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Blackkats_
Samba Member
Joined: March 01, 2019
Posts: 6
Location: Los Angeles
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 Posted: Mon Dec 02, 2019 1:20 pm Post subject: Idiot light? |
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Driving on my way cross country, CA-MA, so options are limited. Wondering if there is any danger in driving with the alternator/ generator light on as long as I'm certain the fan is not slipping. Cylinder head, oil pressure and oil temp are good.
Running a MST serpentine belt system so relatively confident ripped belt shouldn't be an issue. If it was I would see an immediate increase in engine temperature. Not sure what is causing the light to stay on. Guessing its just an alternator issue but it also seems to be charging fine. Idle is fine. Want to make sure I'm not overlooking anything big. Thanks |
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74 Thing
Samba Member
Joined: September 02, 2004
Posts: 7389
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| Posted: Mon Dec 02, 2019 2:07 pm Post subject: Re: Idiot light? |
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Get a volt meter and test the output with the alternator running at the battery (should be approx 13.8-14.8v or so at around 2k rpms).
It could be your fuse or the light bulb in your dash (check and replace those first).
It can also me your regulator or brushes.
If the light is on it should not be charging. |
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Blackkats_
Samba Member
Joined: March 01, 2019
Posts: 6
Location: Los Angeles
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| Posted: Mon Dec 02, 2019 2:48 pm Post subject: Re: Idiot light? |
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| The light goes goes out at sustained high Rpms. If it wasnt charging wouldn't that me a my car wouldn't be able to idle? My guess is that it probably is the brushes. Just trying to figure out what the danger is driving on it other then not charging the battery. Thanks again |
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oprn
Samba Member
Joined: November 13, 2016
Posts: 12683
Location: Western Canada
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| Posted: Mon Dec 02, 2019 7:30 pm Post subject: Re: Idiot light? |
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| Idle would not be effected. |
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slalombuggy
Samba Member
Joined: July 17, 2010
Posts: 9143
Location: Canada
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| Posted: Mon Dec 02, 2019 8:29 pm Post subject: Re: Idiot light? |
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| Turn the key on engine off. Take the small wire off your generator and see if the light goes out. If it does your alternator is not charging. Usually the diodes start to go. With the engine running take a volt meter set on AC voltage and test the B+ terminal on the alternator. Anything more than .5v means a diode is going. |
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YDBD
Samba Member
Joined: February 25, 2017
Posts: 890
Location: Bavaria, Germany
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| Posted: Mon Dec 02, 2019 9:31 pm Post subject: Re: Idiot light? |
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Check the wires-most likely a loose connection or ground on the speedo or ignition switch.
_________________
'56 pan Dune Buggy since '69
don't live in the past...but when I did:
'67 bug
'64 baja
'60 dune buggy
'73 Personenkraftwagen Type 182 "Thing" |
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ekacpuc
Samba Member
Joined: December 08, 2010
Posts: 1414
Location: ketchikan alaska
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| Posted: Mon Dec 02, 2019 11:51 pm Post subject: Re: Idiot light? |
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It’s been awhile but I remember tapping the brushes helped sometimes.
The danger is you’re battery is gonna be totally dead. |
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jeffrey8164 
Samba Member
Joined: January 06, 2018
Posts: 3811
Location: Georgia
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| Posted: Tue Dec 03, 2019 12:46 pm Post subject: Re: Idiot light? |
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Pull the positive off the battery with the engine running.
If the car dies your alternator is out and the car is running off the battery only.
You won’t damage anything running this way but as soon as the battery goes away, so will your locomotion.
_________________
Volkswagen!
Turning owners into mechanics since 1938.
“Let he that is without oil throw the first rod”
(Compression 8.7:1) |
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Cusser
Samba Member
Joined: October 02, 2006
Posts: 31352
Location: Hot Arizona
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| Posted: Tue Dec 03, 2019 1:04 pm Post subject: Re: Idiot light? |
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| jeffrey8164 wrote: |
Pull the positive off the battery with the engine running.
If the car dies your alternator is out and the car is running off the battery only.
You won’t damage anything running this way but as soon as the battery goes away, so will your locomotion. |
FALSE. NEVER PULL A CABLE OFF A BATTERY WHILE THE ENGINE IS RUNNING ON AN ALTERNATOR-EQUIPPED VEHICLE !!!! EVER !!!
Gomer and Goober were too dumb to have a voltmeter or multimeter and/or didn't know how to use it. But that was in the day of GENERATOR-equipped vehicles, you'll kill an alternator most times if you do jeffrey8164's "test".
Correct way to test if VW is charging: use DC volt range 0-20. Put voltmeter cables across the battery cables, start the engine. At about 2000-3000 rpm voltage should read about 13.5 to 14.5 volts.
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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jeffrey8164
Samba Member
Joined: January 06, 2018
Posts: 3811
Location: Georgia
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| Posted: Tue Dec 03, 2019 1:26 pm Post subject: Re: Idiot light? |
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| Cusser wrote: |
| jeffrey8164 wrote: |
Pull the positive off the battery with the engine running.
If the car dies your alternator is out and the car is running off the battery only.
You won’t damage anything running this way but as soon as the battery goes away, so will your locomotion. |
FALSE. NEVER PULL A CABLE OFF A BATTERY WHILE THE ENGINE IS RUNNING ON AN ALTERNATOR-EQUIPPED VEHICLE !!!! EVER !!!
Gomer and Goober were too dumb to have a voltmeter or multimeter and/or didn't know how to use it. But that was in the day of GENERATOR-equipped vehicles, you'll kill an alternator most times if you do jeffrey8164's "test".
Correct way to test if VW is charging: use DC volt range 0-20. Put voltmeter cables across the battery cables, start the engine. At about 2000-3000 rpm voltage should read about 13.5 to 14.5 volts. |
Your opinion apparently.
I’ve done it many times and never damaged a thing, or a Bug, or Ghia, or a Honda, or a Ford, or a Chevy, or a Kia.
_________________
Volkswagen!
Turning owners into mechanics since 1938.
“Let he that is without oil throw the first rod”
(Compression 8.7:1) |
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jeffrey8164
Samba Member
Joined: January 06, 2018
Posts: 3811
Location: Georgia
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| Posted: Tue Dec 03, 2019 1:40 pm Post subject: Re: Idiot light? |
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Just for fun, I just did it to my Ford Ranger work truck.
Truck stayed running and according to my voltmeter is still charging just fine.
_________________
Volkswagen!
Turning owners into mechanics since 1938.
“Let he that is without oil throw the first rod”
(Compression 8.7:1) |
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slalombuggy
Samba Member
Joined: July 17, 2010
Posts: 9143
Location: Canada
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| Posted: Tue Dec 03, 2019 2:56 pm Post subject: Re: Idiot light? |
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When you pull the cable off the alternator goes full field and will eventually melt down as it tries to charge a dead (missing) battery The first thing I was taught as an apprentice is not to pull battery cables off a running engine. You can also create a hell of a spark putting it back on and of the battery has been charging and giving off hydrogen gas it will go bang. I had to take a coworker to the hospital with acid burns on his face hand, arms and eyes, he was fucked up for a month DON'T DO IT. On modern vehicles at also causes a huge power spike that can take out computers. Hook a fluke with a graphing feature up and do it and you can watch it.
brad |
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jeffrey8164
Samba Member
Joined: January 06, 2018
Posts: 3811
Location: Georgia
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| Posted: Tue Dec 03, 2019 3:02 pm Post subject: Re: Idiot light? |
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Call me Mr. Lucky I guess.
_________________
Volkswagen!
Turning owners into mechanics since 1938.
“Let he that is without oil throw the first rod”
(Compression 8.7:1) |
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Cusser
Samba Member
Joined: October 02, 2006
Posts: 31352
Location: Hot Arizona
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| Posted: Tue Dec 03, 2019 3:05 pm Post subject: Re: Idiot light? |
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| jeffrey8164 wrote: |
Just for fun, I just did it to my Ford Ranger work truck.
Truck stayed running and according to my voltmeter is still charging just fine. |
| jeffrey8164 wrote: |
Your opinion apparently.
I’ve done it many times and never damaged a thing, or a Bug, or Ghia, or a Honda, or a Ford, or a Chevy, or a Kia. |
So you've been lucky so far. Keep doing this and one day you'll kick yourself in the a$$ for not doing it the voltmeter way.
I'm sure you are very intelligent, and were a baby genius at some point. Do you know how to use a computer? If so, do a Google search and learn.
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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jeffrey8164
Samba Member
Joined: January 06, 2018
Posts: 3811
Location: Georgia
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| Posted: Tue Dec 03, 2019 3:15 pm Post subject: Re: Idiot light? |
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What’s a computer? Do PLC’s qualify?
Is everything on Google true and trustworthy?
Where have I been all these years?
Sorry. This is inappropriate and totally disrespectful to the OP.
I defer.
_________________
Volkswagen!
Turning owners into mechanics since 1938.
“Let he that is without oil throw the first rod”
(Compression 8.7:1) |
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