I just converted my interior lights in my '04 R53 to LEDs and everything works great - open the door and all the lights go on; close the door the lights go off - but driving home from work tonight i flipped on the headlights and the boot light started to flash about every 3/4 of a second. Turn off the headlights and it stops. Open the door and it comes on constant. But close the door and turn on the headlights and flash flash flash flash... Ideas? The overhead light doesn't flash along and neither do the footwells if that helps.

 

I have not-quite-the-same problem, but similar.
Does it continue to flash for ever? or stop after a while?

Try reversing the bulb - it may not work at all.
Try a different bulb if you have one that fits.
Where did you get the bulbs? There might be a different LED design available.

I have an early '02 Cooper S with NO options. I have all LED interior lights.
When I put the key in, all the LEDs flash for a few seconds. I believe the LCM or BCM is running the bulb-check routine. Pointless, since if a bulb is out, there's nowhere on my basic dashboard to display it!
It might be possible to switch off the bulb-check (dealer $$$$?) & this could be a solution for you.

 

What bulbs did you get, have not seen this on the ziza lights? Sounds like a draw on the system or something.

 

The dome works fine i just can't imagine why there is any current flow at all at the boot light when the headlights are on. It starts to flash as soon as the headlights are turned on and only stops when the door is opened or the headlights are turned off. I'll try reversing the bulb tomorrow and see if it happens with just the marker lights on as well. When installing, it came on as soon as i put the bulb in so I never tried turning it around to see what would happen.

 

Pretty sure that LEDs have polarity and cannot be reversed. With the flashing almost makes me think that somehow the BCM is pulsing the current to that light.