Cuz my fucking car wont start again and Im thinking thats the problem since when its on I can hit the brakes or turn on my high beams and my radio cuts off. Is there a website I can go to which can give me info on it?? TIA

Your alt keeps the system/battery charged while the car is on or driving. If your alt doesn't work right then the car will just run off the battery util it dies. If the battery dies and is jumped enough times, the battery will go bad. I've had bad luck with both in the past with my other cars and it sucks. I hope you figure it out man. I would take it somewhere like Pep Boys and have them test the battery and alt...that will tell you what's wrong.

alternator has NOTHING to do with starting the car. Your best bet is to get some kind of volt gauge, i think you can get them at track auto or pep boys. Jump the car and get the readings. If its under 12volts, its the alternator, if well over (mine reads about 13.5-13.8) then you know its the battery. Thats at idle with nothing on.

Another way to check is when the car is running, unplug one of the terminals on the battery, if the car does not die that means that your alternator is still good, if it dies then your alternator is bad. The battery is responsible for 'starting' up the car. If your battery is bad, it don't matter how good your alternator is, it just won't hold the charge. Good luck!!!!!

oh yeah, you can't just take a regular voltmeter and put it across the battery terminals to get a readout. The battery has to be out 'under load' to properly check it.

DON'T unhood one of the terminals!!!! This can fry your alt is you do that with the car running! And the alternator DOES have something to do with starting the car- if it ain't charging the battery, it wont start :) Easy way to find out, go to pep boys, autozone, they will test it for free. If you have a digital voltmeter, use that and measure with the car running. At idle with NO electrical load, should read about 12.5 volts to 13.8 volts or higher. Now turn on everything electrical you can, and then take anohter measuement. The volts at idle should be no lower than 12.4 volts, and rev the motor, it should go up to 13.8 or higher volts. If its under 12.4 volts, then its you alternator. Also, once a good battery is fully discharged ONCE(dead), the battery will never hold a charge like it did before, it will kill the battery and its capacity. Car off, let it set for about 10 minutes, and check the voltage again. It should not be under 12.4 volts, if it is, then you have a bad battery also...

My grandfather, who's a retired electrician, unhooked one of the terminals in my family's 94 Corolla and it was just fine (haven't tried it in my Eclipse yet). He was testing to see if the alternator was still good, the car kept running. Also, if the alternator DOES have anything to do with 'starting' a car, why would a dead battery prevent you from starting the car. True, a running alternator would charge the battery, but if the battery is shot in the 1st place.....your alternator ain't gonna do you any good.

Oh yeah, my electronics engineering professor said that the battery HAS to be 'under load' to check its conditions. Just putting a multimeter with the battery just sitting there ain't gonna tell you shit. At least that's what he said.

An alternator DIRECTLY has nothing to do with starting the car, i guess that was my point :) A bad battery will be more difficult to test with just a volt meter, BUT, a good, charged battery HAS to have at least 12+ volts for the starter to crank over the motor. If not enough juice to do it, usually the starter will "click" rapidly, indicating a low discharged battery. When the car is running, the battery has nothing to do with how the electrical system operates. The battery is the primary source of power to start the car, that's about it. The alternator is the primary source of power when the car is running, and has to charg at least 12.4 volts to keep enought voltage in the battery for the car to start again.Test the voltage with the car in the cranking position. The voltage shoud be no lower than 11.5 volts. IF it is, bad battery. Threre, thats the load test :) I have read and beed told by MANY ASE certified auto mechanics to NEVER disconnect the battery terminal while the car is running. It even says this on the sticker on a new alternator if you look when buying an new one, and voids the warrenty also. Sorry, i'd rather play it safe and not damage any sensitive electronics in the alt or the car for that matter. A bad battery will not give the problems 1tuff is having. A car will run fine on a bad battery, but will not start for shit. Now if you have elect prob with the car running, then 9 times out of 10 it is the alternator(assuming batt terminals are tight and clean). I test alternators by using my clamp on ammeter. It clamps over the battery wire, and tells how many amps the alt is putting out. With all electricl loads on, the meter should tell how much amps its putting out. If its really low(it should be in the 34-40 amp range), then bad alternator..I tested an alternator at my shop not too long ago, and it was charging like 1 amp with full electrical load. Yep, thats a bad alternator. I just clamp on the alternator charge wire, and works wonders.

Well in terms of our cars, I stand erected....I mean corrected!!! I guess doing something in one car doesn't mean you can do it on another. Like I said, I haven't tried it on my car, but I saw what I saw when the terminal was disconnected. I based my answer on that. Good luck:7 !!!!!

Yeah robo, i have heard many poeple who do that, and works great. But usually they do this on older cars, without the sensitive electronics that almost all newer cars have. I guess i'd say do what you want, but i'm just trying to say to play it safe, rather than being daring and seeing if it works. I personally never have tried it, so i guess i can't tell you for sure if it will do any damage. I guess i just trust the word of many mechanics that i have talked to. But as an electronics installer, i have more fun using all the cool toys like multimeters and ammeters and such :) Good luck 1tuff, i hope you get it figured out, and that we helped you out some..

well I went to advance to get it tested and when we came back out the car wouldnt start at all. I ended up having to get it towed to the dealership. They thought it was either the altenator or some electrical problem. The guy at the service dept told me it may not be covered under warranty but he will see. I havent had the chance to call them to check on everything yet, but I will tomorrow. They also tested the battery (out of the car) and it was good AND fully charged. I dont know what it is, but when I turned the key the lights in the car would barely come on and the fuel pump wouldnt come on at all.

Dude check your terminals. The damn stock ones suck and corrode real easy it seems. Even if they look relatively good and clean pop them off and clean them and tighten them back down. I went through the same damn thing for a while before I went and got the things replaced, no problem since............

for the second time today a couple of the terminals(the white ones) came loose and so far i haven't seen any permanent damage, hopefully there won't be any :), just letting you all know, not encouraging anybody to do it

My guages flicker a little bit every once in a while and then the charging system light comes on.

What does it mean when the charging system light comes on?

I have an valve cover gasket leak on almost every side of the motor. could oil be getting on my alternator and mess things up?

The odd thing is it also happens at idle so I don't think it's the alternator.

When the charging light comes on.. that means that the charging system isn't putting out enough voltage, or maybe you are getting voltage spikes.. either way, not a good thing. First car I had I fried the alternator by driving through a big puddle.. hehe.

Some dude on here a while back said he and his dad were working on his car and his dad took the terminal off while the car was on and it fried his ecu. I wouldnt do it.

The battery works during idle and when the car hits a certain RPM it kick over to the alternator. If thats the case, Why would my lights flicker when I'm at idle as well as when I'm doing 65MPH on the freeway?

I drove the car today and it didn't happen but I still want to know what might be causing the problem to keep it from getting worse or coming back again.

Damn this post is still here, hehe. So everyone knows my problem was caused by my alarm systems starter kill relay and all is now well. Thanks

when the battery light comes on it doesnt mean that the electrical system is bieng charged, it means you have a problem somewhere. When mine came on it was a bad battery. You can get both your battery and altenator tested for free at advance auto parts

Thats it! I'm going to have to check my altrenator. My car is dying when I come to a stop!

Anyone know how hard it is to change the Alternator?