Theory Of Operation
WARNING: This page is about a different car, the 2013 RAM 3500 HD and 2013 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
The Body Control Module (BCM) provides a switched reference voltage on the fuel level signal circuit through a pull-up resistor that is connected to battery voltage. The BCM monitors the voltage on the fuel level signal circuit. The fuel level signal is adjusted for changes in battery voltage. The voltage value is then transmitted as a network message on the communication network.