Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
Turn Hot Water Tap On
Gain access to PCB (use Insulation Mat as required)
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the voltage between pin 2 (brown) and pin 3 (blue) on connector J2 at the control PCB.
Mains voltage should be measured.
Note:
Up to 140V AC may be present without a demand.
Only pass this test if full mains voltage is present.