Set Appliance State:

Mains Power Off
Gas Off
Set Multimeter to DC Volts Set meter to measure DC Volts
Turn Hot Water Tap On
Mode Selector Switch to DHW position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Once Pump has started measure approx 22V DC across connector M5 connection 20 (Blue/Black) (+ve) and connector M4 connection 17 (White/Brown) (-ve).