Go to PAC, or Metra (they are the manufacturers of many of these wiring harnesses and modules needed to retain features such as turn signals, and onstar). Enter your make/model/year, and it will tell you exactly what you need to have what features you want.
Just a tip, even though Metra says their all in one unit works and does all features, they lie and it was confirmed with a technical support rep whom said "we have never been able to make all features available on your car" my response "so why does it explicitly say in your material and application database that it does?" their's, "our apologies, we do our best with keeping applications accurate, but we make mistakes". I could not get some of the features to work, and in the end had to use 2 separate modules/harnesses. But it's not a big deal, most cars with features like on-star, steering wheel buttons, etc, need 2.
Last edited by Carbon Sky; 12-06-2012 at 11:32 AM.