ABS, DSC and Brake lights came on my BMW e46 this afternoon after uninstalling subwoofer speakers?

Question

Is this because the positive terminal of the battery was interrupted?

Answer 1

Did you take out all of the wires also?  Like the power, ground.  It may be because you disconnected the battery and reconnected it.  I would give it a few days to reset on it's own.  If that doesn't work, take it to a auto parts store where they can plug in a scan tool to check the codes and maybe reset your lights.  I had an E36 that would act funny after disconnecting the battery, but after the computer reset (couple of days) everything worked normal again!  Hope this helps.