Thanks for the added info, I didn't realize you had edited your post until today. This is quite interesting:
Because you observed this before I wrote about DOT4 LV possibly effecting the ABS system there isn't any way that you were influenced by it.
I know very little about the differences between E46's and E46 M3's but realoem lists a precharge pump for all years M3:
http://www.realoem.com/bmw/showparts...31&hg=34&fg=20
But only up to 09/2000 for non M3:
http://www.realoem.com/bmw/showparts...93&hg=34&fg=20
Also coincides with this document on E46 Traction Control systems:
http://images.chaleur.com/BMW%20Libr...%20Control.pdf