Brian,

Since I tried with the "Dice radio harness", I think that we can say that it's not #1 and #2. If you are familiar with the Dice product, you know that you can order the trunk harness or the radio harness. I have both.

The radio harness plugs directly into the radio, No luck it's not working either.

Your theory about the previously installed CDC is interesting, that may explain a lot of things.

One more piece on the puzzle is this, when I bought the car, I ask the dealer to install a BMW iPod interface. They spent a day trying to make it works without success. They told me the reason is that the interface is not compatible with the DSP. The BMW iPod interface connects on the radio the same way the Dice does, using the same pins... The one of the CDC (analog)...