Fuel Level Sensor: Description and Operation

FUEL LEVEL SENSOR




The fuel tank level sensor is part of the fuel tank sender assembly inside the fuel tank. This sensor varies resistance according to changes in the level of fuel in the fuel tank. The PCM supplies ignition voltage reference to the sensor, which is connected to ground. A resistor circuit in the PCM slightly lowers the voltage supplied to the sensor to approximately 0.2 volts less than ignition voltage. When the level in the fuel tank is high, the sensor resistance is low (low voltage on signal line). As the fuel level decreases, the sensor resistance increases (voltage increases on the signal line). The PCM uses the signal voltage to determine fuel tank level. The fuel level sensor is also used to determine fuel level necessary for EVAP diagnostics.

FUEL GAUGE - The PCM sends fuel tank level messages over the Class II link to the BCM. The BCM averages the information over time then sends the averaged fuel level to the I/P cluster over the link. The I/P cluster then positions the fuel gauge.

LOW FUEL TELLTALE - If the fuel level is low, the PCM will send a message to the BCM, which sends a message to the I/P cluster over the Class II link to turn On the Low Fuel telltale. The Low Fuel Telltale will turn On when approximately 1.2 gallons (1.0 - 1.5 gallon range) of usable fuel remains in the tank.