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
Remove the speed control electrical connector to pump & make safe
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset boiler if required.
Test 1.
Measure for DC voltage across pin 2 of connector X12 & a suitable earth connection.
Expected voltage approximately 15.0 Vdc.
Test 2.
Turn Hot Water Tap On & repeat test 1.
Expected voltage approximately 1.5 Vdc.