jwc1949gmc,
With electric temperature gauges, it's important to have the gauge itself properly grounded in the dash assembly. The case must be paint free and bonded to a ground, or maybe there is a separate grounding screw provided. The same holds true for the fuel gauge.
A temperature sending unit would be rated for resistance (Ohms), but not for voltage. It would be assumed that to work properly, the sending unit would be installed in a system that had the proper supply voltage the gauge was designed for.
Sending unit ratings for the fuel system were 30 ohms for the AD rigs and 90 ohms for modern systems....I don't know if this is applicable to temperature sending units or not.
Stuart
