Battery Light issue

[christophermccombs]

Good Morning,

 

I am very new to this forum and I have posted my introduction. I know it is a pain for new guys but I have searched long and hard and have not figured this one out. I recently bought a 2002 GMC Sierra extended cab 4x4 and it is my first GM truck. I have started with the common ailments, i have replaced the exhaust manifold bolts, which BTW are a real pita. Anyway, my question is this: I have run into a problem with the charging system. I have had the alternator checked and it has come back fine. I have checked all the connectors and the cables as best as I can for corrosion. Everything has checked OK. I replaced the battery and new posts. On occasion the battery light comes on and the voltage drops, and if left in this condition the battery drains and dies. However, if I disconnect the battery for a few minutes, the warning light goes away, and the gauge returns to normal and not in the low range. The truck returns to "normal" until after a week or so, the light comes on again and the battery drains. I have not checked it with a multi meter while the light is on yet, but I have when the light is off. It ran close to 14 volts running, and 12 standing. This gremlin is really strange and I was looking to see if anyone else has come across this problem and maybe shed some light.

[christophermccombs]

Update: I had noticed the truck began to run really crappy, and the air conditioning started to stop working while idling. I gave it another multimeter test and discovered it was running at 13. 25 volts at idle, and would dip to 12.89 and down to 12. 56. I put a full load on it and it crept up to 13. 13 volts and would only reach 14 if i revved it above 2500 rpm. So, I decided to throw parts at it and replace the alternator. So far it is running 14.35 at idle and 14.25 at full load. So I suppose it was the alternator after all. I was a little disappointed no one offered any advice, Oh well thanks anyway.

[Duelin]

I am sure someone would have came in and suggested the alternator. But in your post you mentioned that you had the alternator checked and it was fine. So in most cases when information like that is given it is ignored. Because the alternator was checked out. Anyway good luck with your new ride.