Does anyone happen to know how I might test these circuits to help find where the problems lies. I found some information on doing this with the fuel sender, and I was able to get that straight.

Would I ground these wires out? What am I looking for on the gauge when I ground it?

Thanks! Oh, it's an '85.

Try here for the temp gauge - http://www.6066gmcguy.org/Electrical-02.htm

Try using Forum "Search" for the pressure gauge.