Fuel Gauge

The fuel gauge is an analog device that is located in the IPC. The IPC software operates the fuel gauge by the use of Class 2 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. The pointer may rest in any position when the ignition switch is in one of the following positions:
^ OFF
^ LOCK
^ START
^ ACC

The VCM/PCM measures the current from a variable resistor inside of the fuel tank. The variable resistor is controlled by a float. When the fuel tank is full and the ignition switch is in the RUN position, the resistance signal to the VCM/PCM is high. The VCM/PCM interprets this signal and sends a message to the IPC. The new message indicates 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, the resistance is low. The VCM/PCM interprets this signal and sends a Class 2 message to the IPC. The fuel gauge indicator then moves to the minimum position, or EMPTY, on the gauge face. Corroded connections or severed ground paths generally cause the indicator to register past FULL on the gauge face. Short circuits to ground cause the indicator to rest below EMPTY. The fuel gauge sender assembly mounts to the top of the fuel tank and is retained by a cam-type locking ring. A seal is used between the fuel tank and the sender.

The fuel gauge sender assembly consists of the following components:
^ A float attached to a variable resistance sender
^ A woven plastic filter on the fuel pickup tube
^ A vane-type electric fuel pump

The fuel gauge sender has 2 or 3 hose connections. One hose is used for the fuel feed hose. The second hose connects to the vapor canister. The third hose is used for the fuel return line to the fuel tank. Some fuel tank senders use a short connector lead. Others have the connector attach directly to the sender.