How to hook up elecrical guages

I would like to install some new guages in my cuda, that are under the dash, a electrical(not mechanical) oil, temp, and amp i already know how to hook up the am guage so no problem there, but how do i hook up the other 2. As of now my stock oil pressure guage doesnt work, i tried grounding it out(if that is the way to check it) and got nothing. i also did this with the stock temp guage, i got nothing.

How do hook these guages up, id like to run new wires, may reuse the old ones if they are good, where should i start besides getting the guages :silent: