SCOSCHE FGAB - Car Stereo Floating Ground Adapter for Car Stereo / Radio Installation

I ordered two of these for a couple of w126 mercedes' that I own #85 300sd & 89 300sel# and without these you would have to rewire the entire system to operate properly when installing an aftermarket headunit. The instructions that came with them are pretty much useless but if you have a basic knowledge of sound systems you can figure it out. They did exactly what they were designed to do. Took about 30 minutes to get everything installed and that was with me having to trace wires in my cars because no one makes an adapter harness to plug into the factory harness. So I cut the factory plugs off, traced out the cables and wired them in.

The product itself isn't bad, and it does exactly what it's supposed to. The problems are with the documentation and construction. My problem with the documentation is that it is completely wrong. The documentation tells you to use the color w\black stipe wires for the positive lines, and to use the solid colored wires for the grounds. The problem is that the color w\black stripe wires all go to blank terminals, while the solid color wires go to the capacitors. This means that when you connect the adapter you have a chassis ground going to the floating ground connection for your amp (which is correct), and you have the negative output from the stereo connected to capacitors going to the positive inputs for the amp (which isn't correct). When I first connected it, all I got was a humming noise from the stereo. After I opened the case and traced the connections, I was able to figure out what had happened. This is where the problem with the construction comes in. Two of the colors were reversed. The solid purple wire connected to a capacitor, but the other end of the capacitor connected to the green wire. The opposite was also true, the green wire went to a capacitor and the other side was connected to the purple wire. The result of this was that the left front\rear channels were reversed. Luckily for me I have a background in electronics so I was able to make it work once I figured out all of the things they did wrong, but most people would have just been screwed. Don't buy this unless you are willing to take it apart to see if they put yours together wrong, but if you can trace a simple circuit to correct the errors it does actually work.