B190 Enthusiasts

My water heater quit lighting and I am not getting any power to the switch. Cannot see any bad fuse so wondered where the 12V power comes from.
I can put a hot wire to the switch from another source and the light comes on, igniter clicks but doesn't light. So first I have a power to switch problem then probably a circuit board problem in the heater unit. Any ideas?

Is there anything else that doesn't work? I don't recall my water heater having a separate circuit, but it has been a while.

You don't say what year Airstream 190 you have. This probably varies by year.

In my 1993 Airstream 190, fuse #2 (counting from the left) is a 15-amp fuse supplying power to a blue wire. The circuit powers:
- The fluorescent light over the sink
- The stove hood light
- The stove hood fan
- The water heater

It is a 96. I have 4 fuses and all are good so thought maybe it is wired into a light or some other accessory. Thanks for the replies.