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jz56oval
Samba Member
Joined: September 03, 2007
Posts: 375
Location: bay area
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 Posted: Sat Feb 28, 2015 9:56 am Post subject: Alternator light comes on |
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Not sure where to put this question.
I'm having a problem with my altenator light. Both light come on when ignition is turned ON. After I start the car and let idle the light lightly glows but when I Rev the engine it turns bright and then dims when idling. This is in a '56 beetle that has been converted to 12volt. I have never seen this since I had it , started doing this yesterday. Converted to 12 volt back in 2004.
Could I take the leads off the battery while running and see if it idles or just dies, for a test?
Has anyone had this happen before?
Last edited by jz56oval on Sat Feb 28, 2015 12:27 pm; edited 1 time in total |
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57BLITZ
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Joined: June 12, 2012
Posts: 2385
Location: DEEK - U.S.A.
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| Posted: Sat Feb 28, 2015 11:53 am Post subject: Re: oil light comes on |
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| jz56oval wrote: |
Could I take the leads off the battery while running and see if it idles or just dies, for a test?
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Don't do that!
You have an alternator . . . . not a generator?
Do you have a VOM?
BTW . . . the title of your thread is "oil light comes on" is confusing . . . the oil pressure light illuminates when there is low oil pressure! I am guessing that you are actually asking about the "charging" light, correct?
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Danwvw
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Joined: July 31, 2012
Posts: 8892
Location: Oregon Coast
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| Posted: Sat Feb 28, 2015 12:28 pm Post subject: |
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The Oil light comes on where there is no oil pressure! But it sounds like you meant to say Alt/Gen light in your subject! When Alt/Gen light get brighter like that when revved up it means they aren't charging. If it still has a generator it could just need a voltage regulator. If it is an alternator it sounds like the alternator has gone bad.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths! |
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jz56oval
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Joined: September 03, 2007
Posts: 375
Location: bay area
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| Posted: Sat Feb 28, 2015 12:29 pm Post subject: |
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| Oops. Just changed the title. I will test with a voltage meter when running. Just wasn't sure if anyone has had this issue where the light gets brighter when revved. |
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Danwvw
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Location: Oregon Coast
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jz56oval
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Joined: September 03, 2007
Posts: 375
Location: bay area
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| Posted: Sat Feb 28, 2015 3:55 pm Post subject: |
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So, with my voltage meter connected to the battery. With the car idling I'm getting 12.08 volts and when driving I'm getting no more than 13.12 volts. Sounds like I have a dying alternator?
What do you guys think? |
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Danwvw
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Joined: July 31, 2012
Posts: 8892
Location: Oregon Coast
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| Posted: Mon Mar 02, 2015 10:32 pm Post subject: |
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Some voltmeters are a little off. A fully charged 12 volt battery in a bug will read 12.6 volts with the key off engine stopped! You can almost calibrate your meter by the 12.6 volt number. Of course if the battery is bad or discharged it will read less.
A good VW alternators will charge to 13.8 to 14 volts dc at a fast say 900 rpm idle. and read about the same 14 volts or so at driving Rpms.
Generators will drop off more at Idle. say to 13 volts then go to 14 volts driving.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths! |
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jz56oval
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Joined: September 03, 2007
Posts: 375
Location: bay area
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| Posted: Mon Mar 02, 2015 10:38 pm Post subject: |
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| Thanks for the help. I believe it to be bad so I bought a life time warranty alternator at autozone. |
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