Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove electrical connector from thermal fuse (top of heat exchanger)
Ensure other stats which were tested previously are connected

Measurement:

Measure the resistance (continuity) of the safety thermostat harness leads.
Connections are (see note);
  • CN3 connector pin 57 to the thermal fuse connector.
  • CN3 connector pin 58 to the thermal fuse connector.
    Expected resistance is continuity (zero resistance).
    Note.
    1. Failure to have previously tested thermostats connected
    will result in misdiagnosis.
    2. When testing the harness, only one lead of the harness
    is being tested at a time.