Just retrofitted a set of original BMW Zenon units to my 1997 535i E39 saloon, I purchased these from e-bay and believe they were previously fitted to an M5 of similar age.
Everything works fine with the replacement units after fitment, only problem is I now have "Check Low Beam Lights" warning!!!
I've owned the 535i from new and so can vouch for its electrical/wiring integrity, prior to retrofit there was no alarm present.
I'd grateful for any suggestions as I was led to believe the units I bought were a like for like replacement!