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DIY: Do It Yourself
Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

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Old 09-18-2013, 02:38 PM   #121
aurelius
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Finally solved my particular low voltage issue. Turns out it was a loose battery ground cable, the cable that goes from the negative battery post to the car body. Loose connection at car body attachment point. Very easy to check this and if yours is loose and you see carbon deposits on the cable or the fastener, these must be thoroughly cleaned. Merely tightening the fastener won't solve the problem.

Last edited by aurelius; 12-23-2013 at 02:05 PM.
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Old 12-12-2013, 12:02 AM   #122
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Hey, I just took my voltage regulator off, and my brushes look fine. I feel resistance as I press it back into place -- resistance on the little spinny thing inside the socket. Also, when I spin the pulley, I hear very slight noises inside the alternator, but nothing near the sounds I hear from videos like this.
: . Is it time I replace the whole thing or can the voltage regulator fail without brushes wearing down?
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Old 12-17-2013, 01:34 AM   #123
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What are your symptoms (what is the car doing or not doing)?
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Old 12-17-2013, 10:30 PM   #124
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Too late, I just replaced the whole thing with an Advance Auto alternator. Car's electronics was dying while I was driving. Battery wasn't charging. Voltage was 12V when the battery was fully charged and it slowly diminished over a few minutes after starting it. Voltage never went up to 14V like it's supposed to when the car's engine is running.
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Old 12-22-2013, 01:16 AM   #125
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can someone help me and tell what part # do i need to replace the voltage regulator, or maybe should i just get the whole new alternator, see image below, thank you
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Old 12-23-2013, 02:04 PM   #126
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BMW E46 Alternator DIY (voltage regulator)

Whether you've replaced your alternator or not, do yourselves a huge favor and check for a loose battery ground cable in the trunk of the car. Look at where the ground cable is connected to the body of the car, under the trunk mat.

If it's loose, remove the fastener and clean the carbon from the area with a battery terminal cleaning product.

A loose connection on that particular cable is common in the E46.


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Old 12-25-2013, 10:24 AM   #127
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Re: BMW E46 Alternator DIY (voltage regulator)

Quote:
Originally Posted by aurelius View Post
Whether you've replaced your alternator or not, do yourselves a huge favor and check for a loose battery ground cable in the trunk of the car. Look at where the ground cable is connected to the body of the car, under the trunk mat.

If it's loose, remove the fastener and clean the carbon from the area with a battery terminal cleaning product.

A loose connection on that particular cable is common in the E46.


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Well do

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Old 12-30-2013, 01:20 PM   #128
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can someone help me and tell what part # do i need to replace the voltage regulator, or maybe should i just get the whole new alternator, see image below, thank you
Can't tell if your alternator needs replacing or just your voltage regulator from that picture. Do about 10 minutes of research, you will find the different symptoms for either one. You can find the part number for any part of your car by going to the realoem website. Alternator stuff is under engine charging systems. This looks like a regulator/alternator for a 3 series, 120 amps. There's a 90 amp one, but I'm guessing you have the HK sound system or navigation, which uses more power.
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Old 01-19-2014, 03:21 PM   #129
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Same here. Seems some E46 models built in 2003 have a 120-amp alternator more commonly associated with the Z4, making it rather difficult to find the relevant VR. If your alternator has the oval electrical connector/plug noted above on the rear of the alt., then you need the VR with Bosch part number F00MA45219. (The 2nd & 3rd being "digit zero," not "letter O.") That number is not easy to come by -- make a note of it if you have the relevant alternator.

As of this writing, Pelican sells it for $65 but it doesn't cross-reference to the E46 and you won't find it on their site. You must call with the Bosch number above.

I should have paid more attention to this thread. Got mine off without removing the alternator, put the new one on before realizing it was a different plug. The old one is back on for now, and I will call Pelican on Monday. The hardest part was getting the screws out.
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Old 01-20-2014, 12:23 PM   #130
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Quote:
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I should have paid more attention to this thread. Got mine off without removing the alternator, put the new one on before realizing it was a different plug. The old one is back on for now, and I will call Pelican on Monday. The hardest part was getting the screws out.
Be sure to see posts 121 and 126 above. You may not need a new VR at all. What are your symptoms?
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Old 01-20-2014, 03:23 PM   #131
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I've read this thread and unless I missed it, nobody here seems to be paying any attention to the slip rings on their alternators as they opt to replace the voltage regulators. I had mine out for a look last time I was in the engine doing something (OFHG) and removed the VR. I noticed the slip rings had deep grooves worn into them from spinning against the brushes.

Replacing the voltage regulator is pointless in this scenario. You need to rebuild the alternator in this case. I can't imagine mine at 125k being much different than anyone else's at 125k. Anything can happen though.

Voltage regulators are over $100 for the Valeo. The cost of all the rebuild parts for the alternator including bearings, slip rings, and new voltage regulators would substantially exceed the cost of a rebuilt alternator, and perhaps be on par with that cost if you just replaced the brushes in the voltage regulator rather than the entire thing. Rebuilt alternators cost $150 after you send in the core.

Rebuilding an alternator yourself is entirely doable. Procuring quality bearings and the correct slip rings & voltage reg/brushes can be a pain, since it doesn't seem possible to just buy it all from one place. The parts must be sourced from at least two different vendors. So you will spend some real time here doing research and procuring parts. Then you need to disassemble the alternator. Getting the bearings in and out require bearing pullers/presses. Replacing the slip ring is a job, have to dig the epoxy from the winding joints, and be careful doing it because you can render your core useless if you hamfist it. And then you have the brushes in the VR which is another fiddly but easy job. Even though I am entirely competent enough to rebuild the unit no problem, there comes a point when saving money yields a diminished return.

To me the choice is obvious. It's not just the voltage regulator that wears out, it's not just the brushes, or the bearings. Unless you are determined to save as much money as you can and you don't care how much fiddling you have to endure to do it, just buy a whole rebuilt alternator and be done with it.
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Old 01-21-2014, 12:44 PM   #132
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Quote:
Originally Posted by aurelius View Post
Be sure to see posts 121 and 126 above. You may not need a new VR at all. What are your symptoms?
Ground cable is solid and clean. I am only getting 13.4 while driving and the alternator is not fully charging the new battery.

On top of that, Bosch has discontinued the round plug regulator. Pelican told me I need to buy an alternator.
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Old 01-27-2014, 09:02 PM   #133
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on our cluster panel do we have a warning light for the alternator?
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Old 07-27-2014, 06:25 PM   #134
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Thanks for the write up I took out the alternator and removed the regulator, Bosch and looks very similar in condition to your pictures. My car has 80k and yesterday I noticed bat/alternator light flickering after radio stopped working. Then when I stopped and checked the battery voltage I noticed it was 10.5V. And it would no longer crank the engine. I started the engine after connecting my other car's batter and looked at the voltage while the engine was running. The voltage rapidly dropped from ~11V to ~10V. So I knew it was the alternator. I removed the alternator after some struggle with tools I had and a trip to hardware store and picked up a new set, $99. I expect it will pay for itself pretty soon. Anyhow I am wondering if I should also change the belt while I am in there.
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Old 07-28-2014, 08:49 PM   #135
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I am not going to change the belts but I will replace the slip ring on the alternator:



http://www.maniacelectricmotors.com/7120202.html

Last edited by Adanali; 07-28-2014 at 08:50 PM.
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Old 07-29-2014, 12:29 PM   #136
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Quote:
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On top of that, Bosch has discontinued the round plug regulator. Pelican told me I need to buy an alternator.
The oval VR is still available as both a Genuine BMW part (12317515319) and for much less on amzn using the Bosch part number W0133-1665703.

Last edited by aurelius; 08-01-2014 at 11:01 AM.
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Old 07-31-2014, 01:18 AM   #137
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Regulator arrived today from Pelicanparts:
12-31-7-559-183-M14 $39.25

Car is back in one piece, alternator is working like a charm. I measured 14.05V at the battery terminals. So overall cost was like $150 out of pocket (counting the new tools I bought, but of course I am going to get more use out of them). I saved $600 based on a quote from an indie shop. But the satisfaction I got out of fixing it myself is priceless!

A few notes before I forget:

I ended up not replacing the slip ring as it was not going to arrive in time to fit all back together today. And after re-checking the state of the existing slip ring I did not think I need to replace it. I think the alternator, with the slip ring as is will last many many more years before it needs attention again.

Reinstalling the alternator was tricky, I sand papered it down where the bolt fits so it would be little looser than it came out. But it was not enough, after struggling to fit the lower bolt all the way through for 10 minutes I took alternator out and filed it little more. It was still pretty snug fit, but I was able to put the bolt through all the way so I could tighten it.

I was most concerned about dealing with the serpentine belt, but it is so easy! And having electric fan is so helpful (easy to remove out of the way).

Next time I do this, before I disconnect the battery and remove the alternator, I need to let the driver's side window down a little so I can close the door with battery disconnected (coupe, the window needs to move down/up a little as you open/close the door and that needs power).

My next project is to fix the oil warning light that comes on 10-15 seconds after I start the engine even if the oil level is fine.
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Old 09-17-2014, 07:22 PM   #138
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Warning light means . . .?

Sorry if this has been answered elsewhere. I need to get to work on the car and can't search thoroughly.

2001 330xi, 192,000-plus miles; red battery icon warning light came on last night, and of course, about the 4th time I went to start it after ignoring that and hoping for the best, the battery was dead. Last night I removed the leads at the battery and at the engine compartment access points, cleaned and checked them and saw no obvious issues.

So, does anybody have reasonable certainty that the warning light is actually triggered by the current output of the alternator, having nothing to do with the battery? I have read that the warning light does not always flag an alternator problem, but can the warning light also flag an overall charging circuit problem that originates with the battery?

I do not know (again, without lots of searching, paper service history documents, in this case) how old the battery or alternator are; I have owned the car three years and I have not replaced either one.

I am trying to ensure that replacing the alternator is the right first step; that the problem does not lie in the battery. Even after the light came on, the battery drove the starter just fine for several times, and I tend toward thinking the battery is OK. I only have an analog tester, and it read @ something like 12+ last night, and 14 or so with the engine running. My thinking is the alternator was not *fully* charging the battery.

Anyone? Is the warning light a function of alternator output? I looked today at lunchtime, and the alternator is clearly marked 120, and has the BMW logo on it. I can't read the full PN or ID the alternator for sure without starting the removal process, and it could either be the original or was replaced at a dealership.
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Old 09-17-2014, 08:32 PM   #139
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I believe that light measures the voltage on your alternator but I may be wrong.

Don't overthink it. It is your alternator. Plain and simple. More specifically it is the voltage regulator on your alternator. Symptoms match exactly.
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Old 09-17-2014, 11:53 PM   #140
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It is possible that if your battery was dead the alternator warning light can come on. You can figure out if your battery is dead or not by trying to charge it using jump cables and another car. Connect the jump cables, do not start your car, but start the other car. Then leave it running for 2-3 minutes, even at idle it should charge your car's battery (providing other car's alternator is working!). Then while the other car is still running start your car. Now stop the other car, remove the jump cable (carefully!). Then with a voltmeter check the voltage at the battery terminals. It should be pushing >12V and as the battery charges (if your alternator is working) the voltage will rise as high as 14v (after charging for a good while since your battery is totally discharged). If you are not reading a voltage above 12v or the voltage is going down gradually then it is your alternator. So if the voltage is >12v but you have a problem starting the car again it means your battery is dead.

Quote:
Originally Posted by TotheMountains! View Post
Sorry if this has been answered elsewhere. I need to get to work on the car and can't search thoroughly.

2001 330xi, 192,000-plus miles; red battery icon warning light came on last night, and of course, about the 4th time I went to start it after ignoring that and hoping for the best, the battery was dead. Last night I removed the leads at the battery and at the engine compartment access points, cleaned and checked them and saw no obvious issues.

So, does anybody have reasonable certainty that the warning light is actually triggered by the current output of the alternator, having nothing to do with the battery? I have read that the warning light does not always flag an alternator problem, but can the warning light also flag an overall charging circuit problem that originates with the battery?

I do not know (again, without lots of searching, paper service history documents, in this case) how old the battery or alternator are; I have owned the car three years and I have not replaced either one.

I am trying to ensure that replacing the alternator is the right first step; that the problem does not lie in the battery. Even after the light came on, the battery drove the starter just fine for several times, and I tend toward thinking the battery is OK. I only have an analog tester, and it read @ something like 12+ last night, and 14 or so with the engine running. My thinking is the alternator was not *fully* charging the battery.

Anyone? Is the warning light a function of alternator output? I looked today at lunchtime, and the alternator is clearly marked 120, and has the BMW logo on it. I can't read the full PN or ID the alternator for sure without starting the removal process, and it could either be the original or was replaced at a dealership.
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