Set Appliance State:
On/Off Switch OFF
Set Multimeter to AC Volts 
DHW Demand - Ensure Store is not up to Temperature
Isolate Mains Power to appliance as per TOPs P4
Gain access to PCB as necessary
Gain access to PCB as necessary
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Appliance On/Off switch On.
Reset lock out if necessary.
Measure voltage across connection 1 (brown lead) and connection 2 (blue lead) on connector J8 on the control PCB.
Reset lock out if necessary.
Measure voltage across connection 1 (brown lead) and connection 2 (blue lead) on connector J8 on the control PCB.
Isolate as per TOPs P4
and refit as necessary