Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
DHW Demand
Access the X20 connector on the right hand side of the PCB
Gas On
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Test 1:
Measure the DC voltage between pin 12 at connector X20 on the PCB to a suitable earth point.
Expect approx 5.5V DC.
Test 2:
Measure the DC voltage between pin 13 at connector X20 on the PCB to a suitable earth point.
Expect between 7V and 18V DC.
Note:
Colour of wires may change but test points remain the same.
Measure the DC voltage between pin 12 at connector X20 on the PCB to a suitable earth point.
Expect approx 5.5V DC.
Test 2:
Measure the DC voltage between pin 13 at connector X20 on the PCB to a suitable earth point.
Expect between 7V and 18V DC.
Note:
Colour of wires may change but test points remain the same.
Isolate as per TOPs P4
and refit as necessary