When you say 3BL, are you talking about the high mounted LED brake light in the spoiler (as in 3rd Brake Light)?
If so, was the modulator in the spoiler itself with the LED's?
Just curious as I hadn't seen anything similar in the circuit diagrams associated with the spoiler light, except for the noise suppression filter.
Whatever the case, good to hear the problem is solved. Definitely not a good thing to be without brake lights.