I recently purchased 2010 r56 non turbo mini (Camden edition) with sunroof, Harmon Kardon stereo.
I've been experiencing some weird electrical issues with it.
1. if listening to the stereo and touch another button, ie windows, dome lite, etc. the stereo cuts out with the message "telephone active" displayed on the computer. (I've turned off bluetooth, and do not have my phone connected) it will also do this at random times on its own.

2. I can't use both windows at the same time.

3. USB port doesn't seem to work. but the 3.5mm jack next to it does. is there a fuse specific to it?

I kind of feel like the things aren't getting full voltage? Could there be a corroded ground or something?
Where should I start looking

 

Your first step is to connect a scan tool and scan all the modules in the car.

Next, MINIs have a technical service bulletin about faulty ground connections in the left front wheel well (Under the DME); check those grounds to make sure they are clean, not corroded, and tight.

Lastly, test the battery for proper voltage and that it's current cranking amp reading is close to what's listed on the label.

The USB port probably doesn't work because some previous owner or passenger slipped with the 3.5mm plug and jammed it into the USB port (shorting it out). My brother did that once.

 

I recently had a strange incident involving the Harmon Kardan system in my 2012 Countryman. When I started the car, the stereo would not turn on and the LCD backlights on the tach were out. I pulled fuse 45 and 49 to check but they were fine. After I reinserted the fuses, everything worked properly. I figured that a bit of moisture may have gotten into that area and caused a problem. About a month later, the same thing happened. This time I pulled just fuse 45 and reinserted it, the stereo turned back on. I rechecked the fuse and there was a very small layer of grey tarnish on the blades. I cleaned the fuse with a bit of sandpaper and it has been fine since. This happened about 4 months ago.

So, check the grounds as mkov608 says and pull the fuses and give them a bit of cleaning.

 

Thanks mkov608, I'll check out those grounds. When I bought the car the dash was lit up lie a christmas tree. I finally got the last light to go off last weekend. (a stubborn brake wear sensor. my scanner wouldn't reset it. read here on the forum how to reset it from the dash.)
I do however still have a couple of codes a0b8 hall sensor, key engaged
e584 k-can line fault
e704 k-can line fault
e104 instr. cl.: k-can low line fault
I've checked the battery for voltage with my multimeter with the engine running and not, they where fine. How do I check the cranking amps?

 

In a CAN bus system, the various ECUs will monitor voltage and current to determine the appropriate function to perform. If battery voltage or ground points are not good, all sorts of issues can arise.

What is the age and function of the battery?

 

Good Idea Denis, I'll try that also.
Coincidentally My mini came from your neck of the woods. Economy, just outside of Truro.

 

The voltages seemed 12.4v not running and just over 14v with engine running. tested at the battery with a multimeter.
I'm not sure how to test amperage or anything else??
I'll check for a date and get back to you...

 

To fully test the battery and the vehicle's charging system, this is my favorite Foxwell tester.
https://foxwelltech.us/product-detail-684.html

 

I think I've figured out why the stereo cuts outs with the "telephone active" message. Because I have the Camden edition it is supposed to be equipped with mission control feature/ gimmick. Its never worked since I've owned so I was never truly clear on what it did. I was watch a video of a car equipped with it and noticed every time the voices spoke the radio showed the message "mission control active" and the frequency that they appeared aligned with my "telephone active" message.
So I looked in the secret compartment and sure enough the LED was lit up on the mission control switch. I turned it off and so far this morning my stereo hasn't cut out,

Fingers crossed that annoyance is solved.