My two cents for a malfunctioning third brake light. Car would not pass a safety check here in Ontario Canada with non operational third brake light. Chrysler says part is obsolete. Mechanic referred me to a place in the US. I said I would have a look myself thank you very much. Removed the trim nearest the latch first (one hidden torx screw) . That exposes two torx screws for the trim covering the third brake light. Pull out tabs with care. I confirmed that the 12V was active at the connector when the brake pedal was applied.
The LED unit itself comes out by loosening three phillips screws and one electrical connector. You can take this unit apart by prying gently at the tabs.. The circuit board comes out as well, gently prying it out (more plastic tabs). Mine did not break. The board is marked with a plus sign to tell you which is the 12V hot side for testing. In my case I had a good look at the connections and could not find any bad solder. It was unlikely that ALL of the LEDs had gone defective, so I concentrated on the resistors and the eventual CULPRIT, a single little black diode (1N4004). It should conduct in one direction and it did not, so was deemed defective. I found a similar one in the junk drawer and soldered it in. Voila, success. Anyone can do this. If you don't have a diode try Radio shack. I went back to the mechanic two hours later and he issued the certificate.