My wife has a 2007 Kia Rio. She started it the other day and when she put her foot on the brake a dashboard indicator about a burnt out light came on.
We looked at it together and found that with the headlights off, only the right brake light came on. Not the left, not the center. With the headlights on and the brake off, both tail lights worked (same illumination level as stepping on the brake with headlights off). But then you step on the brake and the right one gets further illuminated while the left stays the same.
So it doesn't seem like the left bulb is out, because it illuminates normally in response to headlights. But I feel like if it were a switch or something then the right light would behave like the others.
Maybe it's a coincidence that the center light also went out, and I just need to replace the bulb, along with the left light assembly? I don't know. Any ideas?