Set Appliance State:
On/Off Switch OFF
Set Multimeter to DC Volts 
Isolate Mains Power to appliance as per TOPs P4
Remove connector (blue wires) from modulating solenoid
DHW temperature selector at maximum
Remove connector (blue wires) from modulating solenoid
DHW temperature selector at maximum
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Appliance On/Off control set to On position.
Reset lockout as necessary.
Allow ignition sequence to commence.
After approximately 10 seconds measure voltage at disconnected connector.
Reset lockout as necessary.
Allow ignition sequence to commence.
After approximately 10 seconds measure voltage at disconnected connector.
Isolate as per TOPs P4
and refit as necessary