I have a 07 silverado 4x4 ltz, I noticed when the truck starts the voltage is about 14.2, after a bit of driving I noticed the voltage drops to about 12.5 or so. I thought as you drive your vehicle stays at 14 or so volts. The only thing I have on is the radio. I need a bit of help with this, I think its the voltage regulator, any help would be greatly appreciated before I got to the dealer.

 

Hi timmysk,

Welcome to the Chevy Forums.

I'd check your cables. Pay particular attention to the wire coming off your alternator, as well as your engine -to- firewall ground strap. Be sure the bolts holding your battery cables to the battery are not corroded.

You can have your alternator and battery tested for output free at most major auto parts stores.

What's the vehicle mileage?

 

not sure if your truck has it or not. but some of the newer trucks only give the volts needed and will put out what is needs to put out. not sure what year they started doing this or if it is on your truck.

 

look in the owner manual

 

That is exactly how it works.

 

My truck has 120,000 on it, it's funny cause I was driving around last night and the voltage stayed around 14. During the day it drops. I'm kinda confused lol

 

it only puts out what is needed to run your truck. so if your lights are on or other stuff using power it will have to put more power out. rasing the volts. it works on a as needed only.

 

Ok, good to know. Thanks everyone for your in put.

 

Yeah, that kind of mileage, sounds like it may be the end of your alternator's lifespan.
Usually if the diode plate remains intact, they just start producing less and less voltage.