After coding BFD for me this evening My pre LCI e92 there are 2 Levels of BFD
I am only referring to FRM(1)
I now have 3 levels of braking
Normal less than 4m/s
Heavy Braking but no ABS +5m/s = Level 2
ABS = Level 3
You can definitely code Flashing 3rd light on BFD_1 . Thats the only flashing option you get
You can code flashing 3rd light, fogs and BFD brake lights on level BFD_2
It is worth pointing out that as soon as you take your foot off the brake the flashing stops. It also times out after 30 secs if you keep your foot in.
The top video below is a Level 2 stop, the foot was kept on the brake for demonstration purposes .
You can't appear to change the frequency of the flashing on the FRM1 . You may be able to change some PWM setting somewhere. FRM 2&3 modules i think have a dedicated frequency setting.
Video 2 was ABS Flashing 3rd light , fog light and flashing BFD light ( small light situated just above brake light) and was activated by the ABS
The only thing I will add is that on Level 2&3 braking my front sidelights ( angel eyes) pulse too. Not had time to figure that one out yet