Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect gas valve plug from PCB (rightmost plug)
Measurement:
Test 1:
Measure the resistance across the black wire to
the blue wire next to it at the disconnected plug.
(if plug only has 1 blue wire next to the brown then use this.)
Resistance should be approximately 1.5kΩ.
Test 2:
Measure the resistance at black wire at the
disconnected plug to a suitable earth point.
Resistance should be greater than 1MΩ (or O.L).
Note:
Two types of gas valve lead may be fitted, refer to
the image that corresponds to what it is fitted on
the appliance you are working on.
Measure the resistance across the black wire to
the blue wire next to it at the disconnected plug.
(if plug only has 1 blue wire next to the brown then use this.)
Resistance should be approximately 1.5kΩ.
Test 2:
Measure the resistance at black wire at the
disconnected plug to a suitable earth point.
Resistance should be greater than 1MΩ (or O.L).
Note:
Two types of gas valve lead may be fitted, refer to
the image that corresponds to what it is fitted on
the appliance you are working on.
Isolate as per TOPs P4
and refit as necessary