73 Valiant Intermittent Headlight Issue

67Dart273 said
I would start with the light switch harness connector terminals as they can cause HEAT when poor, and heat up the breaker, or the breaker might be getting weak--replace the switch
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There are several important junction points in no particular order of appearance

LOOSE / poor terminal connections cause HEAT which can cause the switch breaker to overheat and TRIP

1...Power for only the headlights (not park, tail, or dome) comes from the ammeter circuit welded splice. RARELY that weld can fail and cause trouble

2...That power goes to B1 at the headlight switch, and THAT TERMINAL can be bad/ loose/ corroded

3...The internal switch breaker can be getting weak and do what you describe

4...The output lead for the headlight power at the switch, that terminal can also be bad/ corroded, and trip the breaker

5...Not breaker related, but the terminals at the floor dimmer switch can be poor, or the contacts in the switch itself. After all, they are down on the floor

6...Next, the hi and the lo beam power goes out through terminals in the bulkhead connector which can give trouble

7...At some point the lo/ hi power wires get out to the headlight where they are branched to left and to right, and of course the lamp connectors can be old/ corroded

8...Many? most? these girls have a common ground eyelet out in the harness which of course must have a good clean solid ground

Most Definately #4 (Output lead - marked H)- (if that's the one going to the Headlight's) It's so bad I can wiggle it back and forth. (Surprised I had headlights at all)
With a Breaker in the Switch itself that makes perfect sense~ adding to that that the Headlight's Supply isn't Fused... >Well that just sounds like a recipe for disaster-= lol < So that's definately part of the issue - tripping the Breaker in the Switch (No noticeable arcing on the terminal itself or the grommet the holds it in)... So this must have been arcing on the inside causing the wire to heat up and melting the housing.
I want to take the switch apart to see what it looks like -I'll try and post something to show what happened.
I see the other steps necessary here so many other things to consider also...
Dimmer Switch - Bulkhead connector - where they branch out... >
What's the route they travel from the Bulkhead?
Lastly and Just now realizing that one of the easiest things to check would be as you said the Headlight connectors at the lamps themselves.
I will definitely be checking a few other things before considering the issue fixed~!

- You're not kidding about the Dimmer switch getting abuse - When my headlights first went out I was punching the thing repeatedly while also hitting the brake and focus memory for road direction among other things. Hoping something would happen when after about 3 or 5 hits I'm already stopped and a split second later the lights popped back on. lol I think the Dimmer may be okay since when the lights are working it responds well? What's a good test for the dimmer?
Thank you for your Response~!