The red and white wire may run to an electric solenoid shut off in your propane line. That was the case with my 2005 Isata, I purchased a kit on line ( can't remember where ) that provided a new gas detector and the replacement shut off valve. Don't purchase the 2 wire detector alarm it has no way to tell the shut off solenoid valve in your propane line to open up, that is what the 3rd wire is for, at least that is how my unit worked. Not a big job, the new parts are a direct fit, Google it, you should be able to find what you need.
2010 Phoenix Cruiser 3100, 2016 Hyundai Veloster, Demco SS dolly