Set Appliance State:
Set Multimeter to AC Volts 
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Boiler Operating Switch / Programmer set to WATER only
Gain access to PCB (use insulation mat as necessary)
Boiler Operating Switch / Programmer set to WATER only
Gain access to PCB (use insulation mat as necessary)
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Allow the fan to operate and the ignition sequence to begin.
Measure the voltage across connection PN (Blue wire) and connection PL (Brown wire) on connector CN4 on the sequence control PCB.
Note:
On some models sequence control PCB may have only numbered connections in which case connections 8 and 9 are used for test.
Measure the voltage across connection PN (Blue wire) and connection PL (Brown wire) on connector CN4 on the sequence control PCB.
Note:
On some models sequence control PCB may have only numbered connections in which case connections 8 and 9 are used for test.
Isolate as per TOPs P4
and refit as necessary