Dude-
That GPS works great, sound too. Try different cables for the audio section. The cabling is finickly...expecially if going from mono to stereo etc. You're probably not getting a good connection where the 2.5mm female on the harness meets with your audio cable. You can easily test this by pulling the male 2.5mm lead out just a bit. That often kicks the sound in.
I had to put a small rubber o-ring on the lead keeping it from going in all the way now it worked fine.
The speaker on the other cord works fine.