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      06-30-2015, 05:31 PM   #1
Mjrmq7
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Having crazy voltage issues, and different at b+ terminal and on the battery itself

I recently rebuilt a wrecked e92 m3, well since its been back and running intermittently it wont start unless a jump pack is on the front jump terminals. It was my understanding that the IBS cable can throw some weird electrical problems so I replaced that, I have also replaced the alternator and battery (twice). I hate throwing parts at a problem, but this is a weird problem : I'll get like 6 volts at the front terminal ( ah it makes sense why the jump pack will start it) and after its running its getting 14 volts so the alternator is working. Well when the car is just sitting there and getting 6 volts at the front the reading directly from the battery is over 12 volts. I am beyond confused and really need some help. Thanks in advance.
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      06-30-2015, 06:38 PM   #2
Mike Benvo
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Perhaps the main cable that runs from the battery in the rear that feeds the starter and alternator is loose? Or perhaps there is a bad ground somewhere?
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      06-30-2015, 07:09 PM   #3
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Quote:
Originally Posted by Mike Benvo View Post
Perhaps the main cable that runs from the battery in the rear that feeds the starter and alternator is loose? Or perhaps there is a bad ground somewhere?
so I would basically have to look at the starter to see if its loose? Or is there a spot I should look along the way where it could be loose. Thanks
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      07-04-2015, 12:25 AM   #4
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do you have MRS fault CURRANT PRESENT ??M OR IBS FAULT STILL PRESENT ?
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      07-04-2015, 12:26 AM   #5
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OR BSD alternative fault ?
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      07-04-2015, 12:58 AM   #6
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Do a resistance check on the positive battery cable, you may have to remove it to do this. To remove the battery cable pull down the right hand side under tray and it is easily accessible! I had some weird issues with my E90 330i and replacing the positive battery lead fixed the problem!
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      07-07-2015, 04:20 PM   #7
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Well I figured it out, the battery didn't have the overflow connected and spilled acid on the connection down at the bottom of the battery terminal. Took it apart cleaned it well and have had no issues.
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