Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove the ignition lead from the spark generator

Measurement:

Measure the resistance between the end of the ignition lead and the earth at the incoming mains supply (X11).
Expect a resistance greater than 1Mohm.
Is the resistance as expected?
Note:
The ignition lead may differ in appearance but the test is
carried out in the same way.