DrewE wrote:
The red light one might be a 120V element in the water heater. It looks like it's probably a 120V switch (rather than a 12V switch). It could be most anything, though.
The little lone one next to the water heater looks more like a 12V switch. I would guess it's either some lights somewhere (maybe in the outside storage compartments) or a water pump switch. Again, it could be most anything.
You might be able to trace wires...though that's not often an easy task.
That's my take- 120 volt water heater, and water pump.