Replaced battery connections thinking it was a bad ground. Checked all ground wires under hood, and they are good. Put a higher ampere fuse in and still blew. Then I put a 30 ampere fuse in and the brake lights dimmed, and shut truck off. Then it wouldn't start back up. Put a 15 ampere fuse back in, which is what it is supposed to be and it fired right up. Now it blows 15 ampere fuse every time.