High and low beams flicker back and forth

[JeffsThing]

I upgraded my 73 VW Thing to LED H4 headlights. Last night I turned them on the low beams and in minutes it started flickering back and forth to the high beams. It was like I was flashing the high beams on and off but it was doing it on its own. It was a fast flicker. When I hit the high beam switch it would stop but only for a few seconds. Any idea where to even start to find this problem?

[Bruce]

It's either the lights or the hi beam relay. Swap in another relay:

I had a similar problem with my car. The lights would just switch to high on its own. If I clicked it down, it would put them back up. In my case, the relay was burning out. I replaced it and opened up the old one. It had lots of melted bits inside.
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[Heiferman]

I have experienced many issues running LEDs in various older cars over the years. The LEDs do not have the high resistance of regular bulbs which often confuses olderrelays and solenoids. That is why special solenoids are often needed if you swap your turn signals to LEDs. Sellers of LEDs sometimes advocate for the installation of a resistor.
I pulled the LEDs the PO had tried to use in my Thing and replaced them with good old Sylvanias.
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- 1973 Thing, some LandCruisers and an old Ambulance

[JeffsThing]

Thanks guys. I will try replacing the relay first before I take out the new headlights.