First start by saying hello. This is my first post. I have an 2005 Toyota Prius with the full loaded package (I think it's the #9). I have 40,380 miles on it. I take pristine care of it. I have my same routine back and forth to work. Usually cruise at 75-80mph. Today on the way home I was set at 75mph. At first all that was happening was it felt like someone kept tapping my accelerator pedal. I didn't pay a whole lot of attention to that, just took a mental note. A few miles later the car would accelerate up to 77-78mph, (with my foot no where near the pedal) than the cruise control would shut off, causing the car to slow down significantly. I reset the cruise control three times at 75mph and all three times it had almost the exact same effect. Accelerate/disengage. Has anyone had this happen? Any suggestions? Thanks,
This would not answer the OP, but maybe the new question. Do all the rest of the steering wheel buttons work? If not, it may be the spiral ("clockspring") cable is starting to fail. Generally the failure mode is the cruise control won't turn on at all, months after several other less noticeable buttons have already failed. And if they work when you turn the wheel 45 degrees (while parked, of course), it's definitely the spiral cable. If this sounds like your car, do a search here, it's fairly well documented. Otherwise, check the brake switch for adjustment/operation. Then get a manual with a wiring diagram and start tracking down all connections. Hopefully it won't come to that. Does the "cruise" light on the dash turn off, too? Can you always turn it back on immediately? Welcome!
I've got the same problem with my 2006, it only happens intermittently. I have since then noticed my "Info" button on the steering wheel has recently within the last 2 weeks stopped working only when the wheel is perfectly centered. If i move it slightly (1/2" or so?) to the right or left it does work. This is the only loss of functionality in the steering wheel buttons. The problem with the cruise control has been happening for the past 4 months. Link to video of it happening.