Set Appliance State:

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

Measurement:

Check for continuity (zero resistance) between the L at the spark generator plug (see picture) and pin 5 at connector X2 at the PCB.
Check for continuity (zero resistance) between the N at the spark generator plug (see picture) and pin 2 at connector X2 at the PCB.
Inspect the harness for good overall condition.