Re Triton 300si?

You can't test that amount of power with a multimeter,is your multimeter an analogue type or digital, if digital the resistance can be checked,if analogue a circuit will have to do.
on top of the heater tank are 4 connections 2 are bonded together just test the left 2 with meter on ohms setting to see if there's a circuit, at the bottom of tank there is a cut out with 2 blue wires,test for continuity.
the stepper motor is on the right it controls the amount of water flowing through the heat exchanger, the only way you can test it is by turning the temperature dial up and down to see if the water flow changes.
log onto www.showerspares .com then spares and locate your shower this will show a blown up view of your shower

toptrish
January 2014