Help with autometer wiring?

You have a shop manual / wiring diagram?

A good plan for testing circuits before you "turn things loose" is to get a BIG wattage "test lamp." There are several ways to "rig" this. One way is to use an old headlamp, another is to use an old stop / tail lamp socket with both wires twisted together to make both filaments work as one

Hook your "big test lamp" IN SERIES to the battery ground. That is, ground the stoplamp socket to the body, and hook the two twisted leads to the battery NEG terminal

Or hook the headlight to body ground, the other terminal to battery NEG terminal.

This makes a SERIES lamp so that ANY current going through the battery is limited by the lamp. This means you cannot run the starter, and if you turn on something like the headlamps, they may not light or may light as a low glow. But on "lighter" loads it gives you a safety in case you have something shorted that would otherwise cause a big cloud of illegal smoke

This of course triggers a full on EPA superfund cleanup