No heat - element measures 31 ohms is that correct ?

31 ohms is probably a good value for an element rated at about 500W. Dishwasher washing cycles use the heating element to keep the water hot during a specific cycle but not necessarily all cycles. Probably you have to select the cycle that deposits the soap. There is also likely a temperature switch in series with the 120 volts that is applied to the element during the cycle. Other cycles may not use the heating element. Be careful about where you put your fingers.