Fuel Gauge

The fuel gauge is an analog device that is located in the instrument cluster. The instrument cluster operates the fuel gauge by the class 2 serial data messages from the VCM/PCM. The fuel gauge indicates the quantity of fuel in the tank when the ignition switch is in the RUN position. When the ignition switch is turned to the OFF, LOCK, START, or ACC position, the pointer may come to rest at any position.

The VCM/PCM measures voltage from a variable resistor inside the fuel tank that is controlled by a float. When the fuel tank is full and the ignition switch is in the RUN position, the resistance is high. The VCM/PCM interprets this signal and sends a message to the instrument cluster indicating the percentage of fuel in the tank over the class 2 serial data line. The fuel gauge indicator then moves to the maximum position or FULL on the gauge face. When the fuel tank is empty, resistance is low. The VCM/PCM interprets this signal and sends a class 2 serial data message to the instrument cluster. The fuel gauge indicator then moves to the minimum position or EMPTY on the gauge face. Failures detected by the PCM/VCM in the fuel gauge signal sends the gauge to EMPTY.