Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to DC Volts Set meter to measure DC Volts
Selector switch set to Hot Water position
Gain access to PCB, use isolation mat as required
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure for DC volts across ON/OFF switch (test point as illustrated) and a suitable earth connection.
Expected voltage 2.4 - 3.4 VDC.
Note.
Voltage measured does fluctuate slightly.