tl;dr I was going down the road and the drcc kicked off and the error message, "cruise control not available", came up. I cleaned the emblem and disconnected the battery hoping it would reset the ecu, and the problem persists. Standard cruise works fine. Car history: The a/c went out a couple of months ago with 50k miles and I took it to a local hybrid shop. The guy told me he hooked their diagnostics up to the car and it was doing odd things to his scanner. He blamed my audio system that I have installed. Then he said he tested the 12v battery and it wasn't charging. After replacing it they hooked the scanner back up and it worked fine and he said he couldn't find anything wrong. He tested the electrical system to see if there was draw on the battery with the car off (testing the audio system install I guess) and said that was fine as well. So they put dye in the a/c. Lo and behold the condensor had a crack in it. They replaced the condensor, charged the a/c and returned the car. Everything was working fine. Even went on a 5 hour road trip. Then driving down the road with the cruise on, the car decelerates and that message popped up with a big orangish triangle. Turning the cruise off and turning it back on gets rid of the message and the triangle, but comes right back on successive attempts. I hooked up my Carista to it and the only thing I could find other than "No fault codes" or "No ECU present" was this: Heater & air conditioning Part # suffix: 47520 Fault codes: U0163 Lost Communication With Navigation Control Module I'm not seeing an option to reset codes with the Carista.
The first thing to do to help eliminate causes is to check the voltage in your new 12 volt battery. So many issues that arise can be traced back to that battery being undercharged.
Is the 12.6v just after you turned the car off? You will need to test it after it sits (overnight of so) to see if the charge holds. This opens up a can of worms because you have to test the battery without "waking" the car. So, if possible unlatch the hood the night before and check the battery in the morning without your key fob close enough that the car recognizes it. That will provide the most reliable results.
That was after the car had been sitting for 3 hours. I did unlock the car to open the hood however. I wouldn't think it would make that big of a difference?
It seems to. Don't really know why or how, but I've seen it mentioned on this site dozens of times...
Yes ... "mentioned". "Mentioned" so often it drags other people into "mentioning" it too, even when they "don't really know why or how" any more than any of the earlier mentioners do. 12.6 is not the explanation of your DRCC question. The car's computers can tell you their reasons for saying DRCC is not available, and then you can follow up with the associated troubleshooting procedures and find out why that is.
I've never heard/seen DRCC malfunction because of a 12v battery problem. Most likely the emblem is dirty and needs cleaning, or something struck the emblem/front end causing the radar dish to misalign or become damaged.
