Interesting. I had not looked to notice if the third brake light was a group of LEDs. I do not know if they can be changed individually. I would suggest asking a Volvo dealer if no one here knows. I will ask when I have my 2002 V70 in for an alightment this Friday.

That said, I do know that they burn out much less frequently than standard filament bulbs. LEDs should last at least 4, maybe up to 10 times longer. That, and the fact that they use about a tenth of the energy, is why all street lights are being changed out. Saves the cities a lot of money.

Sorry, not much help for your problem. But like often happens on this board, it gave me something to look into.