Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect mains (left hand side) plug from the pump

Measurement:

Measure for continuity (zero resistance) between each of the 3 wires, in turn, running from the pins 3 and 4 of X11 to the pump.
Inspect the harness and connectors for good overall condition.
Note:
The third wire in the pump harness is an earth which terminates at the main earthing strip to the left of the PCB.