2012 MCS 140K miles/224K km

The symptoms:

Shaking
Five weeks ago, the motor shook violently when I tried to start it in a store parking lot It did not start. I looked under the hood/bonnet but nothing looked wrong. I tried starting it again, it shook violently again, but started this time and ran normally. No codes off a OBDII reader. I drove straight home, and the car continued to run and idle normally. I parked it next to the garage and decided to deal with it later.

Last week, in order to bring the car into the garage, I had to remove the battery (looked frozen) and warm it up inside and then trickle charge it for 12 hours. It had been 10-25 degrees F/ -12 to -4 C for more than a week. (Yay Massachusetts.). Reinstalled the battery and the car started normally. In the garage, I checked the belt and motor mounts, everything looked normal. No codes again.

The only thing out of the ordinary was that after a few hours of the car shut off and the key in my pocket, I heard short buzzing (1-2 seconds) and some clicks from the MINI's motor.

I decided to start driving the car again, bringing it out on 10-15 mile trips. Car behaved normally.

Dying

Yesterday the car died while driving 75 mph / 120 kph. First the radio went silent, then dark. The motor stopped. Then the dash lights started lighting up, lost power steering, more lights started too flicker. I was distracted by getting the car off the road safely to notice the sequence of how it happened.

Once I shut off the car, I turned the ignition on again to check the codes. Nothing.

When the tow truck came, I was able to start the car normally to get it on the asphalt so the driver could get under it to put it on the flatbed.

Time to pull it back into the garage. I assume it's an electrical issue - it doesn't seem like it's mechanical but I could be wrong.

Also:
- I replaced the alternator less than six months ago (the old one was fluctuating badly).
- Battery is about 12.6 volts before startup
- After startup, the volts read about 14.1-14.6 during operation (both old-school voltmeter and OBDII app).
- I replaced the wedge bulbs a few months ago with LEDs that seem to be throwing an intermittent warning light that indicates a bulb out. Sometimes it doesn't go off, sometimes it goes off every three minutes.
- Footwell module was replaced by MINI approximately 12 months ago.

Looking at the forums, I assume I'm looking at:

• Battery cables & ground/earth points (is there a diagram of those for our cars?)
• The battery itself. Could a faulty battery cause these conditions?
• Footwell module
• Fuse & relay plate (junction box under the fuses)
• Sunroof drains & water (I cleaned them last summer).

What else could I be missing?

Thank you to everyone who has contributed to the forums here, I've learned a lot.


Edit: SOLVED.

Turns out it was simple voltage drop. I used a OBD reader and Dash Command to track the voltage drop from 13.6 to below 12 over a bout 30-40 minutes. I confirmed this by stopping and checking with a multimeter. After some digging around, I found corrosion on the the new alternator post, and cleaning this up solved the problem. The measured voltage at the posts now is 14.6 at startup and about 14.4 a few minutes later. There's only a 0.1 - 0.2 volt drop along the cable between the alternator and the positive post.

Thanks to everyone who helped.

 

Get your hands on a BMW/MINI specific code reader. They will often root out error codes the generic scan tool won't.

 

Thats a good idea. I will try to find one.

EDIT: what constitutes a "real" MINI reader (besides the dealer)?

 

ECS tuning (site sponsor) sells a good one, Schwaben. Mine has paid for itself several times over.

 

Will a reader possibly show a ground fault or something similar?

 

Yep,

It will pull up everything that shows a code. Some you will see even if their has not been a CEL. You will see all the old faults that the dealership never cleared. Thats Zach from Dount Media actually holding the Bentley manual with the tool

https://www.ecstuning.com/b-schwaben...020sch01a~scf/