What wrong?

[Elrey7698 10]

So i just put a new battery on my wifes yukon like 6 months ago...and i turn it on now and the voltage drops very rapidly..i turn on just the switch with the truck off and the voltage goes from 12.3 down to 10.6v is it the battery or is my alternator not charging it right? Its the stock 160a alt...

[ssh 924]

Measuring the voltage when the vehicle is idling could shed some light as to if the the alternator is doing it's job. Autozone/Checkers can also do a simple test to make sure the alt is working.

You can also use a dmm to see if something is draining the battery while the vehicle is off.

[ssh 924]

Does her truck has any additional electrical devices? If so, how much approx how much amperage do you think they are requiring.

[Elrey7698 10]

Just an aftermarket stereo, hid's, an my amp but i dont have any subs connected to it right now...but its still on when im driving...

[Elrey7698 10]

I wired down some subs down to 1ohm and free aired them and i noticed my volts go from 14.1v down to 10.8v

[pmureika 31]

Whats the voltage when you are driving?

[Elrey7698 10]

It used to be 14.0v-13.8 now it goes down to 12v-11.9v

[Impious 1,476]

If your voltage is dropping that significantly with the vehicle running and it's not loaded down excessively, then the alternator has failed.

[Elrey7698 10]

FML!!! An how much is gm gonna charge me for a new alt? An arm an a leg man...this is bs...its a new truck man...im also gonna have to buy a new batt cuz this one is probably destroyed too

[Elrey7698 10]

Ok so i took a drive and the volts were jumping around evrywhere...started off at 14.1v and it stopped now at 12.8...but the stock voltmeter is at 14v

[ricksi30 923]

Ok so i took a drive and the volts were jumping around evrywhere...started off at 14.1v and it stopped now at 12.8...but the stock voltmeter is at 14v

What are you using to measure voltage?

[Elrey7698 10]

Ok so i took a drive and the volts were jumping around evrywhere...started off at 14.1v and it stopped now at 12.8...but the stock voltmeter is at 14v

What are you using to measure voltage?

Im using my stinger voltmeter

[ricksi30 923]

Ok so i took a drive and the volts were jumping around evrywhere...started off at 14.1v and it stopped now at 12.8...but the stock voltmeter is at 14v

What are you using to measure voltage?

Im using my stinger voltmeter

Try a DMM to be sure that the meter isn't messed up.

[Elrey7698 10]

Yeah i thought about that but when the truck is off i can see the stock voltmeter go down really quick...down to 10v

[fearlessgangsta 12]

Ok our trucks have a dumb thing. When you are cruising it drops the voltage because there is no demand. Switching on the headlight puts the vehicle into charge mode and it jumps back up to 14+, but the headlight thing doesn't work for some people. Also some people complain that these new trucks drain batteries like no ones business some people even have to go to the dealer to get the ecu reflashed. I can recommend the TahoeYukonForum just because there are many more who know more than me about these trucks.

Edited March 9, 2012 by Fearz

[Elrey7698 10]

Im actually a member of that forum...im just gonna remove the alt and the batt and have autozone check them..its free...and that headlight thing wont work cuz out trucks have DRL and the lights are on all the time

[fearlessgangsta 12]

Oh yeah the DRL's are the headlights(brain fart). It's a few different tricks to get the alt to charge I just can't remember them.

[Elrey7698 10]

Checked dc power and an alt is $400 dammit! Hope its not that

[fearlessgangsta 12]

Even if you get a HO alt it will still do the floating voltage thing when your driving. The only way I know to stop that is with a MLA module, and then you have to splice into the PCM control to get it to constantly charge at 14.9

That's why you see so many people running dual and triple brackets on these new model trucks.

Edited March 9, 2012 by Fearz

[Elrey7698 10]

But for my 2000w system the stock should be enough..i have the big 3 and a dutalast gold batt

[fearlessgangsta 12]

Just for my bc2000 I'm doing big 3 and remember to ground through the electronic ground clamp to help the alt see the draw. I'm ordering a xs3400 as a secondary batt. I'm doing one run of positive and negative in 0 gauge to back where the amp is from the 3400.

Now when I'm completely finished with that.

I'm saving up for a dual bracket and mike singer alt then running my system completely separate from my stock charging system. Then I will be done with my electrical.

[Elrey7698 10]

Ground the electrical clamp? HUH?

[fearlessgangsta 12]

On the left side of the engine is the engine ground. You can see it running off the battery then it runs through this thing then is grounded to the motor.

This off another guys truck off SMD(I know)

That thin wire on top of the 0 gauge is the headlight ground that goes somewhere on the firewall. The 0 gauge is covering the other wire that is a little thicker then the headlight cable. The thicker wire that you can't see will be the stock engine ground

On now if you find this thing(it should be to the right of the battery just look and you should find it. If you do it currently has to grounds running through it one wire will be thicker then the other. The thicker wire will be the ground from the battery going to the engine block and you would be able to see it. The skinner wire will be the ground for the headlights. Basically the ground current is measured by the clamp and it tells the electrical system what to do.

So what you is just run 0 gauge through the clamp from the negative of the batt and ground it to the engine block with the one that is already there. I'll try to get some pics tomorrow and type a description with pics.

Edited March 9, 2012 by Fearz

[Elrey7698 10]

I gonna check in the morning

[fearlessgangsta 12]

I gonna check in the morning

Cool, I'll try to remember to get more pics for you because the first time I tried to find it I was completely lost.