Car Trouble.....WTF?

I've got a 2002 S-10 LS, Reg. cab, 4.3L V-6, 47K miles. Only options are CC, cd player, & a/c. A little history:
3 Years ago the Delco (pos) battery cracked and leaked out all over the wheel well. Replaced it w/ NAPA '65' batt., and replaced the serpentine belt while I was in there. Fast forward to the Sunday night. Take the truck out, drive all over Columbia, get home, no problems.
Monday night, truck wouldn't start, NADA! Today I jump it with my co. van and check the voltmeter after taking the cables off. When idle, it runs at 14+V. but when I put a load on it, it starts to dip below 14?
And when I shut it off, then restart it, it'll run below 14, until I step on the gas?
So, is it the alt., battery, computer????
Any help is appreciated.

my regulator went bad in mine and those sound about like the issues i was having. i replaced the alternator since i couldn't just replace the regulator no problems now

Alternator. Very easy to swap out- you could probably do it in the parking lot of the automotive store in about 30 minutes and get your deposit back w/o having to go back.

Thanks. That's what I figured it was, but it's been SOOOOO long since I've had to diagnose a car! I think I'll go with a NON Delphi one this time.
Any recommendations for an aftermarket alternator is also, GREATLY appreciated.

Easy way to find out. Loosen the battery cable but leave it connected.

Start the vehicle.

Let it run for a couple of minutes.

Pull the battery cable off of the battery while the car is running. Be careful. This could be a shocking experience if you are careless.

Is the car still running?
- Yes - Your battery is bad
- No - Your alternator is bad.

Another option is to remove said battery from vehicle and take to AutoZone or Pep Boys and have them test it. They should also be able to test an alternator. You can pull that too.

But, if the car starts with a jump and drops voltage quickly when a load is put on it, that's likely the battery. If the car started when jumped and died as soon as the cables were removed, that's a charging problem and either the alternator or voltage regulator or both are bad. You likely have a bad battery and it it should be under a NAPA warranty still.

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Originally Posted by obieone

I've got a 2002 S-10 LS, Reg. cab, 4.3L V-6, 47K miles. Only options are CC, cd player, & a/c. A little history:
3 Years ago the Delco (pos) battery cracked and leaked out all over the wheel well. Replaced it w/ NAPA '65' batt., and replaced the serpentine belt while I was in there. Fast forward to the Sunday night. Take the truck out, drive all over Columbia, get home, no problems.
Monday night, truck wouldn't start, NADA! Today I jump it with my co. van and check the voltmeter after taking the cables off. When idle, it runs at 14+V. but when I put a load on it, it starts to dip below 14?
And when I shut it off, then restart it, it'll run below 14, until I step on the gas?
So, is it the alt., battery, computer????
Any help is appreciated.

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Alternator. Pull it and have the output checked.
I always hate the battery/alternator question.
That's why I got a clamp on amp gauge and a
battery load tester from a pawn shop. Sometimes
it's hard to tell what's bad. It's a lot easier when the
damn thing just goes dead instead of kinda working.

Thanks Jstas. I think I'll just replace both. If I can get the battery under warranty, great. If not I'll live.
I'm just real paranoid about getting stuck somewhere. Especially with this damn cold snap we've been having.

Thanks S2BM too.

the alternator test that auto zone and other stores like them do doesn't test the regulator though. when i went in and had auto zone test mine the voltage meter in my jeep was at 10 and the guy told me that my alternator was working fine and it was my battery so he tested that and it was fine, he then just basically walked away with a puzzled look on his face. called my mechanic in Boise and he said it was the regulator and unfortunately it's inside the alternator so new alternator.
ordered a Mean Green for just under 400 from the manufacture figured if i was going to replace might as well get a good one :)

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Originally Posted by ntculenuff

the alternator test that auto zone and other stores like them do doesn't test the regulator though. when i went in and had auto zone test mine the voltage meter in my jeep was at 10 and the guy told me that my alternator was working fine and it was my battery so he tested that and it was fine, he then just basically walked away with a puzzled look on his face. called my mechanic in Boise and he said it was the regulator and unfortunately it's inside the alternator so new alternator.

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If he tested your alternator and found it to be good then he didn't hook the machine up right.

I worked at Pep Boys, tested dozens of alternators. Our machine would test the alternator output levels and the voltage regulator on alternators with an internal regulator. Or I could hook it up just to see if the alternator was putting out power. That was 10 years ago. If they can't do it now then things have taken a step backwards.

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Originally Posted by Jstas

If he tested your alternator and found it to be good then he didn't hook the machine up right.

I worked at Pep Boys, tested dozens of alternators. Our machine would test the alternator output levels and the voltage regulator on alternators with an internal regulator. Or I could hook it up just to see if the alternator was putting out power. That was 10 years ago. If they can't do it now then things have taken a step backwards.

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wouldn't be surprised :rolleyes:

LOL! 30 seconds after my last post, my cell phone rings.
It's Allstate trying to sell me their version of AAA. Unlimited towing, tire change outs, yada, yada, yada. Special offer of 2 months for $1, then $14/ month after that.
I cancelled my AAA membership a couple of months ago, because I THOUGHT I had a 'bulletproof' vehicle.:p
Well, at least HE was kind enough to make it break down in my driveway:rolleyes::)

BTW, I did an amp check. 3.6-3.7 amps between alt. and batt. with and without a load?

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Originally Posted by Jstas

If he tested your alternator and found it to be good then he didn't hook the machine up right.

I worked at Pep Boys, tested dozens of alternators. Our machine would test the alternator output levels and the voltage regulator on alternators with an internal regulator. Or I could hook it up just to see if the alternator was putting out power. That was 10 years ago. If they can't do it now then things have taken a step backwards.

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Yup. Trained monkeys at the counter. Autozone=lukewarm bodies.
O'reilly is better. At least here local. The really good counter guys are at
NAPA.
I work under the idea that once a battery get 2 or 3 years old and
gets discharged down too low to start, replace. The strain seems
to shorten the life of the battery. Better to change the battery at the same
time as the alternator. It sure beats walking.

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Originally Posted by Jstas

Easy way to find out. Loosen the battery cable but leave it connected.

Start the vehicle.

Let it run for a couple of minutes.

Pull the battery cable off of the battery while the car is running. Be careful. This could be a shocking experience if you are careless.

Is the car still running?
- Yes - Your battery is bad
- No - Your alternator is bad.

Another option is to remove said battery from vehicle and take to AutoZone or Pep Boys and have them test it. They should also be able to test an alternator. You can pull that too.

But, if the car starts with a jump and drops voltage quickly when a load is put on it, that's likely the battery. If the car started when jumped and died as soon as the cables were removed, that's a charging problem and either the alternator or voltage regulator or both are bad. You likely have a bad battery and it it should be under a NAPA warranty still.

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That kind of a test is real "old school" and a big NO-NO with more modern electronics and computers in cars. You run a real risk of causing major damage such as frying the computer.

The very first thing is to test the battery. If it fails the test, replace it. The battery must be in good shape to test the alternator properly (alternator still in the car).

All this assumes of course that you have good clean connections to the battery and to the battery ground.

Joe

Thanks for getting here before I could, Joe! Another vote for NOT disconnecting the battery while the vehicle is running!!!

Also, it is true that a bad battery will cause an alternator to test bad. Go to AZ, have them test the battery under load. If it passes, good. Now test the alternator.

Also note that the battery has to be fully charged to test. A bad alt could cause the battery to test bad in the vehicle if it's not fully charged. Autozone offers charging for free as well, on 1 hour peak chargers. Then they can test it from a full charge. This will remove the alternator from the equation altogether.

ALSO, autozone can test most voltage regulators if they're external. There's a separate machine to do this inside the store. The pushcart alternator tester also checks the regulator, but it's only based on output voltage. Too high/too low will fail.

Wow.

Number one, pulling the battery cable while the battery is still grounded and the alternator is putting out power is not going to fry anything. The alternator is putting out more power than the battery is anyway and the battery doesn't put out power unless a connection is established so that some circuit can draw power from the battery. If you are pulling the connection, especially on a car that had to be jump started, you are not going to cause any kind of surge because there is no grounded connection that shorts the battery's chassis ground. Is there a risk for damage? Yeah, if you do it to a healthy charging system. But if the battery is dead and you pull the positive cable, you aren't doing anything because the car is already running on the alternator. If the alternator is bad and the battery is dead then the car wouldn't be able to remain running after the jump start was complete.

Secondly, a bad battery will not cause an alternator to test bad. The alternator is capable of generating enough power to run the car and charge the battery. If the alternator cannot do both or just one, it's bad. Alternators either work or they don't. There is no in between. Even if you think there is, an alternator should not drop in voltage when load is applied unless the alternator is bad. That's why it has a voltage regulator. If the battery has a bad cell, it will also cause a drop in voltage but the alternator should be able to compensate. If not then the bad cell has likely burned up the alternator and both have to be replaced.


Then again, I was thinking about this earlier. Check your ground and power cables and the grounding strap from the engine to the frame. If any of them look ratty, replace them first. You may not need to replace a battery or alternator. Chevies are notorious for eating grounding straps.

Be aware; that having a bad battery and mostly running the vehicle off the alternator for long periods of time puts a lot of strain on it, causing it to fail early.

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Originally Posted by Jstas

Alternators either work or they don't. There is no in between.

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There is an in between; alternators can exhibit varying degrees of failure. A single diode can fail, and it will reduce the alternators output current while the gauge will show voltage in the 13-14v range. Voltage and current will fall under increased load.

Aside from what has been mentioned about disconnecting a battery while the engine is running, I’d be concerned about sparks around the battery. My bud Doug blew up a battery like that at a Texaco station around 35 years ago.

Have/can you test the alternator under a "load" ? My guess that the alt. is beginning to fail. Good luck,,something similar happened to me,,replaced the alt,,, and the replacement went bad after about a month,,replaced that one,, been fine since( 3 years),Personally,, I like the "hi" output versions,, at least 200 watts:D;):eek:

having a fantastic wrench-head in the family












priceless :)

Edit: nevermind, reread the original quote.

Do you get Disco Lights? Do your headlights pulse?

I would guess it is the alternator. But if you are willing to change both I say go for it. Usually what I do in this situation also.

I've had gauges fluctuate, depending on the load, and there was nothing wrong with either the battery or the alternator.

What year was it when GM finally ditched the generator for the alternator? I know it been a long time, but can't recollect when.

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Originally Posted by george daniel

Have/can you test the alternator under a "load" ? My guess that the alt. is beginning to fail. Good luck,,something similar happened to me,,replaced the alt,,, and the replacement went bad after about a month,,replaced that one,, been fine since( 3 years),Personally,, I like the "hi" output versions,, at least 200 watts:D;):eek:

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I think you meant 200 AMPS...

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Originally Posted by TNRabbit

I think you meant 200 AMPS...

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Probably. But beware of these 'high output' alternators. A lot of time, they arent as good as stock in the 'usable' rpm range. Meaning yea, theyll put out 200A at 5krpms, but from idle to highway cruising speed, your factory does better.
-Cody

Quote:

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Originally Posted by george daniel

Have/can you test the alternator under a "load" ? My guess that the alt. is beginning to fail. Good luck,,something similar happened to me,,replaced the alt,,, and the replacement went bad after about a month,,replaced that one,, been fine since( 3 years),Personally,, I like the "hi" output versions,, at least 200 watts:D;):eek:

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Did Cathy recommend that alternator;)

exalted512 "Music is like candy, you have to get rid of the rappers to enjoy it"

Now that is just funny :)

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Originally Posted by ben62670

Did Cathy recommend that alternator;)

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I was just being sarcastic about the 200 watts,, Ben "got it" ;)

[QUOTE=Jstas;957690]Wow.

Number one, pulling the battery cable while the battery is still grounded and the alternator is putting out power is not going to fry anything. The alternator is putting out more power than the battery is anyway and the battery doesn't put out power unless a connection is established so that some circuit can draw power from the battery. If you are pulling the connection, especially on a car that had to be jump started, you are not going to cause any kind of surge because there is no grounded connection that shorts the battery's chassis ground. Is there a risk for damage? Yeah, if you do it to a healthy charging system. But if the battery is dead and you pull the positive cable, you aren't doing anything because the car is already running on the alternator. If the alternator is bad and the battery is dead then the car wouldn't be able to remain running after the jump start was complete.

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I disagree:
**The alternator needs to see a load, a dead or weak battery can still provide some load for the alternator. Disconnecting the battery while the engine is running can cause the alternator to "spike" and result in other damage.

http://www.aa1car.com/library/charging_checks.htm *Read the line in red*

And read the first line: http://wiki.answers.com/Q/How_do_you..._using_a_meter

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Secondly, a bad battery will not cause an alternator to test bad. The alternator is capable of generating enough power to run the car and charge the battery. If the alternator cannot do both or just one, it's bad. Alternators either work or they don't. There is no in between. Even if you think there is, an alternator should not drop in voltage when load is applied unless the alternator is bad. That's why it has a voltage regulator. If the battery has a bad cell, it will also cause a drop in voltage but the alternator should be able to compensate. If not then the bad cell has likely burned up the alternator and both have to be replaced.

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Again I disagree:
**I've been in the automotive repair business for over 20 years, though I don't work directly on cars anymore, I do make all the estimates and order the parts for the technicians and keep the work flowing. We've got 17 bays and on slow days we service about 30 to 50 cars and on busier days we see upwards of 100 cars.

With certain technicians, I trust their diagnosis of the repair required on the car. With others, I go check the car myself and they need to convince "me" of the required repair before I write up an estimate.

So...when one of my lesser experienced techs tells me that a 2001 Accord needs a battery and an alternator, I have a hard time believing it even when he tells me that that is the result of his test. I give him a battery and tell him to come back with the results "after" he does his test with the new battery. More often that not, the alternator is 'miraculously' alright after it is tested with a good battery.

Now on the other hand, if its' been raining hard for a few days I can pretty much guarantee you that a few Mazda MPV's will be coming in needing alternators.

I've seen and been involved in the repair of so many thousands of cars I practically know what they need before they even get up on the lift.

Joe

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Originally Posted by joeparaski

I've seen and been involved in the repair of so many thousands of cars I practically know what they need before they even get up on the lift.

Joe

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Damn. Why do you have to live in Canada instead of Texas?
I can't seem to find a place that knows crap about cars.
Techs seem to break stuff every time they get close.
I've had to go back to wrenching my own stuff again.

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Originally Posted by Jstas

Wow.

Number one, pulling the battery cable while the battery is still grounded and the alternator is putting out power is not going to fry anything. The alternator is putting out more power than the battery is anyway and the battery doesn't put out power unless a connection is established so that some circuit can draw power from the battery. If you are pulling the connection, especially on a car that had to be jump started, you are not going to cause any kind of surge because there is no grounded connection that shorts the battery's chassis ground. Is there a risk for damage? Yeah, if you do it to a healthy charging system. But if the battery is dead and you pull the positive cable, you aren't doing anything because the car is already running on the alternator. If the alternator is bad and the battery is dead then the car wouldn't be able to remain running after the jump start was complete.

Secondly, a bad battery will not cause an alternator to test bad. The alternator is capable of generating enough power to run the car and charge the battery. If the alternator cannot do both or just one, it's bad. Alternators either work or they don't. There is no in between. Even if you think there is, an alternator should not drop in voltage when load is applied unless the alternator is bad. That's why it has a voltage regulator. If the battery has a bad cell, it will also cause a drop in voltage but the alternator should be able to compensate. If not then the bad cell has likely burned up the alternator and both have to be replaced.


Then again, I was thinking about this earlier. Check your ground and power cables and the grounding strap from the engine to the frame. If any of them look ratty, replace them first. You may not need to replace a battery or alternator. Chevies are notorious for eating grounding straps.

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I found some more info on the net. This guy puts it in words better than I can. Here is what he says on the subject of disconnecting the battery while the car is running:

DON'T do it! Here's the short and simple of it. The alternator produces electricity and the amount it produces is determined by the voltage regulator. The voltage regulator determines how much electricity is needed by monitoring the battery voltage. A battery is like a sponge for electricity. When discharged the voltage is low and it's like a light weight, dry sponge and will "soak" up lots of electricity. When it is fully charged, the voltage is higher and it's like a sponge soaked full of water, heavy and unable to soak up more. Try to put too much electricity into a fully charged battery and it gets hot and boils the water out, just like that full sponge dripping out water. When the engine is running and you disconnect the battery, the voltage regulator senses very low, actually no voltage, and tells the alternator to produce as much electricity as it possibably can. Instead of the voltage being regulated at around a maximum 14.7 volts like normal, it shoots up to around 18 volts, all the alternator can produce. That fries bulbs, voltage regulators, ignitors, fuel injection components and so on. Even a totally dead, non-operative junker battery will soak up electricity (unless bone dry)and keep you from frying the electrical system, it just won't hold a charge, just like a bucket with a hole in the bottom.

So don't listen to what others claim to know, no matter what they tell you. I've been around a long time, have worked on just about everything and I actually know mechanical and electrical theory (how and why things work), something a lot of so called mechanics don't.