the fuel pump (in the fuel tank) has a little arm with a float on it, as the fuel level rises and lowers so does the float, the pump sends the height of the float to the computer, and the computer measures the height to determine how much fuel is in the tank, then sends the data to the instrument cluster. if the float has gotten stuck the guage will get an incorrect reading. are you saying electric door lock wont work? if so, do you encounter the problem when using the keyless entry button? if its the keyless entry button, check the battery. as for the door ajar light, that could be that there is a pin missing in the instrument panels connector, to the door sensor is jammed, to its just broke. i would take it to a napa, those guys are really good about looking it over for you and i never got charged for taking my vehicle to them. good luck with it man.