hey i just wanna throw this out there for any 04 plus grand prix owners. theres a 30 dollar fix for installing a aux input into your cars. If you have xm radio or any slave unit in your car not counting the 6 disc in dash cd changer there is a kit made by pac audio that is 30 bucks on ebay. Its super easy to install and alot more convenient. There is no interference in it like there is in fm modulators or anything. The exact model for it is AAI-GM12.
I posted this a month ago. This adapter will only work if you have a 12 pin connector in the back of your radio and a slave unit with your radio. I recommend pulling your radio out first and looking before ordering. If your in doubt if it will work or not take a picture of the back of your radio and post it on here. Also do you have xm radio, and external cd changer, or any other external operating things hooked up to your radio.