My '98 has this strange behavior where occasionally the headlights and dome lights get really dim when I turn off the ignition. I would generally describe it as behaving like there was a loss of voltage and I would generally assume it was a weak battery or alternator going bad, but both the battery and alternator are less than a year old. It acted this way before those items were replaced. The part that doesn't make sense to me is that after 10 - 15 seconds of the ignition being off, the brightness will return to normal levels. I don't hear a "click" but it's that fast. Any ideas what would cause this or what's going on?