Abstract: The present invention provides improved auxiliary fuel tank control systems and methods that avoid the need for locating, identifying, and tapping into a wire leading from the sending unit of the vehicle's primary fuel tank by connecting directly to a diagnostic port of the vehicle which is in communication with the output from the sending unit. Based on information received from the sending unit, embodiments of the invention may automatically cause fuel to be pumped from an auxiliary tank to the primary tank when the amount of fuel in the primary tank drops below a threshold.

Abstract: The present invention provides improved auxiliary fuel tank control systems and methods that avoid the need for locating, identifying, and tapping into a wire leading from the sending unit of the vehicle's primary fuel tank by connecting directly to a diagnostic port of the vehicle which is in communication with the output from the sending unit. Based on information received from the sending unit, embodiments of the invention may automatically cause fuel to be pumped from an auxiliary tank to the primary tank when the amount of fuel in the primary tank drops below a threshold.