may need to check all your power & ground wires, check this video out may help also...So I have a 2007 5.9 Mega cab with the 5.9 auto & 230k. Bone stock it’s whole life.
Anyways, I just bought the truck and noticed it was slow starting in the mornings. I replaced both batteries and it started normal. Soon after I noticed that the first start in the AM, the truck cranks over a few times then completely cuts out (like you let the key go) and stops, then begains cranking over again. It’s had the p2509 code since this started. I then went out of town for 3 days and came home to a dead truck. Had to jump it before it would start again. The volt meter in the truck shows well over 14 volts when running.
Please any help will be appreciated. I have run out of options.