Hello,
This sounds most like a bad headlight switch. There is nowhere else that changes those settings except the body control module or cabin control module, whichever you have.
There is supposed to be a change in brightness, so I assume that portion of the circuit inside the headlamp switch has failed.
Test before you replace.
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Ended up being a short with one of the wires in the dash. All good!
I have the same exact problem. Do you happen to know what wire, or where, the short was?