Sponsored Links (Register now to hide all advertisements)
If the amp meter pegs as soon as you connect the headlight and horn wires, you may have a short in either or both of those two circuits. You might also have a screw that's too long for the cutout output terminal and shorting out inside the cutout. I assume you have the insulating washers in place on both sides of the cutout. The thinner insulator goes on the side that connects to the generator terminal.
What happens when you touch the headlight/horn and generator wires together, but not connected to the cutout?