Dim Headlights (STILL)

OK guys, I'm still having headlight problems and it's driving me crazy (which I can assure you is a relatively short trip). The headlights are very dim on low beam and only slightly brighter on high beam. At the headlight connector, with the lights on low beam, the voltage is only about 6.5v. But you can probe the high beam wire at the connector with the lights still on low beam and it shows between 10.5 and 11.0v. Why has the high beam wire got nearly battery voltage on it when the lights are on low beam? I've also noticed that the high beam indicator light in the instrument cluster is lit when the lights are on low or high beam which leads me to think it's a ground problem causing a backfeed. It does have a new headlight switch and dimmer switch, but the problem existed with the old ones so nothing has changed. BTW, the headlights are the only lights that are dim. All other lights are bright and functioning properly including the dash lights. Any help is appreciated. Thanks.