DONE...WOO HOO!!! And it works beautifully. I now have 100 CDs in my little MP3 player with me all the time and the sound quality equals that of the CD player.
Klaus, I have no idea how it works, but the radio does sense the auxilary channel (even if the mp3 player is off). I can access the auxilary either through the "band" or "cd/aux" buttons on the radio. No problems.
Here's a few tips I've learned for those installing this thing themselves.
1. For anyone new to this thread, here are the
instructions Happy Jack posted on pulling the center console back and removing the dash cover. This was invaluable.
2. Once you get the dash cover off, put some masking tape over you A/C unit. The radio will hang down in the process and the edges are sharp. I scratched my the face of my A/C.
3. You need to solder on the yellow and black wires of the PAC unit to the corresponding wires going into the radio. If you look at the diagram on the instructions, this become very intuitive.
4. There are 2 ways to solder on the wires. One is to shave the rubber off the factor wire and solder on to it. The other way, which is Klaus's way, is pull the factor wire out of the plastic plug apparatus and solder onto the tip. So what you can do is take the smallest screw driver you can find (the kind to fix eyeglasses) and insert that into the plastic plug where the pin from the radio goes. When you push the screwdriver in deep enough, it deactivates a clip inside the plug and you can then easily pull the factory wire out from the other side. Then, you can solder your yellow and black wires onto the metal pin pieces at the end of the factory wires. Just be careful to not use too much solder and do it in a way that you can insert the metal piece back into the plastic plug. I had to use a file and file down some of the solder so I can get it back in, but this wasn't a big deal.
5. If you are not handy with a soldering iron, you might try those quick-connect wire splicers you can get a Radio Shack. I think you can get away with that, but I agree with Klaus, soldering is a more secure way to go.
6. Important: make sure you adjust the little input volume settings on the auxilary unit. The way mine was originally set, I would have to put my radio on "10" volume in order to play my mp3 player at the level I usually listen to. Then you know what happens when you switch over to radio at that volume.
7. After you solder the wires and clip on the auxilary and it all works, there's little space to slide the radio back in. I shoved the bunch of wires to the lower right where there's space, and hung the auxilary box over the left vent and down the left side where there's lots of space.
8. I taped some foam around the auxilary box so that it doesn't rattle or knock inside when I drive. I noticed GM does this everywhere inside on all it's wires and parts, which is why the H2 drives so quietly and knock-free.
9. You obviously need an adaptor for your mp3 player or whatever you are hooking up to the RCA plugs of the auxilary box. I found the perfect 4 foot wire at Radio Shack with 2 male RCA plugs on one end, and a male 1/8" stereo phone plug on the other for $6. I snaked that down and through the center console, then drilled a small hole in the compartment box and fed the wire into the box. I now keep my mp3 player stowed in the box when not using it, and keep it rested on top when I'm driving which is so convenient.
The whole job probably took me about 4 hours. But it's worth it. I have to say, I love having all my music at my finger tips. I don't think I've gotten this much personal satisfaction from a project like this in a long time.