After months of the mysterious left taillight working/not working and the light on the dash coming and going, I decided to leave the car at the garage to be inspected with instructions to get rid of the pesky light on the dash. We looked the car over at the time and could find no light not working. The car was inspected and passed, the dash light still on. In hindsight, the only clue to the problem was that the left tail light, when it was on, burned slightly dimmer than the right. I went to the dealership, not trusting the local parts store, confirmed and bought two correct eight dollar bulbs (good grief) and carefully put them in. Now, the brake lights work, except when the headlights are on. The bulbs again removed, I sanded and cleaned the contacts in the socket while making sure that the contacts weren't bent or out of form. After reassembly, the left light burned brightly as the right and all other stop/tail light issues were solved. Try it before you invest in the complete taillight assembly, or an illumination control module, or a brake light switch, or some other expensive part or diagnosis, and before you scratch your head bald.