[tdangle]

Originally Posted by gmc684x4

Removing the wire from the sender will not make the guage start reading cold as the circuit is incomplete and will need to read 300 plus ohms to drop its reading
That it re pined reading after you zeroed out tells me that 20Dg wire is shorted to ground somewhere

I believe you are wrong here. I have removed the wire to the sending unit and it reads dead cold. The meter works with +12v from the ignition to the gauge and the other side of the gauge goes to the sending unit. As resistance lowers it reads higher. Basically it is a simple volt meter calibrated to show temperature.