GMC 2001 Sierra - Manual (Page 388)

6-46
Center High-Mounted Stoplamp (CHMSL)
and Cargo Lamp
1. Remove the screws and lift off the lamp assembly.
A. Cargo Lamps
B. Center High - Mounted Stoplamps
2. Remove the CHMSL bulb holder back plate from
the housing by pressing the release tabs.
3. A CHMSL bulb is removed by pulling the bulb
straight out from the holder back plate. A cargo bulb
is removed by turning the socket counterclockwise
and pulling the bulb straight out.