Intermittent charging problem

[MaverickZ71]

On 5/6/2021 at 11:15 AM, Lfd49 said:

Thanks, I have a friend here that has a 2013 Sierra 1500. Basically identical to my truck, and he has never seen it happen to his. 

 

Then he must never look down, or his is messed up.

 

COMPLETELY NORMAL for the needle to gradually move back and forth between the 12 to 16 volt hash-marked area as the alternator charges or coasts as needed. 

 

PS  When in doubt, always use GM/AC Delco replacement parts of the OEM spec. 

Edited May 8, 2021 by MaverickZ71

[Lfd49]

The reason o asked is because it has never happened in any other vehicle I have ever owned regardless of make. Either in Ma. or here in SWFL.  Thank you all for taking the time to comment on the post I appreciate it.

[Chylin73]

Just started dealing with this issue and I am glad I came here. 2007 Sierra classic 5.3 190K miles on it and my truck just started doing this last month. Had the battery tested and the machine said to replace battery. Battery was 8 years old so I didn't think anything of it. I put an Optima in and it was holding 14.4V when truck was running so all was good. This lasted for a week then the Voltmeter on dash started showing the drop to about 12.6. Ran thru the typical tests of checking the Alternator and it was doing its job. So I thought maybe the regulating circuit was going bad. I came here to see if anyone else was having this issue and I see they are. 

[JGoodman]

I drive a 2013 Silverado w/t with the vortec v6 and I have been having the “service battery charging system” light  come on mostly when slowing down. I have a new alternator and have replaced belt and belt tensioner. I believe it is the RVC sensor that is causing this. Would it harm anything if it is unplugged? I know alternators have regulators built into them so by unplugging this it should not overcharge the battery should it?

[09 Sierra]

I have a 2009 Sierra. I noticed the voltage dropping to a concerning voltage for some time now. I changed the alternator and still had the same trouble. I drove down to Florida from Connecticut and when the voltage dropped below 11 I would put the truck in neutral and turn off the key and then restart it and it would start charging again. Sometimes it would charge for a couple hours before dropping that low and sometimes it would only take about 10 or 15 minutes. Because it never really happened until after about 45 minutes the dealer never really was able to find the trouble. I brought it to a local shop and they identified a problem and said it was the ECU. I had that changed out at the dealer because he didn't have the equipment to flash the chip and now it is worse than it was before. Truck only has $65,000 miles on it. This is not the fuel saving programming that they put in to it this is a problem. Once it stops charging it never starts again until I turn off the truck and turn it back on which is telling me it's a computer issue. Any help would be immensely appreciated