Jump to content

Low voltage issue

lance9386

By lance9386
in Troubleshooting & Recalls

 Share

Recommended Posts

lance9386 Enthusiast

lance9386

Posted
Posted

Why is voltage dipping well below 14 when the truck is running?? It's intermittent, it will go back up to normal at times..

fondupot Senior Enthusiast

fondupot

Posted
Posted (edited)

RTFM. If the needle is within the hash marks to either side of 14 volts. Its fine.

 

Straight from my owners manual:

 

"When the engine is running, this gauge shows the condition of the charging system. The gauge can transition from a higher to lower or a lower to higher reading. This is normal. If the vehicle is operating outside the normal operating range, the charging system light comes on."

Edited by fondupot
  • Like 1
MNDaveC Enthusiast

MNDaveC

Posted
Posted

I'd certainly be keeping a close eye on things if it starts fluctuating if there were no obvious electrical drains. Belt slipping? Low RPM?

MikeNH Senior Enthusiast

MikeNH

Posted
Posted

This is normal. Look through the forum or read the manual.

 

Someone posts this question like once a week. ;)

  • Like 1
lance9386 Enthusiast

lance9386

Posted
  • Author
Posted

Thanks guys. I did RTFM... but.. I have never seen a vehicle unable to maintain 14.4V while running unless there was a huge draw on the electrical system. I find that at idle is mostly when this happens. At night with the headlights on it stays right above 14, where it should be. I just think that is very strange, but apparently it is by design.

fondupot Senior Enthusiast

fondupot

Posted
Posted

Thanks guys. I did RTFM... but.. I have never seen a vehicle unable to maintain 14.4V while running unless there was a huge draw on the electrical system. I find that at idle is mostly when this happens. At night with the headlights on it stays right above 14, where it should be. I just think that is very strange, but apparently it is by design.

 

Its a design element that comes from the fuel efficient alternators on these trucks. When the battery is within an acceptable range, the alternator is not engaged, this is less draw on the motor which saves fuel.

  • Like 3
lance9386 Enthusiast

lance9386

Posted
  • Author
Posted

 

Its a design element that comes from the fuel efficient alternators on these trucks. When the battery is within an acceptable range, the alternator is not engaged, this is less draw on the motor which saves fuel.

Thanks for the explanation! That is good to know.

MMC Enthusiast

MMC

Posted
Posted

Saves fuel and extends battery life, GM's been doing this for years.

  • 10 months later...
Silver ice 6.2 Senior Enthusiast

Silver ice 6.2

Posted
Posted (edited)

I haven't seen a pic.. and thought I would post.. here you go when I first noticed i said oh wow that's nice..lmao bit looked online and seen that it's normal. And yes that was my reaction at first

post-145646-0-28256900-1436131420_thumb.jpg

post-145646-0-28256900-1436131420_thumb.jpg

post-145646-0-28256900-1436131420_thumb.jpg

post-145646-0-28256900-1436131420_thumb.jpg

Edited by Silver ice 6.2
  • Like 1
20L8TSierra24 Senior Enthusiast

20L8TSierra24

Posted
Posted

I was just thinking about this because my truck is barely starting at times. My needle looks like above and I load checked the battery and it came back good.

  • 9 months later...
thejimmian Enthusiast

thejimmian

Posted
Posted

does anyone with cooled seats notice a drop in seat fan speed when the voltage goes below 14v o nthe dash? I have recently noticed that when the truck turns the alternator off to save gas i basically loose the highest cooling level (fan speed is the same on level 2 and level 3). pretty annoying. i think it is the same story with the AC blower fan as well.

KLRV6 Enthusiast

KLRV6

Posted
Posted

 

Its a design element that comes from the fuel efficient alternators on these trucks. When the battery is within an acceptable range, the alternator is not engaged, this is less draw on the motor which saves fuel.

And the battery will last longer by not forcing higher voltage on it when not needed. I was worried when I noticed it the first time.

  • Like 1
  • 2 years later...
Kevin Gorczyca New Member

Kevin Gorczyca

Posted
Posted (edited)

Here is my 2017 Denali with the 6.2L and 35,000 miles. Notice my two pictures have different miles on the trip meter. I was driving around for 4 hours yesterday morning and it stayed this low the whole time. This line represents around 12 v. You mean to tell me that this thing was in fuel saver mode charging at 12v for half a day? I’m having tons of electric problems on my truck and the dealer is using this as an excuse to not find the real problem. I’m also having transmission shuddering and slipping trouble, severe detonating on 93 octane (only when it’s cold and dry out), and front parking sensors and crash avoidance sensors throwing codes. Had front power seat and rear wiper not work intermittently too. Dealer is just making excuses but I think in my case this is NOT operating as designed. Can anyone elaborate on this?

F433DB0B-83C9-4CE8-9457-A5D74A616943.jpeg

4793C5DA-EA7F-4EE6-85C5-1F29BA5E396D.jpeg

Edited by Kevin Gorczyca
Added engine size and mileage
  • 1 year later...
Nasir222 Enthusiast

Nasir222

Posted
Posted

I have 2017 Silverado LTZ Crew Cab and it stays low in the daytime and jumps to normal range at night and I have a decent audio system upgrade and never had problems before... or noticed it. I noticed that when I push the audio in the daytime I have a clipping monitor that shuts the amp down when it hits clipping that only has happened when it gets close to the left side mark of the 14v. Weird because I would have never known if I didn't have the clipping monitor on my amp 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.3k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,716
    Total Members
    8,960
    Most Online
    BDS my HD
    Newest Member
    BDS my HD
    Joined

  • Who's Online   5 Members, 0 Anonymous, 591 Guests (See full list)

  • Latest Articles

  • Posts

    • BDS my HD
      Brand new to this forum. Questions about re-gearing my 26’ HD

      By BDS my HD · Posted

      Hello hello looking forward to expanding my knowledge of the 2026 2500 HD that I just bought.   Truck has 3500 miles on it four-wheel-drive crew cab and I’m about to put a 6 1/2 inch BDS lift on it 18 x 10 -25 offset with 37’s   Already have the wheels and tires just waiting on the lift install in about three weeks   Question what surprises am I not gonna be happy with?  I’m not new to lifted trucks so I know that acceleration towing gas mileage all that is affected..   Question is those of you that have this truck this powertrain with a 10 speed Allison and have done the mods that I’m doing,,, how bad is it? Is that Allison constantly gonna be hunting for the right gear to go into? And what about towing, acceleration, fuel consumption as mentioned?    Lastly how come I can’t find any ring pinion gear set up for these axles and when could I expect to see them?   I apologize if there’s any typos I’m doing speech to text on my iPhone.    
    • linc45bn
      2013 2500HD 6.0L intermittent no crank no start

      By linc45bn · Posted

      I've got a 2013 2500 6.0L Flexfuel. Drove the truck earlier today with no issues. Went to run an errand tonight and noticed key fob wouldn't work. Figured battery was dead, so replaced fob batter. Still wasn't working. Grabbed my other set of keys with the other fob and that one wasn't working either. So I manually unlock truck and insert key. Interior lights come on, dashboard lights up, turn key and truck starts. Turn truck off, like a moron, and try starting again. This time no crank, no click, no nothing. Lights still come on and dash lights up, but now I'm getting a service 4wheel drive, service tire monitor, etc. Check voltage on battery and Im showing 12.2v. Throw my battery charger on it and give it 15 mins and try starting again. But still no crank no start. Decide maybe its a bad battery, run to autozone grab a new one and put it in. Same issue. Disconnect battery and let it sit for 15 mins. Try again and still nothing. I had managed to roll the windows down earlier as its a humid night, but now I can't get them to roll up. Power locks are also not working now. Then randomly I try the key again, and it fires right up. Immediately I roll up the windows as we have nothing but rain forecast this week. I shut it back off wait 30 seconds and start up again. Worked a 2nd time. So turn it off, start putting things back together. Try one more time, and back to no crank no start. And now the car alarm starts going off. Had to disconnect battery and leave it that way for the night as I don't think my neighbors would appreciate my alarm going off again tonight. Any thoughts or help would be appreciated. 
    • Grumpy Bear
      first oil change - 2026 2500HD gas

      By Grumpy Bear · Posted

      No one will care for you like you care for you. Do what you can for as long as you can. IMHO of course. 
    • Grumpy Bear
      Oil Consumption

      By Grumpy Bear · Posted

      How about them NICKS!!! 
    • Peoplemvr
      GMC 1500 Illuminated Front Grill Emblem REPLACEMENT.

      By Peoplemvr · Posted

      Hi there.  Long time lurker, first post.    i have read the previous posts regarding the water ingress problem with this emblem.  I bought my 1500 SLT the  summer of 2025 new and after reading the MANY problems with these emblems failing I decided to install one anyways.  As per a YouTube video, I sealed ( or tried to) this sign with silicone sealant around the outer perimeter joint and the holes that were already somewhat sealed on the rear plate of the emblem.  And installed the connector assembly using dielectric grease on the connectors. The installation looked great and worked well for about 4 months……then FAILURE.  Grrrrrr…… I live in the great white north and wash my truck weekly in an automatic car wash  to keep the salt off.  Let me tell you that removing the old, failed emblem is a whole different animal than removing the OEM individual letters without removing the grill assembly. Mainly because the illuminated logo is built differently than the original letters which  you can remove the red surface lettering with a knife or some kind of blade which gives access to the tabs which hold the logo onto the grill. So I had to essentially destroyed the old emblem to remove it. Doing so killed my chance of doing somekind of autopsy on the failed , old logo.  But there was plenty of water inside when I ripped it apart.  Prior to installing the new assembly I tried it with the old harness and it works fine.   Does anyone have any insight as to where the water is getting into this emblem? I intend to seal the new logo with slow curing epoxy this time around using a syringe.  I think this newer emblem may be an updated unit which I hope GM got the vendor to fix. It has an October 2025 date on it.    If this one  fails,  I am just going to revert back to the non-illuminated letters….AFTER PULLING THE GRILL.    Any thoughts on sealing with epoxy would be appreciated. Thx!   Doug  

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...