Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect plug from gas valve

Measurement:

Measure the resistance between pins 1 and 4 at the gas valve.
Resistance should be approximately 7.3kΩ
Measure the resistance between pins 1 and 3 at the gas valve.
Resistance should be greater than 1MΩ (Or O.L.)