Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to DC Volts Set meter to measure DC Volts
Gain access to PCB (use Insulation Mat as required)
Ensure No demand is present
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Cancel boiler purge / self-check (reset) if required.
Test 1. Wait ten seconds then measure for DC voltage across pins 1 to 6 of connector X15 and a suitable earth connection.
Expected voltage approx 12 Vdc present on all pins, if voltages are not as expected then choose that option from below.
Test 2. Power off the boiler, wait 10 seconds then reinstate the power, during initial 5 seconds of self-test, measure for dc voltage across pin 3 of connector X15 & a suitable earth connection.
Voltage should fluctuate during the initial 5 seconds then return to approx 12 Vdc, (Note. Repeat as required until test complete).
Test 3. Repeat test 2 for pins 4, 5 & 6.