I have a 2003 Mini Cooper. The battery has a parasitic draw. I took the car to the shop and the power drain is completely untraceable. It cannot be linked to any fuse or relay switch. So what I was told was I would have to just start replacing electrically driven units in the car. Starter, Alternator, blah blah blah.
I took the time to have a Electrician friend of mine to help me find the drain. We went thru every single fuse wire and relay and determined it can't be found. So he left and I recharged the battery, later to turn on my car, and now I have no dash lights, no radio, no head unit power, and the sunroof wont close. I just recently spent a pretty penny to have the power steering replaced and serpentine belt, as well as a alternator fuse. I checked all the fuses and everything is good! Whats wrong? The headlights still work, the windows still work and the car runs, but I cant close my moon roof and all the buttons and luxuries wont work, making it very hard being as its winter and I cant turn the heat on. Any input?

 

I'm sure you did, but did you go through all of the fuses under the hood? If you are getting power there have you used a manual to isolate to individual relays align the way to components that are not working.

Another possibility is to check the wiring harness. I have seen where rodents get in there and chew out some wires and cause issues like you are describing. If no rodents it could also happen fro something corroding a section of the harness.

I am not sure but I believe part of the electronics could also be at fault. Maybe something with the Can-Bus?

I know it not much of a help. and I am sorry for the problems. Hopefully, this at least, gives you some more to look into.

 

All electrical problems are traceable using the right equipment and technique. First of all, if everthing was working before you started troubleshooting then I would suspect that a fuse or fuses are not seated are installed right. Check the fuses at fuse panel 3, it is located in the engine compartment next to the left strut tower. It houses the main distribution fuses FL1-FL12 and F01-F10. 1 or more fuses may be blown or installed incorrectley. Also verify that the fuse values are correct.

At this point I would suggest that you get the Bently Manual for you Mini.

To troubleshoot a "parasite draw" you will need a milli ampmeter that is found on many digital multimeters. Make sure that the ignition is off during the test, you don't want to damage the meter with excessive current in the system. The meter leads will have to be inserted into the circuit (in series) to measure the current flow (amperage). It should less than 50 miliamps.

Starting at the battery measure the current draw at the positive terminal. This will tell you the total current draw while your ignition is off. From the battery the ciruit branches off into 2 circuits. One goes to the starter and the alternator and the other to the main fuse distribution at Fuse Panel 3, mentioned earlier.

You will measure the amp draw from both circuit to determine which is at fault. The easiest place to start would be the circuit to the main fuse panel 3. Pull all fuses to and meaure the current accross each fuse terminals. You will be able to identify which circuit is drawing to much current. Remember that some circuits always draw some power to run the circuits in the background but it shouldn't more that a few milli amps.

Once you identify which ciruit branch is a fault you can further trace the problem to the sub branch fuse then to the source of your problem.

Good Luck 'cause electrical problem can be a "Bear".

 

Hey Akai, did you ever figure out what was wrong. It looks like I have a similar problem with my daughters mini. Here radio and heater go on and off without her touching any controls and her wipers are on constantly. Nothing responds to controls. Car runs fine.

 

Sounds like a short in the BCU

 

Definitely, it's a kind of short circuit in the BCU, If i were at your place i would prefer hiring an .