Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector CN1 from the programmer PCB

Measurement:

Measure the resistance (continuity) across each wire of the programmer harness (blue wires) which run between CN5 (PCB), CN1 (programmer PCB) & M2 terminal strip.

Note.
The colour of the wiring harness may change but test remains the same.