Originally Posted by cbouch
Guess I wasn’t clear...lower helm always worked....upper helm did not....ran another wire from sending unit directly to upper helm and now both work. New wire is not shown in the picture.
I think what High Wire may have been trying to communicate is that, because of the way the circuit works, there is a different sender with a different resistance range for single gauge systems than there is for two Guage (e.g., upper and lower) systems.
As a result, if one of your gauges was disconnected by a bad wire or connection, the other gauge would have been the only one in a circuit with a dual gauge sender, so the resistance range of the sender would be wrong for the gauge, and the gauge would not read the correct temperature, even if it did start out cold and increase as the engine warmed up.