Had a couple of codes on a 3.0l E85 Z4 the other day
DME BSD Generator Signal and DME Bit-Serial Data Interface BSD Signal
Check on the Alternator made and it was charging ok with engine running so suspected that the single wire plugged into the back of the Alternator that routes the signal from the DME to the regulator pack within the alternator was duff or that part of the regulator was duff. The signal is the way the DME regulates what is required of the alternator so the output is regulated to what the car requires.
Unfortunately the replacement regulator we had turned out to be the wrong part so we fitted a spare rebuilt alternator I had and sure enough when all back together and codes cleared they didn't come back.
DME BSD Generator Signal and DME Bit-Serial Data Interface BSD Signal
Check on the Alternator made and it was charging ok with engine running so suspected that the single wire plugged into the back of the Alternator that routes the signal from the DME to the regulator pack within the alternator was duff or that part of the regulator was duff. The signal is the way the DME regulates what is required of the alternator so the output is regulated to what the car requires.
Unfortunately the replacement regulator we had turned out to be the wrong part so we fitted a spare rebuilt alternator I had and sure enough when all back together and codes cleared they didn't come back.