Speedy Auto > Auto FAQ > Cars > BMW

BMW: voltage regulator/alternator, first five minutes, fog lights


Question
-------------------------
Followup To
Question -
-------------------------
Followup To
Question -
Josh,
I have a similar problem to the previous question regarding dimming lights, but I have a '90 325ic.  It is a regular dimming of all the electrical components (approximately 2 per second).  It occurs regardless of the amount of drain on the system.  I replaced the alternator hoping it would eliminate the problem, but it has only seemed to reduce the amount of dimming.  I should also mention that it only happens 30% of the time (before and after replacing the alternator).  Is it possible there is an external regulator that was not part of the alternator that is causing the problems?  Any other thoughts?
Answer -
Ian,
 Could you give me the EXACT symptoms of the car's problems?  It would help me to know exactly what is going on.  Like when you say "dimming of electrical components", what is dimming, and when?  Does it look like a flicker or is the light going dim and staying dim for a period of time.

 Thanks,
 Josh

Josh,
The car dash lights and headlights flicker at ~2 per second when first turned on at idle.  I also notice that while driving the car in low gear that the car lurches to the same flickering pattern.  Occasionally the flicker will only occur for the first five minutes of driving.  Any other thoughts?
-Ian
Answer -
Ian,
 I am stumped, it could be many things.  Without looking at the car in person It's hard for me to tell what it is.  
 Do you have any accessories on the car, such as a speaker system, fog lights, alarm system, or ANYTHING that uses electricity?
Josh,
Thanks for your help.  I am not running anything out of stock...  One more questions though.  Is the voltage regulator inside or part of the alternator, or is it externally regulated?  If external, it may be that replacing the alternator just helped increase the available power, but the regulator is still having problems.
-Ian  

Answer
Ian,

 Go to this site and look at #10
http://www.realoem.com/bmw/showparts.do?model=BB13&mospid=47326&btnr=12_0566&hg=

 That is the voltage regulator.  The new Alternator should have come new with one.  Unfortunately I dont think that this is the problem, unless you removed yours from the old alternator and replaced it on the new one.

 That's All I can think of at this time
 Josh