Hi all,
Was wondering if anyone can help me diagnose a potential alternator problem?.
2 days ago my car died at the traffic lights. Just quit, lights dim, only a clicking sound from the starter motor when I tried to get it going again. Battery obviously flat as.
A new battery got it going again and got me the 100kms I had to get home. I've since checked the new battery (good spec and make) and it only reads 12 volts, wether engine is running or not. I figured the alternator must be dead and the car had been running off the battery alone and running it down, however the dashboard charge warning light never came on at any time during all of this, so I figured maybe the alternator was ok.
However today I noticed the warning light doesn't even come on with the key in the 'on' position prior to starting the car. I removed the instrument cluster thinking it must be a blown bulb, however the bulb checked out fine. Now for the puzzling bit - the voltage at the warning bulb is only 1.25 V, instead of the 12 V it should be.
If I understand it correctly current flows through the warning bulb to the alternator to get the magnetic field going prior to starting the car, then when the car starts the alternator produces a back emf which stops the current flowing thru the bulb, thereby extinguishing it. However if there's no voltage at the bulb in the first place then maybe the alternator isn't getting any current to start working, rather than it being just dead. Any thoughts ?

 

The time the alternator went bad on my maxima i did not get a warning light... you can take your alternator to autozone and they will test it for free. But my guess is that your alternator isnt completely bad but is getting there, and thats why your car will run for a while and then die, where as if it didnt work at all your car would run for a significantly shorter distance.

 

No it does not.

Your batt is not charged at all. Voltage must be more than 13.5V as engine runs, tested att batt. FSM says 14.2 -14.7V. (14.8Volts will start batt boiling...)

Either Alt is bad, or wiring, fusible link or gnd bad. Check alt wirings first, clic:
http://www.cardomain.com/ride/748507/5
Alt fusible link....

 

What our knowledgable brother said there .................

 

Hi! Long time no see. U had once the voltage problem. It was - was it the alternator?

 

Indeed its been a long time!
In my case it was the alternator but in a very indirect and inexpensive way.....

 

Who told you that?

Your alt. is dead.

 

he is correct in that some cars work like that

 

Thanks for all the feedback. Turned out to be the alternator sure enough. Got second hand replacement with 7 month warranty for $130. Might think about putting a voltage gauge somewhere on the dash for piece of mind in future. Cheers all.

 

I installed a kenwood 400 w amp with a sony head unit and 2 6.5 alpines in the front with 2 6x9 infinity kappas in the rear, and since I have noticed that my electronics get power surges in response to my accelleration. I tested my alternator and it spikes from 14 to almost 19 when i give it gas. Do i need a new alternator or a capacitor for my amp?

 

alternator, and very possibly a battery too depending on how long you let it go like that.

 

will I need to get a capacitor also?

 

Mine was internal.

 

Same happened to me, warning light did not work for some reason. No idea...

Also, you can go quite far with a dead alternator. I've done 100 miles with a dead alternator, just on battery...kind of risky, but heh.