All possible cruise control problems?

I have a 2008 prius and the cruise control has not worked for some time (about a year or two, maybe longer). The light will come on, blink once, and then go off. The cruise control never engages. Occasionally I can get it to engage for a few seconds before it disengages. I had a load of repairs done last week from my super reliable guy a few hours away that does all the repairs almost at-cost for me. He repaired a cylinder misfire I had gotten diagnosed from pepboys by reading their diagnostic readout code and googling it, along with my brights that hadn't worked for a few weeks (I believe I just installed my new headlight bulbs while the brights were engaged so it couldn't disengage), but after replacing the coil behind the steering wheel horn about 4 times, we determined it couldn't be that. There were no other error codes on the diagnostic after replacing the coil, just old ones that had been fixed; but the cruise control still gave me the same trouble. What are all the possible causes for cruise control acting like this and not being able to engage? I'm headed back on tuesday to check it out and we're going to run every possible test to see what is up, but if I have a stepping-off point of the secondary most common problems to address, it might make the process faster and we can identify and fix the problem easier.

 

Hey it's been about a year since I had this problem, but figured I'd followup for anyone else that might run into this with no solution! We replaced the actuator and it wasn't that, and tried messing around more with the steering spindle to see if it was anything around that; as well as electrical; but I noticed one day that whenever I held my brake lever upwards with my foot wedged underneath it, my cruise control would work. My mechanic tightened my brake pedal up a bit higher to see if I'd have any difference, and we figured out that the pads kept engaging while I was driving making the car think that I was braking and disengaging or not even allowing the cruise control to engage the entire time. We fixed this about a year ago and I haven't had cruise control problems whatsoever since. Worth a shot to anyone having a similar issue