Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to DC Volts Set meter to measure DC Volts
Turn Hot Water Tap ON
DHW Temperature Control to MAX
Set flow rate to approx. 3 litres per minute
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure voltage across the yellow and red contacts of the flow turbine inline connector.
Voltages should be measured as in the range below.
Connections
Volts DC
Yellow & Red
2.0-3.0

Note:
Ensure good connections are made whilst carrying out this test.