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Old 12-24-2017, 12:28 PM   #1
Rac65
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Charging issues

I have a new alternator and voltage regulator and all my wires seem to be good but with the engine running voltage at the battery is only 12 volts. I took the alternator back to Auto zone to have it tested and they say it is good. I can put my meter on the post on the back of the alt. With it running and it still only shows 12 volts. Any advice on what to do next?
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Old 12-25-2017, 06:37 PM   #2
mikie 1954
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Re: Charging issues

put this in the electrical section, you will find good people there that know their stuff.
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Old 12-25-2017, 09:31 PM   #3
franken
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Re: Charging issues

Just measure across the battery and post the voltage (to the nearest tenth, as in 12.6V) not running, running at idle, and at a few thousand RPM.
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Old 12-26-2017, 01:33 AM   #4
Captainfab
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Re: Charging issues

It sounds like either the alternator or the voltage regulator. These days, buying new parts does not necessarily mean that are going to work correctly.
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Old 01-07-2018, 05:00 PM   #5
Rac65
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Re: Charging issues

I had the alternator and voltage regulator tested at the local auto electric shop and they both tested good. I guess I will check the wiring next . I glanced at it and didn't see anything obvious.
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Old 01-07-2018, 06:42 PM   #6
Nanook
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Re: Charging issues

Might be obvious, but is the belt tight?
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Old 01-08-2018, 07:23 AM   #7
ImpalaJim
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Re: Charging issues

I tried to get a regulator tested and they told me cant be done
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Old 01-11-2018, 03:13 PM   #8
vince1
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Re: Charging issues

Yup, the electrical guys will probably show you a wiring diagram of how it is supposed to work. I suspect you are not getting voltage to somewhere on the regulator or on the up side the regulators for these things are dirt cheap. Mine was overcharging and from someone on this forum I found that it was probably a bad ground between the regulator and alternator and it was. In the end I had an extra alternator with internal regulator which I used and donated the original to a local re-builder.
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Old 01-12-2018, 12:39 AM   #9
Captainfab
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Re: Charging issues

Is the regulator grounded?
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Old 01-13-2018, 02:27 AM   #10
VetteVet
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Re: Charging issues

Quote:
Originally Posted by Rac65 View Post
I have a new alternator and voltage regulator and all my wires seem to be good but with the engine running voltage at the battery is only 12 volts. I took the alternator back to Auto zone to have it tested and they say it is good. I can put my meter on the post on the back of the alt. With it running and it still only shows 12 volts. Any advice on what to do next?
Pull the small plug off the back of the alternator and check the white wire with your meter. Key off--zero volts Key on--12 volts.

The blue wire should show 12 volts with the key on or off.

Make sure the alternator is grounded, the regulator is grounded to the shroud and connected to the alternator.

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Old 01-13-2018, 10:06 AM   #11
my56chevytruck
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Re: Charging issues

Have you checked all your grounds?
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