I hope I'm doing this right, as I'm new at this.
My headlights are driving me nuts. First my passanger side headlight was very dim, and i had no low beams. I replaced both units with new lights, and the same problem still exists. So i checked the ground wires at the frame, inner fender, and the voltage reg. still no luck.
So itook apart the junction apart at the firewall, and traced the tan wires to the left and right light, and they seem to be okay. I now notice that neither headlight is on and the dimmer switch doesn't seem to change the high beams to lows. Also i checked the fuse, and its ok. What could be the problem?
Any help would be greatly apprec. Thanks, Danny's 72 superchey

if you follow the headlight harness, from the plug on the lamp back, you should find where each side is grounded seperatly. Did you clean that ground? Also, I would personally just run a wire from the neg post on the bat, straight to the rad core support. Try that and see if it gets rid of most of your symptoms.
Your dimmer switch is probably also on it's last leg, 40 years of mus and water and kicking it all the time too.

Thanks Longhornman, I got the hedlights working. Now I have a different problem. When the headlights are on, my right turn signal indicator light glows bright, and my right front marker light is very dim. Dont know where to go with this

Start with checking your bulbs all around. It is probably unrelated to the dim bulb.
Turn on the 4 way flashers, and see if they all 4 light up... esp the ones on the passenger side.
If they all work, then look at that right front and make sure it's ground is good. I'm not familiar with that in the bumper lighting, but I would imagine there is an L bracket or something that supports it and doubles as a ground, make sure it is clean and mounted tight.

one thing i have learned is when you go to plug your headlights into the connector make sure they plug in correctly,,,if one of the connectors get shoved backwards INSTEAD of going on to the terminal on headlight bulb it will give you fits....;) makes some weird stuff happen................

Might want to check on an issue I have had on my 71 Blazer and my wifes 72 Suburban. Sometimes corrosion grows between the front turn signal socket and the housing. You will usually find that you can wiggle the socket a little bit. This corrosion prevents a good ground. My fix was to spray a little penetrating oil on the joint between the socket and the housing.wiggle and twist the socket to remove some of the corrosion then twist the socket until it becomes tight again. I usually have to redo this process about once a year. The real fix is to buy a new turn signal assembly...but I'm to cheap!