weird electrical issue

so I got a 93 integra and I noticed that sometimes my passenger side headlight, fog light, turn signal and corner light bulb will be really dim and then turn signal and high beam indicator on the dash will stay on such as a burnt bulb. when I turn the fog light off, the lights brighten back up and everything goes to normal. this is intermittent. now when I plug in my blower fan, it does this again no matter if the fog lights are on or not. So i was wondering is their a common ground in which all of these systems tie into or where should I start to diagnosis. I also noticed that the passenger side corner light harness has a 2 volts voltage drop so I know the problem is somewhere on that side.