Mine buzzed with the key on, in the day, e-brake on.
You should have talked to that Bronco dude. He did that years ago. LOL
http://chrisb.users.superford.org/Gr...ght_Flash.html
Unplugging will do what you said. I just disabled the yellow wire, which disables just the headlight. Looks like you may have disabled "flash to pass".