Stanton, electrical relay issue!

New problem arose this morning- the relay shown in the photo which is located under the o/s bed on the opposite side of the wall to the Truma (Trauma?) heater keeps cycling: click, click...pause  click, click...pause, so it seems to me that it is making and breaking twice then pausing.
Firstly can anyone tell me what this relay does (I'm guessing something to do with the Truma) and secondly why it should be cycling- the Truma control is switched off btw.

Now it could be that I've inadvertently switched something on somewhere but if so, I can't find it.

I've switched off the ECU and back on; is there some other way of re-booting all the electrical systems? 

I wish that there was a proper technical manual for these vans

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There's no photo Pete.

meanchris wrote:There's no photo Pete.

Well spotted! I was just checking who was paying attention.

Clearly not me.

Pull the relay out and see what stops working?

Spoke to Mark- he knew exactly what it was even before I told him where the relay was!!! He asked if the water tank was full- which it is and he said it's the float switch in the tank which is making the relay operate as I was moving about in the van!

Doh!

That's impressive, top diagnose. 

I don't think I've ever filled the water tank right up- it only happened this time because a delivery arrived and I left the hose running! Normally we just carry enough water to enable us to wash hands or dishes en route.
I see no merit in toting water to Scotland.