There's other more likely suspects but no one should be guessing without doing a proper diagnosis. Visit a mechanic who will connect a scanner to view the state of the various inputs for the cruise system. That will show if the brake pedal is pressed, on / off switch is turned on, and things like that. If it shows, for example, the brake pedal is being pressed when it's not, you'd suspect the brake light switch. For the power switch, there's a "clock spring" under the steering wheel. That's a wound-up ribbon cable that commonly breaks. The clue there is eventually the horn will stop working too and the Air Bag light will turn on.
With Chrysler's scanners, they will show the "reason for last cutout", and I think that can be read on GM cars with aftermarket scanners too. That will tell you why the cruise won't set but you have to read that information on a test drive. If you try to read it in the shop, it will say, "vehicle speed too low". That is really helpful for intermittent problems.
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Monday, July 28th, 2014 AT 9:31 PM