in my 03 z71 sierra, i noticed that in park and running, my truck has in the 12.5 to 13 volt range. when i rev a little it goes up to 14ish. it was my understanding that alternator out put was constant in the 14.2 range. am i crazy? i just remembered this issue, and i have yet to put my multi meter on it. might explain my very slow power windows. can someone straighten me out ?

 

its variable on these new trucks...no worries.

 

The '03s don't have the new system. Your alternator might be getting weak, or you just have a ton of electrical accessories running. Such as a/c on high, headlights, etc. You could take the alternator in to get tested to know for sure. By the way, the windows in my '03 got really slow as the truck got older.

 

you sure 03-06 arent the same?

 

I had an '03. It was over 14 volts all the time. I took my 2010 back to the dealer the day I bought it because I thought the charging system was failing since the '03 was so consistent. I think I remember hearing that they started the whole variable voltage thing in '05.

 

hmm, odd. Asked my buddy at XS Power, he stated 03-up were the same...it's variable. Oh well.

 

I believe your are thinking 05+

 

Yea I might be, then if its dropping that far, agree, possibly need a new alt.