I just go my TC '07 last week and I've got this really high pitched humming sound coming from the front left corner. I can't tell if it's coming from the door panel or the dash. It happens when I go through 67 mph. I've tried banging the dash or door to see if there's something loose, but nothing happens. I can't narrow it down. If I open the window it's not any louder. I can hear the noise even if the radio is off, turned down, or turned up. I just got the scion alarm, interior illumination, and Ipod radio installed and just started noticing this sound. Don't know if it has anything to do with it.

 

Take it back to the dealer. That's my advice. Did it make noise before you had these things installed?

 

check the little black plastic thing runs across the top of the windshield. It could be loose, and vibrating in the wind.