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
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