Xenon issue

Hi all,
I have a 03' S and one of the xenons wont turn on I've changed the globe and ballast from side to side and checked all fuses, it seems to be missing a ignition power compared to the other side, do they go through a body control module? Where is this located? At one stage it would turn on after a short time or turn on and off a few times.
Any info would be handy.

Thanks