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Over 15 volts

Willborio

By Willborio
in Ask A GM Technician

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Willborio Enthusiast

Willborio

Posted
Posted

Recently my voltage meter has been showing up around 16 volts and it don't drop down. Today when I started it after it was turned off for about 15 min. I got a click then it started fine. But it also didn't start with the settings I had the heat to. And there was no sound on the radio. It's an aftermarket radio with the wiring harness to retain all factory controls and functions. I've never had this problem before and noticed the high voltage after this happened. It was on for half an hour and the volts never dropped. Is the high voltage due to a bad regulator. There has been a constant noise under the hood since it got cold. It seems like the alternator is in a constant state of charging. Even though the battery when the truck is off shows good volts. It's an 09 avalanche ltz

Arth Enthusiast

Arth

Posted
Posted

The voltage is controlled by the computer based on battery charge, system load, etc.

 

My volt meter has been reading high on most of my drives because of the hard cold starts and I run my heated seats, A/C, and my headlights were on.

 

You need to check the voltage you are getting to the battery, with a multi meter, with the truck running to see if you are actually running high.

 

Also it sounds like your battery may be heading out... might want to have it tested using the Cold Crank test and see if it passes for what it is rated for.

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

If the sensing wire (whichever one they use) is corroded, it can cause this issue too. The computer will think the battery is low, and give the alternator full duty cycle.

Willborio Enthusiast

Willborio

Posted
  • Author
Posted

Thanks guys I'll check the battery tomorrow and see what I'm getting athe the battery when running. I do run the heated seats the entire time it's on. But what worried me was even just in park with no heated seats on or lights since it was in park it stayed up over 15. It normally drops down to 14 and won't move from there when I'm driving except when it drops down.

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

On 2 vehicles just this week I've seen 15.12v running on my scan tool, mine being one of them. It stays there for a bit, then the computer eventually dials the duty cycle back a bit. After some time passed mine was down to 13.8.

 

It's normal for it to stay high initially - it should dial the duty cycle back over time as the charge comes up.

Willborio Enthusiast

Willborio

Posted
  • Author
Posted

Yea it was doing that originally. But much higher currently than before. Originally it would be about a quarter inch past the 14v. The last couple days it's been more than half way to the 16.5v mark. But I just went out to fiddle around with it. And noticed the positive terminal was very loose. To the point I could have just popped it off. I tightened it up started the truck and I was just past the 14v the meter was showing me a steady 14.78 when I looked on the dash it was in what I see as normal range just past the 14v. I'm guessing the extreme cold to warm over the last few weeks here in northern illinois was the culprit. Probably got it just loose enough I wasn't getting solid contact.

Willborio Enthusiast

Willborio

Posted
  • Author
Posted

Also the battery was reading 11.8 after sitting in the cold garage the last 24 hours and not being started. So it seems I should have checked the connections first then asked for help. Lol

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Well, at least it was a FREE fix! These days those are hard to come by!

 

Glad it's resolved. :thumbs::cheers:

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