Set Appliance State:

Mains Power Off
Set Multimeter to AC Volts Set meter to measure AC Volts
Turn Hot Water Tap On
Use Insulation Mat as required
Selector switch to hot water
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure voltage across the orange wire and violet wire at J2 (white connector block) on the ignition pcb .