Problems with Dynamic Radar Cruise Control?

Have you checked there is not fogging on the inside of the windscreen that goes over the sensor? I have heard of that causing an issue with the ACC and is mentioned in the manual somewhere.

 

It does for the wipers (5 degrees Fahrenheit), but for the DCC it just says extreme cold temperatures (for the hybrid system itself it says -22 degrees Fahrenheit).

 

Might have to spring for a dealer service call.

 

Been having the same problem as the original poster for a few weeks now with no 'clean sensor message' ever appearing.

I was driving at 70mph on a straightaway with no one in front of me with DRCC engaged. Cruise turned off without warning or any obvious change in terrain, speed or weather. I stopped quickly thereafter and cleaned off a bit of ice snow from the front badge which accumulated either the day before or maybe 30 minutes prior (weather was clear and road was dry when cruise stopped working). DRCC still failed to engage. I stopped about 10 miles later and noticed condensation inside the camera cavity so I cleaned that up but made no difference. It hasn't worked once since. Just like the OP, it engages for a split second where I can feel the car lurch forward a bit and then disengages. I didn't realize until today that DRCC can be disabled by holding the cruise on/off button, and 'normal cruise' still works.

 

It is interesting that both cars are 2017 Primes. I would take it to the dealer because my bet would be something went wrong in the electronics, especially since regular Cruise Control works.

 

Did by any chance either one of you disconnect the 12 volt battery shortly before the problem started? This is just a SWAG, but I wonder if it could be one of those things that needs a reset if 12 volt power is lost.

 

Negative. I was driving and using drcc for about an hour when it mysteriously cancelled cruise and never worked again.

 

I've disconnected my 12V lots of times and had no issues with DRCC. If it's not crud blocking the radar or the camera, then I'd say you should have a dealer check it.

 

True, but some weird things have happened when the battery has been disconnected and if BOTH had just done that…. Well it doesn’t matter anyway since that isn’t a commonality.

 

I had this same sequence of events happen to me yesterday on the way back home from work. When I started out, it was just rain. Then rain changed to rain and snow mix, outside air temp 37 F. Then at a temperature of 34 F it was mostly snow and sticking on the windshield and rearview mirrors. Then I got the error message and the car dropped out of cruise. I suspect but didn't confirm that snow and slush had built up on the front Toyota badge, behind which is the DRCC unit. Just outside of town, at a lower elevation and temp of 40 F, I was able to enable it again. And today it worked perfectly.

 

That's the normal sequence for sticky snow. Our symptoms are different where cleaning the sensor has no effect.

 

Took it to my dealer today and they weren't able to figure it out. They are going to have me make another appointment after they consult with Toyota.

 

Fixed. The dealer tech said he performed a radar sensor calibration and it worked after that. He said it was a normally a ~$300 procedure, but the dealer only charged me the diagnosis fee ($140).

Here's a video I just found for the procedure on a 2019 -