Rino1313

From using the search function, it appears my alternator may be on its last leg, but I just wanted some opinions. Here is a detailed description of the problems incurred:
I was driving home on Thursday night when both the Brake and Battery lights came on. From what I have read, this is a sure sign of the alternator. Earlier that day, when I started my car, I noticed a high-pitch whine coming from my front speakers, it was loud, but only lasted about 10 seconds then disappeared, and has never happened again. I go to start my car on Friday morning, nothing. The battery is clearly dead, as if there was a slow draw draining it overnight. I jump off the car, drive a 30 minute drive with no problems, no brake/battery light, ect... I drive home that night with no problems as well. The next morning, my battery is dead again. If the car sits for a period of about 4+ hours, the battery will completely drain. I went to Autozone today and the guy told me everything is in check. I also work at a car dealership and had one of the mechanics check out the alt and battery, and everything appeared to be fine once running. Battery showed acceptable charge, when we connected the (+) from the alt to the (-) of the battery, it showed a steady 14.5V charging load. This is why I question if the alternator is at fault...Any input would be greatly appreciated. Also, the alt was replaced 20,000 miles/18 months ago. Could these symptoms be those of a bad battery instead of the alternator? I do have an aftermarket stereo system, but it was been installed for over a year and has given no troubles before. Also, on the same night of battery/brake lights came on, my tail light fuse blew...Coincidence? I don't know. Today for the first time since Thursday, my brake and battery lights both came on again. When I came to a stop, they would turn off, once I started at 20+ MPH, they would light up. So what do you guys think?
Thanks,
Rob

foetray

If your Taillight fuse blew and you have a brake light showing, the problem could be that you have a fault in your taillight wiring somewhere or a blown rear bulb. That will sometimes send a continuous signal to let you know that it is blown. You just cant see it because a lot of the times the bulb is blown. As for your alternator it really depends on how much amperage youor aftermarket stereo is pulling. Any amount over the factory 95-120 is going to kill it, but the more you go over the quicker it dies. Mine died after three years of an extra 120 amps, but $600 and a new 250 amp alternator later- No probs.

ejj

iTrader: (5)

If your alternator is outputing 14.5V to the battery when running, that's not a problem.

I would say your battery can't hold a charge. Get yourself a voltmeter. After driving for a while, shut the car off and measure the battery's voltage. Then the next morning or whatever measure it again.

I had the same symptoms as you. The battery would read 12.X when I stopped the car, but like 3.X the next morning.

Replaced the battery and it fixed the problem.

Rino1313

Thanks for the quick replies. I was leaning towards the battery as well, just haven't hit the trigger and bought one. I might jump it off right now and head to Discount Auto Parts to see if they can do a test, since all the guy did from Autozone was come out with a voltimeter.
Any other opinions?
Thanks,
Rob

Rino1313

Update: Although not what I was hoping, I have an update. I had a full system test just ran. Battery checked out OK, tested with the car on and off. Second test was for the alternator. Ran the test twice, both times holding the RPMs constant at 2K, both tests came out OK. Just for kicks, ran a starter test and that came out OK as well. On the way to and from the parts store, both the battery and brake lights were illuminated. I did notice something...If the lights were illuminated, by turning on both my headlights and AC, they would turn off, and never came back on. The second I would turn off either the AC or lights, both lights would become illuminated again. Like I mentioned above, when I ran the tests on the alternator with the voltimeter, it came out at a steady 14.5V. What's going on here? Any ideas? I am starting to lean towards a loose ground somewhere. I disconnected and reconnected the electrical connector on the alternator, and made sure the nut was tight on the (+) fitting on the alternator. Also, if the AC and headlights are off, the brake+battery lights will turn off once the brakes are hit. It seems like anytime extra draw is taken, the battery+brake lights turn off. With no AC, lights, or brakes on, the lights steadily stay on.
Thanks guys!

Speed Teal

Hey if you don't get my E-Mail I am very sure you have a bad rectifier in your Alternator and if you had it tested at Scmucks or startmart or another place like that it may have been miss diagnosed. this will sometimes cause a drain. and cause the feedback you were speaking about. If the rectifier is bad it will show a bad AC ripple pattern I would suggest you see a proffesional starter and alternator place or you can call the toll free number to my shop in Everett if you need more help
It is G&H Auto Electric my name is Will we are open 7am PST to 5pm PST
Also if anyone else is having starting or charging problem on there maxima call me. 1-800-784-0443

foetray

Try running the tests with the car at idle rather than 2k rpm. your charging sytem at idle should read at least 14 volts unless you have an aftermarket boosted alternator. Do you have an Autozone battery? I have also seen this kind of problem with those too. Especially when aftermarket stereos are involved. I'd try changing out the battery because you could have a cell dead in it. It will charge and show high voltage when charged fully, but will slowly drain when there is nothing charging it. If you lock your doors when away from your car the factory security or any security system you may have added is also drawing power from it causing it to die as well.

Rino1313

I pulled the trigger and purchased a new alternator today. It is going to be installed tomorrow. Hopefully everyone's input was right. I drove another 30 minutes tonight with the battery+brake lights illuminated with no signs of alternator failure, and it was dark out. I have a 1000 mile roundtrip drive to make this weekend so I need to get to the bottom of this ASAP. With 2 seperate tests ran on the battery, both with the car turned on and with the car turned off, I have pretty much eliminated it. Thank for the input! I am hoping a diode has given out, causing a slow drain throughout the night, but I still can't get over why the alt is showing a solid 14.5 charging volts when the car is running. It seems like that number would be off by a little if a doide has failed. Also a new Nissan alternator failure with 20,000 miles and 2 years doesn't seem likely, but I know the problems these alternators have and it could very well be the culprit. All the warning signs seem to point to this. I was hoping for the alt to just give out tonight just to verify what the problem actually is, but it didn't happen. Any other experts out there that could offer some input to this situation? Time is running out and I can't afford to loose this office visit/interview for a job in Miami. Rental car would always be an option, but I would like to consider that as last resort. Checked all connections on the alt today and everything appeared to be fine, as well as the ground for the battery. Both terminals are tight and no corrosion is present. No fuses blown...nothing. I think I have done a good job narrowing it down.
Thanks!

Pappa Grande

If it makes you feel any better I had the exact same symptoms, changed the alternator and everything was fine.

Rino1313

Better? You just made my night! Reguardless if it's the problem or not, I will be able to sleep tonight now....Unless craming for this tax exam doesn't go as planned. I'll keep you guys updated.
Thanks,
Rob

Speed Teal

Charge is not hindered by a bad rectifier, the volts will show true but the amps will be low. The load of your stereo system most likely caused your failure because to heavy of a load on it caused by a high output stereo system.

Will