12v on voltmeter

[DRM796]

Have a 2004 Silverado duramax. Driving down the road today and the voltmeter went from q4v to 12v with the battery light coming on and off. Never went below 1q and was able to drive another 110 miles. Got to the campground and after letting the truck sit for about 10 minutes it starts right up but still reads just 12v. Also noticed when ever the battery light comes on, if I get up to 2500 rpm the light will go out. Any ideas, alternator?

Thanks

[Thunderbolt]

Yup alternator. Had that happen on my 03. The reason you made it so far may be that the alternator itself is still charging. These alternators have a a separate circuit for the gauges and warning light. This can malfunction even if the alternator is still working. That's what happened to mine. It still requires replacing the alternator though.

[DRM796]

Thanks guys, found an Advance Auto Parts store 10 minutes from campground that had the alternator, replaced it and all is good.

[azrving]

Sounds like worn alt brushes are making intermittent contact with the slip rings. In a pinch tap on it lightly and it may charge until you can replace it.

[time2roll]

Alternator. Just run down get a new one and pop it on.

[horton333]

Ditto, the residual magnetism will sometime provide a little bit of power out at higher RPMs but check the alternator or have it checked ....

[agesilaus]

Check the belt too

[Mandalay_Parr]

Sounds like alternator.