ok so the oil switch/sending unit is basically a sensor? and having had all sorts of oddball sensors in diff vehicles go bad over the years, if this quit working while we were driving would it have caused the pump to quit and therefore the truck to just die? I get the part about how it stops the pump after an accident--so along those lines when the engine unexpectedly quits for mechanical reason, does it also cause the fuel pump to shut down and perhaps not let it restart? how is the switch "reset"? We know the fuel pump initially starts up via the relay we can hear it. but if the oil switch isnt working, or is "off" is that preventing the fuel pump from making the changeover to the other circuit to keep it running?