Eric F

I've got a 2002 6 speed.

The other day when it was cold outside, I started getting the Brake light/Battery light combo for a second or two when I started my car after it had been sitting for a long time. I figured my alternator was on its way out.

Today while I was driving on the freeway, my car wouldn't rev over 1k rpm's. I idled and pulled over to the side of the road. I shut my engine off and then tried starting it again after a minute. It started up and ran just fine for a minute and then did it again.

While it's doing this, the battery and brake lights are off. If I push the gas pedal all the way to the floor, the ABS light goes on after a few seconds (and the RPMs stay at about 1k.)

The battery is fully charged. The lights and all of the electrical inside of the car work just fine.

While I'm idling and it won't rev over 1k rpms, the voltage at the battery is 18-19V. When my radiator fan clicks on, sometimes it will kick out of the "safe mode" or whatever is preventing it from idling over 1k rpms, and start acting normal. The battery voltage is around 15V.

When it does this, the battery is being overcharged. Would a bad alternator cause this, or would it be a relay or something somewhere?

I bought a new alternator, but I don't want to waste $200 if the alternator isn't the problem. I've never heard of a bad alternator overcharging before.

Love_00_Max

The voltage should be around 14.2v when running and with engine off it should be around 12.4-12.6V. I cannot understand how the battery to put out so much voltage in the first place, it should cut off after full charge.

There must be something happening, the ECM should be controlling charge/discharge of the battery.

True, this is a bizzare electrical problem, hope others will help u.

max2001

iTrader: (2)

I had a pathfinder that was over charging and had a lot of driveability problems.

Eric F

I'm going to replace the alternator and see if it fixes my problem. When the engine isn't in "safe mode", test #3 gives a negative voltage.

According to the factory service manual, that means I have a bad alternator.

Eric F

Was the problem a bad alternator, or what it the ECU?

joemax2000

I am having the same problems with my 2000 max at the moment. E-brake light and battery light flip on and off from time to time with no consistency. Having noticed any other electrical or driving problems. Taken it to several shops and they all claim its the alternator. Been running with a bad alternator for bout 3-4 months now....lol.

boris

Low belt tension can cause the battery light blinking..

fflint_18

While it's true a loose belt can cause voltage fluctuations, they will usually be bounces up and down getting lower voltages than normal.

Higher than 14.8 volts means it is probably a bad regulator section in the alternator. If you are getting voiltages of 18 and 19 volts you run the risk of doing some serious damage.

Not only can you cook your battery, but you ECU is not going to like that excessive voltage. Hence the car running bad. And ECUs aren't cheap.

Not to mention all your other sensitive electronic devices (Head Unit, etc.)

You better get it changed before you do some serious damage.

Eric F

I just finished changing the alternator. What a PITA. Hopefully that fixes the problem.

Love_00_Max

I hear u man, there are folks here who say it can be changed in a hr. All BS, replacing the alternator was hell. Real PITA job, one part after the other has to come off to get the alternator out.

Pl. keep us posted on the voltage issue, if it gets resolved, it should go into the DIY/BKM stickes.

maseo77

iTrader: (1)

Voltage regulator. Good thing you swapped out the alternator.

Eric F

Yeah, that fixed it. The regulator on the alternator went out.

Stikya

iTrader: (1)

Is this common on new alts?
Replaced my alt and batt 2 days ago. since then my brake/batt light will occasionally flash then go off.

But, the volt meter in my Bel radar displays spikes over 16.5 many times a drive.

any ideas?

fflint_18

Definitely sounds like the regulator is flaky.

Was it a new Alt or a Rebuilt?

A good brand new alternator should have decent quality control and the regulator should be new and well tested.

If it's a rebuilt sometimes they don't even look too hard at the regulator section. They rebuilt the windings and such for the generator portion and do a quick test and send it on its way. They probably don't test them until they are nice and hot. That's the time when things like regulators fail.

One thing I would never buy is a rebuilt Alt.

Take it to a quality auto place and ask them to test the alt. You'll hopefully find out quick if there is something wrong.

As I stated above waiting too long and you could end up cooking things with overvoltages.

Stikya

iTrader: (1)

I'm assuming it's new, as they told me it came w/ a lifetime warantee from manufacturer.

Yes, I'm worried about it frying my detector or laser jammer.

Problem is in "park" it runs perfectly flat voltage. You can even hit the gas, and no change.

It only spikes while driving. How they going to test that?...I already told them my voltmeter showed driving spikes. I even called my Nissan shop and they said don't worry about it until something quits working or dash lights come on. UGGGGGGH!

fflint_18

Sounds like a problem when warm and under load. They can test it. Either in or out of the car. And just because it has a lifetime warrenty doesn't mean it's new. It can still be a rebuilt.

Did they ask for your old one as a core? Or charge you a core charge?

Stikya

iTrader: (1)

I will call tomorrow and find out the details of new/rebuilt. And ask if they did any under load tests?

If not, I'll take it to another shop, on my day off Monday, for testing under load. Not sure that will get me a new alt though...

Because the shop tested the alt to the best of their ability, even running the car for 2 straight hours, and tested it again. They said the alt manufacturer will run the same tests, and being that they won't find anything wrong either...they will just send the alt back and my shop will not get their money back. They stressed they really aren't keen on doing the work again for free, or giving me a new alternator at their expense.

This shop is honest...and I've had many good experiences there...my whole family has been going there for years. so, I don't feel like they are jerking me around, but are frustrated and don't know what to do, like me.

So, they said since the car is "running fine", and no dash warning lights are on, and they can't get our money back for an alt that tests fine, we are all SOL until something stops working.

illnastyimpreza

any updates? My car(03 maxima) is doing the exact same thing... Except today when I came out of a quick stop @ the post office... my front 2 windows where all the way down !

Redsox200458

same exact problem that Eric F had...
only my automatic climate control wont shut off.
hopefully when i swap out the alternator tomorrow on christmas eve it will be fine... yay for doing it in 12 degree weather!

also fried my amp, hope it didnt fry anything else...

illnastyimpreza

you're a brave man. I said **** it and told my GF to bring hers to the mechanic.... My frozen *** is worth the 380