Both tanks have to have the valves open to do the switch over. When the lead tank goes empty the controller will show the lead tank as empty (Red) but the reserve tank is providing the fuel and will not show green until the controller is manually turned to the reserve tank.
We didn't have the reserve tank open and when the lead tank went empty the controller was not furnishing fuel when we did open the reserve tank, even tho it showed green.
Turned out that the controller has a hidden set screw that needs to be turned fully clockwise to function again.
Also, when opening the tanks go really slow initially and listen for a click that indicates the tank is furnishing fuel - no click no fuel even tho the valve is fully opened.
After the click the valve can be opened normally.
Lucky for us we were in an RV park that filled tanks and when I got the filled tank back I told the guy the second tank or the controller would not work and he came to our site and got us educated.
Most auto switchover valves have a local indicator on the regulator itself that lets you know that it has switched. I've never seen one with a remote signal that would let you know inside the RV that it has switched, as nice as that would be.
Salem 29RKSS Pushing a GMC Sierra 2500HD!
Gotta go campin!
I have the tank check lpg tank monitor. They go on the bottom of the tank and is bluetooth to your smartphone. It tells you the % of gas in tank and you can set notifications on your phone that it alerts you when it hit whatever % you want it to. I have two on my 5er one one my grill and outside patio heater. I love them.
Brian & Terri
Samson (Chocolate Pom)
2017 CC Champagne 38EL
2006 Salem Sport 32 SRV Toy Hauler (still have)