GMC 2000 Sierra - Manual (Page 344)

yellow blue
6-41
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. The CHMSL bulb is removed by pulling the bulb
straight out from the holder back plate. The cargo
lamp is removed by turning the socket
counterclockwise and pulling the bulb straight out.