Today I had my key in the ignition, and I turned it to "on" to activate radio, air blah blah.
It was pretty quiet in the truck, and I heard a strange noise coming from behind the dash, near the middle. The noise originated slightly to the right of my radio.
It almost sounds like a faint sizzle, like someone is frying bacon in another room. The intensity of the sound fluctuated slightly, but mostly kept the same level of volume.
What could this be?