•  The fuel-filler switch consists of a reed contact on which a magnet located in the fuel-filler lid activates.

•  The fuel-filler switch is installed in the tank filler neck panel trim and the actuating magnet is located in a bracket on the Fuel-filler lid.

•  The fuel-filler switch is a reed contact and signals the fuel additive control module that the fuel tank is being filled.

•  When the fuel-filler lid is closed, the fuel-filler switch is open.

•  When the fuel-filler lid is opened, this causes the fuel-filler switch to close and a signal is then sent to the fuel additive control module indicating that the fuel tank is being filled.

•  The fuel additive control module then goes into "sleep" mode until the fuel-filler lid is closed again and, "sleep" mode is cancelled by the fuel-filler switch.

•  The next time the ignition switch is turned to the ON position, the current fuel level is determined and compared with the fuel level before the tank was filled; the difference between the two measurements is calculated.