2005 Chevy Silverado Voltage Problem on 05 Silverado

Tiny
KENNY782
  • MEMBER
  • 2005 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 35,000 MILES
I replied to this post earlier but it's a year old so I doubt the original user will respond. http://www.2carpros.com/forum/here-vp1013813.html

Well I have an '05 Silverado, V8, 5.3L (gas only) Automatic, 4WD

Since I bought the truck the voltage meter on my dash always holds right in the middle at 14.
But last week I noticed that it was moving around just a little, most people probably wouldn't have even noticed.

2 days later it was moving all over the place, depending on the engine temperture it could be anywhere from 11 to almost 16
Shortly after that my battery light came on in the dash. Later I found both my low beams blown out. The headlights where on at the time when I checked the next day it was both the bulbs not the fuses.

I tested it carefully with my multimeter:
Engine off: 12-12.1
Startup: 15.9-16.5
Mid warm up: 13.9
Fully warmed up: 12.5-12.9 on average but drops to 11 sometimes.

I'm no mechanic but I am a bit fimilar with electric/electronics. I replaced the voltage regulator in the alternator with an identical one.
The engine starts up at 13.9 and slowly rises.
When the engine is warmed up it holds at 14.6
Do you
have the same problem?
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No
Monday, October 11th, 2010 AT 6:29 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
It sounds like it was overcharging.
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Tuesday, October 12th, 2010 AT 9:09 AM
Tiny
KENNY782
  • MEMBER
Thanks for the reply I really appreciate it.

Checked it again today same results 13.9-14.7 so it's at least consistent. Voltage held at 14.78 primarily.

With everything off today the battery gave me 12.7
With the engine off I turned the high beams and blower to full.

Voltage dropped to 10.9-11.2
Does that sound right?
I'm just trying to eliminate the battery if I can.
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Tuesday, October 12th, 2010 AT 8:39 PM
Tiny
KENNY782
  • MEMBER
Some more research somebody said that 14.7 is actually the normally operating voltage on this truck. Can anyone confirm?

I also found someone who said that gm found the wiring harness to the alternator was faulty. It fixed the issue for a few months but then the alternator had to be changed anyway.

I just changed the regulator, I could change the harness tomorrow and maybe that will finally fix the issue and prevent any more damage.

What do you think of all this?
I was kinda on the same track but was just gonna clean all the terminals/connectors.
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Tuesday, October 12th, 2010 AT 11:44 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
As far as the voltage, if you are getting 14.7 with the engine running, that sounds good. As far as the drop with the lights on / blower on. It sounds like that is low. Have you had the battery load tested?
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Wednesday, October 13th, 2010 AT 11:50 AM
Tiny
KENNY782
  • MEMBER
Well I let advance run their test yesterday based on the new voltage readings I was getting.

They said everything was okay at this point.

Should I rip out the battery/alternator and run it through their machines or is this just as good?

Thanks,

Kenny
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Thursday, October 14th, 2010 AT 7:01 PM

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