2006 sierra SLE, intermittent charge from alternator

Joined: Jun 21, 2010 Posts: 2 Location: Texas

I have a 2006 GMC, crewcab, 5.3 liter, SLE, 53,000 miles.
Every now and then the amp meter drops to 12.7, from 14 (aprox) volts.
I verified this with a votage minder pluged into the cig. lighter.
No codes, or idiot light comes on. Only one time I caught it doing it and was able to get it into my service tech. It showed a load of 100 amp from the large main battery wire, and then it went back to normal and could not produce the issue again that day. But it still does this on occasion and has be worried as I am planing a 4000 mile trip in a month or so. Makes no difference if any accesories are on or off..

Can a intermittent battery cause this, or some other issue???

Joined: Jun 21, 2010 Posts: 2 Location: Texas

Oppps, sorry. I just found a possible answer.

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INFORMATION

Bulletin No.: 07-06-03-009A

Date: July 21, 2008

Subject:
Information On Voltmeter Gauge Fluctuation Due To Regulated Voltage Control System And Concerns About Camper/Trailer Battery Charging Models:
2005-2009 Cadillac Escalade Models
2005-2009 Chevrolet Avalanche, Silverado, Silverado Classic, Suburban, Tahoe
2005-2009 GMC Sierra, Sierra Classic, Yukon Models
Supercede:

This bulletin is being revised to add the 2009 model year. Please discard Corporate Bulletin Number 07-06-03-009 (Section 06 - Engine/Propulsion System).

Voltmeter Fluctuation Condition

Some customers may comment that the voltmeter is fluctuating between 12 and 14 volts on their full size pickup or utility vehicle. Starting with the 2005 model year, light duty full size pickups and utilities are equipped with a new Regulated Voltage Control (RVC) system. This system reduces the targeted output of the generator to 12.6-13.1 volts when in "Fuel Economy Mode" to improve fuel economy. The generator may exit "Fuel Economy Mode" if additional voltage is required. This will cause the voltmeter to fluctuate between 12 and 14 volts as opposed to non-regulated systems that usually maintain a more consistent reading of 14 volts. This fluctuation with the RVC system is normal system operation and NO repairs should be attempted.