I happened to spend a bunch of time driving a 2011 F10 535i recently which has Xenon flash to pass. I spent half a minute playing with the feature and the lights in general. Yes, it's not an E90 but I bet there are more similarities than differences when compared to LCI E90 flash-to-pass.
The ballast seems completely different. The flash-to-pass ignites WAY different than my pre-LCI E90 and even differently than simply turning on the headlights on the F10. The flash is really intense, instant, and a different colour than a standard HID ignition.
I can only conclude a couple of things:
- the parts involved are significantly different if the vehicle is equipped for Xenon flash-to-pass from off
- flash to pass appears like it may be quite hard on the equipment even when designed to use it