Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove clock harness from PCB

Measurement:

Check for continuity (zero resistance) between the ends of each of the 4 wires (red, black, white and green) of the harness.
Check the harness fits securely to the clock, is orientated correctly (green wire at the top) and is in good overall condition.