My "light failure" light has been on for sometime, informing me on my rear lights is out. It used to only come on when i breaked then just stayed on. I have checked all the fuses, non of those are blown. I have replaced all the rear bulbs. The "light failure" light is still on and my break light only goes out when i brake. This is only the passenger side rear break light.

 

Been reading some other posts with similar problems and alot of people are talking about the "Light sensor relay" where is this located exactly in the trunk.. Not sure if this is really the problem since only one of my brake lights go out and only when braking.

 

Looks like it is in the trunk, drivers side near the antenna motor relay.

Make sure you do not have a short in the wiring, check where the wiring goes from the chassis to the trunk lid.