Using Outlet 2024 Sierra. But you could reuse the factory bed outlet if you. I just found out my 2022 refreshed did not come with a 12v cigarette lighter outlet, none of them do i'm told, but i use to power my dashcam, and a couple other.
2024 hd sierra manual pg 108, when the ignition is on, power is supplied to the outlets after the dc/ac switch is pressed. 120v bed outlet 2023 sierra.