Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect the 4 way connector ( X36) from the PCB
Also disconnect the lead from the gas valve
Also disconnect the lead from the gas valve
Measurement:
Check the harness leads for continuity.
Measure across the exposed ends of the disconnected harness to the other end and check all the leads individually
Check the general lead condition.
Measure across the exposed ends of the disconnected harness to the other end and check all the leads individually
Check the general lead condition.
Isolate as per TOPs P4
and refit as necessary