[Mercman53]

Thank you for all your fast replies. Here are the answers to your suggestions:
1. Yes I connected the battery correctly with the starter cable going to the Negative post and the Positive post cable going to ground.

2. I did disconnect the horn and light wires from the cutout and left only the ammeter yellow wire and poof the fuse still blew.

3. the Diagram shared with me here is what I used as well. But thank you for posting it for me.

Anything else I can do? Or could it just be a bad ammeter?

Thanks again.