Power to Fridge and Charger from Tow Car Problem

A Couple of weeks ago we went away and I noticed that the Blue Power Light on the fridge was flashing, then constant, then flashing etc...
The error on the display shows (Spanner) 10 which looking into informs me to check power from the Towing Vehicle.

I have checked in the car and I can hear the relay in the back switching off and on in time to the fridge light problem.

Where might the problem be. To be honest I have not checked if the relay still does the same when the van is not connected (I'll do this tonight) but will the Relay even do anything when a van is not connected?

Any ideas or things I should check.

I know when I first had the Towbar and Socket fitted, the engine note changed when the van was connected which I gather is the current draw on the alternator but it no longer does this either.

Is there a switch or reset I need to check on the Van power panel or anything like that?
I have a 2010 Lunar Conquest (Quasar derivitive)

Any advice would be great before I resort to the Bar fitters (Cant find the receipt )

Thanks

Andi