I am intending to use a VW "ball type" expansion tank in my build and I thought it might be a nice touch to include an "idiot" light for low water on the dash.
My problem is that I cannot get the level switch on the tank to do anything. Ive had a meter on it and it seems to be open circuit no mater what I do. ie. fill it with water....still open.....turn it upside down....still open.
Can I assume the switch is f***ed or am I missing something?
Is it in fact a switch?
Any info geratfully recieved.

maybe the swich is only working when you use coolant stuff and not water?

maybe its an brake contact switch

in stead of an normal open switch?

make pics!