I don't have the answer for OP, but just want to highlight that the links from Post #2 and #3 showing the LED tail lights, are not the same as the one from the OP (non-LED).

I got the exact same LED version and it works without any issue.

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Here's the Photo Album of my (sold) X3; Album of my (newish) X5 is on the way!
(WARNING: read this before you buy anything from Umnitza)