Weird problems with the light!

The lights on my -89 Suby Coupé GL has gone crazy, and i don't know what to do!
It seems both low and high beam is on at the same time, but at very reduced current... the lights aren't much brighter than the parking lights, when on low beam... and the high beam isn't as bright as it should be.
I've changed all the cables to the lights, as well as the H4 bulbs, but it still sucks...
anyone have an idea as how to fix this?? I can't see more than 10ft when it's dark outside :'(

Your problem may be in the switch rather than the wiring. If there's a short somewhere, it will be sharing the same electricity between the two circuits rather than pouring all the power into the low/high beams. I'd check for shorts in the fixture and in the switch.