On our 06 the problem was just when the engine was running. First power was tapped off the 12v accesory plug on console. After that was a fail power was tapped from under the dash, actualy had local stereo guy do that with no luck. He kept blaming it on aux cables and tried every one in the store with no results. I just left the shop in a bad mood and let it be. The noise was so annoying that I actualy canceled the second subscription to sirius.
My wifes Ipod played great plugged into the aux jack so we just let it be. Well few weeks ago I was looking around in local electronics store and saw the fm modulator connector that was supposed to block the fm signal. Brought what I had found here to ask about what others had thought and luckily MLSD had an even better solution that worked great.