LP gas detector

[roncan1842@...]

PRE-TELL 2 detector seems to have died, my question is just how this device works, I assumed that the voltage passed thru the control to open the valve on the propane tank then should it sense gas the voltage would be interrupted closing the valve on the tank, however when I disconnected the wires to the detector the valve on the propane tank stays open whether the wires to thedetector are connectedor not,what closes the valve on the tank. Before I acquire a replacement detector Iwant to know how the system works. When I reset the detector it goes thru it's chirping cycle however when the reset is turned the green light indicator flashes once then blank no gas, I have checked the detector outside of the coach with the same results.

Any help would be appreciated

Ron & Nita Roberts

1995WBPT40