Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect main solenoid wires
(purple and brown connectors) from the gas valve
Disconnect connector ST16 from the PCB
(purple and brown connectors) from the gas valve
Disconnect connector ST16 from the PCB
Measurement:
Check resistance across pins 7 & 8 (brown wires)
and 9 & 10 (violet wires) on ST16 to the
corresponding connector for the gas valve.
Expect continuity (zero resistance)
on each of the 4 wires.
Also inspect the general condition
of the harness and connectors / plugs.
and 9 & 10 (violet wires) on ST16 to the
corresponding connector for the gas valve.
Expect continuity (zero resistance)
on each of the 4 wires.
Also inspect the general condition
of the harness and connectors / plugs.
Isolate as per TOPs P4
and refit as necessary