Headlights Time to break out the test light , get a good one not a cheapo . I'd bet it's the ground . Unplug both headlights & connect the test light to the engine block , touch it's tip to the + battery post to ensure it's properly grounded then turn on the headlights and probe the connectors , each one should only show current to one leg , and always the same leg on each plug , in each dipper switch position , high or low . Then , connect the test light to the + battery cable & test the remaining leg of each headlight connector , for a good ground ~ the test light *must* light up as brightly as it does when you test it across the battery or the ground is bad . This is basic electrical testing and once you get the hang of it , you can impress your buddies by fixing all their dim / inoperative taillights & turn signals .
Afternoon cord, Nother thing to check is this plug on your firewall. Make sure it's clean and all the prongs are plugged in. Also check to see if your gettin juice to the female side from your dimmer switch. That lil bugger can cause all kind of problems.