure it is latched
securely.
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