Will

Alternator fail ?

10 posts in this topic

I have a 2005 CDI , that now has +200K km on it now.
It is always dry stored, and the alternator has never been a problem.
I do have a ScanGauge.

About 500 km ago, the voltage started to noticeably drop, usually 13.8 or 13.9 .
About 100 km ago The voltage was running 13.5 thru 13.7 .
Today It is running 13.1 thru 13.4 , and at one point it momentarily registered 12.8 .

None of the light are flickering , and the belt is not squealing.

Is this likely a symptom of a failing voltage regulator ?

Thanks for your suggestions , Will

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Just keep an eye on it. The weather is getting warmer so its easier to maintain the battery.

You'll know when it fails.

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Regulator for sure, you may be able to milk it for some months but you had better budget for the replacement now and count on it being done by next fall.

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I verified voltages with a multimeter.
I saved $500+ for a new alternator, but now I have a different problem.

At rest the 'battery' reads 12.6v , but the scangauge reads 12.0v .
At an idle, the 'battery reads 14.1v , but the scangauge reads only 12.6v thru 13.1v .

It seems that the readings from the scangauge are going downhill, but the battery charge is actually doing fine.

Could this be due to a bad ground somewhere?
Does anybody know where to find a wire schema leading to or from the OBD port ?

Thanks for your suggestions , Will

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How does Scangauge read battery voltage?  Does it read voltage directly like a voltmeter or via signal from an ECU?

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That is a great question, for analysis.
I found this site http://pinoutguide.com/CarElectronics/car_obd2_pinout.shtml to be of some help.
I went back to the OBD to check pin #16, expecting it to be 12.6v at rest.
It was only 11.7v . At idle it was only 12.8v
The cigarette lighter was registering the same.
It seems the entire system was low except for the battery.

So I went back to the battery, and found the issue.
The clamp/cable from the alternator/starter was very secure.
However the feeder cables that subsequently bolt to the clamp were a little loose.
Tightened them up, and now everything is back to normal.

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7 hours ago, Will said:


So I went back to the battery, and found the issue.
The clamp/cable from the alternator/starter was very secure.

However the feeder cables that subsequently bolt to the clamp were a little loose.

I was confused by this statement. By typing "alternator/starter" my impression is that these are the same device which is clearly not the case.

 

As a result I am confused about what connections actually needed tightening.

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12 minutes ago, smartdriver said:

I was confused by this statement. By typing "alternator/starter" my impression is that these are the same device which is clearly not the case.

 

As a result I am confused about what connections actually needed tightening.

 

go look at your positive battery cable if you own a smart 450 and youll see really quick what they meant

 

the larger cable that goes to the starter and alternator and the smaller feed lines that go to the sam unit are connected to the terminal in different ways 

 

it is possible for the smaller ones to be loose connection even though the main terminal is tight 

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Posted (edited) · Report post

AHA! The feeder lines connected to the positive BATTERY clamp!

 

My thinking was that these lines go FROM the battery, not FROM the alternator/starter.

 

Thanks for your reply.

Edited by smartdriver

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