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Voltage regulator

Tiny
CHJ
  • MEMBER
  • 1996 NISSAN 200SX
  • 1.6L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 325,000 MILES
Changed alternator. Took car to AutoZone and put on tester. It said bad voltage regulator. So I changed it again. Same thing. Took alternator off and it tested fine so I put it back on. Again it says bad voltage regulator. Checked fuses, all okay. Checked wiring with volt meter and light tester, everything had power where it is supposed to. Alternator is charging battery.
My question is, what are the dangers of running car like this? I do not know what else to do.
Thanks
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Thursday, August 30th, 2018 AT 3:58 AM

11 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning.

What is the voltage at the battery with the engine running? You will need a voltmeter for this.

Are you having an issue that you needed to change the alternator?

Roy

https://www.2carpros.com/articles/how-to-check-a-car-alternator
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Thursday, August 30th, 2018 AT 5:57 AM
Tiny
CHJ
  • MEMBER
  • 12 POSTS
The voltage with car running and while revving it up to 2,000 rpm's is 12.5. Same as when it is not running.
I changed alternator cause battery went dead. After I changed it, the battery charged back up. The bearings in the old alternator pulley went bad.
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Thursday, August 30th, 2018 AT 6:13 AM
Tiny
ASEMASTER6371
  • MECHANIC
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The alternator is not working. It should be 14 to 14.5 volts.

Diagram attached. Check for voltages and the fuses for power in the diagram.

Roy
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Thursday, August 30th, 2018 AT 6:21 AM
Tiny
CHJ
  • MEMBER
  • 12 POSTS
Fuses all good.
Took new alternator off and had tested at AutoZone. It is good.
Cannot really tell anything from diagram you sent. When I enlarge, it gets fuzzy.
When I put alternator back on and test charging system at two different auto stores, it says bad voltage regulator. They both say my battery is good.
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Thursday, August 30th, 2018 AT 8:11 AM
Tiny
ASEMASTER6371
  • MECHANIC
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The voltage regulator is inside the alternator.

You need to return it and get another brand of the alternator. If all the wiring is good and you have correct voltages to the alternator, then the only thing left is the alternator.

Roy
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Thursday, August 30th, 2018 AT 8:25 AM
Tiny
CHJ
  • MEMBER
  • 12 POSTS
It is the same as the original one and I put it on ten months ago.
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Thursday, August 30th, 2018 AT 8:51 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Apparently, the AutoZone ones are not working. You need another parts store and try their brand.

Roy
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Thursday, August 30th, 2018 AT 8:56 AM
Tiny
CHJ
  • MEMBER
  • 12 POSTS
Went to AutoZone after work today. They only carry one brand, so what they going to do is exchange it. Instead of a re-manufactured one, I am getting a brand new one. It will be there Saturday. Hopefully it does the trick.
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Thursday, August 30th, 2018 AT 5:37 PM
Tiny
ASEMASTER6371
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Okay.

Keep me updated with the result.

Roy
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Friday, August 31st, 2018 AT 1:24 AM
Tiny
COREY H JENKINS
  • MEMBER
  • 80 POSTS
Put the new alternator (not a refurbished one) on this morning.
Got my voltage tester on it. When car is running and I touch the posts on battery, it reads 12.7. Same as when it is not running. But when running and I touch the hot wire on back of alternator and the negative post on battery, it reads 14.7. And touching same when it is not running, it reads 12.7
Does this mean the voltage regulator is working?
Thanks
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Sunday, September 2nd, 2018 AT 8:52 AM
Tiny
ASEMASTER6371
  • MECHANIC
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If you have 14.7 coming out of the back, the alternator is working.

You have an issue with the wire from the battery to the alternator.

When it is not running you will only have battery voltage.

Roy
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Sunday, September 2nd, 2018 AT 10:55 AM

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