DavidF

Yea, I have seen that voltage (or something very close) too when the alt settles down. When the alt settles down, the engine settles down too.

DavidF

My main point is that the voltage is no where near consistent. Battery seems fine, but who knows. I have another lying around I will drop in see if symptoms change. I am also going to do a battery disco to hard reset everything.

healthservices

Just off the top of my head i would say your brushes are worn out in your alternator. Tapping the alternator with a rod while running may change output. If it did that I would be more inclined to replace it.

545felix

even on a 4 month old one? I just got a replacement under CPO back in late september. Had the 5 month old 110A battery checked and it came out fine, something over 1000 CCAs available.

note- the A/C compressor actually runs all the time while the button for it is on. funny how BMW cycles the alternator but leaves the compressor running.

DavidF

You definately have a valid point. I may as well just go ahead and pull the alternator and replace the regulator. Good insurance either way and will hopefully take the alternate out of the equation. I hate throwing money at guesses when doing repairs, but the regulator is definately a wear item, so money would not be wasted.

DKNewYork

Had this problem before. It could be the alternator. Everything you described happened to my car. In my situation, after taking it to BMW service department twice. They told me the alternator was over charging and the computer shuts down to keep from damaging other components. After replacing the alternator, everything was fine. Haven't had anymore problems after that.

545felix

yes but they won't replace mine under warranty until it throws out a damn trouble code

matthewlfd

What kind of trouble code are they looking for? I'm sure you can 'create your own' by unplugging some of the various sensors/controllers for the systems you want fault codes for. Once you get the code, plug it back in and see if that stored anything.

pauliehcfr

Before you fork over a couple hundred on a new alternator, try this. Go to the battery and disconnect the small single wire connector on the negative battery cable. That is the intelligent battery sensor. I had the exact same errors popping up and I too thought alternator. I changed the alternator and the problem seemed to go away but came back eventually. I disconnected that IBS sensor and all has been well.

DavidF

Ok, I hooked up my laptop and using INPA and DIS/GT1, the error set is "Electric lock error" DIS/GT1 tells me to disconnect plug at active steering module and measure resistance between pins 21 and 22. Of course since I dont have that capability to do that with my laptop version of GT1, DIS errors out when I try to continue with diagnostics.

I had an error with SZL, but that on was related to heated steering wheel and it cleared without returning.

No alternator error codes. There are miscellaneous error codes (one maybe two) that are low voltage related.

I am fearing active steering module failure, or active steering itself. Ugh! Anyone?