1. The power wire goes to the terminal on the cold side of gauge. The sender wire goes to the terminal on the hot side of the gauge.
2. Gauge is self grounded to the cluster case. I think there is a "slug" on a ground plate at rear of gauge that touches the can and ground is carried thru to the dash/body/motor/frame/battery connections.
3. Most of the time your problem is loss of ground or a bad sender. The gauge being the most reliable component unless you blasted it.
4. When you do the testing per my first post, report what you find.
5. There was no fuse for the temp gauge. Powered directly from ignition switch.
6. If I were you, I would stop applying power to components unless you know what you are doing.


Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn