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Sodium Chloride
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what do you mean it wont charge? as in the car wont start? it doesnt have enough power to start? or the battery just dead after it runs out of juice?
 

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Im Bluffin With My Muffin
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5,992 Posts
the alternator is not charging the battery.... still looking into the regulator....
 

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I am Teh Edumacator.
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revharde30 said:
yeah i put a meter on back of the alternator no charge coming out
You replaced the alternator, the alternator is still spinning with the belts, you tested the alternator terminals during vehicle operation, and no voltage? Sounds like you replaced a bad alternator with a bad alternator.
 

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Discussion Starter #6
i got the alternator from autozone when i took the first one off and took it and got it tested they said it was good but i went ahead and bought it anyways are they somthing in the car that makes it charge like a relay
 

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you need to use a multimeter at the back of the alternator with everything connected check voltages at the large post with red wire (B+) as well as the small post (D+) You should have over 12v at each terminal. Change the meter setting to ohms and check betwen the case of the alternator and 1 of the bolts on the shocktower. You should have less than 1 ohm. Report back with results.
 

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11.21 at BOTH the thicker wire (B+) and the thinner wire (D+) at the back of the alternator?
is this measurement taken with engine running or not running?
does the battery light in the dash illuminate?
 

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Discussion Starter #12
11.66 on big abd 10.65 onlittle as engines running tightened u[ the belt it didnt help and no the batery light is not on so any ideas yet
 

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your alternator needs three things in order to charge.
1) power at B+ which is the big positive wire coming from starter
2) power at the D+ wire also referred to as an exciter wire which is the smaller wire which goes through the instrument cluster and feeds the back of the alternator on the smaller eyelet
3) ground.

We checked all of those things so unless you made a mistake in your measurements then it sounds like a bad alternator. Of course I'm not standing in front of the car so all I can do is make suggestions. I dont know much about autozone alternators because I only use facotry parts for BMW but years ago I used to buy alternators from Kragen and had terrible luck.. one time i purchased 4 alternators before I got a good one.
 

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you can remove the D+ wire from the back of the alternator and check open circuit voltage with the key in pos 2 at the D+ wire ... if you still have your voltage then you know it isnt bleeding through the alternator.
 

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Discussion Starter #19
oh yeah i forgot to tell u when i took the alternator off for the core i asked them to test it and the machine said it was good so i went ahead and bought a new on so please explain if u can
 

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not sure how to explain other than to say i dont trust their machine or the caliber of the guys who run the tests.
Once again I am not telling you that your alternator is bad.. I cant diagnose your car over the internet however you have so far ran a lot of tests and not found anything wrong in the car thus far.
I would try the last test I suggested and let us know what you find. As I mentioned before it may be a good idea to take the car to a qualified BMW shop and have it tested by a qualified technician. Im happy to help as much as possible but theres only so much I can do when im not standing in front of the car.
Best regards,
 
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