So, for the first time since taking delivery of our Prius Plug-in our PIP gets rained on. (All together now......AWWWW) We are on a short trip on a highway going 55 mph. We also had our radar cruise control on when all of a sudden BAM a notice on the dash says "Cruise Control is Not Available" and the car shuts down the cruise control. Holy Cow Batman what the heck just happened? We tried to re-instate it and got the same result. Dang, do we have something wrong here? Don't reply just yet. The rain only lasts a few minutes and the radar cruise control again works normally. When I got home I got out the owners manual and on page 551 (the red section) it says "indicates that the radar cruise control system is unable to judge vehicle-to-vehicle distance." And in the column which describes "Corrective procedure" it says "If the windshield wipers are on, turn them off or set them to either the intermittent or the slow mode." Now it was my understanding that the radar cruise system detector was behind the Toyota emblem on the front of the car. So, four questions: 1. Does anyone understand why turning off the window wipers has anything to do with the radar cruise control system? 2. Will it disengage the Radar Cruise Control system if the wipers are off? 3. How do you turn off the Radar Cruise Control while maintaining the use of the regular cruise control? (yes during the rain) Yes, I am aware that there is the risk of hydroplaning but a low one. Also, if you saw this rain you would agree there would be nearly zero chance of hydroplaning as it was a rain that lasted literally 5 minutes. We are experiencing a drought here. By the way, I put the window wipers to it's fastest position merely to test them in the rain. It was the first rain, remember. 4. Are there any other surprises we should know about like this one? Cheers
The system is set-up to disengage when you select the HI setting for the wipers. Turning off the wipers or setting them in low or intermittent allows you to once again use the radar cruise control. It is as a safety reason that they do not allow you to use the system during rain heavy enough to make the use of the HI setting necessary. They want you to be in full control of the car under those conditions. The radar may also have a reduction in efficiency during heavy rain. The rain itself, may start to affect the radar signature of the vehicle in front of you. This could potentially cause the system to act more erratically. If you want to switch to the non-radar assisted cruise control you will need t: 1) Turn on the cruise control and then push the stalk away from you for approximately two seconds. **if the cruise control was already on and had been previously activated. You have to turn off and on the system before been able to switch between cruise control modes. It was the test of the HI setting that turned off the cruise control during your 5 minute rain experience. I can assure you that the system can tolerate very high levels of rain before been affected. I have used the system under long periods of rain at highway speeds without a problem. As long as I didn't need to use the HI setting. The system at that point will disengage. It will also disengage if VSC kicks in but not if TC kicks in (at least in my experience)
Question #1 Think of it this way. If Toyota assumes that conditions requiring the use of the HI speed setting on you wipers, are not safe enough for the use of the Radar cruise control. Thus making the system unavailable during the use of this wiper speed setting. Then turning the wipers off or to a lower speed setting, lets the car know that conditions are now safe enough to resume the use of the Radar cruise control. It is all designed to prevent any possible liability issues for Toyota. To be honest, I like it this feature. It is good to know that under adverse driving conditions people are force to pay attention and take full control of their cars.
Thanks so much PRPrius for that detailed response. It was very informative for me and no doubt many others. Thanks for making it very clear how to turn off the Radar Cruise Control while retaining regular Cruise Control. Especially that "**" note. That was an "aha" moment for me. Didn't realize you needed to turn it off and back on to turn the radar function with the forward throw of the stalk. Is all this in that 685 page owners manual? (Grin) Always learning. By the way, I "get" the reasoning behind why Toyota did what they did to maintain safety. Sometimes lawyers make life miserable. This time I agree with them. Cheers and thanks again.
