Testing Hot Tub and Spa Sensors
How to Test Spa Sensors for Continuity
With your electrical test meter set to 100k ohms, test the green and black wires for continuity.
Depending on the temperature it will give you a value. It is based on a 10k ohm resister. At 77 degrees it will read 10k ohms. As the temperature rises it will have a lower resistance and as the temperature lowers it will have a higher resistance.
Generally, all of the spa sensors will read 10-12k at 70 to 80F for resistance. If your readings are much less, this can indicate a break in the "Continuous" circuit, power not flowing through properly.