2014 GMC "All Terrain" 1500/ 5.3 V8 /// fluctuating voltage reading on factory gauge

Stan Voth · January 2

HELP !!

I've got a stock 2014 GMC 1500 / 5.3V8 / Loaded.

Intermittent remote start.....sometimes would only "click". One time only, would not start with ignition key either. After it would start, all radio presets were goofy. Weird.

Replaced key fob battery--no change.

Had been noticing that the volt meter seemed to be reading higher than usual (14v-14.3v).

Had the charging system checked: "Alternator is showing a HIGH output & Battery is showing a LOW state. (reading across batt terminals was 15-15.2v)

(Vehicle has VERY low miles & battery appears to be the original)

Replaced the battery with a very good one.

Now it charges @ 13.8-14.2v on factory gauge......but while driving, it will drop to 9-9.5v & stay there untill shut off & restarted....then reads 13.8-14.2v again. Remote start seems to work just fine now.

Does this sound like a ALTERNATOR issue ?

Someone suggested it may be the "SMART-CHARGE" system ???? I dont know if my truck has that option. When did that come out & how does it work....supply & demand amps/volts?

I'd rather not just keep throwing parts at it, especially at the cost of them now !! ($200 for the battery....$335 for an alternator!) OUCH!

Any recommendations would be appreciated !!

God Bless-

Stan

rav3 · January 2

Sounds like K2XX typical bad ground(s).

A couple good videos on YouTube how to clean & add some ground. I'd start there.

https://youtu.be/Dql0Uu8-SNk?si=cIU3Ghq-yBvPbwEk

Edited January 2 by rav3

Stan Voth · January 2

Thanks Leatherneck... I'll scope out the utube videos.

Can I ask ya another non-charging related question about the same truck?

newdude · January 2

If all the grounds are good, its normal operation. The BCM and ECM control the state of alternator charge at all times. It can alter it for electrical load, fuel economy, etc.