[MiraclePieCo]

Sounds like you have the gauge lights connected to the wrong side of your headlight switch. Your gauge lights (yellow wire) need to be connected to a switched 12v source - IOW the output side of your headlight switch. I think American Autowire uses standard GM color coding, so the gauge lights (yellow) should connect to the brown wire out of the headlight switch (may be labeled something like Dash Lights, Park, Tail, etc). Use a test light to confirm.