Hey people its a pleasure to be a part of this form. i recently signed up in an attempt to diagnose/ fix my recently purchased 2004 545i and i search high and low and still to no avail.

So this is my issue, recently i had an active steering waring appear as well as a right parking lamp malfunction. The active steering went away on its own after a few starts but is intermittent and pops up every know and then. The parking lamp malfunction went away one day on its own after bumping my front end (very softly) in to a small dirt embankment in front of my house. It recently just came back, randomly. So this is where im at a loss, i was driving to school and was getting off the freeway. i had the car in auto mode it being an smg tranny, and it was in fourth gear. as i it the gas i heard the engine rev up but i was not moving forward any faster. I looked at my gear indicator an it said forth gear and all off a sudden it went into neutral. i pulled over and messed with it for a while and it went back into gear. this became for frequent and eventually started going into fail safe mode and now i stopped driving the car in order to troubleshoot it. So normally i would suspect, after all the threads i read, that this would be an old battery issue, or the smg pump going out but i just had it replaced with a factory battery and registered a few months ago and just to be sure i took the car to autozone to get the battery tested and it passed. whats interesting is that they told me my alternator did not pass. So i was thinking how can that be if my car is running and the battery is getting charged. Since i have to replace the alt bracket gasket i took the liberty to take the alt to orilleys for a second opinion and they put it on there machine and it fail that as well. so im wondering. Would a bad alternator cause the smg pump not to work properly? And would a bad alternator cause active steering issues an parking lamp issues and also recently high emission warning to come on as well as the SES light? Another thing i noticed, is that when in park and quickly reeving the engine to like 3k my interior light would kinda flickr. like maybe a surge of power went through them. On top of that my idrive kinda flickers and sometimes it turns off or will work but the radio wont work and i cant use the idrive controls until it randomly reboots itself. So im just confused, i dont know if its my alternator causing the smg to not shift and go into neutral and fail safe mode or if its the pump itself. i dont want to buy both parts. im sorry this is kind of a long summary but i trued to put as much detail in and i just need some help figuring this out. thanks i advance for taking the time to look at this and/or help me i really appreciate it.

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First welcome to the forum ... Well ,, a bad or failing alternator will kick the transmission into safe mode . As well as ABS , active steering , dynamic drive errors . The Idrive shutting down , all are classic failing alternator symptoms .
These cars are super sensitive to low voltage and have many power hungry modules that require the correct voltage at all times . When loss of voltage happens the computer shuts down modules and that's when when the cluster lights up like a Christmas tree with errors cause they are not getting the power needed to function properly . So if the alternator is testing bad replace it and it should stop the electrical gremlins ..

 

Its absolutly possible for a faulty alternator to cause all those issues and more!

 

Hi

Yes it's possible , but also a old ( 3-4 year ) battery can couse these problems , so get your battery checked first , then the altenator

 

Buy one of these and you will be able to monitor the alternator output real-time while you drive.

Equus Innova 3721 Battery and Charging System Monitor - Walmart.com

When my voltage regulator failed on my alternator the voltage swung up and down randomly. At times I was reading 17V! Yeah the battery was getting charged (and the water boiled away).

 

thank you guys for your responses i appreciate it. So can a bad or failing alternator also account for the smg tranny popping itself into neutral while driving? or gears not being able to shift at random times, this usually happens before the failsafe comes on for the tranny. i hear the pump prim when i unlock the doors and its for a good 4-5 seconds.