Cat 299D2 stereo wire identification

[trider]

I recently purchased a 2019 Cat 299D2 and have been going over it and checking everything over. The stereo inside the cab is intermittent so I am planning to change it. I noticed a small blue plug on the back of the stereo that I am unfamiliar with. It has a small grey wire coming off it. Inside the grey wire is a very small red and black wire. I have traced it under the cab then it goes back inside the cab on the right side and goes up under the headliner. I can not see what it goes to without pulling the head liner. Does anyone know what this wire and plug goes to?

 

[foton]

I do not know this for sure , but could it be a constant hot and ground for the clock and station memory? put a meter on it, if the switch is off and it is hot I would guess what I thought is what it is.