[Alfredo]

Hey, anyone else run into this? I’ve got a 2014 Silverado LTZ with about 164k on the clock, and lately the voltage has been dropping way low. Is my alternator on its last leg, or is there something else messing with it? Battery’s not super old, but this dip’s got me second-guessing everything. Could it be a grounding issue or just wear and tear showing up? What would you check first if you were in my shoes?

[Chad]

Would have to know what your voltage desired PID is to know. It’s PCM regulated, so if your PCM is only requesting that voltage then it’s fine.

[Walker]

It’s variable, my sierra did that since new it just means it’s at the desired battery voltage and when it drops below a threshold it will be back to charging at 14v.

[Steven]

It’s engineered to do that. When the battery is fully charged and no extra power is needed, the alternator reduces its charging to 12v. It will run between 12v and 14.4v. Cant remember what wire it is under the hood, but if you disconnect it, it won’t do that anymore.

[Phil]

Yes. But the pump has a dictated control for certain situations.

Like some have said.

It keeps it between 14.5 and 12.

Then it will turn on, but at idle it slows the motor and won’t come back up quickly.

It takes time because it’s over 12.

You get that right.

We do not see what else is on the vehicle.

Like I said, if he’s at that voltage at idle and the AC is on. Guess what.

The lv8 on the motor is too great.

Also, it’s just over 37mph.

In overdrive, no doubt. More lv8 on the motor.

The load is kinda big for the alternator itself to catch up.

So it’s getting hot and doing it’s best to keep it over 12v for the battery and also the PCM to keep doing its job.

Sorry, I don’t want to be rude.

I just want to tell you I’m a Triple Master and worked for the fa tory with Engineers.

Also keep in mind. 164k on the clock.

If is an after market alt. It might not be able to do its job under a load.

[Brent]

Probably just fine. Check charging voltage at 2500 rpm if you’re worried about it.

[Charlie]

That; at least from the pic angle, doesn’t look low. Especially if on the freeway and cruising along. Your battery becomes fully charged, and the ECM will command the alternator to reduce its it’s overall charge t reduce drag on engine better fuel economy and doesn’t overcharge the battery.

[Michael]

When the battery is fully charged, the PCM turns of the voltage regulator until the battery needs a charge. The timing depends on. How many accessories are on.

[Michael]

Start loading it up, fans lights everything on, see if it comes up. It’s GM’s way of squeezing every ounce of fuel economy they can. Less load, less out put = less drag.

[Ben]

OK, I have 2011 traverse. Have the same thing happening already had a reman alternator a year ago, it truly went bad. Well, voltage dropped just like this. Replaced the alternator (lifetime warranty) for two weeks, it ran 14 to 14.5 volts. Then this again had it tested (O’Reilly) they said bad voltage regulator. So swapped it again. One week later, same thing. I have been driving it all week, no issues. I never saw it do this in three years. Going to take it to my buddy’s shop, and he is going to put it on a good scan tool. I understand the concept of lower the desired voltage. My question is, why start now?

[Samuel]

It’s variable. Light will come on below predetermined voltage.

[James]

Looks like it’s working to me. Perhaps you added something aftermarket that draws more power than the original system requirements, and you need a higher output alternator.

Or one of the cells in your battery is starting to die, and it’s causing your system to draw more power.

Use a voltage meter across the alternator terminal and see what it’s producing, and that should tell you if it’s working properly.

[Wesley]

There are at least 6 different charging modes with different voltage set points. If you had a problem, there would be an accompanying warning on the message center.

[Jaramia]

They do that once it gets to a certain voltage it’ll kick in and then shut off.

[Tim]

That’s how Chevy did it perhaps they still do—not sure on my 24 but my 15 does this actually quits charging than when voltage gets too low it kicks in again I’ve seen it like this for 60 miles or more depending on load draw it’s normal.

[Ernie]

No, it’s part of how they work. When your battery is fully charged, and you’re not using many volts, it cuts back on charging.

[Author]

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