What did you do to your NNBS GMT900 Tahoe/Yukon Today?

mikeyss said:

I'm with ya on this one. I have dual batteries with a reman 160 amp alt, and the big 3 upgrade. Since it's been 97 degrees, If I have both cooled front seats on, the a/c on full blast, and K5L efans running on hi 90% of the time, I see 12V at red lights. It purks up when moving. I know there has to be a way to keep constant amps.

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I didn't think alternators put out rated amps at idle rpms? Sounds like it's working normal to me[emoji848]

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

I went and picked up Subway for dinner for the family

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

gooffeyguy said:

I didn't think alternators put out rated amps at idle rpms? Sounds like it's working normal to me[emoji848]

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

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perhaps not but when the voltage is dropping to 11.3v that may as well be a dead battery, 11.8v at 3000+ rpm

Doubeleive said:

fighting with this RVC voltage regulation, unplugging the sensor doesn't make any difference, has anybody ever tried to go back to the old 4 pin system or had the rvc programmed out? I thought maybe the alternator was funky again so swapped in the oem one still have the same issue voltage will drop down to 11.3, I have 2 battery's one is slightly newer than the other so switch them just to see and no difference either, I just ******* want 14v steady is that too much to ask??????????

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Doubie, maybe different voltages on the batteries are confusing the system since they are hooked up in parallel.

In stock form (with rvc hooked up) and with a dvom on the back of the alt whats it putting out at idle? 2000rpm?

Whats volts at each battery at idle? 2000rpm?

Whats resting battery voltage?
Volts in morning?

Maybe one of your batteries is losing a cell??

Do all the tests above isolating each battery....with secondary battery connected and disconnected then with main connected and discon.

When i was researching I remember one article mentioning with a parallel system if the batteries are different...voltage, type etc it will funkify the system.

My batteries are exact type, size, and the voltages are with .2v -.3v of each other..

iamdub said:

Drilled a hole in it.


This little ring is the target:

View attachment 226625


This is what I did to it with a step bit- took it to 7/8":

View attachment 226626


Then I plugged it with this:

View attachment 226627


Another perspective (before I cleaned the plastic):

View attachment 226628


I tested it a few times to make sure I knew what I was feeling for inside there. I could easily trip the latch with my finger.

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I need to do this, wheres the plug from @iamdub

Doubeleive said:

ya that's the problem i'm having when the cooling fans are on high there sucking the juice down hard, I was testing the system with basically everything on lights, flashers, both seat coolers, a/c front & rear, wipers on high, rear defrost. lol, the wipers actually just stopped working never had that happen before motor must have overheated, once i restarted they worked again.

I disconnected the rvc sensor for now and with just the headlights and a/c going and cooling fans on low it was giving me 13.8-14

I might contact the company that programs the bcm's for led's and see if they can do something with the rvc also I thinks it's called "white's services" or something like that I'm sure it's just a google away, but probably have to wait till monday to find out anything

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Figured I would save you the trouble.
Here you go...

2007-2014 (GMT900) Truck & SUV – White Automotive & Media Services
https://www.whiteautoandmedia.com/product-category/fullsizetruck/gmt900/

Not sure if the RVC is controlled by the BCM or the ECM... surely won't hurt to ask though.

Doubeleive said:

perhaps not but when the voltage is dropping to 11.3v that may as well be a dead battery, 11.8v at 3000+ rpm

View attachment 226630

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You could always try swapping to a smaller pulley. That way it will spin the alternator faster while its idling, well it will spin it faster all the time but you understand what I'm getting at.

When I had my 1st gen Esky I got rid of the mechanical/engine driven fan and upgraded to the GMT900 dual electric fans.

When my 160A alternator finally crapped out I had a friend of mine that owned a rebuild shop rewind it to a 200A.

He told me he could rewind it up to a 260A but that it basically would not charge at idle.

When I got it back from him it still didn't charge as much as I wanted at idle so I swapped to a smaller pulley from an old alternator I had laying around, it may have been from an old S10 I don't really remember.

Anyway, that did the trick and it charged well at all speeds. The only down side was I had to run a slightly shorter belt to keep the tensioner happy.

If going to a smaller pulley, just don't go too small as it will overspin at higher rpms and could grenade it when heavy on the gas and spinning the motor to 5k or 6k rpms

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

Galante said:

I need to do this, wheres the plug from @iamdub

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I got it from a safe I was working on. That's how I decided on the 7/8" hole versus whatever size (that was larger, IIRC) was detailed in that bulletin Wes posted a while back. 7/8" or even 3/4" is plenty big enough to poke the latch with your finger, so just drill it to fit whatever plug you find. You should be able to find a plug at Home Depot or Lowe's in the electrical and/or data/com section.

Galante said:

I need to do this, wheres the plug from @iamdub

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7/8 hole will be a 1/2" knockout fill.