This worked for me
The situation: Passenger side headlight low beam doesn't work, tail lights and front marker lights don't work, and dash lights don't work.
After a couple days going through wiring testing the switch. After few blown fuses, busted knuckles, and cramped back looking up at a wiring harness under the dash. After replacing a lost switch spring with a cut down Zippo lighter flint spring (great replacement actually works better than original) I have half of the headlight issues figured out.
The reason the connector is burnt is due to arcing, arcing is caused by absence of contact. The switch doesn't make good contact with the wiring harness, it jumps around inside the contact, it needs to fit tighter. I tried grease that didn't work. Finally I did what I have done in the past I slightly bent the contacts a few degrees (about 15 degrees) then reattached and it fits really snug. The first time I twisted them too much and the switch wouldn't attach to the wiring harness so I had to readjust.
Test: Tail lights, front marker lights, and dash lights work. I have not tested to see if passenger light works attached to original harness as I'm happy with my current status and didn't want a let down, will test later.
Conclusion: This section of the wiring harness needs to be replaced along with a new switch, a better switch. The new wiring harness needs to remain snug while attached to the switch. The wiring harness may need to be taped to the bracket to eliminate bouncing during aggressive driving.