As I understand it, it's the same harness for all three years. I recently started trying to add the steering wheel audio controls to my 2010 HHR and bought all the parts from dealerships across the country (for what I spent I probably could have just bought a wheel from LKQ but I was feeling my Cheerios :p). Unfortunately, the harness I got was in the right box but contained only a 3 connector harness, not the 4 connector harness I was needing. I'd appreciate contact by PM and am located in central CA

 

Hellshotrod or a junkyard would be a good idea.