I have this problem, but not as bad.
when I turn lights on (hids) the displays go funny for 1-2seconds then go normal, ive tried all sorts, ive fitted relays to them so they don't use the internal wiring for current, only a switchable signal, and then also put 1 way diodes on the switchable side of the relay to hids, although now ive typed it, maybe I need diodes on supply as well, darn,

maybe that's it, well I was thinking it could be the switch, but will have to try diodes on supply aswell,
lol now ive typed it not sure if ive not done that as well, haha will have to check...
anyway I know there are multiple causes for it, but I know my battery is good as its new, so not that, so have to continue the search..
