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I have 2019 Armada and why not just Un bolt the sensor from the negative terminal. Wouldn’t this give you old school alternator charging. Not stopping charge on quick take offs and charging Immediately not waiting for 8 miles down the road to start.
I simply unplugged the harness. It's been this way for a few weeks now, maybe closer to a month. Needle always sits above 14.
 

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Hey guys and gals, background on the truck. 12 QX56, 83k miles fully loaded, having intermittent issues with the truck not starting for my wife. I had the brake sensor replaced last Dec by Nissan and seemed to be fine for a few months but it left her stranded again (actually started while I was on my way to drop off another vehicle) I dropped it off at Nissan, I shut it off and started it 4 times and it worked fine.

Battery is 13 months old Duralast Gold highest cranking I could find.

I have a battery tender plus I use on the truck every 2 weeks, I had just fully charged the batter the day before.

Nissan says the charging system is fine and they're going to replace the brake switch again ( tech says it's the problem)

Down to my main questions and I've read most of the threads on this issue.

I'm want to disconnect the sensor from the plug but someone said the battery temperature sensor will not work, what good is that and how can it hurt?

What type of a meter do you all suggest I buy to check the voltage?

Thanks all!
 

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in short, when the battery temperature is low, the system voltage is set high and will automatically decrease as the temperature increases. the ECM not reading the voltage could cause surging or other little nuisance issues.

What type of a meter do you all suggest I buy to check the voltage?
I use this:


 

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I simply unplugged the harness. It's been this way for a few weeks now, maybe closer to a month. Needle always sits above 14.
Boys, this is really old school but, hey it’s old school that got us this far so. Just to share a recent battery story. While I’m loaded with six women heading to Blue Ridge, GA for a day of girl stuff and an adult beverage or 2 for me. On a narrow S turn my 07 Armada just died. Every light on the dash lit up but no nothing for electrical. Coast to the roadside and got all 6 of the girls out and up a nearby driveway. Opened the hood and put a little turn on the negative post and cable, all good. Then did the same to the positive post and it felt like it came off in my hand. Lifted up and cable with post firmly attached came right out of the 18 month old Walmart Everstart battery. After the tow truck came for me, the girls had other rescue plans, we made our way to the nearest CarQuest for a new battery. Tech was a former Walmart tech and said he’d seen this several times while working there. He referred to those batteries as “Neverstart”. Lots of issues so be aware of the Everstart issues!
 

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Update on my problem. Talked to Nissan service advisor, wife had the issues of not starting again after Nissan replaced the brake sensor at the brake pedal (2012 QX56) for the second time in 7 months.
I sent the advisor this forum threads but they would not acknowledge any issues having to do with the smart alternator (doubt they read it). Called Infiniti and they did confirm the issues but would not make any recommendations on what I should do because of the state smog reg's. I'm going to replace the battery ( Duralast Gold 930CC warranty) and have the wire spliced on the sensor so I can plug it back in when I take it in for Smog in NV. Can someone please confirm what wire to cut and splice with a connector please.

Thanks in advance guys.
 

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Warrantied Duralast 930cc going in tomorrow without sensor, will report back with update. Thx patrol and everyone else for input!

New Duralast just installed, sensor removed from negative terminal and taped up. Voltage constant as pictured, no drop in voltage when accelerating.

I drove it this morning and it took me 4 pushes for it to start (2nd time in 4 days) hoping those days are gone! Smog in Dec. I'll reinsert the sensor prior to smog certification.

I'll keep this thread updated.
 

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My 2019 Armada has had intermittent "no start" issues; the problem seems to be ocasional battery drain. My dealer just replaced the battery, and "depinned ECU Charge Control Circuit" whatever that means. My amp meter is now showing consistent 14V, when before it fluctuated between 10 and 14. What did they do and how will it help?
 

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your answer is resolved in this thread


bottom line - the ECM only allows the alternator to supply the minimum amount of current to keep the car running efficiently, at the expense of possible battery drain.

go to the first post and read what this does.
 

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I have a 2014 QX80 with the same issue. Seams like unplugging the sensor is a simple solution. But I am wondering if anyone has installed a switch. If you go with the "cut the blue wire" method I would think it would be easy to run some wire to the cabin with a basic switch. That way you can save those MPGs when you don't need it to run fully constantly.

Also, I didn't see anyone post about trailering. I would assume the VVCS would detect the additional draw needed to charge a trailer batter and run its brakes. But when I have the camper hooked up and drive for several hours, I stop for gas and sometimes I wont have enough juice to start the engine. Are others seeing the same?
 

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I have a 2014 QX80 with the same issue. Seams like unplugging the sensor is a simple solution. But I am wondering if anyone has installed a switch. If you go with the "cut the blue wire" method I would think it would be easy to run some wire to the cabin with a basic switch. That way you can save those MPGs when you don't need it to run fully constantly.

Also, I didn't see anyone post about trailering. I would assume the VVCS would detect the additional draw needed to charge a trailer batter and run its brakes. But when I have the camper hooked up and drive for several hours, I stop for gas and sometimes I wont have enough juice to start the engine. Are others seeing the same?
Funny you bring up the towing. 2 out of the 3 times that I had the 1/2 start issue was after long stints towing. I have 2 house batteries on my camper that charge off the tow vehicle.

I will say since unplugging I have taken a lot of long trips and towed a lot. Zero issues and starts stronger now.
 

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Funny you bring up the towing. 2 out of the 3 times that I had the 1/2 start issue was after long stints towing. I have 2 house batteries on my camper that charge off the tow vehicle.

I will say since unplugging I have taken a lot of long trips and towed a lot. Zero issues and starts stronger now.
Thanks for the information. Did you notice much change in MPGs?
 

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Thanks for the information. Did you notice much change in MPGs?
We're talking about a fractional decrease in resistance based on reduced alternator drag. Another way to look at it is the alternator is still taking care of regulating charging, it's not like the alternator is running at full output, full drag, all the time. It's just maintaining a higher voltage.

I'm pulling a trailer on varying terrain that usually weighs somewhere between 5k-6k depending on the trip. Hard to gauge any real MPG gain/loss. I'm usually around 10 towing.

And I'm running load E AT tires. Took about a 1.5mpg hit there.

MPG isn't really of concern to me on this pig. But honestly no noticeable change just from unplugging the battery sensor.
 

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We're talking about a fractional decrease in resistance based on reduced alternator drag. Another way to look at it is the alternator is still taking care of regulating charging, it's not like the alternator is running at full output, full drag, all the time. It's just maintaining a higher voltage.

I'm pulling a trailer on varying terrain that usually weighs somewhere between 5k-6k depending on the trip. Hard to gauge any real MPG gain/loss. I'm usually around 10 towing.

And I'm running load E AT tires. Took about a 1.5mpg hit there.

MPG isn't really of concern to me on this pig. But honestly no noticeable change just from unplugging the battery sensor.
Did you also loose 1.5mpg while towing? Or is that just around town, and while towing it is less of hit because you are already dealing with aerodynamic issues?

I would also like to get load E AT tires for our boondocking trips, but our beast already struggles pulling up mountains, so I hate to worsen the situation even further.
 

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Did you also loose 1.5mpg while towing? Or is that just around town, and while towing it is less of hit because you are already dealing with aerodynamic issues?

I would also like to get load E AT tires for our boondocking trips, but our beast already struggles pulling up mountains, so I hate to worsen the situation even further.
Mainly city, stop and go. But if a towing trip involves a lot of that, the hit is still there. Highway trips, towing or not, not so much of a loss because the mass is already in motion.

The benefits of load E, stability and load carrying capability, outweigh the MPG hit for me. Towing stability noticeably improved. I researched them to the moon and back 3x, ended up at Cooper Discoverer AT3 XLT. It was those or Wildpeak AT3W.

And in an attempt to not entirely derail the thread, that is the same reason I'm unplugging the sensor entirely. The benefits outweigh the (marginal, potential, maybe) MPG gain. I'd rather have my vehicle start everytime, watch my V needle stay around 14, and not need to replace my battery annually. YMMV and I'm not a mechanic.
 

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Well, it didn't work. After the dealer replaced my battery and depinned ECU Charge Control Circuit, my 2019 Armada failed to start (again!) about 6 weeks later. I pushed the start button - nothing; tried again - nothing. Being a little hard of hearing I opened the door to listen if the engine was turning over at all, and bingo ... it started! The truck had been used the day before so it's not as if the truck was in the garage for a week without being started.

I am really getting sick and tired of going to my vehicle, and crossing my fingers hoping it will start! By the way, I noticed no difference in MPG after the dealer depinned the ECU Charge Control Circuit (rural driving without towing).

My dealer didn't seem to know what else to do, so they replaced the brake switch at my suggestion. If this doesn't fix the problem, Lemon Law here I come!
 

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well with the alternator working all the time it will be SOME cost to fuel usage and mileage since the "always on" alternator is putting a load (albeint not much of a load) on the engine.
 

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Marctronixx, I sure can't argue with your reasoning, afterall, you have the laws of physics on your side. I will also add that my mileage estimate is anything but scientific. I'm only going by what the dashboard estimate is displaying, on average, before and after the depinning.
 

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@RustyTailpipe what are you seeing for normal running voltage?
Based on the battery voltage needle on the dash as a rough number do you think it's 14 or higher? Do you ever see that needle dip while driving or when driving conditions change?
I question whether they pulled the correct wires from the harness. There are 4 wires that go to the sensor on the Armada negative terminal. They could have pulled the temperature side of the sensor and the voltage is still connected.

With a multimeter what is your static (vehicle and all accessories off) voltage of your battery?
After the vehicle is started, and the idle is allowed to settle, what is the running voltage?
 

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OBX, thanks for your input. It appears they pulled the proper wire as the voltage gauge is acting quite differently than it did previously. Prior to the service the voltage would fluctuate; normally going down when I accelerated and going up when I would coast. The gauge is now showing a consistent 14-15V, (a little north of the halfway point) only showing slightly lower immediately after start-up (and then only momentarily). No more fluctuations while driving.

The last time the vehicle wouldn't start (after the battery replacement and depinning) I don't believe it was because of a low battery. After attempting to start the truck several times, I opened the driver's door to better hear what was going on under the hood, and the truck started with a very health crank of the starter motor. It sounded absolutely normal.

Having read in other threads that a bad brake switch can be an issue (remember, you have to hold the brake pedal down to start the vehicle), the dealer agreed to replace the switch given that they had on better ideas as to what could be causing the no-starts. So far I have had a software update, new battery, depinning and a new brake switch. Lets see how it goes.
 
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