High-Beams Failing

[MIPS]

I had this problem with high and low beams back in 2019 and it turned out to be a bad lug on the headlamp switch. Replaced the switch, recrimped and repaired the harness connector because one terminal had melted out and it was working fine again.

I'm driving early Saturday morning with the high-beams on and it drops out and starts flickering. Yeah that's a fun thing to happen when driving through the mountains! Dash and marker lights seem to stay on but the high-beams, low-beams and the symbol on the dash flicker in and out. Click back into low-beams and the headlights instantly come back. Using OEM headlamps and no relays.
How are the headlights wired that allows all four lamps and the dash indicator to fail only when switched to high-beam mode and work fine if kept on the low-beams?

[Taylor]

My headlights would dim when I switched on the high beams. The low beams were always a little dim but got progressively worse to the point they wouldn’t pass Virginia inspection. I’ll need to go look at it to let you know if I included the inboard ( high only ) lamps in the new circuit when I rewired it. I added a couple relays to remove the high power that was running through the factory switch. I also used a heavier gauge wire for less resistance.

[rmick]

All the current goes through the factory switch and there is a bi metallic contact in the switch if too much current draw goes through the switch the contact heats up and opens the circuit. Since there is no fuse in the system to protect it from a short. Thats why it is useful to install relays in the head light system so not all the current goes through the switch also lights may be brighter since power goes directly to the lights. Also check your grounds for  the lights this would also cause high current draw if you don't have a good ground.