Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
CH 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 voltage between the black wire 3rd down from the top on the RHS of the connector and a suitable earth.
Expect approx. 5.5V DC.
Test 2:
Measure the voltage between the grey wire 4th down from the top on the RHS of the connector and a suitable earth.
Expect between 7V and 18V DC.
Note:
You may have white and yellow wires instead of grey and black depending on whether you have an older or newer harness, both are the same and interchangeable.
Measure the voltage between the black wire 3rd down from the top on the RHS of the connector and a suitable earth.
Expect approx. 5.5V DC.
Test 2:
Measure the voltage between the grey wire 4th down from the top on the RHS of the connector and a suitable earth.
Expect between 7V and 18V DC.
Note:
You may have white and yellow wires instead of grey and black depending on whether you have an older or newer harness, both are the same and interchangeable.
Isolate as per TOPs P4
and refit as necessary