RyanIS300

I have a 2004 is300, the driver rear trunk light is malfunctioning. I have the lights set on auto mode, with the daytime running lights on the bulb lights up dim. At night the running lights all work except for when I press the brake(driver side tunk). I've replaced the bulb on that light, swapped the harnesses/socket for that light. Still no change. My light is on the dash showing a bulb is out.My tag bulb also does not work Ive replaced the bulb and still no change. I noticed the tag bulb cut on randomly one time. Is this a common problem and would the main harness that the two driver side lamps attach to be the issue?