Hi Everyone,

I have read through tons of threads and replys and havent come across an issue quite like mine. Lately when I start my truck, it has been displaying "Battery Not Charging" in the DIC, the battery light is on and Voltage on the dash is whatever the batteries are holding. I knew my batteries were needing replacing, so I put 2 new ones in. Same thing... "Battery Not Charging" the the battery light and low Volts. I would just go out and get a new alternator, but here is the wierd part. If I get on it getting on the freeway or from a stoplight and can keep it above 2500 RPM for more than about 7-10 seconds. The message goes away, the light goes out and the Volts go back up to 14. Everything is fine until I shut it down. Another strange part about it is, occasionally it will be fine when I start it, but that is rare. Thanks for any help in advance! Anyone think its really the Alternator?

Sounds like the alternator or a poor wire connection. If the alternator starts working once the unit heats up, it could be weak worn brushes or loose connection inside. I think the field connection goes right to your pcm on your truck and it seems to be relaying the correct info to the dic. So if its not your pcm theres not much left besides wire connection and alternator. remove and check your connector at your alternator for bad or corroded contacts and the main terminal or the back of your alternator. If you can get your hands on a wiring diagram you can confirm where your alternator connection go for your specific truck. Good luck.

did you check the terminals under the rubber boots on the battery positive cables, I also was just advised by another member [LtEng5] that there could be corrosion inside the battery cables themselves that you cannot see. When I went to the dealership to get some parts I asked them also and they said the same thing , maybe the battery cables are corroded inside, even though the terminals are clean. just my thoughts again charlie

sounds like the voltage regulator to me...(of course the PCM diag feature on these truck could be leading me astray) once you get the alternator to put out enough to get the regulator excited it starts working. you can probably just rev the motor in park and get it to work.... it could be a combo of things going on inside that puppy, brushes, stator, Etc. depending on your mileage

If Im not mistaken it is an internal regulator on our trucks....
In years past I have replaced just to voltage regulator in various alternators.... solves the problem.... depending on your mileage and how much your wanting to spend it would probably be better to just swap it out... since it can be a bit of a PITA to crack open the alt and change that sucker out....( not sure how hard it is on these specific units) and if you go through all of that you will have an alternator with however many miles you have on the truck.
just stay away from kragen, pep boys, etc.(what I call "plastic parts" store) reman stuff it usually just craps out in 6 months and your back working on it again!

Have the alternator bench tested. The PCM controls the field excitement and loose wires or battery cables, a failing ignition switch, and a host of other things can be going wrong (rub through of the under hood harness or mice eating the wires under the fuse panel come to mind). Bench testing is usually free at most alternator shops (I don't trust just any auto parts counter monkey).