Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Hinge down the PCB housing
Remove 8 way connector from pcb
Remove 8 way connector from pcb
Measurement:
Measure resistance between the purple wires and then between the blue wires fitted to the low voltage harness.
Resistance depends on kW selector setting but should conform approximately to the table below.
Resistance depends on kW selector setting but should conform approximately to the table below.
| kW Selector Setting | Purple Wires | Blue Wires |
| 1 (12kW output) | 150kOhms | 6.2kOhms |
| 2 (15kW output) | 13kOhms | 68kOhms |
| 3 (18kW output) | 150KOhms | 68kOhms |
| 4 (24kW output) | 36kOhms | 1.5kOhms |
| 5 (30kW output) | 36kOhms | 16kOhms |
Isolate as per TOPs P4
and refit as necessary