Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect connector J3 from the ignition PCB

Observation:

Test 1:
Measure the resistance between the brown and blue wires on J3.
Resistance should be approximately 1.56kOhms.
Test 2:
Measure the resistance between the black and blue wires on J3.
Resistance should be approximately 6.32kOhms
Test 3:
Measure the resistance between the brown wire on J3 to a suitable earth point.
Resistance should be greater than 1M Ohm