Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
Boiler mains switch ON
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the voltage across the red and yellow leads at the diverter valve connector. Access to connector is best from underneath the boiler.
Actuator is shown disconnected for illustration purposes only.

Mains voltage should be present.
Note:
Grey lead fitted but not used on this version.