I was informed yesterday that my brake lights weren't working. I've been trying to diagnose the problem and checked up on related threads, but it seems I have a unique situation for which I need some advice.

Long story, short:
-Both brake lights out at same time.
-Tail lights work.
-3rd brake light works (so brake switch seems to not be the issue).
-Checked any related fuses (according to manual), no sign any of them are blown.
-Swapped out the yellow #3 fuse in the relay fuse box, per a suggestion from another thread; no luck.

Have any of you experienced this issue before, or have a remedy?

 

THere is a brake light relay.

http://homepage.mac.com/gregmeach/XF..._8w-Wiring.pdf

 

Thanks John, this put me in the right direction. This must be the source of the problem, I'll be getting it swapped out today.

For anyone in the future that has the same problem, I found these two threads helpful in locating the relay and fixing the issue:

Where is the brake lamp relay located?
Location of the illumination control module

 

Update: I swapped out the brake relay and unfortunately it did not fix the issue. Any advice?

 

Issue resolved: I finally decided to just try swapping the bulbs, despite their filaments both being undamaged; it fixed the problem. I'm assuming there must have been some shock to the original bulbs for them to both go out at the same time. Oddly enough, both bulbs' 5W filament worked fine, while the 25W filaments were both affected.