Is the fuel heater self contained? Does it have a sensor to shut it off if it gets too hot so as not to go boom? or does it stay at a low enough temperature to not burn anything anyways? It's never worked since I got the truck, but I've never tried to start it in the winter either,,,so. I know the intake heater grids are controlled by the ECM,,,but I only saw two wires on the pigtail to it, so I'm wondering if I can just wire it up with a switch on the dash? But I really don't want to burn down my truck lol . Thanks guys.