Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect the modulation solenoid connector from the gas valve
Measurement:
Measure the resistance across the terminals
of the modulating solenoid of the gas valve.
Expected resistance:
S.I.T. Valve (blue modureg) approximately 80 Ohms.
Honeywell Valve (white modureg) approximately 48 Ohms.
of the modulating solenoid of the gas valve.
Expected resistance:
S.I.T. Valve (blue modureg) approximately 80 Ohms.
Honeywell Valve (white modureg) approximately 48 Ohms.
Isolate as per TOPs P4
and refit as necessary