I'm having an issue with the headlight system
In my f350. About a month ago I was headed to a hunting spot at 430 am. While I was driving along there was a pop and a flash under the dash and I lost headlights/ running lights. I turned on hazzard lights which worked until I could find a place to pull over. All of the fuses were fine in the main in cab fuse panel, however there is a secondary fuse panel under the dash which I have no idea if this is factory or not but it's a 6 slot fuse panel with a male spade at a 45° to the side of each. The panel only had three fuses and wires to one side and all the fuses were blown which is where I thought this occurred. I waited until daylight and drove to the nearest parts store for some fuses, but pulled the switch to full on for headlights and all I had was just that, headlights no running lights. I figured out after playing around with wiring under the flatbed and back and forth to the cab that all of the lights actually do turn on if you pull the switch all the way out and then push it in just a little, between headlights and park lights, which I thought seem symptomatic of a bad switch so I got a new one for 20 bones. Still same issue. I noticed the insulator block for the plug in had been hot at one point because its discolored and had a crack or two, but the terminals and wires inside of the block looked fine and had no corrosion. I also noticed the park lights do not come on in park light position, but other than that they seemed to work fine when the switch was just right so I didn't dive any deeper into the problem but on my way home from work today the lights kept flickering on and off which was not kosher so I'm wondering if there is anything I may have missed like a fuse somewhere else or a wire in the harness or lume that might be the culprit

 

What was the condition on the wiring harness the plugs into the switch you replaced? Your symptoms sure sound like a bad light switch. Maybe you got a bad new one, it wouldn't be the first time a MIC piece was bad out of the box.

 

Sorry for the lengthy response time I usually get off after dark but today I had time to take a look. I found the issue fuse #4 hiding up there cant believe I missed it but here's a picture of the plug anyway. Is the condition of the plug something to worry about?

 

Glad you found the problem. The harness has gotten a little warm, but I don't think it is any thing to worry about.

 

the head lights run full current from battery to dash switch and back to lights (simple version)

the heat from the current will discolor the connector over time

 

It would be a good idea to get run a relay or two to power your lights instead of the factory set-up. There are kits out there that have everything you need and they are relatively cheap. Plus your lights should be brighter, not to mention the added safety factor.

Headlight relay upgrade harness