Set Appliance State:

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

Measurement:

Allow fan to start.
Measure voltage between connection 2 (black wire) on X15 on sequence board and neutral X4 on main driver board.