How do you replace a 3rd brake light on a Cadillac CTS?

To replace the 3rd brake light on a Cadillac CTS, first, open the trunk and locate the access panel or the area where the brake light is installed. Remove any screws or clips securing the light assembly and gently pull it out. Disconnect the wiring harness from the old light, replace it with the new one, and reassemble the light assembly by securing it back in place. Finally, test the brake light to ensure it is functioning properly.