[MikeS100]

I never considered phoning Whale, that's good to know, thanks.

Got it working again for now, I think the 1.5 volts on the terminals at the back of the housing was a bit of a red herring. It seems the terminals in the housing had been pushed out of place by the pump connector as I plugged it in. I had to plug the pump in first and then push the connectors in the housing back on from the back of the housing. Once the connection was secure I screwed the housing back on to the caravan. I Need to figure out why the connectors in the housing are moving but at least it's working for now. Not sure why I was only getting 1.5 volts on the terminals yesterday but I'm not going to worry about that too much.