2013 Sierra Volt meter doesn't drop from 14+ volts as designed.

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by bigjer, Jul 12, 2013.

  1. bigjer

    bigjer New Member

    Hi everyone,
    I just took advantage of GM's huge incentives and upgraded my 09 Sierra to a new, 2013 Sierra z71. LOVEEEE it!!
    Being the stickler for details that I am, I noticed that the Variable charging rate system that fluctuated between 12-15v on my 09's volt meter(as designed) hasn't varied at all on my 2013. I only have 300 miles on the new one.
    I realized(from service manual) that many conditions have to be met to lower the voltage output, but I think I am meeting those conditions and the volt meter hasn't dropped off 14+ at all. I even topped off the battery with my C-Tek charger overnight and the battery is fully charged.
    Anyone have any info on this? Is it because of low miles on truck?
  2. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    No insight to repairing your problem, only confirmation that yes you should see some fluctuation on the gauge.
    I assume the truck is properly transitioning to 4 cyl mode.
    One possibility since this system is a learning system is that it might still be putting together information on how you drive. The alternator and AFM systems take quite a few miles before they settle in and operate to their full capacity.
  3. stchman

    stchman Active Member 2 Years 1000 Posts

    We want pics of the truck!!!!!

    I'll check my 2013 Silverado volt meter to see if it drops.
  4. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    It is possible, because of the way the '09 presented the voltage readings (and, my '09 reads the same), that the needle movement was dampened on the newer trucks. Maybe GM just got tired of people asking "how come the voltage gauge readings constantly change"?

    I would run a couple of wires from the battery into the cab and connect a hand-held volt meter. Have someone drive and you compare the DVM to the dash gauge.
  5. GM Customer Service

    GM Customer Service Epic Member 5+ Years 500 Posts


    First, congratulation on your new vehicle. I am sorry to hear that you do have a vehicle concern on your new vehicle. Private message me if I can be of assistance.

    Safe travels,

    Jennifer T.
    GM Customer Care
  6. greywolf11

    greywolf11 New Member

    When I got my '13 back in February I noticed that my voltmeter showed a higher charging level than my '11 when it was charging. I never noticed the truck dropping back below 14 until I probably had 2 or 3 weeks driving. Now it runs at the same level as my '11 and drops back just like the older truck. As posted by others, I bet it is in some sort of learning mode.
  7. stchman

    stchman Active Member 2 Years 1000 Posts

    Ok, after replying to this thread back on 7/12 I kept an eye on my volt meter of my 2013 Silverado.

    I can say when running that meter never drops below 14V. This appears to be just the way it is.
  8. j cat

    j cat Epic Member 5+ Years 1000 Posts

    my idea about this voltage/charge drop out to save fuel ??? is / was a bad idea. this just damages the alternator. best the alternator always supplies the light amount of power to run all the electrical equipment and charge the battery if required.

    drawing down the battery when the alternator drops out is also not good !
  9. stchman

    stchman Active Member 2 Years 1000 Posts

    Can you elaborate on this?
  10. j cat

    j cat Epic Member 5+ Years 1000 Posts

    lead acid batteries need be charged fully at all times. when they discharge[supply power] they must be charged in a short amount of time . the more you discharge a lead acid battery [frequent starts] the shorter the life.

    when operating a vehicle and the alternator drops out the discharge frequency increases this causes damage to the cells due to heat generated when the alternator starts charging the battery. heat is what also kills these batteries. like on some of these new vehicles the battery is up against the fire wall not the best place to put a battery to avoid heat since the air from the engine/radiator is in that area.

    light loading of the alternator is best since it will reduce brush commutator wear . the windings and regulator also get damaged from the heat created with the constant hard charging of the battery so you can save a little fuel or perhaps for GM to pass some EPA mileage law.

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