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Discussion Starter · #1 ·
Hey guys. So my 2004 M3 started giving charging issues. It all started when I was driving on the highway and my negative terminal was loose and corroded. I was driving but my car turned off. I pressed the clutch and turned it back on. Then all the dash lights were illuminated. Battery light came on. Lights got dim. When I came home the oil temp sensor was out and road speed cluster was out. I replaced negative terminal and my battery is brand new. My old alternator was good but I ordered 2 more oem Bosch from FCP euro and tested them at Autozone and all 3 of them were good. Battery light is still on. Alternator is not charging the battery. Where should I start from?
 

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2000 E46 323i, 3.0L, 2.8L and 2.0L Z3's
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So your alternator is not charging. Confirm by testing the voltage on the battery when running. If its not 14 V or there abouts, the alternator is not charging.

There are two wiring diagrams for the 2004 M3
Up to build date 2/2004 Alternator
Build date from 3/2004 Alternator

Both have Fuse 30 as a key part of the system. Is it blown?
 

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Discussion Starter · #6 ·
Fuse 30 was blown at the beginning. So I put a new one that blew immediately. I tried again after few days and now it’s just fine. I checked all the fuses and as if for right now all of them are good
 

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2005 325xi
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Fuse 30 was blown at the beginning. So I put a new one that blew immediately. I tried again after few days and now it’s just fine. I checked all the fuses and as if for right now all of them are good
If the fuse was blown, something must have shorted to have blown the fuse. If it blew again upon putting a new one in, there is still a problem. Fuses don’t just blow, there has to be a reason. I’d start looking for a broken wire or short.


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Discussion Starter · #11 ·
As if for right now all the fuses are working! I have a “schwaban Foxwell” scanner. It reads general codes! But I got INPA from (mikes bmw tools) and it doesn’t seem to read anything.I don’t know why it’s not reading the ecu?! Battery has good voltage. I checked for the grounds in the engine bay... they were good. The moment I start the car battery reads 11.6 volts.
 

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Discussion Starter · #12 ·
Update I got INPA working and scanned the car for errors. Got 2 codes. #1 code 132 dsc botschaft #2 code 139 tempomatsystem. The only light that’s illuminated on the instrument cluster is the battery light. My wheel speed sensors are out too! I’ll prolly start with that.... wheel speed sensor prolly throwing a dsc code?
 

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My old alternator was good but I ordered 2 more oem Bosch from FCP euro and tested them at Autozone and all 3 of them were good. Battery light is still on. Alternator is not charging the battery. Where should I start from?
1)measure voltage at the jumper post to chassis before and while engine running.
2) measure voltage at the big red cable connector on back of alternator while engine running.
3) report back.
 
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