Guys,

I have a 1970 442. I have headlights, brake lights and turn signals.
I have a new dimmer switch, but when I turn on the headlights, only the headlights burn. I found a bad fuse, replaced it, but when I turn the headlights on, it burns the fuse up. Do I need to replace the headlight switch? Also, is there any tips to replacing it? Thanks a bunch...

 

Its probably not the switch, you do have a short somewhere. Which fuse is popping?

 

It is the park lamps fuse. I have checked the bulbs and all the wiring going to them... I figured the switch was bad. Also, I don't have any dash lights...

 

The fuse is after the headlight switch, so it isn't the switch. The dash lights are powered by the park light circuit, so that's why they also don't work. There is a short between the fuse and the park lights. Be aware that there are a number of branches on that fuse - the front park lights, the tail lights, the dash lights, the radio light, etc. You need to check every wire on this circuit to find the short. Start with the wiring diagram in the chassis service manual and trace every wire on the circuit. It's a PITA, but that's the only way to find the short.

 

Start with a good look for loose or dangling wires under the dash that might have shorted out on a ground point. Chafing where wires pass over or around sharp edges.

Worst fear, which I found almost by accident in restoring a 1966- wires within the fuse block / bulkhead crossed each other and from vibration had worn almost thru to one another. Between them where you can't see it unless you pull them apart and look "more closelier" [South Park scene]. I decided to inspect every mm of all those wires while it was apart, and good thing I did. Resolved with physical separation and silicone to insulate and prevent future abrasion.

Let's hope your issue is easier to find.

You can possibly disconnect part of the ckt then another part etc until you find where the problem was.

they made items that looked like a tube fuse but were a self resetting circuit breaker that would help you by eliminating the constant need to put another fuse in. Or, wire a light bulb across the fuse contacts so that if it glows you know current is flowing, but it will not pass so much current as to burn up the wiring.

I would start by distaching the wiring at the front park lites, see if that isolation cures the problem. If so, look for bulb forced in wrong way around, things like that.