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Testing the Murano's Alternator

11K views 44 replies 10 participants last post by  jaak 
#1 ·
Bear with me, there's a few pages here...
 

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#9 ·
Needless to say, Nissan has procedures to check your alternator, that should be able to give them an early warning on failure. If you don't feel comfortable doing it yourself (much of it, doesn't need the special tool), ask them to test it, if you think you might be on your way to a problem.
 

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#10 ·
Wheepee!

Definitely sticky... :)



Nizmo
 
#11 ·
OK, you twisted my arm.... Sticky it shall be.:)
 
#12 ·
Just wanted to add that it is NOT covered under warranty (unless you have a cool dealer) for checks and inspections if there is no evidence of problems beforehand. They may charge you for it, but if you really feel that your alternator is in danger, then I suppose you can get it done.

In 1999, the alternator in my 1997 Maxima started making a whining noise. Took it to the dealer who reported nothing seemed unusual (indeed the noise was gone) and I had to DISPUTE the diagnostic fee they charged me on the bill. Drove it home and the next evening the noise came back and charge light came on. Alternator was replaced under warranty and the only thing the dealer could tell me was that "these parts are unpredictable, they are man made and will fail."

All I am saying is don't be surprised if the dealer tries to charge you for an inspection. They shouldn't, since its a chance for them to find things wrong with your car and hose you on the repair. But we all know how Nissan dealers view "customer service."
 
#13 ·
Well, we still don't know if there is a single point of failure.
And if there is, does it die a slow death that could possibly be found in a diagnostic, or does it just short out instantaneously, in which case it won't show up on a diagnostic.

I lean toward the latter as I look at the test procedure.
I was hoping to see a load tester that would read out Amps.
Don't know what the Murano is speced at, but Nissan does, and if it is a 100 Amp alternator that is putting out 60 AMPs into a full load, you may have yourself an early indication.

Homer
 
#14 ·
It's spec'd in the Service Manual, but I'm not at that PC so I can't pull it up.

I'd rather fight with the dealer for 10 minutes than have to find a tow truck in the middle of the night on some distant highway.

Might be good to put together a version of this diagnostic process using a common multimeter. The automated system Nissan uses, just compares known voltage ranges over time to what's measured and gives an idiot display to the tech.

For example, excess ripple is a result of failing diodes, I would expect. Whereas other voltage problems could be the regulator.

Both items are separate from each other, but built into the alternator, as the SM shows them as distinct items in the exploded diagram. I haven't looked to see if they're replaceable without removing the alternator. In fact, I haven't even looked to see where the alternator is, under the hood!

I haven't had the time to distill a simple test procedure, so if someone else wants to give a shot, go for it!
 
#16 ·
I regularly maintained my battery and my alternator still failed. I don't think it is the cause, but not a bad idea!
 
#18 ·
zofsuvs said:
How about if the battery is not holding a charge sufficently even if maintained properly. Does this put an extra burden on the alternator which could reduce its life?

Despite the fact that the Murano's battery is the maintenance type, its not a terrible battery. Unless you've been driving a lot of short trips, I don't think the battery would drain over time. I suppose a weak battery could strain the alternator, but you would feel the weak battery in the form of slower starts.
 
#20 ·
Down here where the temps are high we are glad to get a maintance battery. YOU CAN ADD water. Lack of water is the number one killer here and high temps evaporate water faster, having caps is great. GRIP :D
 
#21 ·
GripperDon said:
Down here where the temps are high we are glad to get a maintance battery. YOU CAN ADD water. Lack of water is the number one killer here and high temps evaporate water faster, having caps is great. GRIP :D
If you remove the top lable from most maintenace free batteries you will find either a screw type or snap on cap that you can remove to add distilled water.
 
#22 ·
That is true, True, TRUE. But sure is nice to have the screw caps that come on the MO. GRIP :D
 
#24 ·
Relay in the Alternator??? Please elaborate. GRIP :D
 
#25 ·
I have hesitated to get into this discussion of Relays. etc for one reason.
I doubt that the discussion can end up with a known outcome.

Look, I have taught electronics.
I have More experience at some of this stuff than even jaak.
Not all of our experience however (In fact only a small part) is in Automobile electronics. (Jump in here if I Say something you don't agree with jack)

When a SM talks about relays in an alternator, there is a CHANCE he is right. There is also a chance, a good one, that he doesn't know what he is talking about.

Many moons ago, we recharged our batteries with GENERATORS.
Generators had a lot of drawbacks. They couldn't charge batteries at low RPMs for instance.
Anyway, in those days, there was a little metal box off to the side of the generator. This was the voltage regulator.
This Little box contained relays (3 of them if I remember it correctly).
The regulator is required to keep from over charging a battery. You need to be able to sense the "charge" in a battery and decide to connect or disconnect the generator depending on the charge in the battery. The regulator does this.

One day, we went to Alternators. Alternators are cool. They can charge batteries at low RPMS.
When the very first ones came out, we just pulled the generators and plugged in the Alternators and hung a little metal box off to the side with relays in it.
But electronics continued to advance. And soon, the regulator was inside the Alternator with small relays that could still handle heavy current. They still failed a little too often. After all they were electro MECHANICAL.
Then we advanced even further. The relays were replaced by Triacs and zener diodes. The reliability of the Alternator was now amazing.
Most people have driven for years and never have had an alternator (or regulator) go bad...Probably most people on this forum have never had am alternator go bad. I know that after having 2 generators fail on me some 40 or 50 years ago, I have never had an alternator go bad.

SO.
IF there are bad "relays" in the Nissan alternator, then they are many years old. No one uses relays in the regulator which is part of the alternator. No one. Not Hyundai. Not Yugo. no one. Would Nissan use a 30 year old design? VERY unlikely.
(However they did choose to use a Maintenance battery!So.....)

Of course it could be that the SM is wrong and that actually the Triacs have gone bad (And maybe he doesn't want to get into a big discussion).
Or he hasn't a clue and he is inventing a story.

In any event, it doesn't help other than it's fun to bench race these things and try to figure it out.
But in the end, Nissan is pulling a Mitsubishi and the see no evil, hear no evil, speak no evil approach to service.

When your alternator goes bad at 40,000 miles be prepared to pay <> $500 for the replacement. And maybe again at 50,000.

Homer
 
#26 ·
Well Said!! Makes me feel better. GRIP :D
 
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