Quote Originally Posted by firebird77clone View Post
very specific query

For my 75 firebird oil pressure guage:

Does the guage receive full voltage, and ground through the pressure switch?
Your wording is very confusing to me. You say "gauge" but then you ask if it grounds "...through the pressure switch"? That sounds to me like an oil pressure indicating light (aka the "Idiot Light"), not a gauge? If it's a gauge you'll have an oil pressure sending unit, not a pressure switch, right?