Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect the thermostat multiplug from the PCB
Observation:
Test 1: With Thermostat turned Off measure the Resistance between the Yellow/Black and the Yellow/Red wires on the disconnected multiplug, the resistance should be between 3.0 - 48 ohms approximately.
Turn On the Thermostat and gradually increase the setting (turning clockwise), the resistance should increase with a maximum reading of approximately 1 MOhm when turned to maximum.
Test 2: With the Thermostat turned to maximum measure the Resistance between the Yellow/Black and the Red/Blue wires on the multiplug, this reading should be between 3.0 - 48 ohms approximately and will increase to approximately 1 MOhm when the thermostat setting is decreased (turning anticlockwise) to its Off position.
Reconnect the multiplug after the test is completed.
Turn On the Thermostat and gradually increase the setting (turning clockwise), the resistance should increase with a maximum reading of approximately 1 MOhm when turned to maximum.
Test 2: With the Thermostat turned to maximum measure the Resistance between the Yellow/Black and the Red/Blue wires on the multiplug, this reading should be between 3.0 - 48 ohms approximately and will increase to approximately 1 MOhm when the thermostat setting is decreased (turning anticlockwise) to its Off position.
Reconnect the multiplug after the test is completed.
Isolate as per TOPs P4
and refit as necessary