I bought a 1999 VW Golf GTI a few weeks ago. It didn't have a stereo in it. The guy from the dealer I bought the car from gave me a Sony CDX-F7750S. It worked okay, but the CD that was in it wouldn't eject, and I wanted a Stereo that has USB. So I bought a Pioneer MVH-160UI. It gets power but no sound. Can't work it out. So when I put the Sony back in, no power at all. Any ideas would be greatly appreciated. Thanks.