Voltage Spike! Regulator or BCM?
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Junior Member
Joined: Jul 2012
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E430
Voltage Spike! Regulator or BCM?
Ive recently replaced the alternator twice and still having issues. Recently was having a "convenience features turned off light" and something else i cant recall. Figured it was the aux battery this time around and replaced that. Took it for a drive on the hwy and reading the voltage display it would spike to 16.xx and drop down to 12.xx or so and everything in between. Also, when it spiked all the idiot lights would turn on (esc, abs, ect) then when it came back down the lights would go off. So am I looking at a toasted BCM or regulator? My guess is the latter. Thanks
MBWorld Fanatic!
Joined: Jan 2014
Posts: 3,966
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From: Republic of Texas
'99 and '05 E55 AMG
Plutoe is correct. Five minutes on a MB DAS will point you to the problem. And a $50 Solar BA-5 Battery Tester will give you a quick look at your batteries' condition in 30 seconds without blindly replacing what could be a perfectly fine battery.
So far you've installed two alternators (with regulators), the auxiliary battery, you are about to replace another regulator, and you still don't know what is wrong with the car.
If you are going to repair your MB, you *must* invest in the proper diagnostic equipment. Time saving alone makes it worth it.
So far you've installed two alternators (with regulators), the auxiliary battery, you are about to replace another regulator, and you still don't know what is wrong with the car.
If you are going to repair your MB, you *must* invest in the proper diagnostic equipment. Time saving alone makes it worth it.
MBWorld Fanatic!
Joined: Feb 2014
Posts: 6,190
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From: MA
2008 E350 4Matic, 2011 E350 4matic
Yeah, just because you replaced the alternator doesn't mean that it's good, you might still have a bad alternator. Those generic part stores are well known for selling defective rebuilt alternators.
