Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Remove connector CN4 from the main PCB
Measurement:
Test 1:
Measure the resistance between pin 1 (Black) and pin 2 (Blue)
Expect approximately 8.5 KOhm if the valve is in DHW position
and open circuit if in CH position.
Test 2:
Measure the resistance between pin 2 (Blue) and pin 3 (Brown)
Expect approximately 8.5 KOhm if the valve is in CH position
and open circuit if in DHW position.
Test 3:
Measure the resistance between each of the wires
on the connector and earth.
Expect open circuit on each test.
Note: If the valve is half way between the positions expect 8.5 KOhm on tests 1 and 2
Measure the resistance between pin 1 (Black) and pin 2 (Blue)
Expect approximately 8.5 KOhm if the valve is in DHW position
and open circuit if in CH position.
Test 2:
Measure the resistance between pin 2 (Blue) and pin 3 (Brown)
Expect approximately 8.5 KOhm if the valve is in CH position
and open circuit if in DHW position.
Test 3:
Measure the resistance between each of the wires
on the connector and earth.
Expect open circuit on each test.
Note: If the valve is half way between the positions expect 8.5 KOhm on tests 1 and 2
Isolate as per TOPs P4
and refit as necessary