It has been a year since I have messed with this car since I simple could not figure this out.

Vehicle is a 2010 Mini base model (N12 engine). I sold this car in 2020 and unfortunately the gentleman I sold it to passed shortly after. The vehicle sat for a couple of years unused. Someone from the family (I'll refer to him as Dan) ran into several issues when he tried to drive it. I helped out where I could but after a couple of months he gave up and I bought it back at a much lower price. I ended up getting it working and drove it around for about a year. Towards the end of 2023 I went to start it and it did not respond. I found that the battery was dead and it was due to be replaced. But replacing the battery didn't really change anything.

With the new battery, only a few electrics were working. The windows will roll down when the door opens but they have to be rolled up using the switches otherwise they remain down. When trying to start the vehicle I can hear the throttle activating. The only light that comes on in the vehicles is the dash warning light telling me to take it to a shop. Besides those three things, nothing turns on. No radio, no headlights, nothing. Reading other forums points towards the immobilizer. But from what I've seen, people usually still get things like the radio and interior lights when the immobilizer is the issue. I am not saying this isn't my issue but it seems there may be something else going on here. The new battery seems to drain within a week so a parasitic draw is probably present somewhere but I have yet to find it.

I have pulled every fuse and relay and tested them and all seem fine. Using a voltmeter I have tested ground points and those all check out. When I have time I am going to get back in there and see if I can located the parasitic draw but I do not see how that would explain the main issue.

Vehicle Background:

When I bought the vehicle it would crank but would not start. I guess the evap line that runs from the intake manifold to the fuel tank either fell off or was unplugged by Dan. I plugged that back in and it fired up but had multiple misfires. An injector was bad so I replaced the set as well as spark plugs and it ran perfectly.

As the weather got warmer, I noticed that the radiator fan would not turn on. I used INPA to turn the radiator fan on. It would just turn off after a few seconds. I replaced the coolant temp sensor and verified that it was giving accurate readings to the ecu. I never did figure that one out, but I suspect the ecu was receiving the coolant temp sensor and simply failing to tell the radiator fan to turn on. Now heres the part that leads back to what this post is originally about.

I inspected the ecu and noticed a screw was missing from the body. I think Dan (or someone he knew) may have pried open the ecu for some reason and didn't bother putting it back together properly. I took it out and opened it up to inspect the circuits for water corrosion. Everything inside looked pristine. My knowledge with ecus is limited but I did not see anything obviously wrong with it. I gave up on messing with it for awhile after that but I want to get to the bottom of this now. Taking it to a dealer is pretty much out of the question for me right now. I've had too many bad experiences with the local Mini dealership and I don't want to give them a bunch of money for them to shrug their shoulders or give me the wrong answer.

I am hoping someone here has run into a similar issue or can tell me where I am going wrong with my diagnosis attempts. I would love to hook up INPA to the vehicle but thats not an option since it won't get power to the ecu. Any help is appreciated.

 

Does disconnecting the alternator and starter eliminate the parasitic drain?

How do you know that DME does not get voltage?

What collection of fault codes are stored in the many ECUs and which ones return after clearing all codes? When posting codes that return, organize them by ECU.

 

I will charge up the battery and the test it by removing alternator and starter.

It has been about a year since I tested anything but I either held a voltmeter to one of the relays or dme pins. I will consult my wiring diagrams and test that again in case I have something wrong.

I only have the one ecu. There were no codes before everything went dead. I cannot check for codes now since the ecu is not turning on at all.

 

Your Mini has a whole bunch of different ECUs/control units, such as the DME, CAS, KOMBI, SRS, FRM, EPS, SPEG, 2RAD/CD, IHKS, DSC, SZL, and RDCLC.

The MINI ECU for the engine is usually referred to as the DME.

If you connect your MINI to a scan tool capable of reading BMW fault codes, you'll be able see fault codes for all of the different MINI ECUs.

 

Did this ever get solved?

 

Yes and it was the dumbest thing possible.

I was just going to sell the car as is. Needed to get the doors open so I went to jump it to get them unlocked. When I was putting jumper cables on I bumped the negative battery wire and everything turned on. I had tested the ground points multiple times and they seemed fine. But if I move the negative cable around I can get the car to turn on and start. I cleaned the ground and positive connections and applied electric grease. This worked for awhile but I am still having grounding issues.

When I do anything with the car I can hear relays clicking and other things turning on and then it will all shut off. I've concluded that this constant turning on and off is what has been draining the battery. I havent had the time to figure out where the break in the ground wire is but I'm thinking ill just replace the entire cable from the battery and see where I'm at.