my initial reaction would be a bad ground somewhere in the system. as to specifically which one, i have no idea, but i would start at the bulb plugs themselves (sometimes the contacts get corroded), and work your way inwards.
it's possible that it's a radio ground, but given that it's affecting your lights like that, i kinda doubt it. the plugs i'm talking about are the ones that connect to the headlight bulbs themselves. take them off, and look at all the terminals. if you see any build up (it's usually either reddish, or white), then scrape it all off with a wire brush). if that's not it, then keep checking every ground that you see, and look for corrosion. pay special attention to the battery negative post, as well as the chassis ground for the negative terminal itself.
in a pinch, you might also consider adding a ground to the alternator, and see if that works. search around the forums for "DIY ground", and you should be able to find plenty of threads on this. i'd recommend going at least with 8 guage wire if you do this (wire can be bought pretty cheap at Home Depot, and you shouldn't need more than 2 feet for just the alternator ground, maybe not even that much!).
A forum community dedicated to Honda and Acura owners and enthusiasts. Come join the discussion about performance, modifications, concepts, reviews, classifieds, troubleshooting, maintenance, and more!