I just bought an 03 Mini Cooper with a Harmon Kardon system. It works great and sounds great. The previous owner replaced the original AMP with a big Alpine amp mounted in the trunk.
When using the GPS, however, the voice for travel instructions is extremely loud. The volume control to adjust the Navi volume does not do anything. It is the same volume at max or min.
The Navi voice only comes out of the driver side front speaker. Don't know if the original set up was also like this.
I figure it must have something to do with the wiring for the new amp.
Any suggestions of how to troubleshoot this problem? I figure wiring diagrams would be useful. If I could figure out which wires come from the navi unit, I might be able to bypass the amp and get it to work as normal again.
Any suggestions are appreciated, as right now the Navi is basically unusable.

 

try turning the gains down on the amp you'll have to turn up the radiolouder but it might work