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1993 Silverado 1500 200000 miles electrical issue


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lhsmith1007
New User

Apr 16, 2017, 5:14 AM

Post #1 of 7 (1329 views)
1993 Silverado 1500 200000 miles electrical issue Sign In

My truck recently has been acting odd electrically. When the vehicle is running the gauge for the battery used to read 14 volts but recently has been dropping down into the 9 range and will even drop into the critical range if I try to turn the lights on high beam or use the power windows. Yet when I test the battery and the alternator with a voltmeter it reads 12.5 Volts for the battery when the vehicle is off and 14.4 volts when the engine is running both at the alternator and at the battery. I noticed a foul electrical smell also yet I am stumped. Any help is deeply appreciated. Thank you


Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 16, 2017, 5:30 AM

Post #2 of 7 (1321 views)
Re: 1993 Silverado 1500 200000 miles electrical issue Sign In

You need to know gauge is in fact wrong now as your readings are correct for this. What to do for a 1993 I'd watch it inside using a power port/cig lighter as your new gauge. The odor just might be the gauge or dash has a problem and burned out or still in trouble? Can't say unless you dig in more to find out.


What you need to know is it NEVER drops below 9V even while cranking and while running shouldn't really drop below ~13V while using headlights and blower fan on high both a high draw on alternator or it can't keep up. That's telling of its amp ability.


OK - the easy thing isn't sold at any stores I know of. Search out Ebay and Amazon for a 12V cigarette or power port volt meter. They just plug in and show LED what actual voltage is as long as you have it pushed in. This vehicle ports and or lighter are empowered with engine off and key out - some are not,


T
(edit pic of what I mean if it stays showing, Ebay $4 you can find for less)
>>



(This post was edited by Tom Greenleaf on Apr 16, 2017, 5:40 AM)


Hammer Time
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Apr 16, 2017, 6:26 AM

Post #3 of 7 (1300 views)
Re: 1993 Silverado 1500 200000 miles electrical issue Sign In

It is very possible that your alternator has diminished capacity and only fails under load. It requires some additional testing under load.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 16, 2017, 6:32 AM

Post #4 of 7 (1296 views)
Re: 1993 Silverado 1500 200000 miles electrical issue Sign In

Yes! You might see black or ash around alternator or find it much too hot quickly? Careful of course touching a running alternator (engine on) or better a wet rag see if it boils right off instantly maybe. My own hand are burned enough they don't care anymore - don't do that,


T



lhsmith1007
New User

Apr 16, 2017, 10:41 AM

Post #5 of 7 (1268 views)
Re: 1993 Silverado 1500 200000 miles electrical issue Sign In

Thanks for all your help so far I have a question though : remember that my power starts dropping at night the minute I try and turn on high beams or other electrical components so must it be the alternator or can it be something else I can't think of anything else. I agree that the gauge could be misleading but the minute I turn on those components all the power goes off


Hammer Time
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Apr 16, 2017, 11:14 AM

Post #6 of 7 (1262 views)
Re: 1993 Silverado 1500 200000 miles electrical issue Sign In

We don't use the "must be" form of diagnosis. We use testing.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 16, 2017, 11:50 AM

Post #7 of 7 (1256 views)
Re: 1993 Silverado 1500 200000 miles electrical issue Sign In

OK - you can't wait if does it while running that's too low without two power windows (or motor things) and headlights while running is NG. But it doesn't mean any specific thing just yet. Watch it do that with a voltmeter. Don't wait either make this next on your list.


Alternators if a common Delphi I think will burn up and try so hard make the odor and the heat I mentioned. Never minds what's inside that can do that you don't seem the type to take it all apart and not worth it anyway.
Not all but most will be HOT and show it. By this age it might have already burned up a fusible link to alternator would go first as a guess. IF YOU TEST AND CAN BLAME AN ALTERNATOR don't forget you probably have to change the fins if rebuilt or not either way keep you core for a while and get deposit back later ONLY if you test it bad,


T







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