Set Appliance State:

Mains Power Off
Set Multimeter to AC Voltage Set meter to measure AC Volts
Turn Hot Water Tap On
Boiler On/Off Switch ON
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the Diverter Valve Voltage across PCB connector PL5 connection 1 (Live, Brown) and connection 4 (Neutral, Blue).