Technical Getting Real Frustrated with these Headlights

The headlight switch ( lights circuit) should have a circuit breaker not a fuse. I think 30 amp.
The that 50 amp maxi fuse powering the headlight should be replaced with a 30 amp circuit breaker also.
You don't want to blow a fuse on either of those circuits and be stuck in the dark. The circuit breaker will reset after a couple minutes to get you going (unless you have a direct short to ground in which case resetting will be futile).
This is what I would use in the circuit from starter that powers the lights.
https://www.amazon.com/Fastronix-Automatic-Reset-Circuit-Breaker/dp/B07NSD3KYH
Or this
https://www.napaonline.com/en/p/BK_...MIgY25_LHp6gIVEfDACh3QMwNjEAQYBiABEgKiAvD_BwE
This type works in fuse panel to replace fuse.

https://shop.advanceautoparts.com/p...MIvqTE_pDp6gIVk5JbCh2B-QxHEAQYDiABEgLdlvD_BwE[/URL]

 

I did not read all the reply's but had a very similar problem and after fighting the problem I finally found my problem was a faulty headlight switch. HRP

 

Trace how your headlight circuit is wired up through your relays because there are more than one way to do it. I remember an old Toyota that I owned had 4 separate fuses for the headlights - left light, right light, low beam, and hi beam. If any one fuse blew, you still had remaining lights and pinpointed where to look for the fault.