2004 Murano alternator or charging problem?

[Fannel]

I stopped at traffic light and my car went off and won't start again. I had it towed home, it will jump start and keep on running as long as the jump start pack stays connected. As soon as i disconnect the jumpstarter it shuts off. There are no warning lights on the dash while engine is running. My guess is alternator is bad and car ran on battery till battery was discharged and the it stopped on the road. Now if this was the case shouldn't there be a battery and/or break warning light on the dash while car is running on battery?
Also if it were a battery problem then the car should run on power from the alternator once it's jump started right? In which case there should be a battery warning light on the dash right? I know the dash lights aren't bad because when i turn the key to the on position all the lights show up, including the battery light. I will like to take out the alternator and bring it the the shop for testing but before doing this i'll like some input since i'm not very convinced it's the alternator because there's no battery signal on the dash while engine is running on battery.

car is:

2004 Nissan Murano
AWD
CVT trans
106K Miles

[Pilgrim]

Have your charging system tested. It could easily be a combination of things.

The first thing to do is put a digital volt/multimeter across the positive and negative terminals (everyone should own one, so get one if you don't have it) and see what voltage registers...but not while there are jumper cables on it.

I suggest first charging the battery (every garage should have a betery charger, too...) and then doing the voltage check. If the voltage while running is less than 14V, your alternator almost certainly has problems. The Murano will reduce charging voltage below 14V if the battery is at full charge, but even if the battery was fully charged, after running for a few minutes the alternator should kick in.

It's entirely possible that your battery is the problem. Muranos are very sensitive to failing batteries, and can misbehave in many odd ways if the battery isn't taking or holding a charge.

Only a proper charging system test will tell you what's really going on..but I'd go after the battery first.

[Carguy75]

Fisrt, have your battery checked at a autoparts store. If the battery is ok, then check your alternator belt, if that is fine, then have your alternator checked. However, I would say it sounds like a bad battery. P.S. the Murano do not have a battery life indicator, a charging system light I believe, but not a battery warning light.

[Fannel]

Thanks Pilgrim and Carguy for your suggestions. I pulled out the battery and had it charged at Autozone today for an hour. With the ignition off the dogital voltmeter reads 12.45V. With the ignition on and engine running, the Voltmeter reads 12.17V across the battery. So it looks like there's no charge coming from the alternator.
I assume if this is a belt problem then there should still be at least some current from the alternator, so most likely the alternator is bad or there is a circuit problem somewhere. Is there like any charging relay i could check before taking the car to the shop to have the alternator replaced?

[Pilgrim]

With those readings while running, I would go for the alternator...and that belt runs other stuff, including the AC compressor - you'd know if it were broken.

Here's an illustration of the belt routing on a 2004: http://www.2carpros.com/diagrams/nissan/murano/2004

I agree that 12.2V across the battery while running means no alternator output.

[Carguy75]

Sorry man, I hoped that it was a bad battery or loose drive belt instead of the more costly alternator. The alternator should read atleast 14v across the battery terminals, so it looks like it is time for a new one. Before going to a dealership look at some official online nissan parts sellers for a lower priced OEM alternator.

[samson]

Alternator on the 2004 is notorious for failure.....mine went but was warrantied.....look out for that radio cut out issue as well.....

[Fannel]

Thanks Pilgrim, Carguy and Samson. I have ordered an Alternator online. When it arrives I'll have it replaced and post results here. You guys have been very helpful.

[Pilgrim]

You did the critical step with the voltmeter. Interpreting that is what gives the diagnostic results. Well done - and good luck wrenching on that alternator.

[Carguy75]

Originally Posted by Fannel

Thanks Pilgrim, Carguy and Samson. I have ordered an Alternator online. When it arrives I'll have it replaced and post results here. You guys have been very helpful.

No problem. Happy Holidays