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chevy s-10 charging problem
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hds1o
New User
Nov 29, 2008, 12:01 PM
Post #1 of 7
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chevy s-10 charging problem
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Heres a hard one...this question has to do with a 2002 chevy s-10 4.3l with the 5 speed. The truck has 60,000miles. Engine is stock. Truck does have a large sound system.
The issue I'm having is the charging at idle. Now before I tell you the problem, I did replace the battery with an optima red top, and a new alternator. I also ran new cable from the alt to batt, and left the stock wiring as well. All the connections are really clean and tight. Its is a stock 105 amp alternator, but the problem was there before the battery and alternator replacment, and I have not cranked the stereo up since replacing the parts.
My problem is after the engine is warm, when Im slowing down to come to a stop, the voltage drops to 9v for about 4 seconds then goes back to 14. It does recover on its own at idle without me hitting the gas and reving the engine. Its fine at cruise and idle, but for some reason, does not like when the rpm is coming to idle. Its happens everytime I slow down, or if im just sitting there and rev the engine, when the rpms drop to idle the volts drop lights dim, blower slows down then its like the alternator turns back on. I dont get it. It happens day or night, does not seem to matter if anything is on or not. It just seems to be a rpm issue. I have cranked the stereo with the lights on and wipers at idle and its at about 13v. But if the engine is slowing down even with everything off it will drop low enough to almost kill the engine. but comes back to life in a few seconds or if i tap the gas. Like i said, its been doing this for a while, even before i put in the new parts. Any ideas????
Thanks!!!!!
Eric
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 29, 2008, 2:19 PM
Post #2 of 7
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Re: chevy s-10 charging problem
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Guess: Weak grounding somewhere - either at engine from battery or from engine to body,
T
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hds1o
New User
Nov 29, 2008, 2:40 PM
Post #3 of 7
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Re: chevy s-10 charging problem
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Do you think adding a couple 4 gauge ground cables would do it? Im thinking one off the alternator mounting bolt to frame, and battery to frame.
(This post was edited by hds1o on Nov 29, 2008, 2:42 PM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 29, 2008, 6:06 PM
Post #4 of 7
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Re: chevy s-10 charging problem
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First look for any originals that are broken. They hide them here and there and they can either break right off or just not make a good connection. If you find them and they don't look great fix up those and I say it's fine to add more but don't let wire get in the way or rub anything else.
Seeing 9v is a bit extreme. The starter motor doesn't pull most down that far so I think you are seeing a poor return loop and it could be one of these.
Just remember that battery needs make a good ground to block of engine same as the starter does or anything it also is "block" connected. Block then must ground body. You'll see that in some vehicles the metal structure of dash parts also has an extra strap to body. GM and others hide them all over the place and you could use good jumper wire to know which might be the trouble now if this is it at all but they shouldn't hurt anything to just up and add them.......
T
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hds1o
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Nov 29, 2008, 9:28 PM
Post #5 of 7
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Re: chevy s-10 charging problem
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Cool, I'll give that a try tomorrow if the weather isnt too nasty. Now that I think about it, what your saying makes sense. The truck sat alot before I bought it (9,000 miles in late 05) Maybe one of those grounds has corrosion from sitting so much like alot of the frame and engine bay did before I cleaned it up. I still have some leftover 4 gauge from the stereo and some lugs so it will be nice if I can get this fixed for free. Thanks for the help!
Eric
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hds1o
New User
Nov 30, 2008, 2:09 PM
Post #6 of 7
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Re: chevy s-10 charging problem
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Well, checked out the grounds...everything looked good. Also added some cables, which I found out is a common thing among the big sound system guys...they call it "the big three" (+alt to batt,- chassis to batt,- engine to batt). Anyway, it didnt solve the problem . Any chance I just got a bad alternator? I'm not sure how it regulates...but it seems like it thinks when I let off the gas and hit the clutch to come to a stop it thinks its over charging or something. Its like someones hitting a switch and just turning it off for a few seconds. I would hate to take it to a dealer or shop and them to just blame the stereo even though I havent had it loud since installing this alt and battery.
Any other ideas come to mind?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 30, 2008, 4:41 PM
Post #7 of 7
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Re: chevy s-10 charging problem
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Just how many amps does this sound system draw? Will this show that 9v thing if you shut it off? Showing 9v with a good strong battery is very low IMO suggesting more draw than most starter motors use while cranking!
The brute power of a battery is it's "cold cranking amps" and once running the alternator restores it to full charge and then the alternator is really running the electrical devices - WHILE RUNNING. Battery should cover momentary dips below what alternator can provide like low rpms or using too many items all at once like the moment of using a power window and a power seat perhaps at the same time - you wouldn't notice.
Note: Most GM alternators use an internal voltage regulator, there to prevent OVERCHARGE and does permit full alternator output when it senses battery is low. Alternators in general will put out maximum of their rated amps at about 1,500 rpm but frequently still put out substantial amps at normal idle speeds.
For the moment it's not the alternator IMO. The battery if really showing 9v AT THE BATTERY is really getting a work out and may be under powerful for this vehicle with that sound system anyway.
For right now - just tell me/us if you can see that 9v with the stereo OFF and what do you think or are told it draws for amps?
T
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