Set Appliance State:
Mains Power Off
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Remove control box cover
Disconnect plug marked M11
Disconnect plug marked M11
Measurement:
Test 1: With CH temperature selector set to maximum, measure the resistance across the red wire (connection D), and the black wire (connection F).
Resistance measured should be approximately 10 kOhms.
Turn CH temperature selector to minimum.
Resistance should reduce to less than 100 Ohms.
Test 2: With CH temperature selector set at minimum, measure the resistance across the white wire (connection E), and the black wire (connection F).
Resistance measured should be approximately 10 kOhms.
Turn DHW temperature selector to maximum.
Resistance should reduce to less than 100 Ohms.
Replace connector after test.
Resistance measured should be approximately 10 kOhms.
Turn CH temperature selector to minimum.
Resistance should reduce to less than 100 Ohms.
Test 2: With CH temperature selector set at minimum, measure the resistance across the white wire (connection E), and the black wire (connection F).
Resistance measured should be approximately 10 kOhms.
Turn DHW temperature selector to maximum.
Resistance should reduce to less than 100 Ohms.
Replace connector after test.
Isolate as per TOPs P4
and refit as necessary