Set Appliance State:

Mains Power Off
Set Multimeter to AC Volts Set meter to measure AC Volts
Turn Hot Water Tap On
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure voltage at connection 18, marked SL (brown lead) and connection 17, marked N (blue lead) on the lower of the two connector blocks on the right hand side of the PCB.
Note:
This is a variable speed pump, voltage sent to it can vary from 60v AC to 230v AC