Fuel Level Sensors
The AJB (auxiliary junction box) sends a separate signal to each of the fuel level sensors. As the float arms of the fuel level sensors move, the resistance across the fuel level sensors changes. Thus the level in the fuel tank determines the value of the signals from the AJB.
From the two signal values the AJB derives a fuel quantity, which it incorporates into a medium speed CAN (controller area network) message for the instrument cluster.
For additional information, refer to: Instrument Cluster
In addition to using the fuel quantity signal itself, the instrument cluster also transmits it on the high speed CAN for the electronic engine controls system. For additional information, refer to: