Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove 4 way connector from the PCB
Disconnect the electrical lead from the spark generator

Measurement:

Measure the resistance between pins 1 and 2 on the 4 way connector to the corresponding pins of the spark generator cable as indicated below.
Expect continuity / zero resistance on both tests.
Also visually inspect the condition of the harness.