Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect the middle plug (5 pins) from the ignition PCB

Measurement:

Test 1:
Measure the resistance between pin 4 (blue) and pin 5 (brown) of the disconnected plug.
Resistance should be approximately 40 Ohms.
Test 2:
Measure the resistance between pin 5 (brown) to a suitable earth point.
Resistance should be greater than 1M Ohm.