I have a 2010 3500 diesel and my charging system light came on the other day. It would come on and go off intermittently. I had the batteries tested and alternator replaced. Once I replaced the alternator the light went off and voltage read 14. The next morning the light came on and stayed on with voltage reading around 11-12. After driving a little while the volts go up to normal but the light will come on intermittently again. What else could be wrong? Everything is stock on the truck except it's lifted with 38's. 75k mileage