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Old 04-09-2016, 02:24 AM   #1
krajef
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Default alternator problem or not?


Hi my daughters friend visited the other day. He just got his drivers license and he's 19. He had his saturn L300 for two years but didn't drive it. His parents got it inspected and all that good stuff earlier in the week.

Low and behold, he gets his license and comes visit. He leave and his car stalls. We jumped it and it started but after 10 minutes started to idle slower until it died.

the next day I tested the battery with a load tester. the battery reported okay.

We cleaned the terminals

I put a ohm meter on the battery once the car started (jumped) and read a tad over 14 volts.

After 10 minutes the car idled down, the running lights shut off then the car stalled.

The next day I jumped the car. The ohm meter read 14+ volts again. I left the meter on and waited, The voltage started to decline after several minutes.. 12 volts, 11 volts, 9 volts and less and the car sputtered and stalled.

hmmm. I would like to help the kid out.

I put a code reader on it and there are 30 codes. All P
1887, 1860, 1845, 1818, 1816, 0757, 0756, 0752, 0751, 0742, 0716, 0503, 1845, 1843, 1842, 1833, 1831, 1791, 1779, 1621, U2107, 0741, 0727, 0603, 0602, 0601, 0563, 0562, 0502

I'm thinking the alternator is bad. I'm not certain on this.

My neighbor mentioned that some cars stop charging if the ECM instructs to stop charging, not sure if this is true.

Any thoughts

Thanks
Jeff

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Old 04-09-2016, 07:04 AM   #2
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L cars are notoriously sensitive to system voltage.

Apparently, too much of a drop in system voltage while cranking the engine, possibly caused by a tired old battery that, on top of that, sat dead dead dead for 2 years, will wreak havoc with the ECM as without the proper supplied V, it does not pull enough current to operate all of the sensors, switches, etc WHEN CRANKING. The problem is that it tries alot of these self tests in the middle of cranking. Silly but true. And other self tests are constantly running so if the car stalls out, ESPECIALLY in the manner described, it will generate a pile of nonsense codes as it tries to run these self checks to the bitter end, and logs more nonsense codes into the ECM's memory. I'm assuming this is the battery that had been in the car since he got the car as you mentioned load testing it but not replacing it (based on the results).
-------------------
In this case, batt may pass a load test with flying colors, but if the battery voltage while cranking is dropping too low, all hell breaks loose with the electronics, and it's not truly possible draw any conclusion from the codes because they are nonsense. But the PCM thinks the readings are real, so who knows what it is commanding what to do.
__________
I only looked up the first 15 codes or so; they were all tranny codes, so I recognized that these were all likely useless garbage -- but why?

The "why" is as already mentioned, the L car's extreme sensitivity to system voltage. So you have a pile of garbage codes generated at startup if the system V drops too low during cranking AND when the car stalls. Additionally you will see a similar pile of garbage codes right after you REPLACE a battery since the system V dropped below a threshold.
-----------
1)You cleaned the battery terminals; did you slit the insulation a few in to check for signs of corrosion? Also, is the neg batt connection to chassis ground clean and tight?

2) The fact that your alternator puts out less and less current as a function of time (since the output V is dropping) means (to me) either

a) the battery has a marginally bad cell which gets worse with heat, and the battery simply becomes incapable of storing what the alternator is trying to push because the bad cell causes the internal resistance of the battery to rise, and Ohm's law says V=IR, so R is rising fast, I is decreasing, leading to a lower system voltage as a function of time. The impedance (in this case = to the resistance) dictates how much current is demanded for a particular device, and the V changes accordingly per Ohm's law. As the internal resistance of a battery going bad increases, the current that can be pushed into it decreases and so does the voltage

= replace battery

b) the alternator has a heat related issue such as the diodes breaking down and shunting current to ground instead of the battery, and getting worse w time. Usually when a diode breaks down and fails, it cannot repair itself as it is a chemical change. But then again it could be a mechanical issue with the brushes and such causing less and less of an output as things heat up. I do not claim to know the inner workings of an alternator. If you are getting 14 ish V at the beginning it does not sound like a typical diode issue, but stranger things have happened

= replace alternator

How to differentiate between the two?

0) CLEAR ALL CODES BEFORE EACH RESTART
0.5 ) Have a buddy crank the engine while you measure the V across the batt. What is it?
1) Pull the alternator to have it bench tested OR better yet do a load test on the entire charging system at autozone or similar -- it's free. You may have to stop and recharge the batt on the way there, but......

2) swap the battery for a known good one (don't buy one yet -- I do not shotgun parts nor encourage others to do the same with THEIR money) with at least the same ratings for CA and CCA. Hopefully much newer. Monitor the Voltage output of the alt = V across batt under your same previous test conditions AND during cranking.

If the V at the alt output continues to fall as before, the alternator is the culprit.

If everything operates properly, then the battery is the culprit.
------------------
My money is on the.........(if I told you, I'd color your thinking)

Please post results.

This is a wonderfully instructive troubleshooting example (unfortunately at your expense.)
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Old 04-09-2016, 05:42 PM   #3
krajef
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Default 2 hour testing with results

Okay, hereís what Iíve done today. I swapped batteries with my battery from my 2002 Saturn SL2. My battery doesnít look new and I picked up my SL2 last May and I havenít changed my battery but it hasnít given me any problems yet.

In the process, I found my positive terminal on my SL2 was corroded so I cleaned my connectors and re-cleaned the L300 cutting away at those stupid rubber sleeves so I can assure that the entire connections are good though.

Okay back to the troubles L300. With my battery installed, terminals cleaned and my ohm meter attached. Battery voltage with the L300 off read 12.78. I started the car and let it idle for a 90 minute period and it ran okay. Iíve documented meter readings every 10 minutes and here they are while idling.
Note: I frequently checked to make sure the serpentine belt looked fine and that the alternator was spinning and it looked fine.

14.86
14.87
14.39
14.17
14.28
14.17
14.11
14.09
14.13

At this point I turned on the heater full blast, the flashers, high beams and the whippers for a 10 minute test. Start voltage read 13.57 and end reading was 13.38

I went into the cabin and noticed that the batt LED was on. I shut the car off and hooked up the code reader. There were no codes.

Started the car up and the batt led was on.

With the car off, read the volts and this reading was 11.96.
I restarted the car and the volts read 12.51 with everything off except for the runner lights.
At this point I swapped the batteries and concluded these tests for today.
Testing the original battery voltage in the L300 was 10.50

Thoughts?

Thanks!
Jeff
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Old 04-09-2016, 09:35 PM   #4
krajef
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Default one more test for today

I decided to jump the L300 and take another reading. Once I got her running, the volts read around 14.38 fluctuating up and down a bit as usual.

I decided to pull the negative terminal. As soon as the terminal came loose she died instantly.

Is the alternator bad?
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Old 04-11-2016, 09:07 AM   #5
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NEVER disconnect a battery terminal while the engine is running!

That test worked on the non-computer controlled cars back when they had generators and no solid state circuitry.

When you pull the Neg terminal, you risk the V output of the alternator spiking to the order of 100+ V, which the voltage regulator cannot possibly handle.

This CAN destroy the voltage regulator (inside the alternator), the alternator diodes mentioned earlier, and pretty much zap every electronic circuit in your car. Note I said CAN, not ALWAYS WILL.

So the results of that test mean nothing.
-------
The test with the other battery is perplexing.

the 1st 90 min show what appears to be a normalish alternator putting out good juice. However, assuming replacement battery is good, the output starts to droop with time, to a level unacceptable to the PCM. this turning on the batt light.

The added piece of info about the beginning V of the orig L300 batt being
in the 10-11V range is important-hat -but was that batt pulled fully charged???
_______
Do one more test:

outside of the vehicle, charge up the L300 battery.
Take a V reading when you take it off the charger.
Leave it alone till the next day and recheck the voltage.
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Old 04-12-2016, 01:25 AM   #6
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Well,

I think I will just call this one.

Your L300 battery un attached at any point at 10 to 11V indicates if cannot hold a full charge.
I would replace the battery.

The falling output of the alternator with time indicates to me that it is physically and/or electrically incapable of putting out maximum current when called on, leading to an output voltage droop and therefore current droop larger than the voltage regulator in the alternator can't handle if it is even still intact.
I would replace the alternator.

You already know what happens with a good battery and a bad alt; if you find my conclusion suspect, do the alt first and use your sl2 battery. You should see steady output s minimal droop.

And get a name brand one, not aifetime warranty Autozone special, unless you enjoy changing it out every 18 months or so
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Last edited by derfderf; 04-12-2016 at 01:28 AM..
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Old 04-13-2016, 12:52 AM   #7
krajef
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Default last test done

Sorry for the delay

Charged the battery yesterday afternoon. Once the charge was complete, the voltage read 12.34.

I put the battery in the car, leaving disconnected. I tested the voltage yesterday at 7:00PM and it read 12.25.

Today at 7:00PM I tested the voltage and it read 12.17.

I then connected the terminals and shut the hood.

I'll probably pull the alternator and have auto zone run a load test on their bench. On the other hand, I could have the fellow drive it for a day and monitor. Hmm, would you know if I can pull the alternator from the side after pulling the tire and covers or from underneath?

thanks!
Jeff
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Old 04-13-2016, 09:43 AM   #8
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So the L300 can hold an initial charge. Surprising.
But the difference in vehicle behavior vs your sl2 battery still bothers me.

Take the batt and the alt to get load tested. When the Autozone guy asks you why you didn't just drive it in, stare him down till he looks away....

Alt removal requires a few belt tensioners to be removed. Additionally removing the right front wheel and wheel well splash guard will give you addl working room.

Seems like you remove the top 2 alt bolts, put the car on jackstands, turn the steering wheel to the right to expose the third alt bolt, remove that one, then lower car and break the alt free from he block. Removal is tight thru the rt wheel well but with enough twisting turning and wrangling it comes out.

Personally if I'm under the vehicle removing the last of the three alt bolts, I'd keep myself out from under it it physically when I pull out the last bolt in case it comes loose from the block and immediately dives towards you.

see

http://www.justanswer.com/saturn/7eo...lternator.html (ignore video -- for S series)

http://www.saturnfans.com/forums/sho...d.php?t=154883

fdryer post #2

I think you may not need to turn the wheels all the way to the right but i've never done this on an L car

GET THE BATTERY TESTED while you're there
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Old 04-17-2016, 01:43 AM   #9
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And the winning answer is............
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Old 04-26-2016, 03:59 AM   #10
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hellooooooooooooooooooooo??????????
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