Cool! That's good to know, Redfish. I didn't know what that value is (20 ohms). That will also tell if the gauge unit is open, which I would imagine is what usually is the problem, other than the sending units. Thanks
20 ohms is a good sign but lots of different conditions are possible.
The wire insulation in a gauge will get crunchy with carbon buildup then crack. A tiny speck falls off allowing the winding to short to the bimetal.
In this case one gauge post will have some portion of 20 ohms resistance to the gauge can. The other post would have the balance of 20 ohms resistance to the gauge can.