pulsacoil 2000 operating info/sensor info

Does the store need to be up to temperature before the pump will run during hot water demand? Was called out to one today with a new Tennant who was unfamiliar with how to work it re. Off peak etc. And found everything switched off. The header tank was empty however. Refilled it and set it away. Both immersions operate fine but had to leave before it was anywhere near temp. 2 flashes a second indicate sensors are OK but is there anyway to test? What resistances should I be looking for? Thanks for any replies in advance!

After filling and switching on the supply.
The pump should run.
Did you vent the pump?
Did you check for voltage at the pump?
No by all accounts you can not test the sensors.
Mike