Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Remove the 20 way connector from the PCB
Measurement:
Test 1:
Measure the resistance between the two black wires terminal 3 and 4 counting from left to right.
Then measure between the two black wires at terminal 5 and 6 counting from left to right.
Expect approximately 177 ohms on one pair of black wires and 400 ohms on the other pair.
Test2:
Measure the resistance between each of the black wires 3,4,5 and 6 to earth.
Expect open circuit on each test
Note:
The colours of the wires may vary but the terminal locations will remain the same.
Measure the resistance between the two black wires terminal 3 and 4 counting from left to right.
Then measure between the two black wires at terminal 5 and 6 counting from left to right.
Expect approximately 177 ohms on one pair of black wires and 400 ohms on the other pair.
Test2:
Measure the resistance between each of the black wires 3,4,5 and 6 to earth.
Expect open circuit on each test
Note:
The colours of the wires may vary but the terminal locations will remain the same.
Isolate as per TOPs P4
and refit as necessary