Gen2 light stays on, yellow voltage?

[realm]

After I crank up my 09 the Gen2 light stays on for a while, and the voltmeter is in the yellow.
After I drive for about 5 or 10 minutes I'm back in the green and the Gen2 light goes off.

Looking under the hood, my rear battery I think it is looks like it's from '04, but the front battery is considerably older.

Which is Gen1 and which is Gen2, and are these signs I need a new battery or the alts are going out?

Thank you.

 

[doghead]

Gen 1 is on the DS, gen 2 is on the passenger side. Gen1-front battery, gen2- rear battery.

Best to test each component separately. Dig into the TM's, there are easy to follow diagnostic tests, there. The TM's are listed in the WIKI, at the top of the CUCV forum page.

 

[timntrucks]

that is good to know.

 

[BobM]

The Gen 2 light is kinda funny sometimes. As long as it goes off in a few minutes and the voltmeter goes green you are probably alright. But I would clean all the connections as thouroughly as possible. I had problems with my Gen 1 light and it turned out to be the connection I had cleaned twice already!
Remember how long these trucks and their components have been around. A little corrosion can drive ya almost crazy!