Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove the 12 pin connector from the ignition control box
Remove connector J2 from the PCB

Measurement:

Measure the resistance of the following wires:
Pin 4 on ignition control box connector to pin 8 on connector J2.
Pin 10 on ignition control box connector to pin 2 on connector J2.
Pin 11 on ignition control box connector to pin 7 on connector J2.
Expect continuity/zero resistance on each test.
Also visually inspect the condition of the harness.
Are the resistances measured as expected
and is the harness in good condition?