The other thing you might want to check is make sure the big wire on the alternater has power. does not matter if the key is on or off. If it does not have power, follow the wire back and you should find the problem. By looking at the wireing diagram, it shows it going to a fuse link. They are the small wires that are conected to the main battery wire on the starter. Make sure they are all conected. If you find one burnt in half, that is your problem. To fix it right, you need to get fuse link wire. Fuse link saves your truck from a major melt down.
