Wiking

I am working on now with a 2k2 maxima (50kmiles).

Durin last few mths it has had intermittently Alt lamp on - ONLY ALTERNATOR warning lamp. This condition may go off after shutting and restarting engine.

Also few times the MIL check lamp has been flashing for a short period, gone out while driving - NOTE: NO error code was found stored in ECU. This vehicle has been twice at nissan stealership, no help from there ...(yes they would swap new alt with 2500$)

At least once overcharge voltage has been detected at 15.6Volts...

At least this 2002 Maxima seems to have the Brake/Alt warn light connection via a diode. This should mean that no charge causes both lamps to illuminate?

My questions: What should happen
a. when no charge
b. overvoltage (regulator semi dead)
c. rectifier diode problem (Alt pushing AC current).
d. Is my suspicion right (?) that the voltage regulator inside alt is dying causing intermittent AC and/or VERY high charge voltages.
e. Will replace the alt soon, reman 300$ alt is already in the trunk = will this correct this intermittent alt warn lamp issue?
f. Are there any other known problem spots?

Confuzean FSM logic: Contradicting schemas can be found at 2k2 FSM page EL-120,136,139. (At page 120 the alt lamp is connected to MIL lamp via a diode - instead of the mentioned BRAKE warn lamp...)

Hi Quality (?!): My 3gen alt regulator died also at 80k ... that story depicted here: http://www.cardomain.com/ride/748507/23

Max_5gen

iTrader: (2)

You're right - both LEDs should illuminate. You're also correct about FSM inconsistency. I'd say it is connected to BRAKE LED - that one at least has a resistor across which could prevent it from illuminating if ALT output is not low enough. All of this aside - your voltage with engine running at ~2k should be at 14.2-14.4V. If it is more than that you're killing the battery and it will die in 6-8 months. AC in the ALT output would cause lowered output in my opinion. I think, the more probable cause is the voltage regulator. Make sure you can trust your voltmeter. For example, it should show close to 12.6V at the battery when engine is not running for at least 10 minutes.

Scottwax

iTrader: (8)

Agree. Have had the same problem on other cars. Too bad car companies don't have external voltage regulators (like my Chevelle did), so easy to replace instead of the whole alternator.

Probably why they made the change, eh?

Wiking

Thks for the input. So both leds should come on when no charge. Am I reading correctly (?) between your lines: 1 plus 2 = a leaking diode or whatever could cause charge to be about 13Volts ---> only ALT led would be on.

Yes cheap multimeters can show anything, (at least on low battery), learned that the hard way. However, my multimeter no.6 was displaying 14.1V (idle) just prior Nissan Consulttesting at stealership (also 14.1V, idle)...

The battery (replaced 2yrs ago) isnt totally dry. Points to overvoltage.

I'll replace the alt and later open the original, tell what was found. My guess is that it needs just rectifier cleanup like my 3gen alt ... see the pic how brushes wear out and spread conducting dirt all around. My 1. theory is intermittent short circuit across this sludge, 2nd is a dying regulator (because of this?):

http://www.cardomain.com/ride/748507/23

Max_5gen

iTrader: (2)

This is hard to tell for sure without knowing resistor values around BRAKE led but I'd assume so.

It is OK.

If you can see electrolite level then you can monitor it and if it decreases then it is overcharge for sure. Top it up with distilled water if it is already low.

It is hard to leak any significant current at 12V and levels of currents involved. Even if some dirt would cause parasite resistance of 1 kOhm it would create a leak of 12mA which is nothing compare to what is normally going on there. Cleaning won't hurt of course. Electric car shops usually carry voltage regulators so in the worst case you can just replace yours.

leescotty2001

I am havin same issue with my maxima

Wiking

Now tell me WASSUP: test-disconnecting alt charge wire, causes ONLY alt led to come ON at idle. Revving, the lamp shuts OFF after 1500 rpm! ...and all seems to be ok...

Seems like the Alt lamp is living its own life (computer ctrl?) regardless of charge voltage. If so, the FSM schema is bs...

(Note that when the lamp had earlier been on, it had been steady on until shutting engine. Its not std brush wear out/stick problem which normally causes alt warn to blink...)

Tech swap question: Will soon swap the alt anyways. I guess (?) the radiator has to be taken out first as FSM suggests?

Max_5gen

iTrader: (2)

If you were measuring voltage at the battery at the same time and it was below 12.6V I would expect CHARGE led to be ON continiously. Looks like your voltage regulator inside the alternator is at fault. Computer doesn't have any say here as far as I can tell - CHARGE led is driven directly by voltage regulator.

Have no idea, but you can wait until you get there and then take it out if it will look necessary. I think you have enough experience to do it on your own . May be just loosing it will give you enough room.

Wiking

I'd like to believe this is so. Smtg doesnt fit here.

U bet this is not my first alt problem... First one on 2k2 maxima, and THE first one, where no charge warning lamp depends on rpm (charge supply wire disconnected) ... idle ON, revving OFF. I fear that I'll find Intel Inside with semi installed Vista...

I do agree that a short circuit would be seen on that diode dust. As u said, it may cause small .15A batt drain which was my 3gen alt problem.

Seems that taking out rad fan assy is enough to pull alt out... figuring out on the hidden alt bolt. Worst case ever, cant see, cant reach... plus manual pics below Chilton comic book -level.

Wiking

Update; at least two problems found so far:

The alt 2-pin connector did not come out in one piece. One of the pins [S] was heavily oxidized. When installing the new alt, the broken connector and pins were loose: like this, the pins have never made good contact... I bent the pins in the new alt until the connector press in -insertion felt tight (30 degrees with pliers), added contact grease. Then locked the connector with a tiewrap... (Tomorrow new bearing for the tightener pulley, pics will follow some day after opening the used alt)

The 'original' alt had no NISSAN -logo. So it cant be original?

Btw. No need to take radiator or fans out. Best way is to drop the AC compressor and then drop the alt. The compressor has to be taken out anyways to reach the long alt bolt.

Max_5gen

iTrader: (2)

I think, you found your problem - bad contact of the S pin. This pin is the one used by internal voltage regulator to measure battery voltage. I assume 'S' stands for 'Sensor'. Anyway if that pin was loose then voltage regulator sometimes was seeing low voltage on that pin and was trying its best to bring it up overcharging the battery as a result. I think, you have 2 good alternators now. This might very well be a result of the previous repair - I never seen them oxidized let alone heavily. Thanks for the tip about removal procedure. I wish they put this info into stikies.

Wiking

Yes, S comes via 10A fuse and has to be the regulator feedback for adjusting voltage (FSM page SC-23 : fusible link box). I have to check that also for good contact, add contact grease ... where might that box lurk?.

The problem in the first place was that this alt connector did not come out in one piece folks, it wont in your neither). Also you cant see or reach it well enough. One is supposed to push in the alt connector lock clip and then pull, but the lock pin wont release. (Thus I guess I bought unnecessarily that spare alt.)

Third problem is grounding: there is no exxtra GND-wire from the alt shroud. It is a known universal problem that the bolts/shroud lose contact to the engine, and alt GND will eventually become floating = semi connected to engine-GND. 3gen max has that from factory ... I have to add now here.

The tightener pulley bearing was also bad, next have to swap it. (as said, llater I will make a writeup with pics).

I added another to make sure in my 3gen, like this:

HowTo Ground http://www.cardomain.com/ride/748507/10

Wiking

Update:

Heres the alt oxidation [S]-pin pic. The whole alt swap writeup is at bottom of page... http://www.cardomain.com/ride/748507/23

Max_5gen

iTrader: (2)

Nice writeup, makes me think of buying 2k2 as this help exists ...

Has your overvoltage problem gone for good?

Wiking

This problem was on a 'nearby' max ... so his problem has been now out more than 3 weeks. (Also swapped all fluids, 4 shocks, now rides better than new, now I start to like it... )

As new alt has all voltage regulating bits inside it, this same problem should not return. Now all wet with contact grease The only thing I didnt like was the 120A charge fuse at battery terminal - I could not get it out (tried to force it out) and still suspect whats inside there?

Sorry to say folks, but I wont swap my 3gen until a 6gen drops by - u see independent suspension, lacking pwr, etc...