This is only for customers who have already purchased custom BCM tuning with 2007-2014 GMT-900 trucks!
From the factory, the GMT-900 trucks do not have a separate switch for the cargo/bed lights. The cargo lights are (annoyingly) controlled just by the dome light switch. If you have purchased my custom BCM tuning, there is a setting that will allow you to cleanly add an additional button to have full/individual control of the cargo light.
Once you have applied the "Cargo Lamp Control - Discrete" BCM tune setting and flashed your BCM, you must swap your headlight switch out for a switch from a 2014-2017 Chevrolet Traverse, or 2014-2017 Buick Enclave. I do not have any part numbers available, but just search on eBay and you should be able to find one for under $50. Be sure that the switch you are buying has the additional "Ambient Off" button, as shown in the picture.
While the headlight switch is removed, you must run this accessory wire from pin-6 of the headlight switch connector, to the BCM X6 (pink) connector, pin-24.
Plug the new headlight switch in, and then the fog light button will be the center of the headlight knob, and the button marked "ambient off" will be the new cargo lamp control button.
NOTE: The ignition will need to be ON for the new cargo lamp control method to work.