Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect wires from ignition PCB and remove from gas valve

Measurement:

Pins are numbered on the gas valve.
Test 1:
Measure the resistance across pin 10 and 11 of the ignition PCB.
Resistance should be greater than 1M Ohm.
Test 2:
Measure the resistance across pin 10 and 12 of the ignition PCB.
Resistance should be greater than 1M Ohm.