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I have a 2005 nissan altima 3.5 started off as a bad altenator, I replaced the altenator, changed the battery and tensioner pulley Aswell as the belt. I have the belt pretty tight that it should be charging the battery I get the battery to trickle charge to 12v and when I start the car it doesn't want to go to 14 it drops down to 11.8-11.6 until it finally gets down to 10 and dies any ideas what could be going on I need some other ideas
 

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09 Altima 3.5SE 6MT Sedan
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Any dash lights on?

You need to make sure the Alternator/Charge fuse is in good shape. If it does supply power to the alternator, then the alternator won't 'activate' and charge your battery. I'd have to check to be sure, but there could also be a fusible link between the alternator and battery...and if that popped during alternator replacement, then you'd get this situation for sure.

You should also check the negative battery cable...these cars are notorious for them rotting out lower down where they bolt to the chassis and then the transmission housing. A bad -ve cable could've contributed to your alternator issues in the first place.
 

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Just the battery light and ebrake light are on I will check those wires today I will post update after I check it out I have the battery fully charged and the scanner is on it so I can read the voltage
 

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09 Altima 3.5SE 6MT Sedan
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Sounds like you might have a voltmeter too. When the engine is off, check the voltage at the alternator B terminal relative to engine metal (the alternator lug with the thick cable attached) it should read the same voltage as across the battery terminals. If 0V then the cable or fusible link is faulty.
 

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09 Altima 3.5SE 6MT Sedan
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FWIW, the connector with the two smaller wires is at least half working...one of those wires drives the Battery light on the dash...the other supplies power TO the alternator so it can do its thing. Since the light is on, we have some confidence as to the integrity of the connector and harness. I don't think it's the fusible link..as a lot of other stuff wouldn't work, like the horn. Guessing it's the 10A fuse #26
Capture.JPG
 

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So now I've got 12.6 at the battery and 12.6 at the altenator when the car is off where should I go from here when I had the scanner reading the voltage while it was running there is a point where it drops to 0 and shoots right back up to 11. 8
 

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09 Altima 3.5SE 6MT Sedan
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I'm gonna say the the drop is a software glitch in your scanner.

If you start the car and put on some electrical load...say your headlights and blower motor and rear-defog....the alternator should kick in and you should see 14.4V (+/- 0.2V). When you shut off the car, if it's been charging at all, then the resting voltage will start at 13.2V or so and slowly drop over hours to about 12.5V. If you never see a voltage over 13V I'm gonna say your charging fuse is done, or the regulator pack in your alternator is done, or the power feed wire from the fuse to the regulator is done.
 

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Be VERY quick to suspect the 'new' alt as well, as that is so common now you won't believe it. The crap Chinese rebuilds we get now are garbage and even brand new units, I failed 20% of them right out of the boxes when I was in parts. Then another 20% fail in minutes, they do NOT use heavy duty regulators in them to give the company CEOs more money and all modern alts NEED that HD part, they fail QUICK not using them because modern alts charge so much more that temperature control is very needed and the regs supply that. At least the much better ones do.

What modern 'lifetime warranty' parts brought to the table, you think it means the part is good enough quality to last a lifetime, it really means they will supply you ones that break in minutes for a lifetime, two very different things. I had people warranting 'new' alts out 3-4 times a year. I even instilled the 'check it before it goes out the door' policy we went to trying to lower some of the customer anger over the quality of the parts.
 

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I really hope it's not the altenator Ive had my car apart 3 times and in the 3.5 you have to take rad out in order to pull the alt out and summer time was fine just filled it with water but coming into colder weather I need to fix this so I can out coolant back in so I don't freeze my lock
 

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09 Altima 3.5SE 6MT Sedan
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LOL...I am very familiar having done that (see Alternator link in my .sig) on my '03. From what I can tell the Gen4's 3.5's are even worse! Reality is the cheap remans/Chinese units don't always work out of the box...ask anyone who's ever sold parts.
 

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Much of the issue is that the alternator designs now used for the 130-150 amp alts are the same ones used for much older 50-75 amp ones. The only difference now in a $200 alt and the old $50 ones is mainly that lifetime warranty cost, and a small amount of added technology to allow for the engine computers to adjust the alts in finer ways. The added charging is only intended to be used for short periods of time to quickly bring up a very low battery or make up for the window defroster. If something in car is amiss to make the alt begin to charge that much ALL the time (like running too deep and too long into an obviously dead battery that never fills up with charge) then the alt quickly overheats at the regulator and fails. Why using a heavy duty one is so important, and why they WON'T use them, it kills parts sales.

I rebuild my own alts and the first part I go for is that better regulator, it cannot be overemphasized how much longer the alts will last using them.
 

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I'll +1 the new Alt possibly being bad. I had to replace mine on an '03 3.5 a few years ago, bought an Alt from O'reilly, went bad after a day, exchanged it, that one was bad from get go, exchanged it again, that one lasted 3 weeks. Got a refund, ordered one online that wasn't a refurb and that one has been working ever since. I'm now a pro at changing Alt's out.
 

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+2 on the "new" alternator being bad. But check all the other stuff as folks suggested to be sure. You don't want to spend all that time taking it back out. I had the same thing on a remanufactured one. I had put it in, and thought it must be something else, because there's no way a new alternator could be bad....wrong! Get the "new" one tested. Even then, sometimes the local parts stores' testers will read good on a bad alternator (also had that happen). If they can bench test it, that'll be a better test than the in-car test. If you get a replacement, don't accept anything other than Denso. I'd try to get them to do a full refund on the bad new one. No sense in replacing crap with more crap. It'll be your Saturday afternoon, your time, your labor, which is probably about worth the cost of the alternator, when it fails again. Get a Denso from Rockauto.
 
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