Hello all,

2013 R56 N16 Base model Mini Cooper has a brand new OEM Bosch 150amp alternator installed and new AGM battery that I did register via Bimmerlink/code. The alternator will not charge on its own, I'm getting no battery light on dash and if I unplug the green and black wire at alternator still nothing. I tried unplugging IBS harness on negative terminal and still nothing. Found harness X2498 on firewall that has two wires, the black and green wire from alternator that converts to a blue and white wire. There's also a solid white wire along side of it, if I unplug X2498 alternator starts charging and reading 13.99v across battery,when I plug X2498 back in it will continue charging. I back probed x2498 blue and white wire with just ignition on and plugged in receiving 3.75v which I've read is supposed to be between 7v and 11v. If I unplug X2498 with ignition on I get a reading of -10.65v on blue and white pin leading back to dash, If I leave x2498 unplugged, shut car off and try to start it I get nothing. Also radiator fan started staying on even after car is shut off and key is out. Will run for approximately 15-20 minutes before finally shutting off. I have continuity on black and green wire from alternator to harness X2498. I can not find any information nor schematic on this other solid white wire anywhere. Is it a ground wire? Do I have a bad ground somewhere? I'm close but starting to get irritated

 

Any interesting fault codes?

The Black/Green and White/Blue wires that you voltage tested in X2498 are used for communication between the DME and the alternator. You would need an oscilloscope to diagnose proper DME/alternator communication on that BSD interface line.


If you shut car off and leave X2498 connected and then restart the car, does the alternator continue to output 14V?

Do you have a short to ground on the Black/Green and White/Blue wires (with X2498 connected) between the alternator and pin 38 in DME connector 60004?


I believe that the solid white wire in X2498 is the terminal 50 wire that runs between the CAS module and the starter solenoid. The solid white wire is not relevant for the alternator but is almost surely the reason you can't start the engine with X2498 disconnected.

 

 

Alternator will continue charging if x2498 is plugged back together,once car is shut off and restarted back to no charge.
I have not tested from x2498 back to dme yet as I wasn't sure which pin number to reference but I will do that this evening now I know it's pin #38. I did a voltage drop test thinking maybe the alternator itself wasn't properly grounded. Meter read 125.7 mv while car was running which I guess is within spec. You are correct on the solid white wire as I traced it back to starter this afternoon. Took battery out and disconnected negative terminal as I brushed everything clean including battery posts as these minis seem to be quite finicky electrical wise
[img alt="While cleaning up negative terminal I noticed this box that appears to have positive terminal going into it. Not sure what it is
"]https://cimg8.ibsrv.net/gimg/www.northamericanmotoring.com-vbulletin/2000x1504/img_20251120_122020081_183b23a74631b73d17729c0f446 d1da6f19627f4.jpg[/img]
While cleaning up negative terminal I noticed this box that appears to have positive terminal going into it. Not sure what it is

 

You have many fault codes. Am I interpreting correctly that your scan tool fails to clear any of the codes?

Got it.



Can you provide the details for this^ voltage drop test?



​​​​​​​​​​​​​​No change?

 

 

While the car was running I put negative lead on negative battery terminal and positive lead on alternator housing resulting in a reading of .12v/125.7 mv. I did clear a lot of codes but there were some as shown in one of the pictures with the red box that would not let me clear. I used Bimmerlink

 

A604?

 

This^ is an excellent voltage drop. No problem there.

All listed codes cleared EXCEPT those under the message below?

​​​​​​​

 

At this point, my inclination would be to test for a short to ground on the black/green and white/blue wires with the IBS (BSD), alternator (BSD), and DME X60004 connectors unplugged and the key off. If you don't find a short to ground, your new alternator (voltage regulator) may be bad right out of the box.

 

After countless nights of testing and testing I thought I had narrowed down the rabbit whole. Pulled the new Bosch 150amp alternator again after having to disassemble and drop/lift the passenger side of the motor, I replaced the alternator voltage regulator with a new OEM part convinced that it was the only thing left it potentially could be. Of course, only in my world and after reassembling the motor I fired her up only to discover that I was in the same boat I've been sailing for the past 2 weeks. Walking around in circles contemplating on wether I should send this car to mini heaven I went back to the beginning and plugged in the OBD II scanner revealing 37 different error codes. Went through each one deleting what it would let me getting me down to 12 codes. The remaining codes were related to abs/wheel sensors, rear brake pad, restricted voltage to numerous modules, and lastly engine coolant temperature. Installed 2 new front wheel sensors and managed to get error codes down to 8 removing dash abs and traction control warning lights which was a step towards the right direction but still no charge from alternator. Ran the car for roughly 10 minutes and decided to pull the coolant temperature sensor which I hadn't done anything with yet and performed and ohms test. That particular sensor should show the ohms reading declining as the engine is cooling and vise versa when heated. Mine steadily climbed past 3.5 ohms revealing that sensor was at fault. Installed new coolant sensor and was convinced that it wasn't going to change my charging issue, after firing up I could instantly notice a difference in the idling alone before any testing. That was the culprit, this whole time the coolant temperature sensor is linked together on the same bus as the oil pressure sensor, and alternator BSD. Check engine light went out along with the remaining error code except the rear brake pad. I am absolutely amazed at how finicky these mini Coopers electrical/ computer components can be once an issue occurs and how it produces other problems down the line. I did want to point out that trying to find an actual detailed factory wiring schematic showing what components are integrated together electrically is damn near impossible without shelling out more Johnny. I could locate sperate breakdowns but not a color coded detailed factory wiring diagram. Moral of the story? Don't give up

 

Fascinating outcome. Thanks for sharing the solution!

Here's what AI says (though we all know that AI can get it wrong):
In BMW and MINI systems of this era, the BSD bus is typically reserved for more complex, high-speed data exchange with specific smart components, which may include:

• Alternator
• Intelligent Battery Sensor (IBS)
• Electric Water Pump (if equipped; base R56 models generally use a mechanical pump)
• Oil Condition/Level Sensor (distinct from the oil pressure switch)

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A faulty coolant temperature sensor (CTS) prevented proper alternator charging by causing the engine control unit (ECU) to receive incorrect temperature data, which in turn activated a failsafe mode in the vehicle's power management system. This mode likely reduced or shut down the alternator's output to protect the engine from potential damage related to miscalculated operating conditions.
Here is a breakdown of how the systems are connected:

• Engine Control Unit (ECU) Dependence: The ECU relies on the CTS for accurate engine temperature readings to manage critical functions like fuel mixture, ignition timing, and the cooling system.
• Failsafe Activation: When the CTS sends an invalid or permanently cold/hot signal (often indicated by a P0117 or P173B code), the ECU interprets this as a potential severe issue (like overheating). To prevent engine damage, the system activates a protective failsafe mode.
• Alternator Regulation: As part of the power management failsafe, the ECU can control the alternator's voltage regulator to reduce the electrical load on the engine. This is similar to how a vehicle's computer might disable the air conditioning system if it detects overheating. The reduced load lessens the strain on the engine, helping to manage perceived thermal stress.
• Resolution: By replacing the faulty sensor, you restored accurate temperature data to the ECU. This allowed the system to exit the failsafe mode, returning the power management and charging system to normal operation.