Bench testing rally gauges

Steve.
I think what Redfish and Dana are saying is that the oil and temperture gage can be tested by connecting to a low voltage supply - 3 volts would be fine.
But the Fuel gage can't be tested that way. The stud connects to the IVR first, and if that doesn't see something close to 12 volts the fuel gage probably won't get anything from the IVR.