I have a weird noise coming from behind my instrument panel. When the truck is just running it sounds like lightly boiling water/fizzing noise. It is most present when I first start the truck, and when I shut it off, at these instances it makes like a "chshhh" sound. I thought it might have been stepper motors, since it was most present when the gauges first come on and off, but I am not sure. What do you guys think.