The Balance in the sound settings resets all the way forward every time I shut off my 2005 Prius. Anyone experiencing similar glitch?
I have an '04 and the (premium?!?) audio on my car is the only shortfall of the car. Specifically, AM reception. I have not had the problem you mention. It seems like in my case the audio perhaps shorts out and I think it is in the steering mechanism where the short is. I wonder if this is the cause of your problem.
