So I have an (older) Kenwood DNX7120 DVD/GPS head unit in my 04 Silverado. I've been getting a super high pitch "squeal" out of the blue. When it happens, my head unit starts rolling through the different modes it has, tuner to dvd to video and then stops once it's found a mode in which it "likes". I thought it might be the head unit itself, but I purchased a unit exactly like the one I have (just without the GPS feature) and it's still happens. It doesn't happen all the time with either, just kind of randomly. My local audio shop says its the head unit (without even looking into it). But the same problem with two different units? I don't think its the case. Please give any help or thoughts.
Thanks a ton.