Functional Description - Fuel Level Sensors

The Primary Fuel Level Sensor Pulsed Signal  is hard-wired to the Body Control Module (BCM). The primary Fuel Level Sensor signal is a pulsed 12.0 volt signal.

On a normally functioning system,  the raw signal voltage will pulse between approximately 0.5 volts (full stop) and 4.5 volts (empty stop) with the harness connector plugged in. When there is an open in the circuitry the signal circuit voltage will pulse between 12.0 volts and 0 volts.

The data reading value on the scan tool will display an open circuit as 5.0 volts.  The BCM reads each voltage spike and converts the analog signal to a digital signal. The digital signal is broadcast over the CAN bus. The Powertrain Control Module (PCM) receives and interprets the digital signal as a voltage read. The PCM, and in most cases the BCM, perform circuit fault diagnostics on the signal input.

On vehicles equipped with saddle tanks or dual tanks the Secondary Fuel Level Sensor Pulsed Signal  is hard-wired to the Body Control Module (BCM). The secondary Fuel Level Sensor signal is a pulsed 5.0 volt signal.

On a normally functioning system,  the raw signal voltage will pulse between approximately 0.5 volts (full stop) and 4.5 volts (empty stop). When there is an open in the circuitry the signal circuit voltage will pulse between 5.0 volts and 0 volts. The BCM reads each voltage spike and converts the analog signal to a digital signal. The digital signal is broadcast over the CAN bus. The Powertrain Control Module (PCM) receives and interprets the digital signal as a voltage read. The PCM, and in most cases the BCM, perform circuit fault diagnostics on the signal input.

The Fuel Level Rationality diagnostics are only performed by the PCM.  The Fuel Level rationality diagnostics are explained in more detail in the Fuel Level Rationality diagnostic information below.