Temperature & Oil Pressure Gauges

Disconnect lead from sending unit. Connect one lead of a variable resistor to sending unit wire, and the other to ground. A fuel tank sender may be substituted for the resistor.
With 80 ohms resistance, pressure or temperature should read low. With 23 ohms, gauge should read in middle of range. With 10 ohms resistance, gauge should read high and warning indicator should light (if equipped).
If gauge operates properly in testing but not with sending unit, replace sender. If gauge does not operate properly with resistor, check sender wire for shorts. If wire is good, replace gauge.