I got a 2011 wrangler sport that coming home from the dealership the cruise control worked fine. A few weeks later though it began working intermittently. As in the on/off button would only actually turn the system on/off when it was in the right mood.
The warranty fixed it for me I think *knocks on wood* it took them 4 tries though. Whatever the hell was wrong I think they finally fixed, but it seemed to be a problem that kept coming up. Right now it has worked for about a solid month.
I suspect this is of no help though because my cruise control is buttons on the steering wheel, and that you are out of warranty. Plus yours is not working at all rather than intermittently.
I found it tough to find much information on cruise control issues when I looked long ago, therefore I am giving you the best of my knowledge, and letting ya know your not alone.